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Sample records for welded austenitic stainless

  1. Solidification cracking in austenitic stainless steel welds

    Indian Academy of Sciences (India)

    Solidification cracking is a significant problem during the welding of austenitic stainless steels, particularly in fully austenitic and stabilized compositions. Hot cracking in stainless steel welds is caused by low-melting eutectics containing impurities such as S, P and alloy elements such as Ti, Nb. The WRC-92 diagram can be ...

  2. Fatigue behavior of welded austenitic stainless steel in different environments

    Directory of Open Access Journals (Sweden)

    D.S. Yawas

    2014-01-01

    Full Text Available The fatigue behavior of welded austenitic stainless steel in 0.5 M hydrochloric acid and wet steam corrosive media has been investigated. The immersion time in the corrosive media was 30 days to simulate the effect on stainless steel structures/equipment in offshore and food processing applications and thereafter annealing heat treatment was carried out on the samples. The findings from the fatigue tests show that seawater specimens have a lower fatigue stress of 0.5 × 10−5 N/mm2 for the heat treated sample and 0.1 × 10−5 N/mm2 for the unheat-treated sample compared to the corresponding hydrochloric acid and steam samples. The post-welding heat treatment was found to increase the mechanical properties of the austenitic stainless steel especially tensile strength but it reduces the transformation and thermal stresses of the samples. These findings were further corroborated by the microstructural examination of the stainless steel specimen.

  3. Friction welding of Al-Cu-SiC composite to AISI 304 austenitic stainless steel

    OpenAIRE

    Özdemir, Niyazi; Balaban, Zülküf

    2017-01-01

    The present study investigates thefeasibility of joining an aluminium matrix composite reinforced with 5, 10 and15 vol. % of SiCp particles to AISI 304 austenitic stainless steel by usingfriction welding technique. In the present study, optical and electronmicroscopy as well as lap shear strength test and microhardness measurementswere used to evaluate the quality of bonding of Al-Cu-SiC and AISI 304austenitic stainless steel joints produced by friction welding

  4. Effect of Electrode Types on the Solidification Cracking Susceptibility of Austenitic Stainless Steel Weld Metal

    OpenAIRE

    J. U. Anaele; O. O. ONYEMAOBI; C. S. Nwobodo; C. C. Ugwuegbu

    2015-01-01

    The effect of electrode types on the solidification cracking susceptibility of austenitic stainless steel weld metal was studied. Manual metal arc welding method was used to produce the joints with the tungsten inert gas welding serving as the control. Metallographic and chemical analyses of the fusion zones of the joints were conducted. Results indicate that weldments produced from E 308-16 (rutile coated), E 308-16(lime-titania coated) electrodes, and TIG welded joints fall within the range...

  5. Stress corrosion cracking behaviour of gas tungsten arc welded super austenitic stainless steel joints

    OpenAIRE

    Vinoth Kumar, M.; Balasubramanian, V.; Rajakumar, S.; Albert, Shaju K.

    2015-01-01

    Super 304H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power plants and marine vehicles which are intended to operate in chloride rich offshore environment. Chloride stress corrosion cracking is the most likely life limiting failure with austenitic stainless steel tubing. Welding may worsen the stress corrosion cracking susceptibility of t...

  6. Mechanical Properties of Thermally Aged Austenitic Stainless Steel Welds and Cast Austenitic Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sunghoon; Seo, Myeong-Gyu; Jang, Changheui [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Lee, Kyoung Soo [Korea Hydro and Nuclear Power Co. Ltd., Daejeon (Korea, Republic of)

    2015-05-15

    Conventional test methods for tensile and J-R properties of such weld require large size specimens. Meanwhile, small punch (SP) test has advantages of using small size samples at specific location. In this study, the mechanical property changes caused by the thermal aging were evaluated for the stainless steel welds and CASSs using tensile, J-R, and SP test. Based on the results, correlations were developed to estimate the fracture toughness using the load-displacement curve of SP tests. Finally, the fracture surfaces of compact tension (CT) and SP test specimens are compared and discussed in view of the effect of thermal aging on microstructure. Stainless steel welds of ER316L and ER347 as well as CASS (CF8M) were thermally aged at 400 .deg. C for 5,000 h. So far, tensile properties and fracture toughness of un-aged materials were carried out at room temperature and 320 .deg. C as a reference data. In order to evaluate the effect of thermal aging on mechanical properties, aged specimens are being tested and the changes in these properties will be discussed. In addition, correlations will be developed to estimate the fracture toughness in between J-R curve and SP curve.

  7. Investigation on Mechanical Properties of Austenitic Stainless-Steel Pipes Welded by TIG Method

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    Mushtaq Albdiry

    2017-11-01

    Full Text Available This paper investigates the mechanical properties of austenitic stainless steel (type 204 pipes welded by Tungsten Inert Gas (TIG welding process. Testing of hardness (HRC, tensile strength and bending strength was performed for the steel pipes welded at two different welding temperatures (700 °C and 900 °C with and without using the weld filler wire. The microstructure of the welding regions was examined by using an optical microscopy. The properties showed that the steel pipes welded by 900 °C with using the weld filler obtained the highest tensile strength and bending strength versus these welded by 700 °C without the use of the weld filler. This is attributed to the weld filler heated and melt at sufficient temperature (900 °C and compensate losing in the Ni metal occurred in the base steel metal during the welding process.

  8. Effect of Austenitic and Austeno-Ferritic Electrodes on 2205 Duplex and 316L Austenitic Stainless Steel Dissimilar Welds

    Science.gov (United States)

    Verma, Jagesvar; Taiwade, Ravindra V.

    2016-11-01

    This study addresses the effect of different types of austenitic and austeno-ferritic electrodes (E309L, E309LMo and E2209) on the relationship between weldability, microstructure, mechanical properties and corrosion resistance of shielded metal arc welded duplex/austenitic (2205/316L) stainless steel dissimilar joints using the combined techniques of optical, scanning electron microscope, energy-dispersive spectrometer and electrochemical. The results indicated that the change in electrode composition led to microstructural variations in the welds with the development of different complex phases such as vermicular ferrite, lathy ferrite, widmanstatten and intragranular austenite. Mechanical properties of welded joints were diverged based on compositions and solidification modes; it was observed that ferritic mode solidified weld dominated property wise. However, the pitting corrosion resistance of all welds showed different behavior in chloride solution; moreover, weld with E2209 was superior, whereas E309L exhibited lower resistance. Higher degree of sensitization was observed in E2209 weld, while lesser in E309L weld. Optimum ferrite content was achieved in all welds.

  9. Active flux tungsten inert gas welding of austenitic stainless steel AISI 304

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    D. Klobčar

    2016-10-01

    Full Text Available The paper presents the effects of flux assisted tungsten inert gas (A-TIG welding of 4 (10 mm thick austenitic stainless steel EN X5CrNi1810 (AISI 304 in the butt joint. The sample dimensions were 300 ´ 50 mm, and commercially available active flux QuickTIG was used for testing. In the planned study the influence of welding position and weld groove shape was analysed based on the penetration depth. A comparison of microstructure formation, grain size and ferrit number between TIG welding and A-TIG welding was done. The A-TIG welds were subjected to bending test. A comparative study of TIG and A-TIG welding shows that A-TIG welding increases the weld penetration depth.

  10. Thick-section Laser and Hybrid Welding of Austenitic Stainless Steels

    Science.gov (United States)

    Kujanpää, Veli

    Austenitic stainless steels are generally known to have very good laser weldability, when ordinary grades of sheets are concerned. But it is not necessarily the case, if special grades of fully austenitic structures with e.g. high molybdenum, or thick-section are used. It is also known that hot cracking susceptibility is strictly controlled by composition and welding parameters. If solidification is primary ferritic, hot cracking resistance is dramatically increased. It is also well known that laser welding needs a careful control of weld edge preparation and air gap between the edges. The dependence on edge quality can be decreased by using filler metal, either cold wire, hot wire or hybrid laser-arc welding. An additional role is high molybdenum contents where micro segregation can cause low local contents in weld which can decrease the corrosion properties, if filler metal is not used. Another feature in laser welding is its incomplete mixing, especially in thick section applications. It causes inhomogeneity, which can make uneven microstructure, as well as uneven mechanical and corrosion properties In this presentation the features of laser welding of thick section austenitic stainless steels are highlighted. Thick section (up to 60 mm) can be made by multi-pass laser or laser hybrid welding. In addition to using filler metal, it requires careful joint figure planning, laser head planning, weld parameter planning, weld filler metal selection, non-destructive and destructive testing and metallography to guarantee high-quality welds in practice. In addition some tests with micro segregation is presented. Also some examples of incomplete mixing is presented.

  11. Heat sink welding of austenitic stainless steel pipes to control distortion and residual stress

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, H.; Albert, S.K.; Bhaduri, A.K. [Materials Technology Div., Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2007-07-01

    Construction of India's Prototype Fast Breeder Reactor (PFBR) involves extensive welding of austenitic stainless steels pipes of different dimensions. Due to high thermal expansion coefficient and poor thermal conductivity of this class of steels, welding can result in significant distortion of these pipes. Attempts to arrest this distortion can lead to high levels of residual stresses in the welded parts. Heat sink welding is one of the techniques often employed to minimize distortion and residual stress in austenitic stainless steel pipe welding. This technique has also been employed to repair welding of the piping of the Boiling Water Reactors (BWRs) subjected to radiation induced intergranular stress corrosion cracking (IGSCC). In the present study, a comparison of the distortion in two pipe welds, one made with heat sink welding and another a normal welds. Pipes of dimensions 350{phi} x 250(L) x 8(t) mm was fabricated from 316LN plates of dimensions 1100 x 250 x 8 mm by bending and long seam (L-seam) welding by SMAW process. Two fit ups with a root gap of 2 mm, land height of 1mm and a groove angle of 70 were prepared using these pipes for circumferential seam (C-seam) welding. Dimensions at predetermined points in the fit up were made before and after welding to check the variation in radius, circumference and and ovality of the pipes. Root pass for both the pipe fit up were carried out using conventional GTAW process with 1.6 mm AWS ER 16-8-2 as consumables. Welding of one of the pipe fit ups were completed using conventions GTAW process while the other was completed using heat sink welding. For second and subsequent layers of welding using this process, water was sprayed at the root side of the joint while welding was in progress. Flow rate of the water was {proportional_to}6 1/minute. Welding parameters employed were same as those used for the other pipe weld. Results of the dimensional measurements showed that there is no circumferential shrinkage in

  12. Welding of 316L Austenitic Stainless Steel with Activated Tungsten Inert Gas Process

    Science.gov (United States)

    Ahmadi, E.; Ebrahimi, A. R.

    2015-02-01

    The use of activating flux in TIG welding process is one of the most notable techniques which are developed recently. This technique, known as A-TIG welding, increases the penetration depth and improves the productivity of the TIG welding. In the present study, four oxide fluxes (SiO2, TiO2, Cr2O3, and CaO) were used to investigate the effect of activating flux on the depth/width ratio and mechanical property of 316L austenitic stainless steel. The effect of coating density of activating flux on the weld pool shape and oxygen content in the weld after the welding process was studied systematically. Experimental results indicated that the maximum depth/width ratio of stainless steel activated TIG weld was obtained when the coating density was 2.6, 1.3, 2, and 7.8 mg/cm2 for SiO2, TiO2, Cr2O3, and CaO, respectively. The certain range of oxygen content dissolved in the weld, led to a significant increase in the penetration capability of TIG welds. TIG welding with active fluxes can increase the delta-ferrite content and improves the mechanical strength of the welded joint.

  13. Prediction of microsegregation and pitting corrosion resistance of austenitic stainless steel welds by modelling

    Energy Technology Data Exchange (ETDEWEB)

    Vilpas, M. [VTT Manufacturing Technology, Espoo (Finland). Materials and Structural Integrity

    1999-07-01

    The present study focuses on the ability of several computer models to accurately predict the solidification, microsegregation and pitting corrosion resistance of austenitic stainless steel weld metals. Emphasis was given to modelling the effect of welding speed on solute redistribution and ultimately to the prediction of weld pitting corrosion resistance. Calculations were experimentally verified by applying autogenous GTA- and laser processes over the welding speed range of 0.1 to 5 m/min for several austenitic stainless steel grades. Analytical and computer aided models were applied and linked together for modelling the solidification behaviour of welds. The combined use of macroscopic and microscopic modelling is a unique feature of this work. This procedure made it possible to demonstrate the effect of weld pool shape and the resulting solidification parameters on microsegregation and pitting corrosion resistance. Microscopic models were also used separately to study the role of welding speed and solidification mode in the development of microsegregation and pitting corrosion resistance. These investigations demonstrate that the macroscopic model can be implemented to predict solidification parameters that agree well with experimentally measured values. The linked macro-micro modelling was also able to accurately predict segregation profiles and CPT-temperatures obtained from experiments. The macro-micro simulations clearly showed the major roles of weld composition and welding speed in determining segregation and pitting corrosion resistance while the effect of weld shape variations remained negligible. The microscopic dendrite tip and interdendritic models were applied to welds with good agreement with measured segregation profiles. Simulations predicted that weld inhomogeneity can be substantially decreased with increasing welding speed resulting in a corresponding improvement in the weld pitting corrosion resistance. In the case of primary austenitic

  14. INVESTIGATING SPOT WELD GROWTH ON 304 AUSTENITIC STAINLESS STEEL (2 mm SHEETS

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    NACHIMANI CHARDE

    2013-02-01

    Full Text Available Resistance spot welding (RSW has revolutionized automotive industries since early 1970s for its mechanical assemblies. To date one mechanical assembly out five is welded using spot welding technology in various industries and stainless steel became very popular among common materials. As such this research paper analyses the spot weld growth on 304 austenitic stainless steels with 2mm sample sheets. The growth of a spot weld is primarily determined by its parameters such as current, weld time, electrode tip and force. However other factors such as electrode deformations, corrosions, dissimilar materials and material properties are also affect the weld growth. This paper is intended to analyze only the effects of nuggets growth due to the current and weld time increment with constant force and unchanged electrode tips. A JPC 75kVA spot welder was used to accomplish it and the welded samples were undergone tensile test, hardness test and metallurgical test to characterize the formation of weld nuggets.

  15. Shielding gas effect on weld characteristics in arc-augmented laser welding process of super austenitic stainless steel

    Science.gov (United States)

    Sathiya, P.; Kumar Mishra, Mahendra; Soundararajan, R.; Shanmugarajan, B.

    2013-02-01

    A series of hybrid welding (gas metal arc welding-CO2 laser beam welding) experiments were conducted on AISI 904L super austenitic stainless steel sheet of 5 mm thickness. A detailed study of CO2 Laser-GMAW hybrid welding experiments with different shielding gas mixtures (100% He, 50% He+50% Ar, 50%He+45% Ar+5% O2, and 45% He+45% Ar+10% N2) were carried out and the results are presented. The resultant welds were subjected to detailed mechanical and microstructural characterization. Hardness testing revealed that the hardness values in the fusion zone were higher than the base material irrespective of the parameters. Transverse tensile testing showed that the joint efficiency is 100% with all the shielding gas experimented. Impact energy values of the welds were also found to be higher than the base material and the fractrograph taken in scanning electron microscope (SEM) has shown that the welds exhibited dimple fracture similar to the base material.

  16. Effect of Electrode Types on the Solidification Cracking Susceptibility of Austenitic Stainless Steel Weld Metal

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    J. U. Anaele

    2015-01-01

    Full Text Available The effect of electrode types on the solidification cracking susceptibility of austenitic stainless steel weld metal was studied. Manual metal arc welding method was used to produce the joints with the tungsten inert gas welding serving as the control. Metallographic and chemical analyses of the fusion zones of the joints were conducted. Results indicate that weldments produced from E 308-16 (rutile coated, E 308-16(lime-titania coated electrodes, and TIG welded joints fall within the range of 1.5≤Creq./Nieq.≤1.9 and solidified with a duplex mode and were found to be resistant to solidification cracking. The E 308-16 weld metal had the greatest resistance to solidification cracking. Joints produced from E 310-16 had Creq./Nieq. ratio 1.9 and solidified with ferrite mode. It had a low resistance to solidification cracking.

  17. Joining silicon carbide to austenitic stainless steel through diffusion welding; Stellingen behorende bij het proefschrift

    Energy Technology Data Exchange (ETDEWEB)

    Krugers, Jan-Paul

    1993-01-19

    In this thesis, the results are presented of a study dealing with joining silicon carbide to austenitic stainless steel AIS316 by means of diffusion welding. Welding experiments were carried out without and with the use of a metallic intermediate, like copper, nickel and copper-nickel alloys at various conditions of process temperature, process time, mechanical pressure and interlayer thickness. Most experiments were carried out in high vacuum. For reasons of comparison, however, some experiments were also carried out in a gas shielded environment of 95 vol.% Ar and 5 vol.% H2.

  18. Stress corrosion cracking behaviour of gas tungsten arc welded super austenitic stainless steel joints

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    M. Vinoth Kumar

    2015-09-01

    Full Text Available Super 304H austenitic stainless steel with 3% of copper posses excellent creep strength and corrosion resistance, which is mainly used in heat exchanger tubing of the boiler. Heat exchangers are used in nuclear power plants and marine vehicles which are intended to operate in chloride rich offshore environment. Chloride stress corrosion cracking is the most likely life limiting failure with austenitic stainless steel tubing. Welding may worsen the stress corrosion cracking susceptibility of the material. Stress corrosion cracking susceptibility of Super 304H parent metal and gas tungsten arc (GTA welded joints were studied by constant load tests in 45% boiling MgCl2 solution. Stress corrosion cracking resistance of Super 304H stainless steel was deteriorated by GTA welding due to the formation of susceptible microstructure in the HAZ of the weld joint and the residual stresses. The mechanism of cracking was found to be anodic path cracking, with transgranular nature of crack propagation. Linear relationships were derived to predict the time to failure by extrapolating the rate of steady state elongation.

  19. Evaluation of self-welding susceptibility of an austenitic stainless steel (alloy D9) in sodium

    Science.gov (United States)

    Kumar, Hemant; Albert, S. K.; Ramakrishnan, V.; Meikandamurthy, C.; Amarendra, G.; Bhaduri, A. K.

    2008-02-01

    Self-welding susceptibility of a 15Cr-15Ni-2Mo titanium-modified austenitic stainless steel (alloy D9), in both annealed and 20% cold-worked conditions, have been evaluated in flowing sodium at 823 K for 2160 and 4320 h under contact stress of 9.4 MPa. Tests were performed on flat-on-flat geometry of hollow cylindrical specimens under compression. One pair of 20% cold-worked alloy D9 vs. 20% cold-worked alloy D9 specimens tested for 4320 h was self-welded for which the breakaway shear force was measured. Scanning electron micrographs of the self-welded region showed that portions of the original interface no longer existed. The paper discusses the experimental set-up installed in the sodium loop test facility and the results of self-welding susceptibility studies on this material.

  20. Creep-fatigue damage characteristics for a welded cylindrical structure of austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeo Yeon; Kim, Jong Bum; Kim, Seok Hoon; Joo, Young Sang; Lee, Jae Han [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2004-07-01

    In the design and assessment of a high temperature structure, it is important to ensure the structural integrity for the welded joint subjected to a creep-fatigue load because a statistical investigation shows that 29 events out of 46 leaks in liquid metal reactors were caused at the welded joints. As for the structural integrity due to thermal ratchet load at the welded joint, KAERI has performed the test and analysis work for a cylindrical structure with welded joints. As a continuation of the study on welded joints at a high temperature structure, a creep-fatigue structural test and analysis work is now on-going and this paper present the interim findings for the structural test and analysis work. Recently the structural and analysis work for the Y-piece made of a 316L stainless steel structure has been carried out. The objectives of the present structural creep-fatigue test with the welded cylindrical specimen are to compare the creep-fatigue damage mechanisms for the 304 and 316L stainless steels, to compare the different behavior of the welding methods in a high temperature austenitic structures and to quantify the conservatism of the design guidelines for a high temperature structure.

  1. Effects of Heat Input on Microstructure, Corrosion and Mechanical Characteristics of Welded Austenitic and Duplex Stainless Steels: A Review

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    Ghusoon Ridha Mohammed

    2017-01-01

    Full Text Available The effects of input heat of different welding processes on the microstructure, corrosion, and mechanical characteristics of welded duplex stainless steel (DSS are reviewed. Austenitic stainless steel (ASS is welded using low-heat inputs. However, owing to differences in the physical metallurgy between ASS and DSS, low-heat inputs should be avoided for DSS. This review highlights the differences in solidification mode and transformation characteristics between ASS and DSS with regard to the heat input in welding processes. Specifically, many studies about the effects of heat energy input in welding process on the pitting corrosion, intergranular stress, stresscorrosion cracking, and mechanical properties of weldments of DSS are reviewed.

  2. Testing of intergranular and pitting corrosion in sensitized welded joints of austenitic stainless steel

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    Bore V. Jegdic

    2017-06-01

    Full Text Available Pitting corrosion resistance and intergranular corrosion of the austenitic stainless steel X5Cr Ni18-10 were tested on the base metal, heat affected zone and weld metal. Testing of pitting corrosion was performed by the potentiodynamic polarization method, while testing of intergranular corrosion was performed by the method of electrochemical potentiokinetic reactivation with double loop. The base metal was completely resistant to intergranular corrosion, while the heat affected zone showed a slight susceptibility to intergranular corrosion. Indicators of pitting corrosion resistance for the weld metal and the base metal were very similar, but their values are significantly higher than the values for the heat affected zone. This was caused by reduction of the chromium concentration in the grain boundary areas in the heat affected zone, even though the carbon content in the examined stainless steel is low (0.04 wt. % C.

  3. Application of electrochemical methods for the investigation of intergranular corrosion welded joint austenitic stainless steel 19Cr-9Ni

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    Jegdić Bore V.

    2011-01-01

    Full Text Available Sensitization degree of the austenitic stainless steel welded joints was investigated by electrochemical methods of the double loop electrochemical potentiokinetic reactivation (DL EPR in H2SO4 + KSCN solution, and by the measurement of corrosion potential of the steel in the drop of the solution of HNO3 + FeCl3 + HCl. The welded joints were tested by X-ray radiographic method in order to check the presence of the weld defects. Grain size of the base metal and the welded joints were determined by optical microscopy. Good agreement between the results obtained by different electrochemical methods was obtained. Heat-affected zone (HAZ of the austenitic stainless steel welded joints has shown significant degree of sensitization. The double loop electrochemical potentiokinetic method gave quantitative evidence about susceptibility of the stainless steel to intergranular corrosion.

  4. Residual Stresses Due to Circumferential Girth Welding of Austenitic Stainless Steel Pipes

    Science.gov (United States)

    Tarak, Farzan

    Welding, as a joining method in fabrication of engineering products and structural elements, has a direct influence on thermo-mechanical behavior of components in numerous structural applications. Since these thermo-mechanical behaviors have a major role in the life of welding components, predicting thermo-mechanical effects of welding is a major factor in designing of welding components. One of the major of these effects is generation of residual stresses due to welding. These residual stresses are not the causes of failure in the components solely, but they will add to external loads and stresses in operating time. Since, experimental methods are time consuming and expensive, computational simulation of welding process is an effective method to calculate these residual stresses. This investigation focuses on the evaluation of residual stresses and distortions due to circumferential girth welding of austenitic stainless steel pipes using the commercial finite element software ESI Visual-Environment and SYSWELDRTM to simulate welding process. Of particular importance is the comparison of results from three different types of mechanics models: 1) Axisymmetric, 2) Shell, and 3) Full 3-D.

  5. Microstructural observations of HFIR-irratiated austenitic stainless steels including welds from JP9-16

    Energy Technology Data Exchange (ETDEWEB)

    Sawai, T.; Shiba, K.; Hishinuma, A.

    1996-04-01

    Austenitic stainless steels, including specimens taken from various electron beam (EB) welds, have been irradiated in HFIR Phase II capsules, JP9-16. Fifteen specimens irradiated at 300, 400, and 500{degrees}C up to 17 dpa are so far examined by a transmission electron microscope (TEM). In 300{degrees}C irradiation, cavities were smaller than 2nm and different specimens showed little difference in cavity microstructure. At 400{degrees}C, cavity size was larger, but still very small (<8 nm). At 500{degrees}C, cavity size reached 30 nm in weld metal specimens of JPCA, while cold worked JPCA contained a small (<5 nm) cavities. Inhomogeneous microstructural evolution was clearly observed in weld-metal specimens irradiated at 500{degrees}C.

  6. Study on laser welding of austenitic stainless steel by varying incident angle of pulsed laser beam

    Science.gov (United States)

    Kumar, Nikhil; Mukherjee, Manidipto; Bandyopadhyay, Asish

    2017-09-01

    In the present work, AISI 304 stainless steel sheets are laser welded in butt joint configuration using a robotic control 600 W pulsed Nd:YAG laser system. The objective of the work is of twofold. Firstly, the study aims to find out the effect of incident angle on the weld pool geometry, microstructure and tensile property of the welded joints. Secondly, a set of experiments are conducted, according to response surface design, to investigate the effects of process parameters, namely, incident angle of laser beam, laser power and welding speed, on ultimate tensile strength by developing a second order polynomial equation. Study with three different incident angle of laser beam 89.7 deg, 85.5 deg and 83 deg has been presented in this work. It is observed that the weld pool geometry has been significantly altered with the deviation in incident angle. The weld pool shape at the top surface has been altered from semispherical or nearly spherical shape to tear drop shape with decrease in incident angle. Simultaneously, planer, fine columnar dendritic and coarse columnar dendritic structures have been observed at 89.7 deg, 85.5 deg and 83 deg incident angle respectively. Weld metals with 85.5 deg incident angle has higher fraction of carbide and δ-ferrite precipitation in the austenitic matrix compared to other weld conditions. Hence, weld metal of 85.5 deg incident angle achieved higher micro-hardness of ∼280 HV and tensile strength of 579.26 MPa followed by 89.7 deg and 83 deg incident angle welds. Furthermore, the predicted maximum value of ultimate tensile strength of 580.50 MPa has been achieved for 85.95 deg incident angle using the developed equation where other two optimum parameter settings have been obtained as laser power of 455.52 W and welding speed of 4.95 mm/s. This observation has been satisfactorily validated by three confirmatory tests.

  7. Hardness analysis of welded joints of austenitic and duplex stainless steels

    Science.gov (United States)

    Topolska, S.

    2016-08-01

    Stainless steels are widely used in the modern world. The continuous increase in the use of stainless steels is caused by getting greater requirements relating the corrosion resistance of all types of devices. The main property of these steels is the ability to overlap a passive layer of an oxide on their surface. This layer causes that they become resistant to oxidation. One of types of corrosion-resistant steels is ferritic-austenitic steel of the duplex type, which has good strength properties. It is easily formable and weldable as well as resistant to erosion and abrasive wear. It has a low susceptibility to stress-corrosion cracking, to stress corrosion, to intercrystalline one, to pitting one and to crevice one. For these reasons they are used, among others, in the construction of devices and facilities designed for chemicals transportation and for petroleum and natural gas extraction. The paper presents the results which shows that the particular specimens of the ][joint representing both heat affected zones (from the side of the 2205 steel and the 316L one) and the weld are characterized by higher hardness values than in the case of the same specimens for the 2Y joint. Probably this is caused by machining of edges of the sections of metal sheets before the welding process, which came to better mixing of native materials and the filler metal. After submerged arc welding the 2205 steel still retains the diphase, austenitic-ferritic structure and the 316L steel retains the austenitic structure with sparse bands of ferrite σ.

  8. New developments for the ultrasonic inspection of austenitic stainless steel welds

    Energy Technology Data Exchange (ETDEWEB)

    Chassignole, Bertrand; Doudet, Loic; Dupond, Olivier; Fouquet, Thierry; Richard, Benoit [Electricite de France - EDF, 2, rue Louis-Murat, 75008 Paris (France)

    2006-07-01

    EDF R and D undertakes studies in non destructive testing (NDT) for better understanding the influence of various parameters (material, type of defect, geometry) on the 'controllability' of the critical components for nuclear safety. In the field of ultrasonic testing, one of the principal research orientations is devoted to the study of the austenitic stainless steel welds of the primary cooling system. Indeed, the structure of these welds present characteristics making difficult their examination, for example: - a strong anisotropy of the properties of elasticity which, coupled with the heterogeneity of the grain orientations, can involve phenomena of skewing, division and distortion of the beam; - a significant scattering of the waves by the grains involving an high attenuation and sometimes backscattered signals. For several years, actions have been launched to improve comprehension of these disturbing phenomena and to evaluate the controllability of those welds. This work is based on the one hand on experimental analyses on representative mock-ups and on the other hand on the developments of modelling codes taking into account the characteristics of the materials. We present in this document a synthesis of this work by developing the following points in particular: - a description of the phenomena of propagation; - the works undertaken to characterize the structure of the welds; - an example of study coupling experimental and modelling analyses for a butt weld achieved by manual arc welding with coated electrodes. The paper has the following contents: 1. Context; 2. Presentation of the problem; 3. Characterization of austenitic welds; 4. From comprehension to industrial application; 5. Conclusion and perspectives; 5. Conclusion and perspectives. This synthesis shows that each austenitic stainless steel weld is a particular case for the ultrasonic testing. This work allowed to better apprehend the disturbances of the ultrasonic propagation in the

  9. Three-dimensional transient thermoelectric currents in deep penetration laser welding of austenite stainless steel

    Science.gov (United States)

    Chen, Xin; Pang, Shengyong; Shao, Xinyu; Wang, Chunming; Xiao, Jianzhong; Jiang, Ping

    2017-04-01

    The existence of thermoelectric currents (TECs) in workpieces during the laser welding of metals has been common knowledge for more than 15 years. However, the time-dependent evolutions of TECs in laser welding remain unclear. The present study developed a novel three-dimensional theoretical model of thermoelectric phenomena in the fiber laser welding of austenite stainless steel and used it to observe the time-dependent evolutions of TECs for the first time. Our model includes the complex physical effects of thermal, electromagnetic, fluid and phase transformation dynamics occurring at the millimeter laser ablated zone, which allowed us to simulate the TEC, self-induced magnetic field, Lorentz force, keyhole and weld pool behaviors varying with the welding time for different parameters. We found that TECs are truly three-dimensional, time-dependent, and uneven with a maximum current density of around 107 A/m2 located at the liquid-solid (L/S) interface near the front or bottom part of the keyhole at a laser power of 1.5 kW and a welding speed of 3 m/min. The TEC formed three-dimensional circulations moving from the melting front to solidification front in the solid part of workpiece, after which the contrary direction was followed in the liquid part. High frequency oscillation characteristics (2.2-8.5 kHz) were demonstrated in the TEC, which coincides with that of the keyhole instability (2.0-5.0 kHz). The magnitude of the self-induced magnetic field and Lorentz force can reach 0.1 mT and 1 kN/m3, respectively, which are both consistent with literature data. The predicted results of the weld dimensions by the proposed model agree well with the experimental results. Our findings could enhance the fundamental understanding of thermoelectric phenomena in laser welding.

  10. AN ULTRASONIC PHASED ARRAY EVALUATION OF CAST AUSTENITIC STAINLESS STEEL PRESSURIZER SURGE LINE PIPING WELDS

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Moran, Traci L.; Anderson, Michael T.

    2010-07-22

    A set of circumferentially oriented thermal fatigue cracks (TFCs) were implanted into three cast austenitic stainless steel (CASS) pressurizer (PZR) surge-line specimens (pipe-to-elbow welds) that were fabricated using vintage CASS materials formed in the 1970s, and flaw responses from these cracks were used to evaluate detection and sizing performance of the phased-array (PA) ultrasonic testing (UT) methods applied. Four different custom-made PA probes were employed in this study, operating nominally at 800 kHz, 1.0 MHz, 1.5 MHz, and 2.0 MHz center frequencies. The CASS PZR surge-line specimens were polished and chemically etched to bring out the microstructures of both pipe and elbow segments. Additional studies were conducted and documented to address baseline CASS material noise and observe possible ultrasonic beam redirection phenomena.

  11. Feasibility of surface-coated friction stir welding tools to join AISI 304 grade austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    A.K. Lakshminarayanan

    2014-12-01

    Full Text Available An attempt is made to develop the tools that are capable enough to withstand the shear, impact and thermal forces that occur during friction stir welding of stainless steels. The atmospheric plasma spray and plasma transferred arc hardfacing processes are employed to deposit refractory ceramic based composite coatings on the Inconel 738 alloy. Five different combinations of self-fluxing alloy powder and 60% ceramic reinforcement particulate mixtures are used for coating. The best friction stir welding tool selected based on tool wear analysis is used to fabricate the austenitic stainless steel joints.

  12. Tensile properties of a titanium modified austenitic stainless steel and the weld joints after neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shiba, K.; Ioka, I.; Jitsukawa, S.; Hamada, A.; Hishinuma, A. [and others

    1996-10-01

    Tensile specimens of a titanium modified austenitic stainless steel and its weldments fabricated with Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques were irradiated to a peak dose of 19 dpa and a peak helium level of 250 appm in the temperature range between 200 and 400{degrees}C in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) and the High Flux Isotope Reactor (HFIR). The He/dpa ratio of about 13 appm/dpa is similar to the typical helium/dpa ratio of a fusion reactor environment. The tensile tests were carried out at the irradiation temperature in vacuum. The irradiation caused an increase in yield stress to levels between 670 and 800 MPa depending on the irradiation temperature. Total elongation was reduced to less than 10%, however the specimens failed in a ductile manner. The results were compared with those of the specimens irradiated using irradiation capsules producing larger amount of He. Although the He/dpa ratio affected the microstructural change, the impact on the post irradiation tensile behavior was rather small for not only base metal specimens but also for the weld joint and the weld metal specimens.

  13. Effects of Thermocapillary Forces during Welding of 316L-Type Wrought, Cast and Powder Metallurgy Austenitic Stainless Steels

    CERN Document Server

    Sgobba, Stefano

    2003-01-01

    The Large Hadron Collider (LHC) is now under construction at the European Organization for Nuclear Research (CERN). This 27 km long accelerator requires 1248 superconducting dipole magnets operating at 1.9 K. The cold mass of the dipole magnets is closed by a shrinking cylinder with two longitudinal welds and two end covers at both extremities of the cylinder. The end covers, for which fabrication by welding, casting or Powder Metallurgy (PM) was considered, are dished-heads equipped with a number of protruding nozzles for the passage of the different cryogenic lines. Structural materials and welds must retain high strength and toughness at cryogenic temperature. AISI 316L-type austenitic stainless steel grades have been selected because of their mechanical properties, ductility, weldability and stability of the austenitic phase against low-temperature spontaneous martensitic transformation. 316LN is chosen for the fabrication of the end covers, while the interconnection components to be welded on the protrud...

  14. Methodology for Estimating Thermal and Neutron Embrittlement of Austenitic Stainless Steel Welds During Service in Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Rao, A. S.

    2016-04-28

    The effect of thermal aging on the degradation of fracture toughness and Charpy-impact properties of austenitic stainless steel (SS) welds has been characterized at reactor temperatures. The solidification behavior and the distribution and morphology of the ferrite phase in SS welds are described. Thermal aging of the welds results in moderate decreases in Charpy-impact strength and fracture toughness. The upper-shelf Charpy-impact energy of aged welds decreases by 50–80 J/cm2. The decrease in fracture toughness J-R curve, or JIc is relatively small. Thermal aging has minimal effect on the tensile strength. The fracture properties of SS welds are insensitive to filler metal; the welding process has a significant effect. The large variability in the data makes it difficult to establish the effect of the welding process on fracture properties of SS welds. Consequently, the approach used for evaluating thermal and neutron embrittlement of austenitic SS welds relies on establishing a lower-bound fracture toughness J-R curve for unaged and aged, and non-irradiated and irradiated, SS welds. The existing fracture toughness J-R curve data for SS welds have been reviewed and evaluated to define lower-bound J-R curve for submerged arc (SA)/shielded metal arc (SMA)/manual metal arc (MMA) welds and gas tungsten arc (GTA)/tungsten inert gas (TIG) welds in the unaged and aged conditions. At reactor temperatures, the fracture toughness of GTA/TIG welds is a factor of about 2.3 higher than that of SA/SMA/MMA welds. Thermal aging decreases the fracture toughness by about 20%. The potential combined effects of thermal and neutron embrittlement of austenitic SS welds are also described. Lower-bound curves are presented that define the change in coefficient C and exponent n of the power-law J-R curve and the JIc value for SS welds as a function of neutron dose. The potential effects of reactor coolant environment on the fracture toughness of austenitic SS welds are also discussed.

  15. Experimental Analysis of Residual Stresses in Samples of Austenitic Stainless Steel Welded on Martensitic Stainless Steel Used for Kaplan Blades Repairs

    Directory of Open Access Journals (Sweden)

    Vasile Cojocaru

    2011-01-01

    Full Text Available Residual stresses occur in materials as a result of mechanical processes: welding, machining, grinding etc. If residual stresses reach high values they can accelerate the occurrence of cracks and erosion of material. An experimental research was made in order to study the occurrence of residual stresses in the repaired areas of hydraulic turbine components damaged by cavitation erosion. An austenitic stainless steel was welded in various layer thicknesses on a martensitic stainless steel base. The residual stresses were determined using the hole drilling strain gage method.

  16. Through-Thickness Residual Stress Profiles in Austenitic Stainless Steel Welds: A Combined Experimental and Prediction Study

    Science.gov (United States)

    Mathew, J.; Moat, R. J.; Paddea, S.; Francis, J. A.; Fitzpatrick, M. E.; Bouchard, P. J.

    2017-10-01

    Economic and safe management of nuclear plant components relies on accurate prediction of welding-induced residual stresses. In this study, the distribution of residual stress through the thickness of austenitic stainless steel welds has been measured using neutron diffraction and the contour method. The measured data are used to validate residual stress profiles predicted by an artificial neural network approach (ANN) as a function of welding heat input and geometry. Maximum tensile stresses with magnitude close to the yield strength of the material were observed near the weld cap in both axial and hoop direction of the welds. Significant scatter of more than 200 MPa was found within the residual stress measurements at the weld center line and are associated with the geometry and welding conditions of individual weld passes. The ANN prediction is developed in an attempt to effectively quantify this phenomenon of `innate scatter' and to learn the non-linear patterns in the weld residual stress profiles. Furthermore, the efficacy of the ANN method for defining through-thickness residual stress profiles in welds for application in structural integrity assessments is evaluated.

  17. Through-Thickness Residual Stress Profiles in Austenitic Stainless Steel Welds: A Combined Experimental and Prediction Study

    Science.gov (United States)

    Mathew, J.; Moat, R. J.; Paddea, S.; Francis, J. A.; Fitzpatrick, M. E.; Bouchard, P. J.

    2017-12-01

    Economic and safe management of nuclear plant components relies on accurate prediction of welding-induced residual stresses. In this study, the distribution of residual stress through the thickness of austenitic stainless steel welds has been measured using neutron diffraction and the contour method. The measured data are used to validate residual stress profiles predicted by an artificial neural network approach (ANN) as a function of welding heat input and geometry. Maximum tensile stresses with magnitude close to the yield strength of the material were observed near the weld cap in both axial and hoop direction of the welds. Significant scatter of more than 200 MPa was found within the residual stress measurements at the weld center line and are associated with the geometry and welding conditions of individual weld passes. The ANN prediction is developed in an attempt to effectively quantify this phenomenon of `innate scatter' and to learn the non-linear patterns in the weld residual stress profiles. Furthermore, the efficacy of the ANN method for defining through-thickness residual stress profiles in welds for application in structural integrity assessments is evaluated.

  18. The influence of the heat treatment on delta ferrite transformation in austenitic stainless steel welds

    Directory of Open Access Journals (Sweden)

    B. Mateša

    2012-04-01

    Full Text Available Shielded metal arc (SMAW welded specimens using austenitic consumable materials with different amount of delta-ferrite are annealed in range 650-750 °C through 2-10 hours. Factorial plan 33 with influenced factors regression analyze of measured delta-ferrite values is used. The transformation i.e. decomposition of delta ferrite during annealing was analyzed regarding on weld cracking resistance using metallographic examination and WRC-1992 diagram.

  19. Towards a Map of Solidification Cracking Risk in Laser Welding of Austenitic Stainless Steels

    Science.gov (United States)

    Bermejo, María-Asunción Valiente; DebRoy, Tarasankar; Hurtig, Kjell; Karlsson, Leif; Svensson, Lars-Erik

    In this work, two series of specimens with Hammar and Svensson's Cr- and Ni-equivalents (Creq+Nieq) = 35 and 45 wt% were used to cover a wide range of austenitic grades. These were laser welded with different energy inputs achieving cooling rates in the range of 103 °C/s to 104 °C/s. As high cooling rates and rapid solidification conditions could favour fully austenitic solidification and therefore raise susceptibility to solidification cracking, the solidification modes of the laser welded specimens were compared to the ones experienced by the same alloys under arc welding conditions. It was found that high cooling rates experienced in laser welding promoted fully austenitic solidification for a wider range of compositions, for example specimens with (Creq+Nieq) = 35% under arc welding cooling conditions at 10 °C/s showed fully austenitic solidification up to Creq/Nieq = 1.30, whilst the same specimens laser cooled at 103 °C/s showed fully austenitic solidification up to Creq/Nieq = 1.50 and those cooled at 104 °C/s showed it up to Creq/Nieq = 1.68. Therefore, high cooling rates extended the solidification cracking risk to a wider range of Creq/Nieq values. This work also compares the cooling rates experimentally determined by thermocouples to the computed cooling rates calculated by a highly-advanced computational model. The distance between the thermocouple's wires and the thermal resistance of thermocouples together with the small size of the weld pools proved to be practical limitations in the experimental determination of cooling rates. However, an excellent agreement was found between computed and experimental solidus isotherms at high energy input settings. For low energy input settings cooling rate was in the order of magnitude of 104 °C/s, whilst for high energy input settings cooling rate was found to be in the order of magnitude of 103 °C/s.

  20. Measurement of ultrasonic scattering attenuation in austenitic stainless steel welds: realistic input data for NDT numerical modeling.

    Science.gov (United States)

    Ploix, Marie-Aude; Guy, Philippe; Chassignole, Bertrand; Moysan, Joseph; Corneloup, Gilles; El Guerjouma, Rachid

    2014-09-01

    Multipass welds made of 316L stainless steel are specific welds of the primary circuit of pressurized water reactors in nuclear power plants. Because of their strong heterogeneous and anisotropic nature due to grain growth during solidification, ultrasonic waves may be greatly deviated, split and attenuated. Thus, ultrasonic assessment of the structural integrity of such welds is quite complicated. Numerical codes exist that simulate ultrasonic propagation through such structures, but they require precise and realistic input data, as attenuation coefficients. This paper presents rigorous measurements of attenuation in austenitic weld as a function of grain orientation. In fact attenuation is here mainly caused by grain scattering. Measurements are based on the decomposition of experimental beams into plane-wave angular spectra and on the modeling of the ultrasonic propagation through the material. For this, the transmission coefficients are calculated for any incident plane wave on an anisotropic plate. Two different hypotheses on the welded material are tested: first it is considered as monoclinic, and then as triclinic. Results are analyzed, and validated through comparison to theoretical predictions of related literature. They underline the great importance of well-describing the anisotropic structure of austenitic welds for UT modeling issues. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. EFFECTS OF ELECTRODE DEFORMATION OF RESISTANCE SPOT WELDING ON 304 AUSTENITIC STAINLESS STEEL WELD GEOMETRY

    Directory of Open Access Journals (Sweden)

    Nachimani Charde

    2012-12-01

    Full Text Available The resistance spot welding process is accomplished by forcing huge amounts of current flow from the upper electrode tip through the base metals to the lower electrode tip, or vice versa or in both directions. A weld joint is established between the metal sheets through fusion, resulting in a strong bond between the sheets without occupying additional space. The growth of the weld nugget (bond between sheets is therefore determined from the welding current density; sufficient time for current delivery; reasonable electrode pressing force; and the area provided for current delivery (electrode tip. The welding current and weld time control the root penetration, while the electrode pressing force and electrode tips successfully accomplish the connection during the welding process. Although the welding current and weld time cause the heat generation at the areas concerned (electrode tip area, the electrode tips’ diameter and electrode pressing forces also directly influence the welding process. In this research truncated-electrode deformation and mushrooming effects are observed, which result in the welded areas being inconsistent due to the expulsion. The copper to chromium ratio is varied from the tip to the end of the electrode whilst the welding process is repeated. The welding heat affects the electrode and the electrode itself influences the shape of the weld geometry.

  2. Laser-induced fluorescence applied to laser welding of austenitic stainless steel for dilute alloying element detection

    Science.gov (United States)

    Simonds, Brian J.; Sowards, Jeffrey W.; Williams, Paul A.

    2017-08-01

    Optical spectral analysis of the laser weld plume is a common technique for non-contact, in situ weld plume analysis. However, the low sensitivity of optical emission spectroscopy limits the available information during 1070 nm wavelength laser welding, which is becoming the standard in many industrial operations. Here we demonstrate an improved sensitivity of optical spectroscopy by applying laser-induced fluorescence (LIF) for probing the hot gas plume induced during fiber laser welding of 304L austenitic stainless steel. As a proof-of-principle, we show that LIF is capable of resolving a spectral signal from silicon being emitted during welding. Optical detection of such a low concentration alloying element has not previously been reported and shows the capability of LIF for increased sensitivity. Silicon atoms in the weld plume were excited in the ultraviolet at 221.09 nm and detected at 221.64 nm. We demonstrate the detection of silicon LIF down to laser welding powers of 600 W (210 kW cm-2) making this technique applicable even in low-power laser welding or additive manufacturing scenarios.

  3. Influence of Material Model on Prediction Accuracy of Welding Residual Stress in an Austenitic Stainless Steel Multi-pass Butt-Welded Joint

    Science.gov (United States)

    Deng, Dean; Zhang, Chaohua; Pu, Xiaowei; Liang, Wei

    2017-04-01

    Both experimental method and numerical simulation technology were employed to investigate welding residual stress distribution in a SUS304 steel multi-pass butt-welded joint in the current study. The main objective is to clarify the influence of strain hardening model and the yield strength of weld metal on prediction accuracy of welding residual stress. In the experiment, a SUS304 steel butt-welded joint with 17 passes was fabricated, and the welding residual stresses on both the upper and bottom surfaces of the middle cross section were measured. Meanwhile, based on ABAQUS Code, an advanced computational approach considering different plastic models as well as annealing effect was developed to simulate welding residual stress. In the simulations, the perfect plastic model, the isotropic strain hardening model, the kinematic strain hardening model and the mixed isotropic-kinematic strain hardening model were employed to calculate the welding residual stress distributions in the multi-pass butt-welded joint. In all plastic models with the consideration of strain hardening, the annealing effect was also taken into account. In addition, the influence of the yield strength of weld metal on the simulation result of residual stress was also investigated numerically. The conclusions drawn by this work will be helpful in predicting welding residual stresses of austenitic stainless steel welded structures used in nuclear power plants.

  4. Effect of plasma arc welding variables on fusion zone grain size and hardness of AISI 321 austenitic stainless steel

    Science.gov (United States)

    Kondapalli, S. P.

    2017-12-01

    In the present work, pulsed current microplasma arc welding is carried out on AISI 321 austenitic stainless steel of 0.3 mm thickness. Peak current, Base current, Pulse rate and Pulse width are chosen as the input variables, whereas grain size and hardness are considered as output responses. Response surface method is adopted by using Box-Behnken Design, and in total 27 experiments are performed. Empirical relation between input and output response is developed using statistical software and analysis of variance (ANOVA) at 95% confidence level to check the adequacy. The main effect and interaction effect of input variables on output response are also studied.

  5. Microstructural origin of the skeletal ferrite morphology of austenitic stainless steel welds

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, J A; Williams, J C; Thompson, A W

    1982-04-01

    Scanning transmission electron microscopy was conducted on welds exhibiting a variety of skeletal, or vermicular ferrite morphologies in addition to one lathy ferrite morphology. These ferrite morphologies result from primary ferrite solidification followed by a solid state transformation upon cooling. During cooling, a large fraction of the ferrite transforms to austenite leaving a variety of ferrite morphologies. Comparison of composition profiles and alloy partitioning showed both the skeletal and lathy ferrite structures result from a diffusion controlled solid state transformation. However, the overall measured composition profiles of the weld structure are a result of partitioning during both solidification and the subsequent solid state transformation.

  6. Ultrasonic Flaw Detection of Cracks and Machined Flaws as Observed Through Austenitic Stainless Steel Piping Welds

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Michael T.; Cinson, Anthony D.; Crawford, Susan L.; Cumblidge, Stephen E.; Diaz, Aaron A.

    2009-07-01

    Piping welds in the pressure boundary of light water reactors (LWRs) are subject to a volumetric examination based on Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. Due to access limitations and high background radiation levels, the technique used is primarily ultrasonic rather than radiographic. Many of the austenitic welds in safety-related piping systems provide limited access to both sides of the weld, so a far-side examination is necessary. Historically, far-side inspections have performed poorly because of the coarse and elongated grains that make up the microstructures of austenitic weldments. The large grains cause the ultrasound to be scattered, attenuated, and redirected. Additionally, grain boundaries or weld geometry may reflect coherent ultrasonic echoes, making flaw detection and discrimination a more challenging endeavor. Previous studies conducted at the Pacific Northwest National Laboratory (PNNL) on ultrasonic far-side examinations in austenitic piping welds involved the application of conventional transducers, use of low-frequency Synthetic Aperture Focusing Techniques (SAFT), and ultrasonic phased-array (PA) methods on specimens containing implanted thermal fatigue cracks and machined reflectors [1-2]. From these studies, PA inspection provided the best results, detecting nearly all of the flaws from the far side. These results were presented at the Fifth International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurised Components in 2006. This led to an invitation to examine field-removed specimens containing service-induced intergranular stress corrosion cracks (IGSCC) at the Electric Power Research Institute’s (EPRI) Nondestructive Evaluation (NDE) Center, in Charlotte, North Carolina. Results from this activity are presented.

  7. Nickel-based alloy/austenitic stainless steel dissimilar weld properties prediction on asymmetric distribution of laser energy

    Science.gov (United States)

    Zhou, Siyu; Ma, Guangyi; Chai, Dongsheng; Niu, Fangyong; Dong, Jinfei; Wu, Dongjiang; Zou, Helin

    2016-07-01

    A properties prediction method of Nickel-based alloy (C-276)/austenitic stainless steel (304) dissimilar weld was proposed and validated based on the asymmetric distribution of laser energy. Via the dilution level DC-276 (the ratio of the melted C-276 alloy), the relations between the weld properties and the energy offset ratio EC-276 (the ratio of the irradiated energy on the C-276 alloy) were built, and the effects of EC-276 on the microstructure, mechanical properties and corrosion resistance of dissimilar welds were analyzed. The element distribution Cweld and EC-276 accorded with the lever rule due to the strong convention of the molten pool. Based on the lever rule, it could be predicted that the microstructure mostly consists of γ phase in each weld, the δ-ferrite phase formation was inhibited and the intermetallic phase (P, μ) formation was promoted with the increase of EC-276. The ultimate tensile strength σb of the weld joint could be predicted by the monotonically increasing cubic polynomial model stemming from the strengthening of elements Mo and W. The corrosion potential U, corrosion current density I in the active region and EC-276 also met the cubic polynomial equations, and the corrosion resistance of the dissimilar weld was enhanced with the increasing EC-276, mainly because the element Mo could help form a steady passive film which will resist the Cl- ingress.

  8. Effects of stop-start features on residual stresses in a multipass austenitic stainless steel weld

    Energy Technology Data Exchange (ETDEWEB)

    Turski, M., E-mail: Mark.Turski@magnesium-elektron.com [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom); Francis, J.A. [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom)] [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Hurrell, P.R. [Rolls-Royce Plc., Raynesway, Derby DE21 7XX (United Kingdom); Bate, S.K. [Serco Technical Services, Birchwood Park, Warrington, Cheshire WA3 6GA (United Kingdom); Hiller, S. [Materials Engineering, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Withers, P.J. [School of Materials, University of Manchester, Grosvenor Street, Manchester M1 7HS (United Kingdom)

    2012-01-15

    In this article we describe experiments that characterise and quantify the localised perturbations in residual stress associated with both ramped and abrupt stop-start features in a multipass weld. Residual stress distributions in AISI Grade 304L/308L stainless steel groove-welded specimens, containing weld interruptions that were introduced in a controlled manner, have been characterised using both neutron diffraction and the incremental deep hole drilling method. The extent to which the localised stresses associated with the interruptions were annealed by overlayed passes was also assessed. The results suggest that, regardless of the type of interruption, there can be significant localised increases in residual stress if the stop-start feature is left exposed. If further weld passes are deposited, then the localised increases in stress are likely to persist if the interruption was abrupt, whereas for a ramped interruption they may be dissipated. - Highlights: Black-Right-Pointing-Pointer In this study the residual stress-field surrounding weld interruptions was measured. Black-Right-Pointing-Pointer Localised stresses were found to increase at weld interruptions. Black-Right-Pointing-Pointer Both ramped and abrupt weld interruptions were investigated. Black-Right-Pointing-Pointer After subsequent weld passes, localised stresses persisted for abrupt interruptions. Black-Right-Pointing-Pointer After subsequent weld passes, localised stresses dissipated for ramped interruptions.

  9. Tensile properties of shielded metal arc welded dissimilar joints of nuclear grade ferritic steel and austenitic stainless steel

    Science.gov (United States)

    Karthick, K.; Malarvizhi, S.; Balasubramanian, V.; Krishnan, S. A.; Sasikala, G.; Albert, Shaju K.

    2016-12-01

    In nuclear power plants, modified 9Cr-1Mo ferritic steel (Grade 91 or P91) is used for constructing steam generators (SG's) whereas austenitic stainless steel (AISI 316LN) is a major structural member for intermediate heat exchanger (IHX). Therefore, a dissimilar joint between these materials is unavoidable. In this investigation, dissimilar joints were fabricated by Shielded Metal Arc Welding (SMAW) process with Inconel 82/182 filler metals. Transverse tensile properties and Charpy V-notch impact toughness for different regions of dissimilar joints of modified 9Cr-1Mo ferritic steel and AISI 316LN austenitic stainless steel were evaluated as per the standards. Microhardness distribution across the dissimilar joint was recorded. Microstructural features of different regions were characterized by optical and scanning electron microscopy. The transverse tensile properties of the joint is found to be inferior to base metals. Impact toughness values of different regions of dissimilar metal weld joint (DMWJ) is slightly higher than the prescribed value. Formation of a soft zone at the outer edge of the HAZ will reduce the tensile properties of DMWJ. The complex microstructure developed at the interfaces of DMWJ will reduce the impact toughness values.

  10. Friction Welding For Cladding Applications: Processing, Microstructure and Mechanical Properties of Inertia Friction Welds of Stainless Steel to Low Carbon Steel and Evaluation of Wrought and Welded Austenitic Stainless Steels for Cladding Applications in Acidchloride Service

    Science.gov (United States)

    Switzner, Nathan

    -state mixing. Thirdly, the corrosion resistance of multiple austenitic stainless steels (types 304, 316, and 309) processed in varying ways was compared for acid chloride environments using advanced electrochemical techniques. Physical simulation of fusion claddings and friction weld claddings (wrought stainless steels) was used for sample preparation to determine compositional and microstructural effects. Pitting resistance correlated firstly with Cr content, with N and Mo additions providing additional benefits. The high ferrite fraction of as-welded samples reduced their corrosion resistance. Wrought type 309L outperformed as-welded type 309L in dissolved mass loss and reverse corrosion rate from the potentiodynamic scan in 1.0 N HCl/3.5% NaCl solution. Electrochemical impedance results indicated that wrought 309L and 316L developed a corrosion resistant passive film more rapidly than other alloys in 0.1 N HCl/3.5% NaCl, and also performed well in long term (160-day) corrosion testing in the same environment. Fourthly, to prove the concept of internal CR lining by friction welding, a conical work piece of 304L stainless steel was friction welded internally to 1018 steel.

  11. Austenitic stainless steels for cryogenic service

    Energy Technology Data Exchange (ETDEWEB)

    Dalder, E.N.C.; Juhas, M.C.

    1985-09-19

    Presently available information on austenitic Fe-Cr-Ni stainless steel plate, welds, and castings for service below 77 K are reviewed with the intent (1) of developing systematic relationships between mechanical properties, composition, microstructure, and processing, and (2) of assessing the adequacy of these data bases in the design, fabrication, and operation of engineering systems at 4 K.

  12. Effect of welding process, type of electrode and electrode core diameter on the tensile property of 304L austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Akinlabi OYETUNJI

    2014-11-01

    Full Text Available The effect of welding process, type of electrode and electrode core diameter on the tensile property of AISI 304L Austenitic Stainless Steel (ASS was studied. The tensile strength property of ASS welded samples was evaluated. Prepared samples of the ASS were welded under these three various variables. Tensile test was then carried out on the welded samples. It was found that the reduction in ultimate tensile strength (UTS of the butt joint samples increases with increase in core diameter of the electrode. Also, the best electrode for welding 304L ASS is 308L stainless steel-core electrode of 3.2 mm core diameter. It is recommended that the findings of this work can be applied in the chemical, food and oil industries where 304L ASS are predominantly used.

  13. Modelling the attenuation in the ATHENA finite elements code for the ultrasonic testing of austenitic stainless steel welds.

    Science.gov (United States)

    Chassignole, B; Duwig, V; Ploix, M-A; Guy, P; El Guerjouma, R

    2009-12-01

    Multipass welds made in austenitic stainless steel, in the primary circuit of nuclear power plants with pressurized water reactors, are characterized by an anisotropic and heterogeneous structure that disturbs the ultrasonic propagation and makes ultrasonic non-destructive testing difficult. The ATHENA 2D finite element simulation code was developed to help understand the various physical phenomena at play. In this paper, we shall describe the attenuation model implemented in this code to give an account of wave scattering phenomenon through polycrystalline materials. This model is in particular based on the optimization of two tensors that characterize this material on the basis of experimental values of ultrasonic velocities attenuation coefficients. Three experimental configurations, two of which are representative of the industrial welds assessment case, are studied in view of validating the model through comparison with the simulation results. We shall thus provide a quantitative proof that taking into account the attenuation in the ATHENA code dramatically improves the results in terms of the amplitude of the echoes. The association of the code and detailed characterization of a weld's structure constitutes a remarkable breakthrough in the interpretation of the ultrasonic testing on this type of component.

  14. Solidification Behavior and Weldability of Dissimilar Welds Between a Cr-Free, Ni-Cu Welding Consumable and Type 304L Austenitic Stainless Steel

    Science.gov (United States)

    Sowards, Jeffrey W.; Liang, Dong; Alexandrov, Boian T.; Frankel, Gerald S.; Lippold, John C.

    2012-04-01

    The solidification behavior of a Cr-free welding consumable based on the Ni-Cu system was evaluated in conjunction with Type 304L stainless steel. The weld metal microstructure evolution was evaluated with optical and secondary electron microscopy, energy dispersive spectroscopy, X-ray diffraction, button melting, and thermodynamic (CALPHAD-based) modeling. Solidification partitioning patterns showed that higher dilutions of the filler metal by Type 304L increased segregation of Ti, Cu, and Si to interdendritic regions. Button melting experiments showed a widening of the solidification temperature range with increasing dilution because of the expansion of the austenite solidification range and formation of Ti(C,N) via a eutectic reaction. The model predictions showed good correlation with button melting experiments and were used to evaluate the nature of the Ti(C,N) precipitation reaction. Solidification cracking susceptibility of the weld metal was shown to increase with dilution of 304L stainless steel based on testing conducted with the cast pin tear test. The increase in cracking susceptibility is associated with expansion of the solidification temperature range and the presence of eutectic liquid at the end of solidification that wets solidification grain boundaries.

  15. Controlling Angular Distortion in Manual Metal Arc Welding of Austenitic Stainless Steels Using Back-step Technique

    Directory of Open Access Journals (Sweden)

    Abdul Sameea Jasim Abdul Zehra Jilabi

    2018-01-01

    Full Text Available Nowadays, austenitic stainless steels (A.S.S. have many industrial applications in the fields of chemical and petrochemical processing, marine, medicine, water treatment, petroleum refining, food and drinks processing, nuclear power generation etc. The secret behind this wide range of applications is the fact that A.S.S. have great corrosion resistance, high strength and scale resistance at elevated temperatures, good ductility at low temperatures approached to absolute zero in addition to notable weldability. On the other hand, manual metal arc (MMA is probably the most common process used for the welding of A.S.S. Unfortunately, MMA welding of A.S.S. could be associated with considerable distortion. Uncontrolled or excessive distortion usually increases the cost of the production process due to the high expense of rectification or replacing the weldment by a non-distorted one. MMA welding of A.S.S. was carried out using the back-step technique with various bead lengths, and without using this technique for comparison. Results have showed that the angular distortion was a function of the bead length in the back-step welding of A.S.S. The angular distortion decreased by (14.32% when the back-step technique was used with a (60 mm length for each bead, and by (41.08% when the bead length was (40 mm. On the other hand, it increased by (25% when the back-step technique was done with a (30 mm length for each bead.

  16. Effect of flux powder SiO2 for the welding of 304-austenitic stainless ...

    African Journals Online (AJOL)

    . 1, 2017, pp. 34-45. 35. From the above literature, it can be conclude that most of the research was done for materials such as Steel, Nimonic 263 alloy,. Stainless Steel 308, Ferritic Stainless Steel and 202Stainless Steel with fluxes such as ...

  17. Effect of flux powder SiO 2 for the welding of 304-austenitic stainless ...

    African Journals Online (AJOL)

    Three input machine parameters namely current, welding speed and gas flow rate at three different levels have been considered in order to find out the influence of parameters on weld bead geometry, i.e. weld bead width, penetration and angular distortion. Taguchi method has been used in order to analyse the effect of ...

  18. Effect of cooling rate on the microstructure and hardness of austenitic stainless steel welds

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, A. [ISEC - IPC, Quinta da Nora, Coimbra (Portugal); Loureiro, A. [DEM - FCTUC, Polo II, Coimbra (Portugal)

    2004-07-01

    The aim of this work is to study the effect of the cooling rate on the microstructure and hardness of the melted material of welds in steels AISI 304 and AISI 316L. The increase of weld heat input, consequently the decrease in the cooling rate, produces only a smooth increase of the ferrite content and a small decrease of hardness in the melted material of autogeneous TIG welds. (orig.)

  19. Technical Letter Report Assessment of Ultrasonic Phased Array Testing for Cast Austenitic Stainless Steel Pressurizer Surge Line Piping Welds and Thick Section Primary System Cast Piping Welds JCN N6398, Task 2A

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Aaron A.; Denslow, Kayte M.; Cinson, Anthony D.; Morra, Marino; Crawford, Susan L.; Prowant, Matthew S.; Cumblidge, Stephen E.; Anderson, Michael T.

    2008-07-21

    Research is being conducted for the NRC at PNNL to assess the effectiveness and reliability of advanced NDE methods for the inspection of LWR components. The scope of this research encompasses primary system pressure boundary materials including cast austenitic stainless steels (CASS), dissimilar metal welds (DMWs), piping with corrosion-resistant cladding, weld overlays, and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in coarse-grained steel components. This interim technical letter report (TLR) provides a synopsis of recent investigations at PNNL aimed at evaluating the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of CASS welds in nuclear reactor piping. A description of progress, recent developments and interim results are provided.

  20. Experimental analysis of dissimilar metal weld joint: Ferritic to austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Rathod, Dinesh W., E-mail: dineshvrathod@gmail.com [Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi 110016 (India); Pandey, Sunil [Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi 110016 (India); Singh, P.K. [Bhabha Atomic Research Centre, Mumbai 400085 (India); Prasad, Rajesh [Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2015-07-15

    The dissimilar metal weld (DMW) joint between SA508Gr.3Cl.1 ferritic steel and SS304LN using Inconel 82/182 consumables was required in the nuclear power plants. The joint integrity assessment of these welds requires mechanical and metallurgical properties evaluation in weldment regions. The joint was subjected to 100% radiography test and bend test and transverse tensile test. Welding and testing were carried out as per the requirements of ASME Sec-IX and acceptance criteria as per ASME Sec-III. The transverse tensile test results indicated the failure from the weld metal although it satisfies the minimum strength requirement of the ASME requirements; therefore, the DMW joint was analyzed in detail. Straight bead deposition technique, fine slag inclusion, less reliable radiograph technique, plastic instability stress, yield strength ratio and metallurgical deteriorations have been contributed to failure of the DMW joint from the weld region. In the present work, the factors contributing to the fracture from weld metal have been discussed and analyzed.

  1. Qualification of phased array ultrasonic examination on T-joint weld of austenitic stainless steel for ITER vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G.H. [ITER Korea, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Park, C.K., E-mail: love879@hanmail.net [ITER Korea, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Jin, S.W.; Kim, H.S.; Hong, K.H.; Lee, Y.J.; Ahn, H.J.; Chung, W. [ITER Korea, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Jung, Y.H.; Roh, B.R. [Hyundai Heavy Industries Co. Ltd., Ulsan 682-792 (Korea, Republic of); Sa, J.W.; Choi, C.H. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

    2016-11-01

    Highlights: • PAUT techniques has been developed by Hyundai Heavy Industries Co., LTD (HHI) and Korea Domestic Agency (KODA) to verify and settle down instrument calibration, test procedures, image processing, and so on. As the first step of development for PAUT technique, Several dozens of qualification blocks with artificial defects, which are parallel side drilled hole, embedded lack of fusion, embedded repair weld notch, and so on, have been designed and fabricated to simulate all potential defects during welding process. Real UT qualification group-1 for T-joint weld was successfully conducted in front of ANB inspector. • In this paper, remarkable progresses of UT qualification are presented for ITER vacuum vessel. - Abstract: Full penetration welding and 100% volumetric examination are required for all welds of pressure retaining parts of the ITER Vacuum Vessel (VV) according to RCC-MR Code and French Order of Nuclear Pressure Equipment (ESPN). The NDE requirement is one of important technical issues because radiographic examination (RT) is not applicable to many welding joints. Therefore the ultrasonic examination (UT) has been selected as an alternative method. Generally the UT on the austenitic welds is regarded as a great challenge due to the high attenuation and dispersion of the ultrasonic signal. In this paper, Phased array ultrasonic examination (PAUT) has been introduced on double sided T-shape austenitic welds of the ITER VV as a major NDE method as well as RT. Several dozens of qualification blocks with artificial defects, which are parallel side drilled hole, embedded lack of fusion, embedded repair weld notch, embedded parallel vertical notch, and so on, have been designed and fabricated to simulate all potential defects during welding process. PAUT techniques on the thick austenitic welds have been developed taking into account the acceptance criteria. Test procedure including calibration of equipment is derived and qualified through

  2. Optimal design for laser beam butt welding process parameter using artificial neural networks and genetic algorithm for super austenitic stainless steel

    Science.gov (United States)

    Sathiya, P.; Panneerselvam, K.; Soundararajan, R.

    2012-09-01

    Laser welding input parameters play a very significant role in determining the quality of a weld joint. The joint quality can be defined in terms of properties such as weld bead geometry, mechanical properties and distortion. Therefore, mechanical properties should be controlled to obtain good welded joints. In this study, the weld bead geometry such as depth of penetration (DP), bead width (BW) and tensile strength (TS) of the laser welded butt joints made of AISI 904L super austenitic stainless steel were investigated. Full factorial design was used to carry out the experimental design. Artificial Neural networks (ANN) program was developed in MatLab software to establish the relationships between the laser welding input parameters like beam power, travel speed and focal position and the three responses DP, BW and TS in three different shielding gases (Argon, Helium and Nitrogen). The established models were used for optimizing the process parameters using Genetic Algorithm (GA). Optimum solutions for the three different gases and their respective responses were obtained. Confirmation experiment has also been conducted to validate the optimized parameters obtained from GA.

  3. Finite element modeling of the effect of welding parameters on solidification cracking of Austenitic Stainless Steel 310

    Directory of Open Access Journals (Sweden)

    Eslam Ranjbarnodeh

    2016-12-01

    Full Text Available A transient thermo-mechanical model is employed to study the effects of welding parameters on the occurrence of solidification cracking. A finite element program, ANSYS, is employed to solve the thermal and mechanical equations while the different variables such as welding current, speed and sequence are considered in the simulation. The studied geometry was butt joint of two stainless steel plates with the thickness of 2 mm. Then, the samples were welded by TIG method without filler. To verify the numerical results, the model outputs were checked with the experimental observations and good agreement was observed. It was found that the increasing of welding current from 70 A to 100 A resulted in the increase in transverse tensile strain from 1.2 to 2.1 which can facilitate the occurrence of solidification cracking. Furthermore, the application of symmetric welding layout is an effective method to prevent solidification cracking.

  4. Feasibility of surface-coated friction stir welding tools to join AISI 304 grade austenitic stainless steel

    OpenAIRE

    A.K. Lakshminarayanan; C.S. Ramachandran; V. Balasubramanian

    2014-01-01

    An attempt is made to develop the tools that are capable enough to withstand the shear, impact and thermal forces that occur during friction stir welding of stainless steels. The atmospheric plasma spray and plasma transferred arc hardfacing processes are employed to deposit refractory ceramic based composite coatings on the Inconel 738 alloy. Five different combinations of self-fluxing alloy powder and 60% ceramic reinforcement particulate mixtures are used for coating. The best friction sti...

  5. Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by austenitic filler metal

    Energy Technology Data Exchange (ETDEWEB)

    Eghlimi, Abbas, E-mail: a.eghlimi@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Shamanian, Morteza [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Eskandarian, Masoomeh [Department of Materials Engineering, Shiraz University, Shiraz 71348-51154 (Iran, Islamic Republic of); Zabolian, Azam [Department of Natural Resources, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Szpunar, Jerzy A. [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9 (Canada)

    2015-08-15

    The evolution of microstructure and texture across an as-welded dissimilar UNS S32750 super duplex/UNS S30403 austenitic stainless steel joint welded by UNS S30986 (AWS A5.9 ER309LMo) austenitic stainless steel filler metal using gas tungsten arc welding process was evaluated by optical micrography and EBSD techniques. Due to their fabrication through rolling process, both parent metals had texture components resulted from deformation and recrystallization. The weld metal showed the highest amount of residual strain and had large austenite grain colonies of similar orientations with little amounts of skeletal ferrite, both oriented preferentially in the < 001 > direction with cub-on-cube orientation relationship. While the super duplex stainless steel's heat affected zone contained higher ferrite than its parent metal, an excessive grain growth was observed at the austenitic stainless steel's counterpart. At both heat affected zones, austenite underwent some recrystallization and formed twin boundaries which led to an increase in the fraction of high angle boundaries as compared with the respective base metals. These regions showed the least amount of residual strain and highest amount of recrystallized austenite grains. Due to the static recrystallization, the fraction of low degree of fit (Σ) coincident site lattice boundaries, especially Σ3 boundaries, was increased in the austenitic stainless steel heat affected zone, while the formation of subgrains in the ferrite phase increased the content of < 5° low angle boundaries at that of the super duplex stainless steel. - Graphical abstract: Display Omitted - Highlights: • Extensive grain growth in the HAZ of austenitic stainless steel was observed. • Intensification of < 100 > orientated grains was observed adjacent to both fusion lines. • Annealing twins with Σ3 CSL boundaries were formed in the austenite of both HAZ. • Cub-on-cube OR was observed between austenite and ferrite in the weld

  6. Effect of long-term thermal aging on the fracture toughness of austenitic stainless steel base and weld metals

    Energy Technology Data Exchange (ETDEWEB)

    Huang, F.F.

    1995-09-27

    Compact tension specimens taken from FFTF primary piping materials (Type 316 stainless steel (SS) and 16-8-2 SS weld metal) and from reactor vessel materials (304 SS and 308 SS weld metal) were heated in laboratory furnaces from 100,000 hours. Fracture toughness testing was performed on these specimens, which are 7.62- and 25.4-mm thick, respectively at the aging temperature (482 and 427 degrees). Results were analyzed with the multiple-specimen method. Thermal aging continues to reduce the fracture toughness of FFTF component materials. Results show that thermal aging has a strong effect on the toughness degradation of weld metals, particularly for 16-8-2 SS weld whose aged/unaged Jc ratio is only 0.31 after 100,000-hour aging. The fracture toughness of the 308 and 16-8-2 SS weld metals fluctuated during 20,000 to 50,000-hour aging but deteriorated as the aging time increased to 100,000 hours; the toughness degradation is significant. Fracture control based on a fracture mechanics approach should be considered

  7. Study of austenitic stainless steel welded with low alloy steel filler metal. [tensile and impact strength tests

    Science.gov (United States)

    Burns, F. A.; Dyke, R. A., Jr.

    1979-01-01

    The tensile and impact strength properties of 316L stainless steel plate welded with low alloy steel filler metal were determined. Tests were conducted at room temperature and -100 F on standard test specimens machined from as-welded panels of various chemical compositions. No significant differences were found as the result of variations in percentage chemical composition on the impact and tensile test results. The weldments containing lower chromium and nickel as the result of dilution of parent metal from the use of the low alloy steel filler metal corroded more severely in a marine environment. The use of a protective finish, i.e., a nitrile-based paint containing aluminum powder, prevented the corrosive attack.

  8. The effect of CO{sub 2} laser beam welded AISI 316L austenitic stainless steel on the viability of fibroblast cells, in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Köse, Ceyhun, E-mail: ceyhun.kose@gop.edu.tr [Faculty of Natural Sciences and Engineering, Department of Mechanical Engineering, Gaziosmanpaşa University, Tokat (Turkey); Kaçar, Ramazan, E-mail: rkacar@karabuk.edu.tr [Faculty of Technology Department of Manufacturing Engineering, Karabuk University, Karabuk 78050 (Turkey); Zorba, Aslı Pınar, E-mail: aslipinarzorba@gmail.com [Graduate School of Natural and Applied Sciences, Department of Bioengineering Cell Culture and Tissue Engineering, Yıldız Technical University, Istanbul (Turkey); Bağırova, Melahat, E-mail: mbagir@yildiz.edu.tr [Department of Bioengineering Cell Culture and Tissue Engineering, Yıldız Technical University, Istanbul (Turkey); Allahverdiyev, Adil M., E-mail: adil@yildiz.edu.tr [Department of Bioengineering Cell Culture and Tissue Engineering, Yıldız Technical University, Istanbul (Turkey)

    2016-03-01

    It has been determined by the literature research that there is no clinical study on the in vivo and in vitro interaction of the cells with the laser beam welded joints of AISI 316L biomaterial. It is used as a prosthesis and implant material and that has adequate mechanical properties and corrosion resistance characteristics. Therefore, the interaction of the CO{sub 2} laser beam welded samples and samples of the base metal of AISI 316L austenitic stainless steel with L929 fibroblast cells as an element of connective tissue under in vitro conditions has been studied. To study the effect of the base metal and the laser welded test specimens on the viability of the fibroblast cells that act as an element of connective tissues in the body, they were kept in DMEMF-12 medium for 7, 14, 28 days and 18 months. The viability study was experimentally studied using the MTT method for 7, 14, 28 days. In addition, the direct interaction of the fibroblast cells seeded on 6 different plates with the samples was examined with an inverted microscope. The MTT cell viability experiment was repeated on the cells that were in contact with the samples. The statistical relationship was analyzed using a Tukey test for the variance with the GraphPad statistics software. The data regarding metallic ion release were identified with the ICP-MS method after the laser welded and main material samples were kept in cell culture medium for 18 months. The cell viability of the laser welded sample has been detected to be higher than that of the base metal and the control based on 7th day data. However, the laser welded sample's viability of the fibroblast cells has diminished by time during the test period of 14 and 28 days and base metal shows better viability when compared to the laser welded samples. On the other hand, the base metal and the laser welded sample show better cell viability effect when compared to the control group. According to the ICP-MS results of the main material and

  9. The effect of CO2 laser beam welded AISI 316L austenitic stainless steel on the viability of fibroblast cells, in vitro.

    Science.gov (United States)

    Köse, Ceyhun; Kaçar, Ramazan; Zorba, Aslı Pınar; Bağırova, Melahat; Allahverdiyev, Adil M

    2016-03-01

    It has been determined by the literature research that there is no clinical study on the in vivo and in vitro interaction of the cells with the laser beam welded joints of AISI 316L biomaterial. It is used as a prosthesis and implant material and that has adequate mechanical properties and corrosion resistance characteristics. Therefore, the interaction of the CO2 laser beam welded samples and samples of the base metal of AISI 316L austenitic stainless steel with L929 fibroblast cells as an element of connective tissue under in vitro conditions has been studied. To study the effect of the base metal and the laser welded test specimens on the viability of the fibroblast cells that act as an element of connective tissues in the body, they were kept in DMEMF-12 medium for 7, 14, 28 days and 18 months. The viability study was experimentally studied using the MTT method for 7, 14, 28 days. In addition, the direct interaction of the fibroblast cells seeded on 6 different plates with the samples was examined with an inverted microscope. The MTT cell viability experiment was repeated on the cells that were in contact with the samples. The statistical relationship was analyzed using a Tukey test for the variance with the GraphPad statistics software. The data regarding metallic ion release were identified with the ICP-MS method after the laser welded and main material samples were kept in cell culture medium for 18 months. The cell viability of the laser welded sample has been detected to be higher than that of the base metal and the control based on 7th day data. However, the laser welded sample's viability of the fibroblast cells has diminished by time during the test period of 14 and 28 days and base metal shows better viability when compared to the laser welded samples. On the other hand, the base metal and the laser welded sample show better cell viability effect when compared to the control group. According to the ICP-MS results of the main material and laser welded

  10. Technical Letter Report Assessment of Ultrasonic Phased Array Inspection Method for Welds in Cast Austenitic Stainless Steel Pressurizer Surge Line Piping JCN N6398, Task 1B

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Mathews, Royce; Moran, Traci L.; Anderson, Michael T.

    2009-07-28

    Research is being conducted for the U.S. Nuclear Regulatory Commission (NRC) at the Pacific Northwest National Laboratory (PNNL) to assess the effectiveness and reliability of advanced nondestructive examination (NDE) methods for the inspection of light water reactor components. The scope of this research encompasses primary system pressure boundary materials including cast austenitic stainless steels (CASS); dissimilar metal welds; piping with corrosion-resistant cladding; weld overlays, inlays and onlays; and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in coarse-grained steel components. In this effort, PNNL supports cooperation with Commissariat à l’Energie Atomique (CEA) to assess reliable inspection of CASS materials. The NRC Project Manager has established a cooperative effort with the Institut de Radioprotection et de Surete Nucleaire (IRSN). CEA, under funding from IRSN, are supporting collaborative efforts with the NRC and PNNL. Regarding its work on the NDE of materials, CEA is providing its modeling software (CIVA) in exchange for PNNL offering expertise and data related to phased-array detection and sizing, acoustic attenuation, and back scattering on CASS materials. This collaboration benefits the NRC because CEA performs research and development on CASS for Électricité de France (EdF). This technical letter report provides a summary of a technical evaluation aimed at assessing the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of welds in CASS pressurizer (PZR) surge line nuclear reactor piping. A set of thermal fatigue cracks (TFCs) was implanted into three CASS PZR surge-line specimens (pipe-to-elbow welds) that were fabricated using vintage CASS materials formed in the 1970s, and flaw responses from these cracks were used to evaluate detection and sizing

  11. The Effect of Shielding N{sub 2} gas on The Pitting Corrosion of Seal-welded Super Austenitic Stainless Steel by Autogenous Welding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Tae; Kim, Young Sik [Andong National University, Andong (Korea, Republic of); Chang, Hyun Young [KEPCO Engineering and Construction Company, Gimcheon (Korea, Republic of)

    2017-04-15

    Many research efforts on the effect of nitrogen on the corrosion resistance of stainless steels have been reported, but little research has been conducted on the effect of nitrogen for the weldment of stainless steels by the seal-weld method. Therefore, this work focused on the determining the corrosion resistance of tube/tube sheet mock-up specimen for sea water condensers, and elucidating the effect of shielding nitrogen gas on its resistance. The pitting corrosion of autogenously welded specimen propagated preferentially along the dendritic structure. Regardless of the percent of shielding nitrogen gas, the analyzed nitrogen contents were very much lower than that of the bulk specimen. This can be arisen because the nitrogen in shielding gas may partly dissolve into the weldment, but simultaneously during the welding process, nitrogen in the alloy may escape into the atmosphere. However, the pitting resistance equivalent number (PREN) of the interdendrite area was higher than that of the dendrite arm, regardless of the shielding gas percent; and the PREN of the interdendrite area was higher than that of the base metal; the PREN of the dendrite arm was lower than that of the base metal because of the formation of (Cr, Mo) rich phases by welding.

  12. Welding Behavior of Free Machining Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    BROOKS,JOHN A.; ROBINO,CHARLES V.; HEADLEY,THOMAS J.; MICHAEL,JOSEPH R.

    2000-07-24

    The weld solidification and cracking behavior of sulfur bearing free machining austenitic stainless steel was investigated for both gas-tungsten arc (GTA) and pulsed laser beam weld processes. The GTA weld solidification was consistent with those predicted with existing solidification diagrams and the cracking response was controlled primarily by solidification mode. The solidification behavior of the pulsed laser welds was complex, and often contained regions of primary ferrite and primary austenite solidification, although in all cases the welds were found to be completely austenite at room temperature. Electron backscattered diffraction (EBSD) pattern analysis indicated that the nature of the base metal at the time of solidification plays a primary role in initial solidification. The solid state transformation of austenite to ferrite at the fusion zone boundary, and ferrite to austenite on cooling may both be massive in nature. A range of alloy compositions that exhibited good resistance to solidification cracking and was compatible with both welding processes was identified. The compositional range is bounded by laser weldability at lower Cr{sub eq}/Ni{sub eq} ratios and by the GTA weldability at higher ratios. It was found with both processes that the limiting ratios were somewhat dependent upon sulfur content.

  13. Welding hot cracking in an austenitic stainless steel; Fissuration a chaud en soudage d'un acier inoxydable austenitique

    Energy Technology Data Exchange (ETDEWEB)

    Kerrouault, N

    2001-07-01

    The occurrence of hot cracking is linked to several conditions, in particular, the composition of the material and the local strains due to clambering. The aim of this study is to better analyse the implied mechanisms and to lead to a local thermomechanical criterion for hot cracking. The example studied is an AISI 321-type stainless steel (X10CrNiTi18-12) strongly prone to cracking. Two weldability tests are studied: - the first one consists in carrying out a fusion line by the TIG process on a thin sheet. In the case of the defect occurrence, the crack is longitudinal and follows the back of the molten bath. The influence of the operating conditions welding (speed, welding heat input, width test sample) is studied. - the second one is the Varestraint test. It is widely used to evaluate the sensitivity of a material to hot cracking. It consists in loading the material by bending during a fusion line by the TIG process and in characterising the defects quantity (length, number). Various thermal and mechanical instrumentation methods were used. The possibilities of a local instrumentation instrumentation being limited because of the melting, the experimental results were complemented by a numerical modelling whose aim is to simulate the thermomechanical evolution of the loading thanks to the finite element analysis code ABAQUS. First, the heat input for thermal simulation is set by the use of an inverse method in order to optimise the energy deposit mode during welding in the calculation. Then, the mechanical simulation needs the input of a constitutive law that fits the mechanical behaviour over a wide temperature range from ambient to melting temperature. Thus, a mechanical characterization is performed by selecting strain values and strain rates representative of what the material undergoes during the tests. The results come from tensile and compressive tests and allow to settle an elasto-visco-plastic constitutive law over temperatures up to liquidus. Once

  14. High Mn austenitic stainless steel

    Science.gov (United States)

    Yamamoto, Yukinori [Oak Ridge, TN; Santella, Michael L [Knoxville, TN; Brady, Michael P [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Liu, Chain-tsuan [Knoxville, TN

    2010-07-13

    An austenitic stainless steel alloy includes, in weight percent: >4 to 15 Mn; 8 to 15 Ni; 14 to 16 Cr; 2.4 to 3 Al; 0.4 to 1 total of at least one of Nb and Ta; 0.05 to 0.2 C; 0.01 to 0.02 B; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1W; up to 3 Cu; up to 1 Si; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale including alumina, nanometer scale sized particles distributed throughout the microstructure, the particles including at least one of NbC and TaC, and a stable essentially single phase FCC austenitic matrix microstructure that is essentially delta-ferrite-free and essentially BCC-phase-free.

  15. Consitutive modeling of metastable austenitic stainless steel

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Perdahcioglu, Emin Semih

    2008-01-01

    Metastable austenitic stainless steels combine high formability and high strength, which are generally opposing properties in materials. This property is a consequence of the martensitic phase transformation that takes place during deformation. This transformation is purely mechanically induced

  16. Constitutive modeling of metastable austenitic stainless steel

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Geijselaers, Hubertus J.M.; Huetink, Han; Khan, A.

    2010-01-01

    A physically based, macroscale constitutive model has been developed that can describe the complex mechanical behavior of metastable austenitic stainless steels. In the developed model a generalized model for the mechanically induced martensitic transformation is introduced. Mechanical tests have

  17. Development and application of specially-focused ultrasonic transducers to location and sizing of defects in 75 mm- to 127 mm-thick austenitic stainless steel weld metals

    Energy Technology Data Exchange (ETDEWEB)

    Dalder, E.N.C.; Benson, S.; McKinley, B.J.; Carodiskey, T.

    1992-08-01

    Special UT transducer parts, capable of focusing incident signals within a 25 mm {times} 25 mm {times} 25 mm volume in an austenitic stainless weld metal at depths that varied from 25 mm to 127 mm, were developed and demonstrated to be capable of detecting a defect with cross section equivalent to that of a 4.76 mm-dia flat-bottom hole. Defect length sizing could be accomplished to {plus_minus}50% for 100% of the time and to {plus_minus}25% on selected defect types as follows: porosity groups, 100%; cracks, 67%; combined slag and porosity, 60%; and linear slag indications, 59%. Extensive linear elastic-fracture-mechanics analyses were performed to establish allowable defect sizes at functions of stress, based on a cyclic-life criterion of 10{sup 3} full power cycles of the MFTF-B magnet system. These defect sizes were used to determine which UT indicating were to be removed and repaired and which were to be retained and their recorded sizes and locations.

  18. Pulsed current and dual pulse gas metal arc welding of grade AISI: 310S austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    A. Mathivanan

    2015-09-01

    Full Text Available The transverse shrinkage, mechanical and metallurgical properties of AISI: 310S ASS weld joints prepared by P-GMAW and DP-GMAW processes were investigated. It was observed that the use of the DP-GMAW process improves the aforementioned characteristics in comparison to that of the P-GMAW process. The enhanced quality of weld joints obtained with DP-GMAW process is primarily due to the combined effect of pulsed current and thermal pulsation (low frequency pulse. During the thermal pulsation period, there is a fluctuation of wire feed rate, which results in the further increase in welding current and the decrease in arc voltage. Because of this synchronization between welding current and arc voltage during the period of low frequency pulse, the DP-GMAW deposit introduces comparatively more thermal shock compared to the P-GMAW deposit, thereby reducing the heat input and improves the properties of weld joints.

  19. Experimental Determination of the Primary Solidification Phase dependency on the solidification velocity for 17 different austenitic stainless steel compositions

    DEFF Research Database (Denmark)

    Laursen, Birthe Nørgaard; Olsen, Flemming Ove; Yardy, John

    1997-01-01

    , the primary solidification phase is found to change from ferrite to austenite.A novel laser remelting technique has been modified to enable the transition velocity for laser welded austenitic stainless steels to be deermined experimentally and on the basis of results from 17 different alloy compositions......When studying laser welding of austenitic stainless steel, hot cracking is frequently observed. To prevent hot cracking in laser welded stainless steel it is advantageous to obtain primary solidification of the ferrite phase that subsequently, on cooling, transforms in the solid state...... to the austenite phase.Most stainless steels are weldable by conventional welding techniques. However, during laser weldng the solidification velocities can be very much higher than by conventional welding techniques. By increasing the solidification velocity to a critical value known as the transition velocity...

  20. Characterization of Stainless Steel Welding Fume Particles : Influence of Stainless Steel Grade, Welding Parameters and Particle Size

    OpenAIRE

    Mei, Nanxuan

    2016-01-01

    Welding is a widely used method to join two pieces of stainless steel. Since it produces a large amount of fume during the process, it can cause adverse health effects. The welding fume particles contain many elements. Among them Cr, Mn and Ni are of concern. These three elements can cause diseases if inhaled by humans, especially Cr(VI). In this project, welding fume particles are collected during welding of different stainless steel grades (austenitic AISI 304L and duplex LDX2101). Furtherm...

  1. Cast alumina forming austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P

    2013-04-30

    An austenitic stainless steel alloy consisting essentially of, in terms of weight percent ranges 0.15-0.5C; 8-37Ni; 10-25Cr; 2.5-5Al; greater than 0.6, up to 2.5 total of at least one element selected from the group consisting of Nb and Ta; up to 3Mo; up to 3Co; up to 1W; up to 3Cu; up to 15Mn; up to 2Si; up to 0.15B; up to 0.05P; up to 1 total of at least one element selected from the group consisting of Y, La, Ce, Hf, and Zr; <0.3Ti+V; <0.03N; and, balance Fe, where the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale comprising alumina, and a stable essentially single phase FCC austenitic matrix microstructure, the austenitic matrix being essentially delta-ferrite free and essentially BCC-phase-free. A method of making austenitic stainless steel alloys is also disclosed.

  2. Pitting corrosion resistant austenite stainless steel

    Science.gov (United States)

    van Rooyen, D.; Bandy, R.

    A pitting corrosion resistant austenite stainless steel comprises 17 to 28 wt. % chromium, 15 to 26 wt. % nickel, 5 to 8 wt. % molybdenum, and 0.3 to 0.5 wt. % nitrogen, the balance being iron, unavoidable impurities, minor additions made in the normal course of melting and casting alloys of this type, and may optionally include up to 10 wt. % of manganese, up to 5 wt. % of silicon, and up to 0.08 wt. % of carbon.

  3. Market Opportunities for Austenitic Stainless Steels in SO2 Scrubbers

    Science.gov (United States)

    Michels, Harold T.

    1980-10-01

    Recent U.S. federal legislation has created new opportunities for SO2 scrubbers because all coals, even low-sulfur western coals, will probably require scrubbing to remove SO2 from gaseous combustion products. Scrubbing, the chemical absorption of SO2 by vigorous contact with a slurry—usually lime or limestone—creates an aggressive acid-chloride solution. This presents a promising market for pitting-resistant austenitic stainless steels, but there is active competition from rubber and fiberglass-lined carbon steel. Since the latter are favored on a first-cost basis, stainless steels must be justified on a cost/performance or life-cost basis. Nickel-containing austenitic alloys are favored because of superior field fabricability. Ferritic stainless steels have little utility in this application because of limitations in weldability and resulting poor corrosion resistance. Inco corrosion test spools indicate that molybdenum-containing austenitic alloys are needed. The leanest alloys for this application are 316L and 317L. Low-carbon grades of stainless steel are specified to minimize corrosion in the vicinity of welds. More highly alloyed materials may be required in critical areas. At present, 16,000 MW of scrubber capacity is operational and 17,000 MW is under construction. Another 29,000 MW is planned, bringing the total to 62,000 MW. Some 160,000 MW of scrubber capacity is expected to be placed in service over the next 10 years. This could translate into a total potential market of 80,000 tons of alloy plate for new power industry construction in the next decade. Retrofitting of existing power plants plus scrubbers for other applications such as inert gas generators for oil tankers, smelters, municipal incinerators, coke ovens, the pulp and paper industry, sulfuric acid plants, and fluoride control in phosphoric acid plants will add to this large market.

  4. Condition and problems of ultrasonic inspection of austenitic weld joints

    Energy Technology Data Exchange (ETDEWEB)

    Grebennikov, V.V.; Gurvich, A.K.

    1986-05-01

    A review is presented of methods and means of ultrasonic inspection of austenitic weld joints. The basic structural factors influencing the propagation of ultrasonic vibrations in austenitic weld joints are considered. The influence of the ultrasonic inspection parameters on the ratio of the useful signal to the average level of structural interferences is shown. Acoustic models of austenitic weld joints are presented. The basic methods of increasing the interference resistance and apparatus for inspection of acoustic weld joints are described.

  5. Weld bonding of stainless steel

    DEFF Research Database (Denmark)

    Santos, I. O.; Zhang, Wenqi; Goncalves, V.M.

    2004-01-01

    This paper presents a comprehensive theoretical and experimental investigation of the weld bonding process with the purpose of evaluating its relative performance in case of joining stainless steel parts, against alternative solutions based on structural adhesives or conventional spot-welding. Th...

  6. Transformation in austenitic stainless steel sheet under different loading directions

    NARCIS (Netherlands)

    van den Boogaard, Antonius H.; Krauer, J.; Hora, P.

    2011-01-01

    The stress-strain relation for austenitic stainless steels is based on 2 main contributions: work hardening and a phase transformation from austenite to martensite. The transformation is highly temperature dependent. In most models for phase transformation from austenite to martensite, the stress

  7. Transformation in Austenitic Stainless Steel Sheet under Different Loading Directions

    NARCIS (Netherlands)

    van den Boogaard, Antonius H.; Krauer, J.; Hora, P.

    2011-01-01

    The stress-strain relation for austenitic stainless steels is based on 2 main contributions: work hardening and a phase transformation from austenite to martensite. The transformation is highly temperature dependent. In most models for phase transformation from austenite to martensite, the stress

  8. Cast alumina forming austenitic stainless steels

    Science.gov (United States)

    Muralidharan, Govindarajan; Yamamoto, Yukinori; Brady, Michael P

    2013-04-30

    An austenitic stainless steel alloy consisting essentially of, in terms of weight percent ranges 0.15-0.5C; 8-37Ni; 10-25Cr; 2.5-5Al; greater than 0.6, up to 2.5 total of at least one element selected from the group consisting of Nb and Ta; up to 3Mo; up to 3Co; up to 1W; up to 3Cu; up to 15Mn; up to 2Si; up to 0.15B; up to 0.05P; up to 1 total of at least one element selected from the group consisting of Y, La, Ce, Hf, and Zr; stainless steel alloys is also disclosed.

  9. Studies of Hot Crack Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther

    During the present work crack testing concerning small and fast solidifying laser welds in austenitic stainless steel has been studied. A set of methods has been applied to investigate alloy properties, including ·Application of known information to predict solidification phases from the alloy...... composition. ·Weld metal solidification rate measurements for prediction of phases. ·Various crack tests to assess the crack susceptibility of alloys. ·A combination of the above for selection of suitable, weldable alloys. The possibility of using such specific methods for alloys and applications has been...... investigated and recommendations are given. From studies of literature it is found that the austenitic stainless steels have lowest crack susceptibility by a solidification course leaving approximately 15% rest ferrite in the weld metal. The alloys properties and the solidification rate determines the amount...

  10. Weld solidification cracking in 304 to 304L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Martinez, Raymond J [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-01-01

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found. This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GT A W showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  11. Weld solidification cracking in 304 to 204L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-09-15

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found.This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GTAW showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  12. Nickel-free austenitic stainless steels for medical applications

    OpenAIRE

    Yang, Ke; Ren, Yibin

    2010-01-01

    The adverse effects of nickel ions being released into the human body have prompted the development of high-nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also much improves steel properties. Here we review the harmful effects associated with nickel in medical stainless steels, the advantages of nitrogen in stainless steels, and emphatically, the development of high-nitrogen nickel-free stainl...

  13. Nickel-free austenitic stainless steels for medical applications

    Directory of Open Access Journals (Sweden)

    Ke Yang and Yibin Ren

    2010-01-01

    Full Text Available The adverse effects of nickel ions being released into the human body have prompted the development of high-nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also much improves steel properties. Here we review the harmful effects associated with nickel in medical stainless steels, the advantages of nitrogen in stainless steels, and emphatically, the development of high-nitrogen nickel-free stainless steels for medical applications. By combining the benefits of stable austenitic structure, high strength and good plasticity, better corrosion and wear resistances, and superior biocompatibility compared to the currently used 316L stainless steel, the newly developed high-nitrogen nickel-free stainless steel is a reliable substitute for the conventional medical stainless steels.

  14. Mechanical characteristics of welded joints between different stainless steels grades

    Science.gov (United States)

    Topolska, S.; Łabanowski, J.

    2017-08-01

    Investigation of mechanical characteristics of welded joints is one of the most important tasks that allow determining their functional properties. Due to the very high, still rising, cost of some stainless steels it is justified, on economic grounds, welding austenitic stainless steel with steels that are corrosion-resistant like duplex ones. According to forecasts the price of corrosion resistant steels stil can increase by 26 ÷ 30%. For technical reasons welded joints require appropriate mechanical properties such as: tensile strength, bending, ductility, toughness, and resistance to aggressive media. Such joints are applied in the construction of chemical tankers, apparatus and chemical plants and power steam stations. Using the proper binder makes possible the welds directly between the elements of austenitic stainless steels and duplex ones. It causes that such joits behave satisfactorily in service in such areas like maritime constructions and steam and chemical plants. These steels have high mechanical properties such as: the yield strength, the tensile strength and the ductility as well as the resistance to general corrosion media. They are resistant to both pitting and stress corrosions. The relatively low cost of production of duplex steels, in comparison with standard austenitic steels, is inter alia, the result of a reduced amount of scarce and expensive Nickel, which is seen as a further advantage of these steels.

  15. Radiation resistant austenitic stainless steel alloys

    Science.gov (United States)

    Maziasz, P.J.; Braski, D.N.; Rowcliffe, A.F.

    1987-02-11

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01 to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties. 4 figs.

  16. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing

    National Research Council Canada - National Science Library

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process...

  17. Cyclic shear behavior of austenitic stainless steel sheet

    NARCIS (Netherlands)

    Geijselaers, Hubertus J.M.; Bor, Teunis Cornelis; Hilkhuijsen, P.; van den Boogaard, Antonius H.

    2015-01-01

    An austenitic stainless steel has been subjected to large amplitude strain paths containing a strain reversal. During the tests, apart from the stress and the strain also magnetic induction was measured to monitor the transformation of austenite to martensite. From the in-situ magnetic induction

  18. Characterization of duplex stainless steel weld metals obtained by hybrid plasma-gas metal arc welding

    Directory of Open Access Journals (Sweden)

    Koray Yurtisik

    2013-09-01

    Full Text Available Despite its high efficiency, autogenous keyhole welding is not well-accepted for duplex stainless steels because it causes excessive ferrite in as-welded duplex microstructure, which leads to a degradation in toughness and corrosion properties of the material. Combining the deep penetration characteristics of plasma arc welding in keyhole mode and metal deposition capability of gas metal arc welding, hybrid plasma - gas metal arc welding process has considered for providing a proper duplex microstructure without compromising the welding efficiency. 11.1 mm-thick standard duplex stainless steel plates were joined in a single-pass using this novel technique. Same plates were also subjected to conventional gas metal arc and plasma arc welding processes, providing benchmarks for the investigation of the weldability of the material. In the first place, the hybrid welding process enabled us to achieve less heat input compared to gas metal arc welding. Consequently, the precipitation of secondary phases, which are known to be detrimental to the toughness and corrosion resistance of duplex stainless steels, was significantly suppressed in both fusion and heat affected zones. Secondly, contrary to other keyhole techniques, proper cooling time and weld metal chemistry were achieved during the process, facilitating sufficient reconstructive transformation of austenite in the ferrite phase.

  19. Welding of nickel free high nitrogen stainless steel: Microstructure and mechanical properties

    Directory of Open Access Journals (Sweden)

    Raffi Mohammed

    2017-04-01

    Full Text Available High nitrogen stainless steel (HNS is a nickel free austenitic stainless steel that is used as a structural component in defence applications for manufacturing battle tanks as a replacement of the existing armour grade steel owing to its low cost, excellent mechanical properties and better corrosion resistance. Conventional fusion welding causes problems like nitrogen desorption, solidification cracking in weld zone, liquation cracking in heat affected zone, nitrogen induced porosity and poor mechanical properties. The above problems can be overcome by proper selection and procedure of joining process. In the present work, an attempt has been made to correlate the microstructural changes with mechanical properties of fusion and solid state welds of high nitrogen steel. Shielded metal arc welding (SMAW, gas tungsten arc welding (GTAW, electron beam welding (EBW and friction stir welding (FSW processes were used in the present work. Optical microscopy, scanning electron microscopy and electron backscatter diffraction were used to characterize microstructural changes. Hardness, tensile and bend tests were performed to evaluate the mechanical properties of welds. The results of the present investigation established that fully austenitic dendritic structure was found in welds of SMAW. Reverted austenite pools in the martensite matrix in weld zone and unmixed zones near the fusion boundary were observed in GTA welds. Discontinuous ferrite network in austenite matrix was observed in electron beam welds. Fine recrystallized austenite grain structure was observed in the nugget zone of friction stir welds. Improved mechanical properties are obtained in friction stir welds when compared to fusion welds. This is attributed to the refined microstructure consisting of equiaxed and homogenous austenite grains.

  20. Effect of high energy shot peening pressure on the stress corrosion cracking of the weld joint of 304 austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhiming, Lu, E-mail: lzm@zjut.edu.cn; Laimin, Shi, E-mail: 810050107@qq.com; Shenjin, Zhu, E-mail: 523469865@qq.com; Zhidong, Tang, E-mail: 466054569@qq.com; Yazhou, Jiang, E-mail: 191268219@qq.com

    2015-06-18

    The weld joint of 304 stainless steel is treated using high energy shot peening(HESP) with various shot peening pressures. The grain size and metallographic microstructure of the specimen surface layer are analyzed using the X-ray diffraction method, and the surface hardness is measured. Slow strain rate tension tests are then performed to investigate the effect of shot peening pressure on the stress corrosion sensitivity. The results show that in the surface layer of the specimen, the grain refinement, hardness and the strain-induced plastic deformation all increase with the increasing shot peening pressure. Martensitic transformation is observed in the surface layer after being treated with HESP. The martensite phase ratio is found to increase with increasing shot peening pressure. The result also shows that the effects of the shot peening treatment on the stress corrosion sensitivity index depend on the shot peening pressure. When the shot peening pressure is less than 0.4 MPa, the grain refinement effect plays the main role, and the stress corrosion sensitivity index decreases with the increasing shot peening pressure. In contrast, when the shot peening pressure is higher than 0.4 MPa, the martensite transformation effect plays the main role, the stress corrosion sensitivity index increases with increasing shot peening pressure.

  1. The influence of austenite texture on the martensitic transformation of an austenitic stainless steel.

    NARCIS (Netherlands)

    Hilkhuijsen, P.; Geijselaers, Hubertus J.M.; Bor, Teunis Cornelis

    2013-01-01

    Uniaxial tensile tests on a highly textured, fully austenitic stainless steel were performed in the transverse and rolling directions. Differences in overall material and transformation behavior were observed: transformation from the austenite phase to the martensite phase during a test in the

  2. Delta ferrite-containing austenitic stainless steel resistant to the formation of undesirable phases upon aging

    Science.gov (United States)

    Leitnaker, James M.

    1981-01-01

    Austenitic stainless steel alloys containing delta ferrite, such as are used as weld deposits, are protected against the transformation of delta ferrite to sigma phase during aging by the presence of carbon plus nitrogen in a weight percent 0.015-0.030 times the volume percent ferrite present in the alloy. The formation of chi phase upon aging is controlled by controlling the Mo content.

  3. Assessment of Hot Crack Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther; Olsen, Flemming Ove

    2003-01-01

    Crack testing concerning small and fast solidifying laser welds in austenitic stainless steel has been studied. A set of methods has been applied to investigate alloy properties, including (1) Application of known information to predict solidification phases, (2) Weld metal solidification rate...... measurements for prediction of phases, (3) Various crack tests to assess the crack susceptibility of alloys and (4) A combination of the above for selection of suitable, weldable alloys. The possibility of using such specific methods for alloys and applications has been investigated and recommendations...... crack tests, the Weeter spot weld test has been chosen to form a basis for the development of a practicable method to select specific alloys for welding applications. A new test, the Groove weld test was developed, which has reduced the time consumption and lightened the analysis effort considerably...

  4. Low-temperature creep of austenitic stainless steels

    Science.gov (United States)

    Reed, R. P.; Walsh, R. P.

    2017-09-01

    Plastic deformation under constant load (creep) in austenitic stainless steels has been measured at temperatures ranging from 4 K to room temperature. Low-temperature creep data taken from past and unreported austenitic stainless steel studies are analyzed and reviewed. Creep at cryogenic temperatures of common austenitic steels, such as AISI 304, 310 316, and nitrogen-strengthened steels, such as 304HN and 3116LN, are included. Analyses suggests that logarithmic creep (creep strain dependent on the log of test time) best describe austenitic stainless steel behavior in the secondary creep stage and that the slope of creep strain versus log time is dependent on the applied stress/yield strength ratio. The role of cold work, strain-induced martensitic transformations, and stacking fault energy on low-temperature creep behavior is discussed. The engineering significance of creep on cryogenic structures is discussed in terms of the total creep strain under constant load over their operational lifetime at allowable stress levels.

  5. Welding stainless steels for structures operating at liquid helium temperature

    Energy Technology Data Exchange (ETDEWEB)

    Witherell, C.E.

    1980-04-18

    Superconducting magnets for fusion energy reactors require massive monolithic stainless steel weldments which must operate at extremely low temperatures under stresses approaching 100 ksi (700 MPa). A three-year study was conducted to determine the feasibility of producing heavy-section welds having usable levels of strength and toughness at 4.2/sup 0/K for fabrication of these structures in Type 304LN plate. Seven welding processes were evaluated. Test weldments in full-thickness plate were made under severe restraint to simulate that of actual structures. Type 316L filler metal was used for most welds. Welds deposited under some conditions and which solidify as primary austenite have exhibited intergranular embrittlement at 4.2/sup 0/K. This is believed to be associated with grain boundary metal carbides or carbonitrides precipitated during reheating of already deposited beads by subsequent passes. Weld deposits which solidify as primary delta ferrite appear immune. Through use of fully austenitic filler metals of low nitrogen content under controlled shielded metal arc welding conditions, and through use of filler metals solidifying as primary delta ferrite where only minimum residuals remain to room temperature, welds of Type 316L composition have been made with 4.2K yield strength matching that of Type 304LN plate and acceptable levels of soundness, ductility and toughness.

  6. Modelling of sound fields through austenitic welds

    Science.gov (United States)

    Schmitz, V.; Kröning, M.; Chakhlov, S.

    2000-05-01

    The propagation paths of ultrasonic waves through austenitic weld material can not be predicted due to the anisotropic and inhomogeneous structure of the weld. To support an NDT-inspector Ogilvy's ray tracing algorithm has been implemented to follow virtually in three dimensions longitudinal, horizontal and vertical polarized shear wave propagation from the basic material through the cladding. The algorithm has been implemented in a software package "3D-CAD-Ray" which allows to model the experiment in a 3D-CAD drawing and to visualize the rays including reflections from lack of side wall fusions or inner surface connected cracks. The defects can be placed, sized or oriented arbitrarily which allows to perform a parametric study. Results of the algorithm are presented and checked against the experiment. The measured elastic constants and the orientation of the grains taken from micrographs have been entered properly into the CAD-model. The spreading effect for the sound field perpendicular to the orientation of the weld—observed during the experiments—could be confirmed for the SH-, SV- and longitudinal waves by the theoretical predictions. Animations are shown for fixed probe positions where rays and mode converted rays are shown marching on in time and for scans in pulse echo technique where the probe is moved towards the weld.

  7. Influence of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel welding joints

    Science.gov (United States)

    Zhang, Zhiqiang; Jing, Hongyang; Xu, Lianyong; Han, Yongdian; Zhao, Lei; Zhang, Jianli

    2017-02-01

    The influences of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel joints welded by gas tungsten arc welding (GTAW) and flux-cored arc welding (FCAW) with different shielding gas compositions were studied by optical microscopy, electron backscatter diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron probe microanalysis, and potentiostatic and potentiodynamic polarization methods The adding 2% N2 in shielding gas facilitated primary austenite formation in GTAW weld metal (WM) and suppressed Cr2N precipitation in GTAW weld root. In the HAZ, the banded microstructure disappeared while the coarse ferrite grains maintained same orientation as the banded ferrite in the BM. In the WM, the ferrite had one single orientation throughout a grain, whereas several families of austenite appeared. The austenite both in BM and WM enriched in Ni and nitro`gen, while Cr and Mo were concentrated in the ferrite and thus no element showed clear dendritic distribution in the WM (ER2209 and E2209T1). In addition, the secondary austenite had higher Ni content but lower Cr and Mo content than the primary austenite. The N2-supplemented shielding gas promoted nitrogen solid-solution in the primary and secondary austenite. Furthermore, the secondary austenite had relatively lower pitting resistance equivalent number (PREN) than the ferrite and primary austenite, thereby resulting in its preferential corrosion. The Cr2N precipitation led to relatively poor resistance to pitting corrosion in three HAZs and pure Ar shielding GTAW weld root. The N2-supplemented shielding gas improved pitting corrosion resistance of GTAW joint by increasing PREN of secondary austenite and suppressing Cr2N precipitation. In addition, the FCAW WM had much poorer resistance to pitting corrosion than the GTAW WM due to many O-Ti-Si-Mn inclusions. In the BM, since the austenite with lower PREN compared

  8. Weld Properties of a Free Machining Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    J. A. Brooks; S. H. Goods; C. V. Robino

    2000-08-01

    The all weld metal tensile properties from gas tungsten arc and electron beam welds in free machining austenitic stainless steels have been determined. Ten heats with sulfur contents from 0.04 to 0.4 wt.% and a wide range in Creq/Nieq ratios were studied. Tensile properties of welds with both processes were related to alloy composition and solidification microstructure. The yield and ultimate tensile strengths increased with increasing Creq/Nieq ratios and ferrite content, whereas the ductility measured by RA at fracture decreased with sulfur content. Nevertheless, a range in alloy compositions was identified that provided a good combination of both strength and ductility. The solidification cracking response for the same large range of compositions are discussed, and compositions identified that would be expected to provide good performance in welded applications.

  9. Rapid solidification in laser welding of stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Zambon, A. (Univ. di Padova (Italy)); Bonollo, F.

    1994-04-30

    The microstructural characterization of both weld beads and heat affected zones (HAZ) was carried out on austenitic (AISI 304, 316) and duplex (UNS 31803) stainless steels, laser welded under various working parameters (power, traverse speed, shielding gas), by means of light microscopy, SEM, TEM, and image analysis, with the aim of pointing out changes in the amounts of the present phases, with respect to those predicted by equilibrium diagrams. Moreover, an analytical thermal model of laser beam welding was employed in order to evaluate the cooling rates involved in the process. The thermal field analysis, checked by comparing the calculated and the actual weld beads, has been used as a tool aimed at correlating cooling rates and microstructural characteristics. (orig.)

  10. Corrosion Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Weldingh, Jakob; Olsen, Flemmming Ove

    1997-01-01

    In this paper the corrosion properties of laser welded AISI 316L stainless steel are examined. A number of different welds has been performed to test the influence of the weld parameters of the resulting corrosion properties. It has been chosen to use the potential independent critical pitting...... temperature (CPT) test as corrosion test. The following welding parameters are varied: Welding speed, lsser power, focus point position and laser operation mode (CW or pulsed)....

  11. Ultrasonic methods of testing austenite weld joints and identifying defects

    Energy Technology Data Exchange (ETDEWEB)

    Grebennikov, V.V.; Glek, Yu.S.; Grigor' ev, M.V.; Gurvich, A.K.; Markelova, E.A.; Matynova, N.A.; Zakharov, Yu.V.

    1985-01-01

    Testing welds with an austenitic structure and determining the nature of the defect by ultrasonic methods are the most complex and urgent problems in non-destructive testing of nuclear power station equipment and in many other engineering fields. A dual-frequency method and device for ultrasonic testing of austenitic welds are described. A method is presented for identifying the defects, based on ultrasonic-wave diffraction on the defect tips.

  12. The Effect of Welding Current and Composition of Stainless steel on the Panetration in GTAW

    Directory of Open Access Journals (Sweden)

    Ramazan Yılmaz

    2012-06-01

    Full Text Available In this study, welding was performed on the plates of two different types of AISI 316 and AISI 316Ti austenitic stainless steels by GTAW (Gas Tungsten Arc Welding without using welding consumable in flat position. Automatic GTAW welding machine was used to control and obtain the exact values. The effects of welding currents used in welding process and the compositions of the stainless steels materials on the penetration were investigated. Weld bead size and shape such as bead width and dept were important considerations for penetration. Welding process was performed using various welding current values. The study showed that both welding parameters and composition of the stainless steels has influence on the penetration and It is increased with increasing of welding current. Besides, P/W rate of the weldments were influenced by the current and hardness values of the weld metal decrease with increasing welding current. The microstructure of the weld metal was also changed by variation of welding current.

  13. Measurement and tailoring of residual stress in expanded austenite on austenitic stainless steel

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Winther, Grethe

    2017-01-01

    Expanded austenite on stainless steel with a high interstitial nitrogen content is characterized by elasto-plastic accommodation of the large composition-induced lattice expansion leading to huge compressive residual stress. The elasto-plastic accommodation as well as the (steep) concentration...... profile has implications for the measurement strategy to determine lattice strains and associated residual stresses with X-ray diffraction. Lattice strain measurements were performed on nitrided as well as subsequently de-nitrided expanded austenite on AISI 316L stainless steel, for various grazing...

  14. X-Ray diffraction technique applied to study of residual stresses after welding of duplex stainless steel plates

    Energy Technology Data Exchange (ETDEWEB)

    Monin, Vladimir Ivanovitch; Assis, Joaquim Teixeira de [Instituto Politecnico do Rio e Janeiro (IPRJ), Nova Friburgo, RJ (Brazil); Lopes, Ricardo Tadeu; Turibus, Sergio Noleto; Payao Filho, Joao C., E-mail: sturibus@nuclear.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil)

    2014-08-15

    Duplex stainless steel is an example of composite material with approximately equal amounts of austenite and ferrite phases. Difference of physical and mechanical properties of component is additional factor that contributes appearance of residual stresses after welding of duplex steel plates. Measurements of stress distributions in weld region were made by X-ray diffraction method both in ferrite and austenite phases. Duplex Steel plates were joined by GTAW (Gas Tungsten Arc Welding) technology. There were studied longitudinal and transverse stress components in welded butt joint, in heat affected zone (HAZ) and in points of base metal 10 mm from the weld. Residual stresses measured in duplex steel plates jointed by welding are caused by temperature gradients between weld zone and base metal and by difference of thermal expansion coefficients of ferrite and austenite phases. Proposed analytical model allows evaluating of residual stress distribution over the cross section in the weld region. (author)

  15. Effect of prior cold work on the degree of sensitisation of welded joints of AISI 316L austenitic stainless steel studied by using an electrochemical minicell

    Energy Technology Data Exchange (ETDEWEB)

    De Tiedra, Pilar [Ciencia de los Materiales e Ingenieria Metalurgica, Departamento CMeIM/EGI/ICGF/IM/IPF, Universidad de Valladolid, Escuela de Ingenierias Industriales, Paseo del Cauce 59, Valladolid 47011 (Spain); Martin, Oscar, E-mail: oml@eis.uva.es [Ciencia de los Materiales e Ingenieria Metalurgica, Departamento CMeIM/EGI/ICGF/IM/IPF, Universidad de Valladolid, Escuela de Ingenierias Industriales, Paseo del Cauce 59, Valladolid 47011 (Spain); Garcia, Cristina; Martin, Fernando; Lopez, Manuel [Ciencia de los Materiales e Ingenieria Metalurgica, Departamento CMeIM/EGI/ICGF/IM/IPF, Universidad de Valladolid, Escuela de Ingenierias Industriales, Paseo del Cauce 59, Valladolid 47011 (Spain)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Double loop shows greater sensitivity to interdendritic corrosion than single loop. Black-Right-Pointing-Pointer Fusion line sensitisation is lower than that of weld metal for all prior cold works. Black-Right-Pointing-Pointer Heat affected zone sensitisation is maximum at a prior cold work of 10%. Black-Right-Pointing-Pointer Heat affected zone sensitisation Much-Less-Than base material sensitisation for a prior cold work of 20%. - Abstract: This work aims to assess the effect of prior cold work on the degree of sensitisation of each of the four welding zones of welded joints of AISI 316L subjected to post-welding sensitisation. Electrochemical potentiokinetic reactivation and double loop electrochemical potentiokinetic reactivation tests are performed on each of the four zones by using a small-scale electrochemical cell (minicell). The results show that the degree of sensitisation of heat affected zone, which achieves its maximum at a prior cold work level of 10%, is significantly lower than that of base material for a prior cold work of 20%.

  16. Influence of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel welding joints

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhiqiang; Jing, Hongyang [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Xu, Lianyong, E-mail: xulianyong@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Han, Yongdian; Zhao, Lei [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Zhang, Jianli [Welding laboratory, Offshore Oil Engineering (Qing Dao) Company, Qing Dao 266520 (China)

    2017-02-01

    Highlights: • N{sub 2}-supplemented shielding gas promoted nitrogen solid-solution in the austenite. • Secondary austenite had higher Ni but lower Cr and Mo than primary austenite. • Pitting corrosion preferentially occurred at secondary austenite and Cr{sub 2}N. • Adding N{sub 2} in shielding gas improved pitting corrosion resistance of GTAW joint. • E2209T{sub 1} weld metal had very poor pitting corrosion resistance due to inclusions. - Abstract: The influences of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel joints welded by gas tungsten arc welding (GTAW) and flux-cored arc welding (FCAW) with different shielding gas compositions were studied by optical microscopy, electron backscatter diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron probe microanalysis, and potentiostatic and potentiodynamic polarization methods The adding 2% N{sub 2} in shielding gas facilitated primary austenite formation in GTAW weld metal (WM) and suppressed Cr{sub 2}N precipitation in GTAW weld root. In the HAZ, the banded microstructure disappeared while the coarse ferrite grains maintained same orientation as the banded ferrite in the BM. In the WM, the ferrite had one single orientation throughout a grain, whereas several families of austenite appeared. The austenite both in BM and WM enriched in Ni and nitrogen, while Cr and Mo were concentrated in the ferrite and thus no element showed clear dendritic distribution in the WM (ER2209 and E2209T{sub 1}). In addition, the secondary austenite had higher Ni content but lower Cr and Mo content than the primary austenite. The N{sub 2}-supplemented shielding gas promoted nitrogen solid-solution in the primary and secondary austenite. Furthermore, the secondary austenite had relatively lower pitting resistance equivalent number (PREN) than the ferrite and primary austenite, thereby resulting in its preferential

  17. Page 1 Stress corrosion cracking of austenitic stainless steels 691 ...

    Indian Academy of Sciences (India)

    Stress corrosion cracking of austenitic stainless steels 691 and crack growth per event computed from acoustic emission and crack growth data are presented in table 3. The crack growth per event varies from less than a micron for a solution annealed material to 15 pm for 10% cold worked material. 4.4 Fractographic ...

  18. Formation and stabilization of reversed austenite in supermartensitic stainless steel

    DEFF Research Database (Denmark)

    Nießen, Frank; Grumsen, Flemming Bjerg; Hald, John

    2017-01-01

    The formation and stabilization of reversed austenite upon inter-critical annealing was investigated in a X4CrNiMo16-5-1 (EN 1.4418) supermartensitic stainless steel by means of scanning electron microscopy, electron backscatter-diffraction, transmission electron microscopy, energy-dispersive X...

  19. Automatic welding of stainless steel tubing

    Science.gov (United States)

    Clautice, W. E.

    1978-01-01

    The use of automatic welding for making girth welds in stainless steel tubing was investigated as well as the reduction in fabrication costs resulting from the elimination of radiographic inspection. Test methodology, materials, and techniques are discussed, and data sheets for individual tests are included. Process variables studied include welding amperes, revolutions per minute, and shielding gas flow. Strip chart recordings, as a definitive method of insuring weld quality, are studied. Test results, determined by both radiographic and visual inspection, are presented and indicate that once optimum welding procedures for specific sizes of tubing are established, and the welding machine operations are certified, then the automatic tube welding process produces good quality welds repeatedly, with a high degree of reliability. Revised specifications for welding tubing using the automatic process and weld visual inspection requirements at the Kennedy Space Center are enumerated.

  20. Fiber laser welding of austenitic steel and commercially pure copper butt joint

    Science.gov (United States)

    Kuryntsev, S. V.; Morushkin, A. E.; Gilmutdinov, A. Kh.

    2017-03-01

    The fiber laser welding of austenitic stainless steel and commercially pure copper in butt joint configuration without filler or intermediate material is presented. In order to melt stainless steel directly and melt copper via heat conduction a defocused laser beam was used with an offset to stainless steel. During mechanical tests the weld seam was more durable than heat affected zone of copper so samples without defects could be obtained. Three process variants of offset of the laser beam were applied. The following tests were conducted: tensile test of weldment, intermediate layer microhardness, optical metallography, study of the chemical composition of the intermediate layer, fractography. Measurements of electrical resistivity coefficients of stainless steel, copper and copper-stainless steel weldment were made, which can be interpreted or recalculated as the thermal conductivity coefficient. It shows that electrical resistivity coefficient of cooper-stainless steel weldment higher than that of stainless steel. The width of intermediate layer between stainless steel and commercially pure copper was 41-53 μm, microhardness was 128-170 HV0.01.

  1. The Microstructure and Pitting Resistance of Weld Joints of 2205 Duplex Stainless Steel

    Science.gov (United States)

    Wu, Mingfang; Liu, Fei; Pu, Juan; Anderson, Neil E.; Li, Leijun; Liu, Dashuang

    2017-11-01

    2205 duplex stainless steel (DSS) was welded by submerged arc welding. The effects of both heat input and groove type on the ferrite/austenite ratio and elemental diffusion of weld joints were investigated. The relationships among welding joint preparation, ferrite/austenite ratio, elemental diffusion, and pitting corrosion resistance of weld joints were analyzed. When the Ni content of the weld wire deposit was at minimum 2-4% higher than that of 2205 DSS base metal, the desired ratio of ferrite/austenite and elemental partitioning between the austenite and ferrite phases were obtained. While the pitting sensitivity of weld metal was higher than that of base metal, the self-healing capability of the passive film of weld metal was better than that of the base metal when a single V-type groove was used. Furthermore, the heat input should be carefully controlled since pitting corrosion occurred readily in the coarse-grained heat-affected zone near the fusion line of welded joints.

  2. The propagation of ultrasound in an austenitic weld

    DEFF Research Database (Denmark)

    Halkjær, Søren; Sørensen, Mads Peter; Kristensen, Anders Wang

    2000-01-01

    The propagation of ultrasound through an austenitic weld is investigated experimentally as well as in a numerical simulation. The weld is insonified at normal incidence to the fusion line with a longitudinal contact transducer. In order to experimentally trace the ultrasound through the weld......, slices of different thicknesses from the original weld have been fabricated. Through-transmission A-scans have then been produced for each weld slice and compared with the corresponding numerical simulation. A comparison of the direction of ultrasound propagation through the weld for the two approaches...... shows quite good agreement. However, attenuation due to scattering at grain boundaries in the weld is poorly modelled in the simulation. In order to improve this, a better model of the weld is needed....

  3. Oxidation resistant high creep strength austenitic stainless steel

    Science.gov (United States)

    Brady, Michael P.; Pint, Bruce A.; Liu, Chain-Tsuan; Maziasz, Philip J.; Yamamoto, Yukinori; Lu, Zhao P.

    2010-06-29

    An austenitic stainless steel displaying high temperature oxidation and creep resistance has a composition that includes in weight percent 15 to 21 Ni, 10 to 15 Cr, 2 to 3.5 Al, 0.1 to 1 Nb, and 0.05 to 0.15 C, and that is free of or has very low levels of N, Ti and V. The alloy forms an external continuous alumina protective scale to provide a high oxidation resistance at temperatures of 700 to 800.degree. C. and forms NbC nanocarbides and a stable essentially single phase fcc austenitic matrix microstructure to give high strength and high creep resistance at these temperatures.

  4. The sub-zero Celsius treatment of precipitation hardenable semi-austenitic stainless steel

    DEFF Research Database (Denmark)

    Villa, Matteo; Hansen, Mikkel Fougt; Somers, Marcel A. J.

    2015-01-01

    A precipitation hardenable semi-austenitic stainless steel AISI 632 grade was austenitized according to industrial specifications and thereafter subjected to isothermal treatment at sub-zero Celsius temperatures. During treatment, austenite transformed to martensite. The isothermal austenite-to-m...

  5. Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    NARCIS (Netherlands)

    Bojack, A.; Zhao, L.; Morris, P.F.; Sietsma, J.

    2016-01-01

    The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two

  6. Double-Sided Single-Pass Submerged Arc Welding for 2205 Duplex Stainless Steel

    Science.gov (United States)

    Luo, Jian; Yuan, Yi; Wang, Xiaoming; Yao, Zongxiang

    2013-09-01

    The duplex stainless steel (DSS), which combines the characteristics of ferritic steel and austenitic steel, is used widely. The submerged arc welding (SAW) method is usually applied to join thick plates of DSS. However, an effective welding procedure is needed in order to obtain ideal DSS welds with an appropriate proportion of ferrite (δ) and austenite (γ) in the weld zone, particularly in the melted zone and heat-affected zone. This study evaluated the effectiveness of a high efficiency double-sided single-pass (DSSP) SAW joining method for thick DSS plates. The effectiveness of the converse welding procedure, characterizations of weld zone, and mechanical properties of welded joint are analyzed. The results show an increasing appearance and continuous distribution feature of the σ phase in the fusion zone of the leading welded seam. The converse welding procedure promotes the σ phase to precipitate in the fusion zone of leading welded side. The microhardness appears to significantly increase in the center of leading welded side. Ductile fracture mode is observed in the weld zone. A mixture fracture feature appears with a shear lip and tears in the fusion zone near the fusion line. The ductility, plasticity, and microhardness of the joints have a significant relationship with σ phase and heat treatment effect influenced by the converse welding step. An available heat input controlling technology of the DSSP formation method is discussed for SAW of thick DSS plates.

  7. Microstructural characterisation of carbon implanted austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, M.E. [Scientific Affairs Research Group, Stryker Orthopaedics, Raheen Business Park, Limerick (Ireland)]. E-mail: matthew.murphy@stryker.com; Insley, G.M. [Scientific Affairs Research Group, Stryker Orthopaedics, Raheen Business Park, Limerick (Ireland); Laugier, M.T. [Department of Physics, University of Limerick, Limerick (Ireland); Newcomb, S.B. [Sonsam Ltd., Glebe Laboratories, Newport, Tipperary (Ireland)

    2005-06-01

    Low carbon (316L) austenitic stainless steel has been implanted with carbon ions with a fluence of 5 x 10{sup 17} C ions/cm{sup 2} using an ion energy of 75 keV. The effect of carbon ion implantation on the microstructure of the austenitic steel has been examined in cross-section using transmission electron microscopy (TEM) both before and after implantation, and the implantation data correlated with a computer based simulation, TRIM (Transport and Range of Ions in Matter). It has been found that the high-fluence carbon ion implantation modified the microstructure of the steel, as demonstrated by the presence of two amorphous layers separated by a layer of expanded austenite.

  8. Microstructural and Mechanical Characterization of Solidified Austenitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Aktaş Çelik G.

    2017-09-01

    Full Text Available Among the family of stainless steels, cast austenitic stainless steels (CASSs are preferably used due to their high mechanical properties and corrosion resistance. These steels owe their properties to their microstructural features consisting of an austenitic matrix and skeletal or lathy type δ-ferrite depending on the cooling rate. In this study, the solidification behavior of CASSs (304L and 316L grades was studied using ThermoCalc software in order to determine the solidification sequence and final microstructure during cooling. Theoretical findings were supported by the microstructural examinations. For the mechanical characterization, not only hardness measurements but also tribological studies were carried out under dry sliding conditions and worn surfaces were examined by microscopy and 3D profilometric analysis. Results were discussed according to the type and amount of microstructural features.

  9. Crevice Corrosion Behavior of Nitrogen Bearing Austenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Ono, A.A.; Shinohara, Tadashi.; Tsujikawa, Shigeo. [The University of Tokyo, Tokyo (Japan). Graduate School of Engineering

    1999-03-15

    The effect of nitrogen alloying on the initiation, propagation and repassivation of crevice corrosion of SUS 304 and SUS 316 austenitic stainless steels was investigated through potentiostatic polarizations, cyclic polarizations and in-situ measurements of depth profiles by the moire method. The results showed that nitrogen alloying in austenitic stainless steels increased to more noble values both the critical potential for steady crevice corrosion, V{sub C,CREV}, and the critical potential for repassivation of crevice corrosion E{sub C,CREV}. Concerning the in-situ measurements results, the disolution rate just above the repassivation potential, V{sub I}I*, decreased with nitrogen alloying for the SUS 304 alloys, and did not change in the SUS 316 alloys. The ratio of repassivating picture elements increased in both SUS 304 and SUS 316 with nitrogen alloying. (author)

  10. Anisotropy of nickel release and corrosion in austenitic stainless steels.

    Science.gov (United States)

    Reclaru, L; Lüthy, H; Ziegenhagen, R; Eschler, P-Y; Blatter, A

    2008-05-01

    The study of 316L-type stainless steel reveals a significant anisotropy of nickel release that is dependent on the orientation of the test surface with respect to the casting and rolling direction. Cross-sectional specimens (transversal cuts with respect to the rolling direction) show a substantially higher sensitivity to corrosion phenomena compared with longitudinal cuts and they release nickel ions at rates 10-100 times higher. These findings indicate that orientation needs to be taken into account when interpreting test results, in particular when comparing different grades of austenitic stainless steel, as well as in product and production design.

  11. Effects of thermal oxidation and subsequent pickling on pitting geometry of austenitic stainless steels in chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Alar, Vesna; Esih, Ivan; Budic, Ivan; Brod, Slavonski [Zagreb Univ. (Croatia). Dept. of Materials

    2011-07-01

    Harmful effects of thermal oxides formed on austenitic stainless steels (SS) like AISI 304 and 316L by heating in air or other oxidizing gases on their pitting liability in chloride solutions have been studied by pursuing geometric characteristics of corrosion process (pits density, their depths, and mouth areas, ie. penetrating and superficial detrimental consequences etc.). The possibility of preventing the decay of thermally oxidized austenitic SS by chemical removal (pickling) of oxides before exposure to chloride solutions was successfully applied on simple specimens but serious difficulties arose on welded parts and on parts exposed to other temperature gradients during manufacture or in exploitation. (orig.)

  12. Research on stress corrosion behavior of CCSE40 welded by underwater wet welding with austenitic welding rod in seawater

    Science.gov (United States)

    Zou, Y.; Bai, Q.; Dong, S.; Yang, Z. L.; Gao, Y.

    2017-09-01

    The stress corrosion behavior of CCSE40 welded by underwater wet welding with austenitic welding rod in seawater was studied. Microstructure, mechanical property and stress corrosion cracking susceptibility of the underwater wet welding joint were analyzed by metallographic observation, tensile and bending tests, slow strain rate test (SSRT) and SEM. The results indicated that the weld zone (WZ) and the heat affected zone (HAZ) were all sensitive to the stress corrosion, and the WZ was more sensitive than the HAZ.

  13. Effects of nitrogen in shielding gas on microstructure evolution and localized corrosion behavior of duplex stainless steel welding joint

    Science.gov (United States)

    Zhang, Zhiqiang; Jing, Hongyang; Xu, Lianyong; Han, Yongdian; Zhao, Lei; Zhou, Chao

    2017-05-01

    The effects of nitrogen addition in shielding gas on microstructure evolution and localized corrosion behavior of duplex stainless steel (DSS) welds were studied. N2-supplemented shielding gas facilitated the primary austenite formation, suppressed the Cr2N precipitation in weld root, and increased the microhardnesses of weld metal. Furthermore, N2-supplemented shielding gas increased pitting resistance equivalent number (PREN) of austenite, but which decreased slightly PREN of ferrite. The modified double loop electrochemical potentiokinetic reactivation in 2 M H2SO4 + 1 M HCl was an effective method to study the localized corrosion of the different zones in the DSS welds. The adding 2% N2 to pure Ar shielding gas improved the localized corrosion resistance in the DSS welds, which was due to compensation for nitrogen loss and promoting nitrogen further solution in the austenite phases, suppression of the Cr2N precipitation in the weld root, and increase of primary austenite content with higher PREN than the ferrite and secondary austenite. Secondary austenite are prone to selective corrosion because of lower PREN compared with ferrite and primary austenite. Cr2N precipitation in the pure Ar shielding weld root and heat affected zone caused the pitting corrosion within the ferrite and the intergranular corrosion at the ferrite boundary. In addition, sigma and M23C6 precipitation resulted in the intergranular corrosion at the ferrite boundary.

  14. Study of irradiation damage structures in austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Shozo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-08-01

    The irradiation damage microstructures in austenitic stainless steels, which have been proposed to be a candidate of structural materials of a fusion reactor, under ions and neutrons irradiation have been studied. In ion irradiation experiments, cross-sectional observation of the depth distribution of damage formed due to ion irradiation became available. Comparison and discussion between experimental results with TEM and the calculated ones in the depth profiles of irradiation damage microstructures. Further, dual-phase stainless steels, consisted of ferritic/austenitic phases, showed irradiation-induced/enhanced precipitation during ion irradiation. High Flux Isotope Reactor with high neutron fluxes was employed in neutron-irradiation experiments. Swelling of 316 steel showed irradiation temperature dependence and this had strong correlation with phase instability under heavy damage level. Swelling resistance of Ti-modified austenitic stainless steel, which has good swelling resistance, decreased during high damage level. This might be caused by the instability of Ti-carbide particles. The preparation method to reduce higher radioactivity of neutron-irradiated TEM specimen was developed. (author). 176 refs.

  15. Laser etching of austenitic stainless steels for micro-structural evaluation

    Science.gov (United States)

    Baghra, Chetan; Kumar, Aniruddha; Sathe, D. B.; Bhatt, R. B.; Behere, P. G.; Afzal, Mohd

    2015-06-01

    Etching is a key step in metallography to reveal microstructure of polished specimen under an optical microscope. A conventional technique for producing micro-structural contrast is chemical etching. As an alternate, laser etching is investigated since it does not involve use of corrosive reagents and it can be carried out without any physical contact with sample. Laser induced etching technique will be beneficial especially in nuclear industry where materials, being radioactive in nature, are handled inside a glove box. In this paper, experimental results of pulsed Nd-YAG laser based etching of few austenitic stainless steels such as SS 304, SS 316 LN and SS alloy D9 which are chosen as structural material for fabrication of various components of upcoming Prototype Fast Breeder Reactor (PFBR) at Kalpakkam India were reported. Laser etching was done by irradiating samples using nanosecond pulsed Nd-YAG laser beam which was transported into glass paneled glove box using optics. Experiments were carried out to understand effect of laser beam parameters such as wavelength, fluence, pulse repetition rate and number of exposures required for etching of austenitic stainless steel samples. Laser etching of PFBR fuel tube and plug welded joint was also carried to evaluate base metal grain size, depth of fusion at welded joint and heat affected zone in the base metal. Experimental results demonstrated that pulsed Nd-YAG laser etching is a fast and effortless technique which can be effectively employed for non-contact remote etching of austenitic stainless steels for micro-structural evaluation.

  16. Effect of Post-weld Heat Treatment on the Mechanical Properties of Supermartensitic Stainless Steel Deposit

    Science.gov (United States)

    Zappa, Sebastián; Svoboda, Hernán; Surian, Estela

    2017-02-01

    Supermartensitic stainless steels have good weldability and adequate tensile property, toughness and corrosion resistance. They have been developed as an alternative technology, mainly for oil and gas industries. The final properties of a supermartensitic stainless steel deposit depend on its chemical composition and microstructure: martensite, tempered martensite, ferrite, retained austenite and carbides and/or nitrides. In these steels, the post-weld heat treatments (PWHTs) are usually double tempering ones, to ensure both complete tempering of martensite and high austenite content, to increase toughness and decrease hardness. The aim of this work was to study the effect of post-weld heat treatments (solution treatment with single and double tempering) on the mechanical properties of a supermartensitic stainless steel deposit. An all-weld metal test coupon was welded according to standard ANSI/AWS A5.22-95 using a GMAW supermartensitic stainless steel metal cored wire, under gas shielding. PWHTs were carried out varying the temperature of the first tempering treatment with and without a second tempering one, after solution treatment. All-weld metal chemical composition analysis, metallurgical characterization, hardness and tensile property measurements and Charpy-V tests were carried out. There are several factors which can be affected by the PWHTs, among them austenite content is a significant one. Different austenite contents (0-42%) were found. Microhardness, tensile property and toughness were affected with up to 15% of austenite content, by martensite tempering and carbide precipitation. The second tempering treatment seemed not to have had an important effect on the mechanical properties measured in this work.

  17. Relaxation cracking in austenitic welded joints: an underestimated problem

    NARCIS (Netherlands)

    Wortel, J.C. van

    1995-01-01

    In both power generation and chemical process industries austenitic materials, including 800H, 321H and 316H, are often used at temperatures between 500 and 700 degrees Celsius. The critical pressure containment components typically contain circumferential and longitudinal welded joints of varying

  18. Crack growth rates and fracture toughness of irradiated austenitic stainless steels in BWR environments.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Shack, W. J.

    2008-01-21

    In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. However, exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). Experimental data are presented on the fracture toughness and crack growth rates (CGRs) of wrought and cast austenitic SSs, including weld heat-affected-zone materials, that were irradiated to fluence levels as high as {approx} 2x 10{sup 21} n/cm{sup 2} (E > 1 MeV) ({approx} 3 dpa) in a light water reactor at 288-300 C. The results are compared with the data available in the literature. The effects of material composition, irradiation dose, and water chemistry on CGRs under cyclic and stress corrosion cracking conditions were determined. A superposition model was used to represent the cyclic CGRs of austenitic SSs. The effects of neutron irradiation on the fracture toughness of these steels, as well as the effects of material and irradiation conditions and test temperature, have been evaluated. A fracture toughness trend curve that bounds the existing data has been defined. The synergistic effects of thermal and radiation embrittlement of cast austenitic SS internal components have also been evaluated.

  19. Effect of Dynamic Reheating Induced by Weaving on the Microstructure of GTAW Weld Metal of 25% Cr Super Duplex Stainless Steel Weld Metal

    Directory of Open Access Journals (Sweden)

    Hee-Joon Sung

    2017-11-01

    Full Text Available The importance of the additional growth and/or transformation of the austenite phase that occurs in weld metals of super duplex stainless steel upon reheating is known. However, the effects have not been fully investigated, especially with respect to reheating induced by weaving during single-pass welding. In this work, bead-on-pipe gas tungsten arc welding (GTAW was conducted on super duplex stainless steel to understand the effect of weaving on the microstructure of weld metal. Microstructural analysis, electron backscatter diffraction (EBSD, and focused ion beam transmission electron microscopy (FIB-TEM were carried out to investigate the relationship between weaving and microstructural change. The weaving of GTAW produced a dynamic reheated area just before the weld bead during welding. It was revealed that extensive reheated weld existed even after one welding pass, and that the content of the austenite phase in the reheated area was higher than that in the non-reheated area, indicating the existence of a large quantity of intragranular austenite phase. In addition, the Cr2N content in the reheated area was lower than that in the non-reheated area. This reduction of Cr2N was closely related to the reheating resulting from weaving. TEM analysis revealed that Cr2N in the non-reheated area was dispersed following heating and transformed to secondary austenite.

  20. Study of the Performance of Stainless Steel A-TIG Welds

    Science.gov (United States)

    Shyu, S. W.; Huang, H. Y.; Tseng, K. H.; Chou, C. P.

    2008-04-01

    The purpose of the present work was to investigate the effect of oxide fluxes on weld morphology, arc voltage, mechanical properties, angular distortion and hot cracking susceptibility obtained with TIG welding, which applied to the welding of 5 mm thick austenitic stainless steel plates. A novel variant of the autogenous TIG welding process, oxide powders (Al2O3, Cr2O3, TiO2, SiO2 and CaO) was applied on a type 304 stainless steel through a thin layer of the flux to produce a bead on plate welds. The experimental results indicated that the increase in the penetration is significant with the use of Cr2O3, TiO2, and SiO2. A-TIG welding can increase the weld depth to bead-width ratio, and tends to reduce the angular distortion of the weldment. It was also found that A-TIG welding can increase the retained delta-ferrite content of stainless steel 304 welds and, in consequence, the hot-cracking susceptibility of as-welded is reduced. Physically constricting the plasma column and reducing the anode spot are the possible mechanism for the effect of certain flux on A-TIG penetration.

  1. In situ laser-induced breakdown spectroscopy measurements of chemical compositions in stainless steels during tungsten inert gas welding

    Science.gov (United States)

    Taparli, Ugur Alp; Jacobsen, Lars; Griesche, Axel; Michalik, Katarzyna; Mory, David; Kannengiesser, Thomas

    2018-01-01

    A laser-induced breakdown spectroscopy (LIBS) system was combined with a bead-on-plate Tungsten Inert Gas (TIG) welding process for the in situ measurement of chemical compositions in austenitic stainless steels during welding. Monitoring the weld pool's chemical composition allows governing the weld pool solidification behavior, and thus enables the reduction of susceptibility to weld defects. Conventional inspection methods for weld seams (e.g. ultrasonic inspection) cannot be performed during the welding process. The analysis system also allows in situ study of the correlation between the occurrence of weld defects and changes in the chemical composition in the weld pool or in the two-phase region where solid and liquid phase coexist. First experiments showed that both the shielding Ar gas and the welding arc plasma have a significant effect on the selected Cr II, Ni II and Mn II characteristic emissions, namely an artificial increase of intensity values via unspecific emission in the spectra. In situ investigations showed that this artificial intensity increase reached a maximum in presence of weld plume. Moreover, an explicit decay has been observed with the termination of the welding plume due to infrared radiation during sample cooling. Furthermore, LIBS can be used after welding to map element distribution. For austenitic stainless steels, Mn accumulations on both sides of the weld could be detected between the heat affected zone (HAZ) and the base material.

  2. Corrosion resistance of kolsterised austenitic 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Abudaia, F. B., E-mail: fabudaia@yahoo.com; Khalil, E. O., E-mail: ekhalil9@yahoo.com; Esehiri, A. F., E-mail: Hope-eseheri@hotmail.co.uk; Daw, K. E., E-mail: Khawladaw@yahoo.com [University of Tripoli Department of Materials and Metallurgical Eng, Tripoli-Libya P.O.Box13589 (Libya)

    2015-03-30

    Austenitic stainless suffers from low wear resistance in applications where rubbing against other surfaces is encountered. This drawback can be overcome by surface treatment such as coating by hard materials. Other treatments such as carburization at relatively low temperature become applicable recently to improve hardness and wear resistance. Carburization heat treatment would only be justified if the corrosion resistance is unaffected. In this work samples of 304 stainless steels treated by colossal supersaturation case carburizing (known as Kolsterising) carried out by Bodycote Company was examined for pitting corrosion resistance at room temperature and at 50 °C. Comparison with results obtained for untreated samples in similar testing conditions show that there is no deterioration in the pitting resistance due to the Kolsterising heat treatment. X ray diffraction patterns obtained for Kolsterising sample showed that peaks correspond to the austenite phase has shifted to lower 2θ values compared with those of the untreated sample. The shift is an indication for expansion of austenite unit cells caused by saturation with diffusing carbon atoms. The XRD of Kolsterising samples also revealed additional peaks appeared in the patterns due to formation of carbides in the kolsterised layer. Examination of these additional peaks showed that these peaks are attributed to a type of carbide known as Hagg carbide Fe{sub 2}C{sub 5}. The absence of carbides that contain chromium means that no Cr depletion occurred in the layer and the corrosion properties are maintained. Surface hardness measurements showed large increase after Kolsterising heat treatment.

  3. Microstructural characterization and electron backscatter diffraction analysis across the welded interface of duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhiqiang; Jing, Hongyang [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Xu, Lianyong, E-mail: xulianyong@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Han, Yongdian; Gao, Zhanqi; Zhao, Lei [School of Materials Science and Engineering, Tianjin University, Tianjin 300350 (China); Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350 (China); Zhang, Jianli [Welding laboratory, Offshore Oil Engineering (Qing Dao) Company, Qing Dao 266520 (China)

    2017-08-15

    Highlights: • Apparent change in LTHAZ was the intergranular secondary austenite precipitation. • Ferrite in HAZ maintained same distribution as ferrite texture in base metal. • Different austenite in different zones showed different orientation with ferrite. • Ferrite and austenite grains exhibited different boundary characteristics. • Local deformations were generated in grain boundary and within deformed grain. - Abstract: The microstructural evolution, orientation relationships, boundary characteristics, grain type, local deformation, and microhardness across the welded interface of duplex stainless steel (DSS) were investigated. The DSS welded joint consisted of four typical zones: base metal (BM), low-temperature heat-affected zone (LTHAZ), high-temperature heat-affected zone (HTHAZ), and weld metal (WM). The apparent microstructural changes in the HTHAZ and LTHAZ were secondary austenite and Cr{sub 2}N precipitation. A modified cooperative precipitation mechanism of secondary austenite and Cr{sub 2}N at the interface was proposed. Furthermore, the ferrite in both the HTHAZ and LTHAZ maintained the same distribution as the ferrite texture in the BM, while this ferrite texture disappeared completely in the WM. Different austenite grains in the different zones exhibited different orientation relationships with the ferrite matrix. Special grain boundaries were mainly distributed between the austenite grains, while the ferrite grains primarily contained random grain boundaries. Austenite twins constituted the largest proportion of the special boundaries. The special austenite grain boundaries in the BM and LTHAZ were higher in relative frequency than those in the HTHAZ and WM. The ferrite grains in the HTHAZ and WM mainly consisted of substructured grains. In the BM, the recrystallization degree of ferrite was significantly lower than that of austenite grains. The local deformations were mainly generated in the grain boundaries and within the deformed

  4. Weld bead profile of laser welding dissimilar joints stainless steel

    Science.gov (United States)

    Mohammed, Ghusoon R.; Ishak, M.; Aqida, S. N.; Abdulhadi, Hassan A.

    2017-10-01

    During the process of laser welding, the material consecutively melts and solidifies by a laser beam with a peak high power. Several parameters such as the laser energy, pulse frequency, pulse duration, welding power and welding speed govern the mode of the welding process. The aim of this paper is to investigate the effect of peak power, incident angle, and welding speed on the weld bead geometry. The first investigation in this context was conducted using 2205-316L stainless steel plates through the varying of the welding speed from 1.3 mm/s to 2.1 mm/s. The second investigation was conducted by varying the peak power from 1100 W to 1500 W. From the results of the experiments, the welding speed and laser power had a significant effect on the geometry of the weld bead, and the variation in the diameter of the bead pulse-size. Due to the decrease in the heat input, welding speed affected penetration depth more than bead width, and a narrow width of heat affected zone was achieved ranging from 0.2 to 0.5 mm. Conclusively, weld bead geometry dimensions increase as a function of peak power; at over 1350 W peak power, the dimensions lie within 30 μm.

  5. Effect of shot peening on metastable austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Fargas, G., E-mail: gemma.fargas@upc.edu [CIEFMA - Departament de Ciència dels Materials i Enginyeria Metallúrgica, Universitat Politècnica de Catalunya, 08028 Barcelona (Spain); CRnE, Centre de Recerca en Nanoenginyeria, Universitat Politècnica de Catalunya, 08028 Barcelona (Spain); Roa, J.J.; Mateo, A. [CIEFMA - Departament de Ciència dels Materials i Enginyeria Metallúrgica, Universitat Politècnica de Catalunya, 08028 Barcelona (Spain); CRnE, Centre de Recerca en Nanoenginyeria, Universitat Politècnica de Catalunya, 08028 Barcelona (Spain)

    2015-08-12

    In this work, shot peening was performed in a metastable austenitic stainless steel EN 1.4318 (AISI 301LN) in order to evaluate its effect on austenite to martensite phase transformation and also the influence on the fatigue limit. Two different steel conditions were considered: annealed, i.e., with a fully austenitic microstructure, and cold rolled, consisting of a mixture of austenite and martensite. X-ray diffraction, electron back-scattered diffraction and focus ion beam, as well as nanoindentation techniques, were used to elucidate deformation mechanisms activated during shot peening and correlate with fatigue response. Results pointed out that extensive plastic deformation and phase transformation developed in annealed specimens as a consequence of shot peening. However, the increase of roughness and the generation of microcracks led to a limited fatigue limit improvement. In contrast, shot peened cold rolled specimens exhibited enhanced fatigue limit. In the latter case, the main factor that determined the influence on the fatigue response was the distance from the injector, followed successively by the exit speed of the shots and the coverage factor.

  6. STRUCTURAL STABILITY OF HIGH NITROGEN AUSTENITIC STAINLESS STEELS

    Directory of Open Access Journals (Sweden)

    Jana Bakajová

    2011-05-01

    Full Text Available This paper deals with the structural stability of an austenitic stainless steel with high nitrogen content. The investigated steel was heat treated at 800°C using different annealing times. Investigation was carried out using light microscopy, transmission electron microscopy and thermodynamic calculations. Three phases were identified by electron diffraction: Cr2N, sigma – phase and M23C6. The thermodynamic prediction is in good agreement with the experimental result. The only is the M23C6 carbide phase which is not thermodynamically predicted. Cr2N is the majority secondary phase and occurs in the form of discrete particles or cells (lamellas of Cr2N and austenite.

  7. High Nitrogen Austenitic Stainless Steel Precipitation During Isothermal Annealing

    Directory of Open Access Journals (Sweden)

    Maria Domankova

    2016-07-01

    Full Text Available The time-temperature-precipitation in high-nitrogen austenitic stainless steel was investigated using light optical microscopy, transmission electron microscopy, selected area diffraction and energy-dispersive X-ray spectroscopy. The isothermal precipitation kinetics curves and the corresponding precipitation activation energy were obtained. The diffusion activation energy of M2N precipitation is 129 kJ/mol. The results show that critical temperature for M2N precipitation is about 825°C with the corresponding incubation period 2.5 min.

  8. Ductility of stabilized ferritic stainless steel welds

    Science.gov (United States)

    Hunter, G. B.; Eagar, T. W.

    1980-02-01

    An investigation was made into the mechanism of ductility loss in low interstitial 18 Cr-2Mo ferritic stainless steel welds stabilized with Ti and Nb. It was found that stabilizing TiN or Nb(C,N) precipitates are dissolved during the welding process, resulting in a finer distribution of precipitates in the weld metal than in the base metal. Furthermore, the FATT was found to increase by more than 200°C, leading to decreased room temperature ductility. Such an increase in FATT may not be explained solely in terms of grain growth. Internal friction measurements indicate that no free nitrogen is present in the weld metal, yet wet chemical analysis reveals that the nitrogen is present in a soluble form. Kinetic arguments suggest that the stabilized nitrogen dissolved during welding tends to reprecipitate during solidification in the form of a chromium rich nitride phase.

  9. Biofouling on austenitic stainless steels in spent nuclear fuel pools

    Energy Technology Data Exchange (ETDEWEB)

    Sarro, M.I.; Moreno, D.A.; Chicote, E.; Lorenzo, P.I.; Garcia, A.M. [Universidad Politecnica de Madrid, Departamento de Ingenieria y Ciencia de los Materiales, Escuela Tecnica Superior de Ingenieros Industriales, Jose Gutierrez Abascal, 2, E-28006 Madrid (Spain); Montero, F. [Iberdrola Generacion, S.A., y C.M.D.S., Centro de Tecnologia de Materiales, Paseo de la Virgen del Puerto, 53, E-28005 Madrid (Spain)

    2003-07-01

    The objective of this study was to investigate the biofilm formation on three different types of austenitic stainless steel (UNS S30400, S30466 and S31600) submerged in a spent nuclear fuel pool. The presence of microorganisms in coupons was characterised using standard culture microbiological methods, microscopic techniques (epifluorescence microscopy and scanning electron microscopy), and molecular biology techniques (denaturing gradient gel electrophoresis and sequencing fragments of 16S rDNA). The microscopy techniques showed signs of colonisation of stainless steels in spite of these extreme conditions. Based on sequencing of cultured microorganisms, different bacteria belonging to {alpha}, {beta}, {gamma}-Proteobacteria, Bacilli, and Actinobacteria classes have been identified. The biofilm radioactivity was measured using gamma-ray spectrometry and, according to the data gathered, the radionuclides present in the water pool were entrapped in the biofilm increasing the amount of radiation at the surface of the different materials. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  10. Surface treatment and corrosion behaviour of austenitic stainless steel biomaterial

    Science.gov (United States)

    Oravcová, M.; Palček, P.; Zatkalíková, V.; Tański, T.; Król, M.

    2017-02-01

    In this article results from corrosion behaviour of austenitic stainless steel AISI 316L after different surface treatments are published. “As received” surface and surface after grinding resulted in lower resistance to pitting corrosion in physiological solution than electrochemically polished in H3PO4+H2SO4+H2O. Electropolishing also improved the surface roughness in comparison with the “as received” surface. Deposition of Al2O3 nanometric ALD coating improves the corrosion resistance of stainless steel in chloride-containing environment by shifting the breakdown potential toward more positive values. This oxide coating not only improves the corrosion resistance but it also affects the wettability of the surface, resulting in hydrophobic surface.

  11. Deformation behavior around grain boundaries for SCC propagation in hardened low-carbon austenitic stainless steel by micro hardness test

    Energy Technology Data Exchange (ETDEWEB)

    Nagashima, N.; Hayakawa, M. [National Inst. for Materials Science (NIMS), Ibaraki (Japan); Tsukada, T; Kaji, Y.; Miwa, Y. [Japan Atomic Energy Agency (JAEA), Ibaraki (Japan); Ando, M.; Nakata, K. [Japan Nuclear Energy Safety Organization (JNES), Tokyo (Japan)

    2007-07-01

    Stress corrosion cracking (SCC) was found in shroud and PLR piping made of low-carbon austenitic stainless steels in Japanese BWR plants. The intergranular type (IG) SCC propagated in hardened heat affected zones (HAZ) around welds. Strength behavior and local plastic deformation for a low-carbon austenitic stainless steel 316L, rolled at the reductions in area of 10, 30% at room temperature to simulate the hardened HAZ, were measured by a micro-hardness test machine and observed by atomic force microscopy (AFM), respectively. The tensile deformation at yield point (0.2% plastic strain) had given to the work-hardened 316L to simulate the plastic zone at the crack tip. It is suggested that one of the IGSCC propagation mechanism for 316L was related with the intergranular strength behavior and local plastic deformation around grain boundaries. (author)

  12. Phase transformations in a manganese-alloyed austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Jargelius-Pettersson, R.F.A. (Swedish Inst. for Metals Research, Stockholm (Sweden))

    1994-05-01

    The increasing demands placed on the corrosion resistance of stainless steels has led to the successive development of more highly alloyed materials. In this context nitrogen has shown considerable value as an alloying element but its use is restricted by a solubility limit of approximately 0.2 wt% in conventional austenitic stainless steel grades. Manganese increases the nitrogen solubility appreciably and for this reason there has also been an increased interest in its use as an alloying addition but numerous questions remain to be answered about the effect of both nitrogen and manganese on structural stability. Although much work has been published on the precipitation of secondary phases in CrNi(Mo) stainless steels, there is a relative paucity of information available on manganese-alloyed steels. Brandis et al. investigated precipitation in a 25Cr 17Ni 3Mo 6Mn 0.2Nb steel and found no manganese-enriched phases to occur. Sigma phase was the predominant intermetallic precipitate at low nitrogen contents while higher nitrogen contents retarded the onset of sigma phase precipitation but caused the appearance of chi phase. Boothby et al. investigated a 12Cr 11-35Ni (3Mo) steel in which the nickel was partially replaced by 20 or 30% manganese and found the precipitation of the intermetallic sigma, chi and Laves phases to be promoted by manganese, although again no manganese-enriched phases were observed. Fritscher demonstrated however the existence in the Fe-Cr-Ni system of a brittle ternary Y phase containing 30--60% manganese which was destabilized by nitrogen. The present work represents part of a study designed to gain greater understanding of the precipitation and sensitization behavior of highly alloyed austenitic stainless steels and concentrates on the influence of nitrogen additions up to 0.5wt% on precipitation of secondary phases in a 20Cr 18Ni 4.5Mo 10Mn steel.

  13. Fracture toughness of irradiated wrought and cast austenitic stainless steels in BWR environment

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O.K.; Gruber, E.E.; Shack, W.J. [Argonne National Lab., Nuclear Engineering Div., Argonne, Illinois (United States)

    2007-07-01

    Experimental data are presented on the fracture toughness of wrought and cast austenitic stainless steels (SSs) that were irradiated to a fluence of {approx} 1.5 x 10{sup 21} n/cm{sup 2} (E > 1 MeV){sup *} ({approx} 2.3 dpa) at 296-305{sup o}C. To evaluate the possible effects of test environment and crack morphology on the fracture toughness of these steels, all tests were conducted in normal-water-chemistry boiling water reactor (BWR) environments at {approx} 289{sup o}C. Companion tests were also conducted in air on the same material for comparison. The fracture toughness J-R curves for SS weld heat-affected-zone materials in BWR water were found to be comparable to those in air. However, the results of tests on sensitized Type 304 SS and thermally aged cast CF-8M steel suggested a possible effect of water environment. The available fracture toughness data on irradiated austenitic SSs were reviewed to assess the potential for radiation embrittlement of reactor-core internal components. The synergistic effects of thermal and radiation embrittlement of cast austenitic SS internal components are also discussed. (author)

  14. Study on Microstructure and Mechanical Properties of 304 Stainless Steel Joints by Tig-Mig Hybrid Welding

    Science.gov (United States)

    Ogundimu, Emmanuel O.; Akinlabi, Esther T.; Erinosho, Mutiu F.

    Stainless steel is a family of Fe-based alloys having excellent resistance to corrosion and as such has been used imperatively for kitchen utensils, transportation, building constructions and much more. This paper presents the work conducted on the material characterizations of a tungsten inert gas (TIG)-metal inert gas (MIG) hybrid welded joint of type 304 austenitic stainless steel. The welding processes were conducted in three phases. The phases of welding employed are MIG welding using a current of 170A, TIG welding using a current of 190A, and a hybrid TIG-MIG welding with currents of 190/170A, respectively. The MIG, TIG, and hybrid TIG-MIG weldments were characterized with incomplete penetration, full penetration and excess penetration of weld. Intergranular austenite was created toward transition and heat affected zones. The thickness of the delta ferrite (δ-Fe) formed in the microstructures of the TIG weld is more than the thickness emerged in the microstructures of MIG and hybrid TIG-MIG welds. A TIG-MIG hybrid weld of specimen welded at the currents of 190/170A has the highest ultimate tensile strength value and percentage elongation of 397.72MPa and 35.7%. The TIG-MIG hybrid welding can be recommended for high-tech industrial applications such as nuclear, aircraft, food processing, and automobile industry.

  15. Investigations on structure–property relationships of activated flux TIG weldments of super-duplex/austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Devendranath Ramkumar, K., E-mail: ramdevendranath@gmail.com; Bajpai, Ankur; Raghuvanshi, Shubham; Singh, Anshuman; Chandrasekhar, Aditya; Arivarasu, M.; Arivazhagan, N.

    2015-06-25

    This research work articulated the effect of SiO{sub 2} flux assisted tungsten inert gas (TIG) welding on the microstructure and mechanical properties of marine grade stainless steel weldments, such as super-duplex stainless steel (UNS S32750) and austenitic stainless steel (AISI 316L). The studies showed that the use of flux decreased the heat input required to obtain complete penetration. Microstructure studies revealed the presence of ferrite at the heat affected zone of AISI 316L and the fusion zone which obviated the hot cracking tendency. Tensile studies corroborated that the joint strength was sufficiently greater than that of the parent metals. Impact toughness slightly impoverished owing to the presence of large platelets of Widmanstätten austenite in the fusion zone. The study also explored the structure–property relationships of the flux assisted weldments using the combined techniques of optical and scanning electron microscopy analysis. Owing to the better metallurgical and mechanical properties, this study recommends the use of SiO{sub 2} flux for joining the dissimilar metals involving austenitic and super-duplex stainless steels.

  16. EBSD study of a hot deformed austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Mirzadeh, H., E-mail: h-m@gmx.com [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB, Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Cabrera, J.M. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB, Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Fundacio CTM Centre Tecnologic, Av. Bases de Manresa 1, 08242 Manresa (Spain); Najafizadeh, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Calvillo, P.R. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB, Universitat Politecnica de Catalunya, Av. Diagonal 647, 08028 Barcelona (Spain); Fundacio CTM Centre Tecnologic, Av. Bases de Manresa 1, 08242 Manresa (Spain)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Microstructural characterization of an austenitic stainless steel by EBSD. Black-Right-Pointing-Pointer The role of twins in the nucleation and growth of dynamic recrystallization. Black-Right-Pointing-Pointer Grain refinement through the discontinuous dynamic recrystallization. Black-Right-Pointing-Pointer Determination of recrystallized fraction using the grain average misorientation. Black-Right-Pointing-Pointer Relationship between recrystallization and the frequency of high angle boundaries. - Abstract: The microstructural evolution of a 304 H austenitic stainless steel subjected to hot compression was studied by the electron backscattered diffraction (EBSD) technique. Detailed data about the boundaries, coincidence site lattice (CSL) relationships and grain size were acquired from the orientation imaging microscopy (OIM) maps. It was found that twins play an important role in the nucleation and growth of dynamic recrystallization (DRX) during hot deformation. Moreover, the conventional discontinuous DRX (DDRX) was found to be in charge of grain refinement reached under the testing conditions studied. Furthermore, the recrystallized fraction (X) was determined from the grain average misorientation (GAM) distribution based on the threshold value of 1.55 Degree-Sign . The frequency of high angle boundaries showed a direct relationship with X. A time exponent of 1.11 was determined from Avrami analysis, which was related to the observed single-peak behavior in the stress-strain flow curves.

  17. Microstructure characterization and corrosion testing of MAG pulsed duplex stainless steel welds

    Energy Technology Data Exchange (ETDEWEB)

    Mitelea, Ion; Utu, Ion Dragos; Urlan, Sorin Dumitru; Karancsi, Olimpiu [Politehnica Univ. Timisoara (Romania). Faculty of Mechanical Engineering

    2017-08-01

    Duplex stainless steels are extremely attractive construction materials for their usage in intense aggressive environments. They offer numerous advantages compared to the austenitic stainless steels having an excellent behavior to pitting and cavernous corrosion, and a high resistance to stress cracking corrosion in chlorides media. However, their corrosion properties are largely dependent on the microstructural factors such as: the quantitative ratio of the two phases ferrite/austenite (F/A), the presence of intermetallic compounds and the distribution of the alloying elements between the ferrite and austenite. As a result of the thermal cycles experienced by the base metal without a post-weld heat treatment, the mechanical properties are significantly different in the heat affected zone and the deposited metal compared with the properties of the base metal. The present paper highlights the effect of the post-weld solution treatment in order to restore the balance between austenite and ferrite in the welded joint areas and also to limit undesirable precipitation of secondary phases with implications for increasing the corrosion resistance.

  18. Expanded austenite in nitrided layers deposited on austenitic and super austenitic stainless steel grades; Analise da austenita expandida em camadas nitretadas em acos inoxidaveis austeniticos e superaustenitico

    Energy Technology Data Exchange (ETDEWEB)

    Casteletti, L.C.; Fernandes, F.A.P.; Heck, S.C. [Universidade de Sao Paulo (EESC/USP), Sao Carlos, SP (Brazil). Escola de Engenharia. Dept. de Engenharia de Materais, Aeronautica e Automobilistica; Oliveira, A.M. [Instituto de Educacao, Ciencia e Tecnologia do Maranhao (IFMA), Sao Luis, MA (Brazil); Gallego, J., E-mail: gallego@dem.feis.unesp.b [UNESP, Ilha Solteira, SP (Brazil). Dept. Engenharia Mecanica

    2010-07-01

    In this work nitrided layers deposited on austenitic and super austenitic stainless steels were analyzed through optical microscopy and X-rays diffraction analysis (XRD). It was observed that the formation of N supersaturated phase, called expanded austenite, has promoted significant increment of hardness (> 1000HV). XRD results have indicated the anomalous displacement of the diffracted peaks, in comparison with the normal austenite. This behavior, combined with peaks broadening, it was analyzed in different nitriding temperatures which results showed good agreement with the literature. (author)

  19. UNS S31603 Stainless Steel Tungsten Inert Gas Welds Made with Microparticle and Nanoparticle Oxides.

    Science.gov (United States)

    Tseng, Kuang-Hung; Lin, Po-Yu

    2014-06-20

    The purpose of this study was to investigate the difference between tungsten inert gas (TIG) welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO₂ and Al₂O₃ were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results show that the use of SiO₂ leads to a satisfactory surface appearance compared to that of the TIG weld made with Al₂O₃. The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type. Compared with microparticle SiO₂, the TIG welding with nanoparticle SiO₂ has the potential benefits of high joint penetration and less angular distortion in the resulting weldment. The TIG welding with nanoparticle Al₂O₃ does not result in a significant increase in the penetration or reduction of distortion. The TIG welding with microparticle or nanoparticle SiO₂ uses a heat source with higher power density, resulting in a higher ferrite content and hardness of the stainless steel weld metal. In contrast, microparticle or nanoparticle Al₂O₃ results in no significant difference in metallurgical properties compared to that of the C-TIG weld metal. Compared with oxide particle size, the thermal stability of the oxide plays a significant role in enhancing the joint penetration capability of the weld, for the UNS S31603 stainless steel TIG welds made with activated oxides.

  20. UNS S31603 Stainless Steel Tungsten Inert Gas Welds Made with Microparticle and Nanoparticle Oxides

    Directory of Open Access Journals (Sweden)

    Kuang-Hung Tseng

    2014-06-01

    Full Text Available The purpose of this study was to investigate the difference between tungsten inert gas (TIG welding of austenitic stainless steel assisted by microparticle oxides and that assisted by nanoparticle oxides. SiO2 and Al2O3 were used to investigate the effects of the thermal stability and the particle size of the activated compounds on the surface appearance, geometric shape, angular distortion, delta ferrite content and Vickers hardness of the UNS S31603 stainless steel TIG weld. The results show that the use of SiO2 leads to a satisfactory surface appearance compared to that of the TIG weld made with Al2O3. The surface appearance of the TIG weld made with nanoparticle oxide has less flux slag compared with the one made with microparticle oxide of the same type. Compared with microparticle SiO2, the TIG welding with nanoparticle SiO2 has the potential benefits of high joint penetration and less angular distortion in the resulting weldment. The TIG welding with nanoparticle Al2O3 does not result in a significant increase in the penetration or reduction of distortion. The TIG welding with microparticle or nanoparticle SiO2 uses a heat source with higher power density, resulting in a higher ferrite content and hardness of the stainless steel weld metal. In contrast, microparticle or nanoparticle Al2O3 results in no significant difference in metallurgical properties compared to that of the C-TIG weld metal. Compared with oxide particle size, the thermal stability of the oxide plays a significant role in enhancing the joint penetration capability of the weld, for the UNS S31603 stainless steel TIG welds made with activated oxides.

  1. Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, J. A.; Ambriz, R. R.; Cuenca-Alvarez, R.; Alatorre, N.; Curiel, F. F.

    2016-10-01

    Welds without filler metal and welds using a conventional austenitic stainless steel filler metal (ER308L) were performed to join a ferritic stainless steel with Gas Tungsten Arc Welding process (GTAW). Welding parameters were adjusted to obtain three different heat input values. Microstructure reveals the presence of coarse ferritic matrix and martensite laths in the Heat Affected Zone (HAZ). Dilution between filler and base metal was correlated with the presence of austenite, martensite and ferrite in the weld metal. Weld thermal cycles were measured to correlate the microstructural transformation in the HAZ. Microhardness measurements (maps and profiles) allow to identify the different zones of the welded joints (weld metal, HAZ, and base metal). Comparing the base metal with the weld metal and the HAZ, a hardness increment (∼172 HV{sub 0}.5 to ∼350 HV{sub 0}.5 and ∼310 HV{sub 0}.5, respectively) was observed, which has been attributed to the martensite formation. Tensile strength of the welded joints without filler metal increased moderately with respect to base metal. In contrast, ductility was approximately 25% higher than base metal, which provided a toughness improvement of the welded joints. (Author)

  2. Irradiation-Assisted Stress Corrosion Cracking of Austenitic Stainless Steels in BWR Environments

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y. [Argonne National Lab. (ANL), Argonne, IL (United States); Chopra, O. K. [Argonne National Lab. (ANL), Argonne, IL (United States); Gruber, Eugene E. [Argonne National Lab. (ANL), Argonne, IL (United States); Shack, William J. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2010-06-01

    The internal components of light water reactors are exposed to high-energy neutron irradiation and high-temperature reactor coolant. The exposure to neutron irradiation increases the susceptibility of austenitic stainless steels (SSs) to stress corrosion cracking (SCC) because of the elevated corrosion potential of the reactor coolant and the introduction of new embrittlement mechanisms through radiation damage. Various nonsensitized SSs and nickel alloys have been found to be prone to intergranular cracking after extended neutron exposure. Such cracks have been seen in a number of internal components in boiling water reactors (BWRs). The elevated susceptibility to SCC in irradiated materials, commonly referred to as irradiation-assisted stress corrosion cracking (IASCC), is a complex phenomenon that involves simultaneous actions of irradiation, stress, and corrosion. In recent years, as nuclear power plants have aged and irradiation dose increased, IASCC has become an increasingly important issue. Post-irradiation crack growth rate and fracture toughness tests have been performed to provide data and technical support for the NRC to address various issues related to aging degradation of reactor-core internal structures and components. This report summarizes the results of the last group of tests on compact tension specimens from the Halden-II irradiation. The IASCC susceptibility of austenitic SSs and heat-affected-zone (HAZ) materials sectioned from submerged arc and shielded metal arc welds was evaluated by conducting crack growth rate and fracture toughness tests in a simulated BWR environment. The fracture and cracking behavior of HAZ materials, thermally sensitized SSs and grain-boundary engineered SSs was investigated at several doses (≤3 dpa). These latest results were combined with previous results from Halden-I and II irradiations to analyze the effects of neutron dose, water chemistry, alloy compositions, and welding and processing conditions on IASCC

  3. Mechanical Properties of Austenitic Stainless Steel Made by Additive Manufacturing.

    Science.gov (United States)

    Luecke, William E; Slotwinski, John A

    2014-01-01

    Using uniaxial tensile and hardness testing, we evaluated the variability and anisotropy of the mechanical properties of an austenitic stainless steel, UNS S17400, manufactured by an additive process, selective laser melting. Like wrought materials, the mechanical properties depend on the orientation introduced by the processing. The recommended stress-relief heat treatment increases the tensile strength, reduces the yield strength, and decreases the extent of the discontinuous yielding. The mechanical properties, assessed by hardness, are very uniform across the build plate, but the stress-relief heat treatment introduced a small non-uniformity that had no correlation to position on the build plate. Analysis of the mechanical property behavior resulted in four conclusions. (1) The within-build and build-to-build tensile properties of the UNS S17400 stainless steel are less repeatable than mature engineering structural alloys, but similar to other structural alloys made by additive manufacturing. (2) The anisotropy of the mechanical properties of the UNS S17400 material of this study is larger than that of mature structural alloys, but is similar to other structural alloys made by additive manufacturing. (3) The tensile mechanical properties of the UNS S17400 material fabricated by selective laser melting are very different from those of wrought, heat-treated 17-4PH stainless steel. (4) The large discontinuous yielding strain in all tests resulted from the formation and propagation of Lüders bands.

  4. Plasma spot welding of ferritic stainless steels

    Directory of Open Access Journals (Sweden)

    Lešnjak, A.

    2002-06-01

    Full Text Available Plasma spot welding of ferritic stainless steels is studied. The study was focused on welding parameters, plasma and shielding gases and the optimum welding equipment. Plasma-spot welded overlap joints on a 0.8 mm thick ferritic stainless steel sheet were subjected to a visual examination and mechanical testing in terms of tension-shear strength. Several macro specimens were prepared. Plasma spot welding is suitable to use the same gas as shielding gas and as plasma gas, i.e., a 98 % Ar/2 % H 2 gas mixture. Tension-shear strength of plasma-spot welded joints was compared to that of resistance-spot welded joints. It was found that the resistance welded joints withstand a somewhat stronger load than the plasma welded joints due to a larger weld spot diameter of the former. Strength of both types of welded joints is approximately the same.

    El artículo describe el proceso de soldeo de aceros inoxidables ferríticos por puntos con plasma. La investigación se centró en el establecimiento de los parámetros óptimos de la soldadura, la definición del gas de plasma y de protección más adecuado, así como del equipo óptimo para la realización de la soldadura. Las uniones de láminas de aceros inoxidables ferríticos de 0,8 mm de espesor, soldadas a solape por puntos con plasma, se inspeccionaron visualmente y se ensayaron mecánicamente mediante el ensayo de cizalladura por tracción. Se realizaron macro pulidos. Los resultados de la investigación demostraron que la solución más adecuada para el soldeo por puntos con plasma es elegir el mismo gas de plasma que de protección. Es decir, una mezcla de 98 % de argón y 2 % de hidrógeno. La resistencia a la cizalladura por tracción de las uniones soldadas por puntos con plasma fue comparada con la resistencia de las uniones soldadas por resistencia por puntos. Se llegó a la conclusión de que las uniones soldadas por resistencia soportan una carga algo mayor que la uniones

  5. Plastic strain characterization in austenitic stainless steels and nickel alloys by electron backscatter diffraction

    Science.gov (United States)

    Sáez-Maderuelo, A.; Castro, L.; de Diego, G.

    2011-09-01

    Stress corrosion cracking (SCC) is enhanced by cold work and causes many problems in components of the nuclear power plants. Besides, during manufacturing, installation, welding and service of the material, residual strains can be produced increasing the susceptibility to SCC. For this reason, it is important to characterize the degree of plastic strain due to dislocation accumulation in each crystal. Electron backscatter diffraction (EBSD), in conjunction with scanning electron microscope (SEM), has been a great advance in this field because it enables to estimate the plastic strain in a quick and easy way. Nevertheless, over the last few years, a lot of different mathematical expressions to estimate the plastic strain have appeared in the literature. This situation hinders the election of one of them by a novel scientist in this field. Therefore, in this paper some of the more common expressions used in the calculation of the angular misorientation have been presented and discussed in order to clarify their more important aspects. Then, using one of these expressions (average local misorientation), curves relating misorientation density with known levels of strain will be obtained for an austenitic stainless steel 304L and nickel base alloy 690, which have shown a linear behaviour that is in good agreement with results found in the literature. Finally, using curves obtained in previous steps, levels of plastic strain in a plate of nickel base alloy 600 welded with weld metal 182 were estimated between 8 and 10% for a high temperature mill annealing sample.

  6. Cavitation Erosion Tests Performed by Indirect Vibratory Method on Stainless Steel Welded Samples with Hardened Surface

    Directory of Open Access Journals (Sweden)

    Marian-Dumitru Nedeloni

    2012-09-01

    Full Text Available The paper presents the results of cavitation erosion tests performed on two types of samples. The materials of the samples are frequently used for manufacturing and repairs of the hydro turbines components submitted to cavitation. The first sample was made by welding of an austenitic stainless steel on austenito-feritic base material. The second sample was made similarly with the first but with a martensitic base material. After the welding processes, on both samples was applied a hardening treatment by surface peening. The cavitation erosion tests were performed on vibratory equipment using the indirect method with stationary specimen. The results show a good cavitation erosion resistance on both samples.

  7. Dynamic recrystallization in friction surfaced austenitic stainless steel coatings

    Energy Technology Data Exchange (ETDEWEB)

    Puli, Ramesh, E-mail: rameshpuli2000@gmail.com; Janaki Ram, G.D.

    2012-12-15

    Friction surfacing involves complex thermo-mechanical phenomena. In this study, the nature of dynamic recrystallization in friction surfaced austenitic stainless steel AISI 316L coatings was investigated using electron backscattered diffraction and transmission electron microscopy. The results show that the alloy 316L undergoes discontinuous dynamic recrystallization under conditions of moderate Zener-Hollomon parameter during friction surfacing. - Highlights: Black-Right-Pointing-Pointer Dynamic recrystallization in alloy 316L friction surfaced coatings is examined. Black-Right-Pointing-Pointer Friction surfacing leads to discontinuous dynamic recrystallization in alloy 316L. Black-Right-Pointing-Pointer Strain rates in friction surfacing exceed 400 s{sup -1}. Black-Right-Pointing-Pointer Estimated grain size matches well with experimental observations in 316L coatings.

  8. Small Punch Creep Test in a 316 Austenitic Stainless Steel

    Science.gov (United States)

    Saucedo-Muñoz, Maribel L.; Komazaki, Ken-Icbi; Ortiz-Mariscal, Arturo; Lopez-Hirata, Victor M.

    The small punch creep test was used to evaluate the creep behavior of a 316 type austenitic stainless steel at temperatures of 650, 675 and 700 °C and loads from 199 to 512 N using a creep tester with a specimen size of 10 x 10 x 0.3 mm under an argon atmosphere. The small punch creep curves shows the three stages found in the creep curves of the conventional uniaxial test. The time to rupture decreases as the testing temperature and load increase. The secondary stage is also reduced with the increase in test load. An intergranular ductile fracture mode was observed at a testing temperature of 700 °C, while intergranular brittle mode at 650 °C which is associated with the absence of abundant precipitation at 650 °C.

  9. Experimental determination of the constitutive behaviour of a metastable austenitic stainless steel

    NARCIS (Netherlands)

    Post, J.; Nolles, H.; Datta, K.; Datta, K.; Geijselaers, Hubertus J.M.

    2008-01-01

    This article presents measurements to describe the constitutive behaviour of a semi-austenitic precipitation hardenable stainless steel called Sandvik Nanoflex™, during metal forming and hardening. The material is metastable, which causes strain-induced transformation during forming. Depending on

  10. The influence of nickel-nitrogen ratio on the deformation behaviour of austenitic stainless steels

    CSIR Research Space (South Africa)

    Schmid, OE

    1992-01-01

    Full Text Available This study examines the effect that a partial substitution of nickel with nitrogen has on the deformation behaviour of a metastable austenitic stainless steel, AISI 301. The effect on the tensile deformation behaviour is studied in detail...

  11. Structural stability of super duplex stainless weld metals and its dependence on tungsten and copper

    Science.gov (United States)

    Nilsson, J.-O.; Huhtala, T.; Jonsson, P.; Karlsson, L.; Wilson, A.

    1996-08-01

    Three different superduplex stainless weld metals have been produced using manual metal arc welding under identical welding conditions. The concentration of the alloying elements tungsten and copper corresponded to the concentrations in commercial superduplex stainless steels (SDSS). Aging experiments in the temperature range 700 °C to 1110 °C showed that the formation of intermetallic phase was enhanced in tungsten-rich weld metal and also dissolved at higher temperatures compared with tungsten-poor and tungsten-free weld metals. It could be inferred from time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams produced in the present investigation that the critical cooling rate to avoid 1 wt pct of intermetallic phase was 2 times faster for tungsten-rich weld metal. Microanalysis in combination with thermodynamic calculations showed that tungsten was accommodated in χ phase, thereby decreasing the free energy. Experimental evidence supports the view that the formation of intermetallic phase is enhanced in tungsten-rich weld metal, owing to easier nucleation of nonequilibrium χ phase compared with σ phase. The formation of secondary austenite (γ2) during welding was modeled using the thermodynamic computer program Thermo-Calc. Satisfactory agreement between theory and practice was obtained. Thermo-Calc was capable of predicting observed lower concentrations of chromium and nitrogen in γ2 compared with primary austenite. The volume fraction of γ2 was found to be significantly higher in tungsten-rich and tungsten + copper containing weld metal. The results could be explained by a higher driving force for precipitation of γ2 in these.

  12. General and Localized Corrosion of Austenitic And Borated Stainless Steels in Simulated Concentrated Ground Waters

    Energy Technology Data Exchange (ETDEWEB)

    Estill, J C; Rebak, R B; Fix, D V; Wong, L L

    2004-03-11

    Boron containing stainless steels are used in the nuclear industry for applications such as spent fuel storage, control rods and shielding. It was of interest to compare the corrosion resistance of three borated stainless steels with standard austenitic alloy materials such as type 304 and 316 stainless steels. Tests were conducted in three simulated concentrated ground waters at 90 C. Results show that the borated stainless were less resistant to corrosion than the witness austenitic materials. An acidic concentrated ground water was more aggressive than an alkaline concentrated ground water.

  13. General and Localized corrosion of Austenitic and Borated Stainless Steels in Simulated Concentrated Ground Waters

    Energy Technology Data Exchange (ETDEWEB)

    D. Fix; J. Estill; L. Wong; R. Rebak

    2004-05-28

    Boron containing stainless steels are used in the nuclear industry for applications such as spent fuel storage, control rods and shielding. It was of interest to compare the corrosion resistance of three borated stainless steels with standard austenitic alloy materials such as type 304 and 316 stainless steels. Tests were conducted in three simulated concentrated ground waters at 90 C. Results show that the borated stainless were less resistant to corrosion than the witness austenitic materials. An acidic concentrated ground water was more aggressive than an alkaline concentrated ground water.

  14. Strain direction dependency of martensitic transformation in austenitic stainless steels: The effect of gamma-texture

    NARCIS (Netherlands)

    Hilkhuijsen, P.; Geijselaers, Hubertus J.M.; Bor, Teunis Cornelis; Perdahcioglu, Emin Semih; van den Boogaard, Antonius H.; Akkerman, Remko

    2013-01-01

    Uniaxial tensile tests on both a non-textured and a highly textured, fully austenitic stainless steel were performed in both the rolling and the transverse directions. Both materials show mechanically induced phase transformation from the austenitic FCC to the martensitic BCC phase. Differences in

  15. In Situ Techniques for the Investigation of the Kinetics of Austenitization of Supermartensitic Stainless Steel

    DEFF Research Database (Denmark)

    Nießen, Frank; Villa, Matteo; Apel, Daniel

    2016-01-01

    The austenitization and inter-critical annealing of X4CrNiMo16-5-1 (1.4418) supermartensitic stainless steel were investigated in-situ with synchrotron X-ray diffraction (XRD), dilatometry and differential scanning calorimetry (DSC) under isochronal heating conditions. Austenitization occurred...

  16. V and Nb Influence on the Austenitic Stainless Steel Corrosion in 0.1 M HCl

    Directory of Open Access Journals (Sweden)

    Amel GHARBI

    2014-05-01

    Full Text Available Vanadium and niobium were added in AISI309 austenitic stainless steel composition to modify their structure and pitting corrosion resistance in 0.1 M HCl. The structural characterization was carried out by X-rays diffraction and optical microscopy. Corrosion behavior was investigated using potentiodynamic tests and electrochemical impedance measurements (EIS .Results showed that vanadium and niobium addition precipitated stable carbides (VC, NbC to chromium carbides’ detriment and improved austenitic stainless steel corrosion resistance.

  17. Effect of Stress Relief Annealing on Microstructure & Mechanical Properties of Welded Joints Between Low Alloy Carbon Steel and Stainless Steel

    Science.gov (United States)

    Nivas, R.; Das, G.; Das, S. K.; Mahato, B.; Kumar, S.; Sivaprasad, K.; Singh, P. K.; Ghosh, M.

    2017-01-01

    Two types of welded joints were prepared using low alloy carbon steel and austenitic stainless steel as base materials. In one variety, buttering material and weld metal were Inconel 82. In another type, buttering material and weld metal were Inconel 182. In case of Inconel 82, method of welding was GTAW. For Inconel 182, welding was done by SMAW technique. For one set of each joints after buttering, stress relief annealing was done at 923 K (650 °C) for 90 minutes before further joining with weld metal. Microstructural investigation and sub-size in situ tensile testing in scanning electron microscope were carried out for buttered-welded and buttered-stress relieved-welded specimens. Adjacent to fusion boundary, heat-affected zone of low alloy steel consisted of ferrite-pearlite phase combination. Immediately after fusion boundary in low alloy steel side, there was increase in matrix grain size. Same trend was observed in the region of austenitic stainless steel that was close to fusion boundary between weld metal-stainless steel. Close to interface between low alloy steel-buttering material, the region contained martensite, Type-I boundary and Type-II boundary. Peak hardness was obtained close to fusion boundary between low alloy steel and buttering material. In this respect, a minimum hardness was observed within buttering material. The peak hardness was shifted toward buttering material after stress relief annealing. During tensile testing no deformation occurred within low alloy steel and failure was completely through buttering material. Crack initiated near fusion boundary between low alloy steel-buttering material for welded specimens and the same shifted away from fusion boundary for stress relieved annealed specimens. This observation was at par with the characteristics of microhardness profile. In as welded condition, joints fabricated with Inconel 82 exhibited superior bond strength than the weld produced with Inconel 182. Stress relief annealing

  18. Corrosion Behavior of Austenitic and Duplex Stainless Steels in Lithium Bromide

    Directory of Open Access Journals (Sweden)

    Ayo Samuel AFOLABI

    2009-07-01

    Full Text Available The corrosion behavior of austenitic and duplex stainless steels in various concentrations of lithium, bromide solution was investigated by using the conventional weight loss measurement method. The results obtained show that corrosion of these steels occurred due to the aggressive bromide ion in the medium. Duplex stainless steel shows a greater resistance to corrosion than austenitic stainless steel in the medium. This was attributed to equal volume proportion of ferrite and austenite in the structure of duplex stainless steel coupled with higher content of chromium in its composition. Both steels produced electrochemical noise at increased concentrations of lithium bromide due to continuous film breakdown and repair caused by reduction in medium concentration by the alkaline corrosion product while surface passivity observed in duplex stainless steel is attributed to film stability on this steel.

  19. An experience with in-service fabrication and inspection of austenitic stainless steel piping in high temperature sodium system

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, S., E-mail: sravi@igcar.gov.in; Laha, K.; Sakthy, S.; Mathew, M.D.; Bhaduri, A.K.

    2015-04-01

    Highlights: • Procedure for changing 304L SS pipe to 316L SS in sodium loop has been established. • Hot leg made of 304L SS was isolated from existing cold leg made of 316LN SS. • Innovative welding was used in joining the new 316L SS pipe with existing 316LN SS. • The old components of 304L SS piping have been integrated with the new piping. - Abstract: A creep testing facility along with dynamic sodium loop was installed at Indira Gandhi Centre for Atomic Research, Kalpakkam, India to assess the creep behavior of fast reactor structural materials in flowing sodium. Type 304L austenitic stainless steel was used in the low cross section piping of hot-leg whereas 316LN austenitic stainless steel in the high cross section cold-leg of the sodium loop. The intended service life of the sodium loop was 10 years. The loop has performed successfully in the stipulated time period. To enhance its life time, it has been decided to replace the 304L piping with 316L piping in the hot-leg. There were more than 300 welding joints involved in the integration of cold-leg with the new 316L hot-leg. Continuous argon gas flow was maintained in the loop during welding to avoid contamination of sodium residue with air. Several innovative welding procedures have been adopted for joining the new hot-leg with the existing cold-leg in the presence of sodium residue adopting TIG welding technique. The joints were inspected for 100% X-ray radiography and qualified by performing tensile tests. The components used in the discarded hot-leg were retrieved, cleaned and integrated in the renovated loop. A method of cleaning component of sodium residue has been established. This paper highlights the in-service fabrication and inspection of the renovation.

  20. Microstructural evolution in fast-neutron-irradiated austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Stoller, R.E.

    1987-12-01

    The present work has focused on the specific problem of fast-neutron-induced radiation damage to austenitic stainless steels. These steels are used as structural materials in current fast fission reactors and are proposed for use in future fusion reactors. Two primary components of the radiation damage are atomic displacements (in units of displacements per atom, or dpa) and the generation of helium by nuclear transmutation reactions. The radiation environment can be characterized by the ratio of helium to displacement production, the so-called He/dpa ratio. Radiation damage is evidenced microscopically by a complex microstructural evolution and macroscopically by density changes and altered mechanical properties. The purpose of this work was to provide additional understanding about mechanisms that determine microstructural evolution in current fast reactor environments and to identify the sensitivity of this evolution to changes in the He/dpa ratio. This latter sensitivity is of interest because the He/dpa ratio in a fusion reactor first wall will be about 30 times that in fast reactor fuel cladding. The approach followed in the present work was to use a combination of theoretical and experimental analysis. The experimental component of the work primarily involved the examination by transmission electron microscopy of specimens of a model austenitic alloy that had been irradiated in the Oak Ridge Research Reactor. A major aspect of the theoretical work was the development of a comprehensive model of microstructural evolution. This included explicit models for the evolution of the major extended defects observed in neutron irradiated steels: cavities, Frank faulted loops and the dislocation network. 340 refs., 95 figs., 18 tabs.

  1. Effect of electromagnetic interaction during fusion welding of AISI 2205 duplex stainless steel on the corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    García-Rentería, M.A., E-mail: marcogarciarenteria@uadec.edu.mx [Faculty of Metallurgy, Autonomous University of Coahuila, Carretera 57 Km. 5, CP 25720, Monclova, Coahuila (Mexico); López-Morelos, V.H., E-mail: vhlopez@umich.mx [Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, A.P. 888, CP 58000, Morelia, Michoacán (Mexico); González-Sánchez, J., E-mail: jagonzal@uacam.mx [Centre for Corrosion Research, Autonomous University of Campeche, Av. Agustín Melgar s/n, Col. Buenavista, CP 24039, Campeche, Cam (Mexico); García-Hernández, R., E-mail: rgarcia@umich.mx [Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo, A.P. 888, CP 58000, Morelia, Michoacán (Mexico); Dzib-Pérez, L., E-mail: franciscocl7@yahoo.com.mx [Centre for Corrosion Research, Autonomous University of Campeche, Av. Agustín Melgar s/n, Col. Buenavista, CP 24039, Campeche, Cam (Mexico); Curiel-López, F.F., E-mail: franciscocl7@yahoo.com.mx [Faculty of Metallurgy, Autonomous University of Coahuila, Carretera 57 Km. 5, CP 25720, Monclova, Coahuila (Mexico)

    2017-02-28

    Highlights: • Application of EMILI during welding 2205 Duplex stainless steel hindered the coarsening of δ grains in HTHAZ and promoted regeneration of γ. • Welds made with simultaneous EMILI presented TPI values at the HTHAZ similar to those for BM. • Welds made under 3, 12 and 15 mT presented a mass loss by anodic polarisation similar to that observed for the as-received BM. • This behaviour is due to changes in the dynamics of microstructural evolution during welding with EMILI. - Abstract: The effect of electromagnetic interaction of low intensity (EMILI) applied during fusion welding of AISI 2205 duplex stainless steel on the resistance to localised corrosion in natural seawater was investigated. The heat affected zone (HAZ) of samples welded under EMILI showed a higher temperature for pitting initiation and lower dissolution under anodic polarisation in chloride containing solutions than samples welded without EMILI. The EMILI assisted welding process developed in the present work enhanced the resistance to localised corrosion due to a modification on the microstructural evolution in the HAZ and the fusion zone during the thermal cycle involved in fusion welding. The application of EMILI reduced the size of the HAZ, limited coarsening of the ferrite grains and promoted regeneration of austenite in this zone, inducing a homogeneous passive condition of the surface. EMILI can be applied during fusion welding of structural or functional components of diverse size manufactured with duplex stainless steel designed to withstand aggressive environments such as natural seawater or marine atmospheres.

  2. Quantitative ultrasonic testing of acoustically anisotropic materials with verification on austenitic and dissimilar weld joints

    Science.gov (United States)

    Boller, C.; Pudovikov, S.; Bulavinov, A.

    2012-05-01

    Austenitic stainless steel materials are widely used in a variety of industry sectors. In particular, the material is qualified to meet the design criteria of high quality in safety related applications. For example, the primary loop of the most of the nuclear power plants in the world, due to high durability and corrosion resistance, is made of this material. Certain operating conditions may cause a range of changes in the integrity of the component, and therefore require nondestructive testing at reasonable intervals. These in-service inspections are often performed using ultrasonic techniques, in particular when cracking is of specific concern. However, the coarse, dendritic grain structure of the weld material, formed during the welding process, is extreme and unpredictably anisotropic. Such structure is no longer direction-independent to the ultrasonic wave propagation; therefore, the ultrasonic beam deflects and redirects and the wave front becomes distorted. Thus, the use of conventional ultrasonic testing techniques using fixed beam angles is very limited and the application of ultrasonic Phased Array techniques becomes desirable. The "Sampling Phased Array" technique, invented and developed by Fraunhofer IZFP, allows the acquisition of time signals (A-scans) for each individual transducer element of the array along with fast image reconstruction techniques based on synthetic focusing algorithms. The reconstruction considers the sound propagation from each image pixel to the individual sensor element. For anisotropic media, where the sound beam is deflected and the sound path is not known a-priori, a novel phase adjustment technique called "Reverse Phase Matching" is implemented. By taking into account the anisotropy and inhomogeneity of the weld structure, a ray tracing algorithm for modeling the acoustic wave propagation and calculating the sound propagation time is applied. This technique can be utilized for 2D and 3D real time image reconstruction. The

  3. Measured Resolved Shear Stresses and Bishop Hill Stress States in Individual Grains of Austenitic Stainless Steel (Postprint)

    Science.gov (United States)

    2017-09-13

    AFRL-RX-WP-JA-2017-0330 MEASURED RESOLVED SHEAR STRESSES AND BISHOP-HILL STRESS STATES IN INDIVIDUAL GRAINS OF AUSTENITIC STAINLESS ...IN INDIVIDUAL GRAINS OF AUSTENITIC STAINLESS STEEL (POSTPRINT) 5a. CONTRACT NUMBER IN-HOUSE 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...grains in austenitic stainless steel 316 L at 0.1 and 1% sample elongation has been determined with sufficient accuracy to allow comparison with the

  4. A study of chromium carbide precipitation at interphase boundaries in stainless steel welds

    Energy Technology Data Exchange (ETDEWEB)

    Willis, C.F.

    1990-04-01

    Sensitization is a deleterious process which can occur in stainless steels. It is caused by grain boundary or phase boundary precipitation of chromium carbides and the resulting formation of a chromium depleted zone adjacent to these boundaries. The carbides in question actually have the composition (Cr,Fe){sub 23}C{sub 6} (usually written M{sub 23}C{sub 6}), and precipitate in the temperature range 450--900{degree}C. Since a minimum chromium content is required to maintain the passive film necessary for resistance to electrochemical attack, the result of chromium depletion is that the steel becomes sensitized'' to possible intergranular corrosion. Sensitization often occurs as a result of welding operations. The material close to the fusion line reaches temperatures within the sensitization range. This region is called the heat affected zone (HAZ). Since many welds are multi-pass welds, the actual weld bead of one pass may lie in the heat affected zone of the next pass. The weld bead of the first pass might therefore be sensitized. Furthermore there are applications where welds will be exposed to sensitizing temperatures for very long periods of time, such as welded labels on retrievable nuclear waste containers. For these reasons the sensitization behavior of the actual weld-bead microstructures must be understood. It has been known for many years that duplex stainless steels (steels with both ferrite and austenite phases present at room temperature) have superior resistance to intergranular corrosion. A model has been proposed to explain the sensitization behavior of these alloys. This work will be concerned with testing the validity of aspects of this model using transmission electron microscopy and further understanding of the sensitization process in duplex stainless steel welds. 52 refs., 23 figs.

  5. Constitutive modeling of metastable austenitic stainless steel (CD-rom)

    NARCIS (Netherlands)

    Perdahcioglu, Emin Semih; Geijselaers, Hubertus J.M.; Huetink, Han; Boisse, P.

    2008-01-01

    A stress-update algorithm is developed for austenitic metastable steels which undergo phase evolution during deformation. The material initially comprises only the soft and ductile austenite phase which due to the phenomenon of mechanically induced martensitic transformation, transforms completely

  6. Accumulation of uranium on austenitic stainless steel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Dombovari, Peter [Department of Radiochemistry, Pannon University, H-8201 Veszprem, P.O. Box 158 (Hungary); Kadar, Peter [Department of Radiochemistry, Pannon University, H-8201 Veszprem, P.O. Box 158 (Hungary); Kovacs, Tibor [Department of Radiochemistry, Pannon University, H-8201 Veszprem, P.O. Box 158 (Hungary); Somlai, Janos [Department of Radiochemistry, Pannon University, H-8201 Veszprem, P.O. Box 158 (Hungary); Rado, Krisztian [Department of Radiochemistry, Pannon University, H-8201 Veszprem, P.O. Box 158 (Hungary); Varga, Istvan [Department of Radiochemistry, Pannon University, H-8201 Veszprem, P.O. Box 158 (Hungary); Bujak, Renata [Department of Radiochemistry, Pannon University, H-8201 Veszprem, P.O. Box 158 (Hungary); Varga, Kalman [Department of Radiochemistry, Pannon University, H-8201 Veszprem, P.O. Box 158 (Hungary)]. E-mail: vargakl@almos.vein.hu; Halmos, Pal [Analytical Chemistry Research Group, Hungarian Academy of Sciences, Veszprem (Hungary); Borszeki, Janos [Department of Analytical Chemistry, Pannon University, Veszprem (Hungary); Konya, Jozsef; Nagy, Noemi M. [Department of Colloid- and, Environmental Chemistry, Isotope Laboratory, University of Debrecen, Debrecen (Hungary); Koever, Laszlo; Varga, Dezso; Cserny, Istvan; Toth, Jozsef [Section of Electron Spectroscopy and Materials Science, Institute of Nuclear Research of the Hungarian Academy of Sciences (MTA ATOMKI), P.O. Box 51, H-4001 Debrecen (Hungary); Fodor, Lajos; Horvath, Attila [Department of General and Inorganic Chemistry, Pannon University, Veszprem (Hungary); Pinter, Tamas; Schunk, Janos [Paks NPP Ltd., Paks (Hungary)

    2007-02-01

    The surface contamination by uranium in the primary circuit of PWR type nuclear reactors is a fairly complex problem as (i) different chemical forms (molecular, colloidal and/or disperse) of the uranium atoms can be present in the boric acid coolant, and (ii) only limited pieces of information about the extent, kinetics and mechanism of uranium accumulation on constructional materials are available in the literature. A comprehensive program has been initiated in order to gain fundamental information about the uranium accumulation onto the main constituents of the primary cooling circuit (i.e., onto austenitic stainless steel type 08X18H10T (GOSZT 5632-61) and Zr(1%Nb) alloy). In this paper, some experimental findings on the time and pH dependences of U accumulation obtained in a pilot plant model system are presented and discussed. The surface excess, oxidation state and chemical forms of uranium species sorbed on the inner surfaces of the stainless steel tubes of steam generators have been detected by radiotracer (alpha spectrometric), ICP-OES and XPS methods. In addition, the passivity, morphology and chemical composition of the oxide-layers formed on the studied surfaces of steel specimens have been analyzed by voltammetry and SEM-EDX. The experimental data imply that the uranium sorption is significant in the pH range of 4-8 where the intense hydrolysis of uranyl cations in boric acid solution can be observed. Some specific adsorption and deposition of (mainly colloidal and disperse) uranyl hydroxide to be formed in the solution prevail over the accumulation of other U(VI) hydroxo complexes. The maximum surface excess of uranium species measured at pH 6 ({gamma} {sub sample} = 1.22 {mu}g cm{sup -2} U {approx_equal} 4 x 10{sup -9} mol cm{sup -2} UO{sub 2}(OH){sub 2}) exceeds a monolayer coverage.

  7. Study of biocompatibility of medical grade high nitrogen nickel-free austenitic stainless steel in vitro.

    Science.gov (United States)

    Li, Menghua; Yin, Tieying; Wang, Yazhou; Du, Feifei; Zou, Xingzheng; Gregersen, Hans; Wang, Guixue

    2014-10-01

    Adverse effects of nickel ions being released into the living organism have resulted in development of high nitrogen nickel-free austenitic stainless steels for medical applications. Nitrogen not only replaces nickel for austenitic structure stability but also improves steel properties. The cell cytocompatibility, blood compatibility and cell response of high nitrogen nickel-free austenitic stainless steel were studied in vitro. The mechanical properties and microstructure of this stainless steel were compared to the currently used 316L stainless steel. It was shown that the new steel material had comparable basic mechanical properties to 316L stainless steel and preserved the single austenite organization. The cell toxicity test showed no significant toxic side effects for MC3T3-E1 cells compared to nitinol alloy. Cell adhesion testing showed that the number of MC3T3-E1 cells was more than that on nitinol alloy and the cells grew in good condition. The hemolysis rate was lower than the national standard of 5% without influence on platelets. The total intracellular protein content and ALP activity and quantification of mineralization showed good cell response. We conclude that the high nitrogen nickel-free austenitic stainless steel is a promising new biomedical material for coronary stent development. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Modified Monkman-Grant relationship for austenitic stainless steel foils

    Science.gov (United States)

    Osman Ali, Hassan; Tamin, Mohd Nasir

    2013-02-01

    Characteristics of creep deformation for austenitic stainless steel foils are examined using the modified Monkman-Grant equation. A series of creep tests are conducted on AISI 347 steel foils at 700 °C and different stress levels ranging from 54 to 221 MPa. Results showed that at lower stress levels below 110 MPa, the creep life parameters ɛ, ɛr, tr can be expressed using the modified Monkman-Grant equation with exponent m'= 0.513. This indicates significant deviation of the creep behavior from the first order reaction kinetics theory for creep (m' = 1.0). The true tertiary creep damage in AISI 347 steel foil begins after 65.9% of the creep life of the foil has elapsed at stress levels above 150 MPa. At this high stress levels, Monkman-Grant ductility factor λ' saturates to a value of 1.3 with dislocation-controlled deformation mechanisms operating. At low stress levels, λ' increases drastically (λ'=190 at 54 MPa) when slow diffusion-controlled creep is dominant.

  9. Pitting corrosion in austenitic and duplex stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Jargelius-Pettersson, R.F.A.; Pires Duarte, B.; Duchamp, G. [Swedish Inst. for Metals Research, Stockholm (Sweden)

    1998-12-31

    Various electrochemical methods have been used to evaluate the pitting corrosion resistance of two austenitic and two duplex stainless steels. Testing has been performed in a purpose-built electrochemical cell which permits simultaneous evaluation of twelve specimens and in which crevice corrosion is avoided using a flushed-port design. A potential-independent critical pitting temperature below which pitting is not observed has been evaluated from potentiodynamic measurements, pitting potentials and pit induction times have also been evaluated at various temperatures above this critical value. Statistical treatment of the data has been used to evaluate the elementary pitting probability and pit generation rates. The good differentiation obtained using a large number of pitting potential measurements has permitted quantitative evaluation of the effect of testing and alloy variables. The surface finish is shown to have a significant effect on measured pitting resistance, as has the passivation time between specimen preparation and testing. The decrease in pitting resistance as a result of short-term sensitising heat treatment of the steels has also been evaluated. (orig.) 9 refs.

  10. Overview of Intergranular Fracture of Neutron Irradiated Austenitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Anna Hojná

    2017-09-01

    Full Text Available Austenitic stainless steels are normally ductile and exhibit deep dimples on fracture surfaces. These steels can, however, exhibit brittle intergranular fracture under some circumstances. The occurrence of intergranular fracture in the irradiated steels is briefly reviewed based on limited literature data. The data are sorted according to the irradiation temperature. Intergranular fracture may occur in association with a high irradiation temperature and void swelling. At low irradiation temperature, the steels can exhibit intergranular fracture at low or even at room temperatures during loading in air and in high temperature water (~300 °C. This paper deals with the similarities and differences for IG fractures and discusses the mechanisms involved. The intergranular fracture occurrence at low temperatures might be correlated with decohesion or twinning and strain martensite transformation in local narrow areas around grain boundaries. The possibility of a ductile-to-brittle transition is also discussed. In case of void swelling higher than 3%, quasi-cleavage at low temperature might be expected as a consequence of ductile-to-brittle fracture changes with temperature. Any existence of the change in fracture behavior in the steels of present thermal reactor internals with increasing irradiation dose should be clearly proven or disproven. Further studies to clarify the mechanism are recommended.

  11. Metallurgical and Corrosion Characterization of POST Weld Heat Treated Duplex Stainless Steel (uns S31803) Joints by Friction Welding Process

    Science.gov (United States)

    Asif M., Mohammed; Shrikrishna, Kulkarni Anup; Sathiya, P.

    2016-02-01

    The present study focuses on the metallurgical and corrosion characterization of post weld heat treated duplex stainless steel joints. After friction welding, it was confirmed that there is an increase in ferrite content at weld interface due to dynamic recrystallization. This caused the weldments prone to pitting corrosion attack. Hence the post weld heat treatments were performed at three temperatures 1080∘C, 1150∘C and 1200∘C with 15min of aging time. This was followed by water and oil quenching. The volume fraction of ferrite to austenite ratio was balanced and highest pit nucleation resistance were achieved after PWHT at 1080∘C followed by water quench and at 1150∘C followed by oil quench. This had happened exactly at parameter set containing heating pressure (HP):40 heating time (HT):4 upsetting pressure (UP):80 upsetting time (UP):2 (experiment no. 5). Dual phase presence and absence of precipitates were conformed through TEM which follow Kurdjumov-Sachs relationship. PREN of ferrite was decreasing with increase in temperature and that of austenite increased. The equilibrium temperature for water quenching was around 1100∘C and that for oil quenching was around 1140∘C. The pit depths were found to be in the range of 100nm and width of 1.5-2μm.

  12. Effect of the purging gas on properties of Ti stabilized AISI 321 stainless steel TIG welds

    Energy Technology Data Exchange (ETDEWEB)

    Taban, Emel; Kaluc, Erdinc; Aykan, T. Serkan [Kocaeli Univ. (Turkey). Dept. of Mechanical Engineering

    2014-07-01

    Gas purging is necessary to provide a high quality of stainless steel pipe welding in order to prevent oxidation of the weld zone inside the pipe. AISI 321 stabilized austenitic stainless steel pipes commonly preferred in refinery applications have been welded by the TIG welding process both with and without the use of purging gas. As purging gases, Ar, N{sub 2}, Ar + N{sub 2} and N{sub 2} + 10% H{sub 2} were used, respectively. The aim of this investigation is to detect the effect of purging gas on the weld joint properties such as microstructure, corrosion, strength and impact toughness. Macro sections and microstructures of the welds were investigated. Chemical composition analysis to obtain the nitrogen, oxygen and hydrogen content of the weld root was done by Leco analysis. Ferrite content of the beads including root and cap passes were measured by a ferritscope. Vickers hardness (HV10) values were obtained. Intergranular and pitting corrosion tests were applied to determine the corrosion resistance of all welds. Type of the purging gas affected pitting corrosion properties as well as the ferrite content and nitrogen, oxygen and hydrogen contents at the roots of the welds. Any hot cracking problems are not predicted as the weld still solidifies with ferrite in the primary phase as confirmed by microstructural and ferrite content analysis. Mechanical testing showed no significant change according to the purge gas. AISI 321 steel and 347 consumable compositions would permit use of nitrogen rich gases for root shielding without a risk of hot cracking.

  13. Low Cycle Fatigue behavior of SMAW welded Alloy28 superaustenitic stainless steel at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kchaou, Y., E-mail: yacinekchaou@yahoo.fr [Institut Pprime, Département Physique et Mécanique des Matériaux, UPR 3346 CNRS ISAE-ENSMA Université de Poitiers, Téléport 2, 1, avenue Clément Ader, BP 40109, F – 86961 Futuroscope Chasseneuil Cedex (France); Laboratoire de Génie des Matériaux et Environnement (LGME), ENIS, BPW 1173, Sfax (Tunisia); Pelosin, V.; Hénaff, G. [Institut Pprime, Département Physique et Mécanique des Matériaux, UPR 3346 CNRS ISAE-ENSMA Université de Poitiers, Téléport 2, 1, avenue Clément Ader, BP 40109, F – 86961 Futuroscope Chasseneuil Cedex (France); Haddar, N.; Elleuch, K. [Laboratoire de Génie des Matériaux et Environnement (LGME), ENIS, BPW 1173, Sfax (Tunisia)

    2016-01-10

    This paper focused on the study of Low Cycle Fatigue of welded joints of superaustenitic (Alloy28) stainless steels. Chemical composition and microstructure investigation of Base Metal (BM) and Weld Metal (WM) were identified. The results showed that both of composition is fully austenitic with a dendritic microstructure in the WM. Low cycle fatigue tests at different strain levels were performed on Base Metal (BM) and Welded Joint (WJ) specimens with a strain ratio R{sub ε}=−1. The results indicated that the fatigue life of welded joints is lower than the base metal. This is mainly due to the low ductility of the Welded Metal (WM) and the presence of welding defects. Simultaneously, Scanning Electron Microscope (SEM) observations of fractured specimens show that WJ have brittle behavior compared to BM with the presence of several welding defects especially in the crack initiation site. An estimation of the crack growth rate during LCF tests of BM and WJ was performed using distance between striations. The results showed that the crack initiation stage is shorter in the case of WJ compared to BM because of the presence of welding defects in WJ specimens.

  14. Microstructural, compositional and residual stress evaluation of CO{sub 2} laser welded superaustenitic AISI 904L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Zambon, A. [DIMEG, University of Padova, Via Marzolo, 9 I-35131 Padova (Italy)]. E-mail: a.zambon@unipd.it; Ferro, P. [Department of Management and Engineering, University of Padova, Str.lla S. Nicola, 3 I-36100 Vicenza (Italy); Bonollo, F. [Department of Management and Engineering, University of Padova, Str.lla S. Nicola, 3 I-36100 Vicenza (Italy)

    2006-05-25

    CO{sub 2} laser welding was performed on AISI 904L superaustenitic stainless steel sheets, with optimised processing parameters determined by means of melt run trial evaluations. X-ray diffraction phase identification and light microscopy confirmed that the weld structure is fully austenitic and dendritic. A hardness increase in the weld bead with respect to the parent metal occurred and was related to both the microstructural refinement induced by a rapid cooling of the fusion zone and the presence of nanometric scale precipitates observed by TEM in the weld bead. Residual stresses were determined by means of X-ray diffraction, exhibiting tensile stresses, close to the yield strength, in the longitudinal direction in the weld bead, while the stresses were compressive in the transverse direction and in the base material. Tensile tests showed that welded specimens retained strength and ductility values comparable to those of the base material.

  15. Evaluation of welding by MIG in martensitic stainless steel; Avaliacao da soldagem pelo processo MIG em aco inoxidavel martensitico

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, M.A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Mariano, N.A.; Marinho, D.H.C. Marinho, E-mail: neideaparecidamariano@gmail.co [Universidade Federal de Alfenas (UNIFAL), Pocos de Caldas, MG (Brazil)

    2010-07-01

    This work evaluated structure's characterization and mechanical properties after the welding process of the stainless steel CA6NM. The employed welding process was the metal active gas with tubular wire. The control of the thermal cycle in the welding process has fundamental importance regarding the properties of the welded joint, particularly in the thermally affected zone. The mechanical properties were appraised through impact resistance tests and the hardness and microstructure through metallographic characterization and Ray-X diffraction. The parameters and the process of welding used promoted the hardness and toughness appropriate to the applications of the steel. Welding energy's control becomes an essential factor that can affect the temperature of carbide precipitation and the nucleation of the retained austenite in the in the region of the in the thermally affected zone. (author)

  16. Genetic algorithm based optimization of the process parameters for gas metal arc welding of AISI 904 L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Sathiya, P. [National Institute of Technology Tiruchirappalli (India); Ajith, P. M. [Department of Mechanical Engineering Rajiv Gandhi Institute of Technology, Kottayam (India); Soundararajan, R. [Sri Krishna College of Engineering and Technology, Coimbatore (India)

    2013-08-15

    The present study is focused on welding of super austenitic stainless steel sheet using gas metal arc welding process with AISI 904 L super austenitic stainless steel with solid wire of 1.2 mm diameter. Based on the Box - Behnken design technique, the experiments are carried out. The input parameters (gas flow rate, voltage, travel speed and wire feed rate) ranges are selected based on the filler wire thickness and base material thickness and the corresponding output variables such as bead width (BW), bead height (BH) and depth of penetration (DP) are measured using optical microscopy. Based on the experimental data, the mathematical models are developed as per regression analysis using Design Expert 7.1 software. An attempt is made to minimize the bead width and bead height and maximize the depth of penetration using genetic algorithm.

  17. Assessment of Stress Corrosion Cracking Resistance of Activated Tungsten Inert Gas-Welded Duplex Stainless Steel Joints

    Science.gov (United States)

    Alwin, B.; Lakshminarayanan, A. K.; Vasudevan, M.; Vasantharaja, P.

    2017-11-01

    The stress corrosion cracking behavior of duplex stainless steel (DSS) weld joint largely depends on the ferrite-austenite phase microstructure balance. This phase balance is decided by the welding process used, heat input, welding conditions and the weld metal chemistry. In this investigation, the influence of activated tungsten inert gas (ATIG) and tungsten inert gas (TIG) welding processes on the stress corrosion cracking (SCC) resistance of DSS joints was evaluated and compared. Boiling magnesium chloride (45 wt.%) environment maintained at 155 °C was used. The microstructure and ferrite content of different weld zones are correlated with the outcome of sustained load, SCC test. Irrespective of the welding processes used, SCC resistance of weld joints was inferior to that of the base metal. However, ATIG weld joint exhibited superior resistance to SCC than the TIG weld joint. The crack initiation and final failure were in the weld metal for the ATIG weld joint; they were in the heat-affected zone for the TIG weld joint.

  18. Assessment of Stress Corrosion Cracking Resistance of Activated Tungsten Inert Gas-Welded Duplex Stainless Steel Joints

    Science.gov (United States)

    Alwin, B.; Lakshminarayanan, A. K.; Vasudevan, M.; Vasantharaja, P.

    2017-12-01

    The stress corrosion cracking behavior of duplex stainless steel (DSS) weld joint largely depends on the ferrite-austenite phase microstructure balance. This phase balance is decided by the welding process used, heat input, welding conditions and the weld metal chemistry. In this investigation, the influence of activated tungsten inert gas (ATIG) and tungsten inert gas (TIG) welding processes on the stress corrosion cracking (SCC) resistance of DSS joints was evaluated and compared. Boiling magnesium chloride (45 wt.%) environment maintained at 155 °C was used. The microstructure and ferrite content of different weld zones are correlated with the outcome of sustained load, SCC test. Irrespective of the welding processes used, SCC resistance of weld joints was inferior to that of the base metal. However, ATIG weld joint exhibited superior resistance to SCC than the TIG weld joint. The crack initiation and final failure were in the weld metal for the ATIG weld joint; they were in the heat-affected zone for the TIG weld joint.

  19. Laser-Beam Welding Impact on the Deformation Properties of Stainless Steels When Used for Automotive Applications

    Directory of Open Access Journals (Sweden)

    Evin Emil

    2016-09-01

    Full Text Available Materials other than standard and advanced high strength steels are remarkable for the thin-walled structures of the car-body in recent years in order to safety enhancement, weight and emission reduction, corrosion resistance improvement. Thus, there are presented in the paper the deformation properties of laser welded austenitic AISI 304 and ferritic AISI 430 stainless steels compared to these one measured for the high strength low alloyed steel H220PD. The properties were researched by tensile test and 3-point bending test with fixed ends on specimens made of basic material and laser welded one. The specimens were welded by solid state fiber laser YLS-5000 in longitudinal direction (the load direction. The deformation properties such as strength, stiffness and deformation work were evaluated and compared. The strength and stiffness were calculated from tensile test results and the deformation work was calculated from both, tensile test and 3-point bending test results. There has been found only minor effect of laser welding to the deformation properties for high strength low alloyed steel H220PD and austenitic stainless steel AISI 304. Otherwise, the laser welding strongly influenced the deformation work of the ferritic stainless steel AISI 430 as well as the elongation at tensile test.

  20. Corrosion And Thermal Processing In Cold Gas Dynamic Spray Deposited Austenitic Stainless Steel Coatings

    Science.gov (United States)

    2016-06-01

    REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE CORROSION AND THERMAL PROCESSING IN COLD GAS DYNAMIC SPRAY DEPOSITED AUSTENITIC...THERMAL PROCESSING IN COLD GAS DYNAMIC SPRAY DEPOSITED AUSTENITIC STAINLESS STEEL COATINGS by John A Luhn June 2016 Thesis Advisor: Sarath...precipitate. The resolution of the EDS process may not have been sufficient to show very small precipitates however. SEM imaging at higher

  1. Corrosion fatigue behaviour of 317LN austenitic stainless steel in phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Onoro, J. [Ingenieria y Ciencia de los Materiales, ETSI Industriales, Universidad Politecnica de Madrid, c/Jose Gutierrez Abascal, 2, 28006 Madrid (Spain)], E-mail: javier.onoro@upm.es

    2009-10-15

    The corrosion fatigue crack-growth behaviour of AISI 317LN stainless steel was evaluated in air and in 85% phosphoric acid at 20 deg. C. Austenitic stainless steels with high molybdenum content have high corrosion resistance and good mechanical properties. However, this increase in the molybdenum content and other elements such as nitrogen can also modify the microstructure. This leads to a modification of its mechanical properties. The corrosion fatigue crack-growth rate was higher in phosphoric acid immersion than in air. Austenitic stainless steels with a fully austenitic microstructure were more ductile, tough, and behave better against corrosion fatigue. The higher resistance to corrosion fatigue was directly associated to its higher resistance to corrosion.

  2. Gas tungsten arc welding and friction stir welding of ultrafine grained AISI 304L stainless steel: Microstructural and mechanical behavior characterization

    Energy Technology Data Exchange (ETDEWEB)

    Sabooni, S., E-mail: s.sabooni@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Karimzadeh, F.; Enayati, M.H. [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of); Ngan, A.H.W. [Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Jabbari, H. [Department of Materials Engineering, Isfahan University of Technology, 84156-83111 Isfahan (Iran, Islamic Republic of)

    2015-11-15

    In the present study, an ultrafine grained (UFG) AISI 304L stainless steel with the average grain size of 650 nm was successfully welded by both gas tungsten arc welding (GTAW) and friction stir welding (FSW). GTAW was applied without any filler metal. FSW was also performed at a constant rotational speed of 630 rpm and different welding speeds from 20 to 80 mm/min. Microstructural characterization was carried out by High Resolution Scanning Electron Microscopy (HRSEM) with Electron Backscattered Diffraction (EBSD) and Transmission Electron Microscopy (TEM). Nanoindentation, microhardness measurements and tensile tests were also performed to study the mechanical properties of the base metal and weldments. The results showed that the solidification mode in the GTAW welded sample is FA (ferrite–austenite) type with the microstructure consisting of an austenite matrix embedded with lath type and skeletal type ferrite. The nugget zone microstructure in the FSW welded samples consisted of equiaxed dynamically recrystallized austenite grains with some amount of elongated delta ferrite. Sigma phase precipitates were formed in the region ahead the rotating tool during the heating cycle of FSW, which were finally fragmented into nanometric particles and distributed in the weld nugget. Also there is a high possibility that the existing delta ferrite in the microstructure rapidly transforms into sigma phase particles during the short thermal cycle of FSW. These suggest that high strain and deformation during FSW can promote sigma phase formation. The final austenite grain size in the nugget zone was found to decrease with increasing Zener–Hollomon parameter, which was obtained quantitatively by measuring the peak temperature, calculating the strain rate during FSW and exact examination of hot deformation activation energy by considering the actual grain size before the occurrence of dynamic recrystallization. Mechanical properties observations showed that the welding

  3. Corrosion behaviour of austenitic stainless steel, nickel-base alloy and its weldments in aqueous LiBr solutions

    Energy Technology Data Exchange (ETDEWEB)

    Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia Anton, J.; Garcia-Garcia, D. [Departamento de Ingenieria Quimica y Nuclear. E.T.S.I.Industriales, Universidad Politecnica de Valencia, P.O. Box 22012 E-46071 Valencia (Spain)

    2004-07-01

    With the advances in materials production new alloys have been developed, such as High- Alloy Austenitic Stainless Steels and Nickel-base alloys, with high corrosion resistance. These new alloys are finding applications in Lithium Bromide absorption refrigeration systems, because LiBr is a corrosive medium which can cause serious corrosion problems, in spite of its favourable properties as absorbent. The objective of the present work was to study the corrosion resistance of a highly alloyed austenitic stainless steel (UNS N08031) used as base metal, a Nickel-base alloy (UNS N06059) used as its corresponding filler metal, and the weld metal obtained by the Gas Tungsten Arc Welding (GTAW) procedure. The materials have been tested in different LiBr solutions (400 g/l, 700 g/l, 850 g/l and a commercial 850 g/l LiBr heavy brine containing Lithium Chromate as corrosion inhibitor), at 25 deg. C. Open Circuit Potential tests and potentiodynamic anodic polarization curves have been carried out to obtain information about the general electrochemical behaviour of the materials. The polarization curves of all the alloys tested were typical of passivable materials. Pitting corrosion susceptibility has been evaluated by means of cyclic potentiodynamic curves, which provide parameters to analyse re-passivation properties. The galvanic corrosion generated by the electrical contact between the welded and the base material has been estimated from the polarization diagrams according to the Mixed Potential Method. Samples have been etched to study the microstructure by Scanning Electron Microscopy (SEM). The results demonstrate that the pitting resistance of all these materials increases as the LiBr concentration decreases. In general, the presence of chromate tended to shift the pitting potential to more positive values than those obtained in the 850 g/l LiBr solution. (authors)

  4. Effect of Austenitizing Heat Treatment on the Microstructure and Hardness of Martensitic Stainless Steel AISI 420

    Science.gov (United States)

    Barlow, L. D.; Du Toit, M.

    2012-07-01

    The effect of austenitizing on the microstructure and hardness of two martensitic stainless steels was examined with the aim of supplying heat-treatment guidelines to the user that will ensure a martensitic structure with minimal retained austenite, evenly dispersed carbides and a hardness of between 610 and 740 HV (Vickers hardness) after quenching and tempering. The steels examined during the course of this examination conform in composition to medium-carbon AISI 420 martensitic stainless steel, except for the addition of 0.13% vanadium and 0.62% molybdenum to one of the alloys. Steel samples were austenitized at temperatures between 1000 and 1200 °C, followed by oil quenching. The as-quenched microstructures were found to range from almost fully martensitic structures to martensite with up to 35% retained austenite after quenching, with varying amounts of carbides. Optical and scanning electron microscopy was used to characterize the microstructures, and X-ray diffraction was employed to identify the carbide present in the as-quenched structures and to quantify the retained austenite contents. Hardness tests were performed to determine the effect of heat treatment on mechanical properties. As-quenched hardness values ranged from 700 to 270 HV, depending on the amount of retained austenite. Thermodynamic predictions (using the CALPHAD™ model) were employed to explain these microstructures based on the solubility of the carbide particles at various austenitizing temperatures.

  5. The effect of grain size on the mechanical response of a metastable austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Sinclair C.W.

    2013-11-01

    Full Text Available The combination of high environmental resistance and excellent strength, elongation and energy absorption make austenitic stainless steels potentially attractive for transportation applications. In the case of metastable grades that undergo a strain induced martensitic transformation it is possible to significantly change the mechanical properties simply by changing the austenite grain size. Predicting such behaviour using physically based models is, however, extremely challenging. Here, some recent work on the coupling between grain size and mechanical response will be presented for a metastable AISI 301 LN stainless steel. Successes and continuing challenges will be highlighted.

  6. Effect of massive transformation on formation of acicular structure in austenitic stainless steel weld metal solidified as ferritic single phase. Report 5. Study on solidification and subsequent transformation of Cr-Ni stainless steel weld metals; Feraito tanso de gyokosuru osutenaito kei sutenresu ko yosetsu kinzoku ni okeru ashikyura jo soshiki no keisei ni oyobosu masshibu hentai no eikyo.5. Cr-Ni kei sutenresu ko yosetsu kinzoku no gyoko/hentai ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, H.; Koseki, T.; Okita, S.; Fuji, M. [Nippon Steel Corp., Tokyo (Japan)

    1997-05-05

    The authors clarified that massive transformation occurs at two phase region under To temperature and there is K-S relation between the massive formation phase and base phase using {gamma} stainless steel that solidifies at F mode and forms acicular structure at room temperature structure. There is a possibility of massive transformation in weld metals because the cooling rate below the high temperature To was high even for normal welding process. Thereupon, in this report, whether the massive transformation effects the formation of acicular structure or not was studied as for {gamma} stainless steel weld metal that solidifies at F mode and room temperature structure becomes acicular form of two {delta} and {gamma} phase. As a result, it was clarified that massive transformation occurs at two phase region with temperature below To, and the room temperature structure was acicular form structure irrespective to massive transformation in case of composition with small Cr/Ni ratio even in case of stainless steel that solidifies at F mode. 20 refs., 15 figs., 1 tab.

  7. Small punch creep test in a 316 austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Saucedo-Muñoz, Maribel L.

    2015-03-01

    Full Text Available The small punch creep test was applied to evaluate the creep behavior of a 316 type austenitic stainless steel at temperatures of 650, 675 and 700 °C. The small punch test was carried out using a creep tester with a specimen size of 10×10×0.3 mm at 650, 675 and 700 °C using loads from 199 to 512 N. The small punch creep curves show the three stages found in the creep curves of the conventional uniaxial test. The conventional creep relationships which involve parameters such as creep rate, stress, time to rupture and temperature were followed with the corresponding parameters of small punch creep test and they permitted to explain the creep behavior in this steel. The mechanism and activation energy of the deformation process were the grain boundary sliding and diffusion, respectively, during creep which caused the intergranular fracture in the tested specimens.El ensayo de termofluencia por indentación se utilizó para evaluar el comportamiento a la termofluencia en un acero inoxidable austenítico 316. Este ensayo se realizó en una máquina de indentación con muestras de 10×10×0,3 mm a temperaturas de 650, 675 y 700 °C con cargas de 199 a 512 N. Las curvas de termofluencia del ensayo mostraron las tres etapas características observadas en el ensayo convencional de tensión. Asimismo, las principales relaciones de termofluencia entre parámetros como velocidad de termofluencia, esfuerzo, tiempo de ruptura y temperatura se observaron en los parámetros correspondientes al ensayo de indentación, lo que permitió caracterizar el comportamiento de termofluencia en este acero. El mecanismo y la energía de activación del proceso de deformación en la termofluencia corresponden al deslizamiento de los límites de grano y la difusión a través de los mismos, respectivamente, lo cual causó la fractura intergranular en las muestras ensayadas.

  8. Effects of X-rays Radiation on AISI 304 Stainless Steel Weldings with AISI 316L Filler Material: A Study of Resistance and Pitting Corrosion Behavior

    Directory of Open Access Journals (Sweden)

    Francisco Javier Cárcel-Carrasco

    2016-04-01

    Full Text Available This article investigates the effect of low-level ionizing radiation, namely X-rays, on the micro structural characteristics, resistance, and corrosion resistance of TIG-welded joints of AISI 304 austenitic stainless steel made using AISI 316L filler rods. The welds were made in two different environments: natural atmospheric conditions and a closed chamber filled with inert argon gas. The influence of different doses of radiation on the resistance and corrosion characteristics of the welds is analyzed. Welded material from inert Ar gas chamber TIG showed better characteristics and lesser irradiation damage effects.

  9. Acoustic Emission Technique for Characterizing Deformation and Fatigue Crack Growth in Austenitic Stainless Steels

    Science.gov (United States)

    Raj, Baldev; Mukhopadhyay, C. K.; Jayakumar, T.

    2003-03-01

    Acoustic emission (AE) during tensile deformation and fatigue crack growth (FCG) of austenitic stainless steels has been studied. In AISI type 316 stainless steel (SS), AE has been used to detect micro plastic yielding occurring during macroscopic plastic deformation. In AISI type 304 SS, relation of AE with stress intensity factor and plastic zone size has been studied. In AISI type 316 SS, fatigue crack growth has been characterised using acoustic emission.

  10. Attenuation capability of low activation-modified high manganese austenitic stainless steel for fusion reactor system

    Energy Technology Data Exchange (ETDEWEB)

    Eissa, M.M. [Steel Technology Department, Central Metallurgical Research and Development Institute (CMRDI), Helwan (Egypt); El-kameesy, S.U.; El-Fiki, S.A. [Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt); Ghali, S.N. [Steel Technology Department, Central Metallurgical Research and Development Institute (CMRDI), Helwan (Egypt); El Shazly, R.M. [Physics Department, Faculty of Science, Al-Azhar University, Cairo (Egypt); Saeed, Aly, E-mail: aly_8h@yahoo.com [Nuclear Power station Department, Faculty of Engineering, Egyptian-Russian University, Cairo (Egypt)

    2016-11-15

    Highlights: • Improvement stainless steel alloys to be used in fusion reactors. • Structural, mechanical, attenuation properties of investigated alloys were studied. • Good agreement between experimental and calculated results has been achieved. • The developed alloys could be considered as candidate materials for fusion reactors. - Abstract: Low nickel-high manganese austenitic stainless steel alloys, SSMn9Ni and SSMn10Ni, were developed to use as a shielding material in fusion reactor system. A standard austenitic stainless steel SS316L was prepared and studied as a reference sample. The microstructure properties of the present stainless steel alloys were investigated using Schaeffler diagram, optical microscopy, and X-ray diffraction pattern. Mainly, an austenite phase was observed for the prepared stainless steel alloys. Additionally, a small ferrite phase was observed in SS316L and SSMn10Ni samples. The mechanical properties of the prepared alloys were studied using Vickers hardness and tensile tests at room temperature. The studied manganese stainless steel alloys showed higher hardness, yield strength, and ultimate tensile strength than SS316L. On the other hand, the manganese stainless steel elongation had relatively lower values than the standard SS316L. The removal cross section for both slow and total slow (primary and those slowed down in sample) neutrons were carried out using {sup 241}Am-Be neutron source. Gamma ray attenuation parameters were carried out for different gamma ray energy lines which emitted from {sup 60}Co and {sup 232}Th radioactive sources. The developed manganese stainless steel alloys had a higher total slow removal cross section than SS316L. While the slow neutron and gamma rays were nearly the same for all studied stainless steel alloys. From the obtained results, the developed manganese stainless steel alloys could be considered as candidate materials for fusion reactor system with low activation based on the short life

  11. The influence of texture on phase transformation in metastable austenitic stainless steel

    NARCIS (Netherlands)

    Hilkhuijsen, P.

    2013-01-01

    Metastable austenitic stainless steels are used in many applications, from shavers and kitchen sinks to various applications in the food industry. The diversity in applications of this type of steels is possible due to the many positive properties of the steel. It is not only esthetically pleasing,

  12. Influence of surface texture on the galling characteristics of lean duplex and austenitic stainless steels

    DEFF Research Database (Denmark)

    Wadman, Boel; Eriksen, J.; Olsson, M.

    2010-01-01

    Two simulative test methods were used to study galling in sheet forming of two types of stainless steel sheet: austenitic (EN 1.4301) and lean duplex LDX 2101 (EN 1.4162) in different surface conditions. The pin-on-disc test was used to analyse the galling resistance of different combinations...

  13. Copper modified austenitic stainless steel alloys with improved high temperature creep resistance

    Science.gov (United States)

    Swindeman, R.W.; Maziasz, P.J.

    1987-04-28

    An improved austenitic stainless steel that incorporates copper into a base Fe-Ni-Cr alloy having minor alloying substituents of Mo, Mn, Si, T, Nb, V, C, N, P, B which exhibits significant improvement in high temperature creep resistance over previous steels. 3 figs.

  14. The Formation of Multipoles during the High-Temperature Creep of Austenitic Stainless Steels

    DEFF Research Database (Denmark)

    Howell, J.; Nielsson, O.; Horsewell, Andy

    1981-01-01

    It is shown that multipole dislocation configurations can arise during power-law creep of certain austenitic stainless steels. These multipoles have been analysed in some detail for two particular steels (Alloy 800 and a modified AISI 316L) and it is suggested that they arise either during...

  15. Austenitic stainless steel alloys having improved resistance to fast neutron-induced swelling

    Science.gov (United States)

    Bloom, Everett E.; Stiegler, James O.; Rowcliffe, Arthur F.; Leitnaker, James M.

    1977-03-08

    The present invention is based on the discovery that radiation-induced voids which occur during fast neutron irradiation can be controlled by small but effective additions of titanium and silicon. The void-suppressing effect of these metals in combination is demonstrated and particularly apparent in austenitic stainless steels.

  16. The adhesion of hot-filament CVD diamond films on AISI type 316 austenitic stainless steel

    NARCIS (Netherlands)

    Buijnsters, J.G.; Shankar, P.; Enckevort, W.J.P. van; Schermer, J.J.; Meulen, J.J. ter

    2004-01-01

    Steel ball indentation and scratch adhesion testing of hot filament chemical vapour deposited diamond films onto AISI type 316 austenitic stainless steel substrates using two different interlayer systems, namely chromium nitride and borided steel, have been investigated. In order to compare the

  17. Void Volume Swelling Dependent on Grain Size in Austenitic Stainless Steel

    DEFF Research Database (Denmark)

    Singh, Bachu Narain

    1973-01-01

    Describes some of the main findings of a systematic study of the effect of grain size on the void volume swelling. In this study a powder-produced 20 Ni/20 Cr austenitic stainless steel, with 0.02% carbon and without carbide-forming elements was used. Some specimens containing dispersions...

  18. Stress and Composition of Carbon Stabilized Expanded Austenite on Stainless Steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A. J.

    2009-01-01

    Low-temperature gaseous carburizing of stainless steel is associated with a colossal supersaturation of the fcc lattice with carbon, without the development of carbides. This article addresses the simultaneous determination of stress and composition profiles in layers of carbon xpanded austenite ...

  19. The efficiency of ion nitriding of austenitic stainless steel 304 using the “active screen”

    OpenAIRE

    M. Ogórek; Z. Skuza; T. Frączek

    2015-01-01

    The study examined layers were formed on the outer surface of austenitic stainless steel 304 under glow discharge conditions in the low-temperature and short-term ion nitriding. The outer layers analyzed in the work produced in parallel in the classical process of cathode and a novel method of “active screen”, intensifying the process of nitriding.

  20. The efficiency of ion nitriding of austenitic stainless steel 304 using the “active screen”

    Directory of Open Access Journals (Sweden)

    M. Ogórek

    2015-01-01

    Full Text Available The study examined layers were formed on the outer surface of austenitic stainless steel 304 under glow discharge conditions in the low-temperature and short-term ion nitriding. The outer layers analyzed in the work produced in parallel in the classical process of cathode and a novel method of “active screen”, intensifying the process of nitriding.

  1. Dependence of corrosion properties of AISI 304L stainless steel on the austenite grain size

    Energy Technology Data Exchange (ETDEWEB)

    Sabooni, Soheil; Rashtchi, Hamed; Eslami, Abdoulmajid; Karimzadeh, Fathallah; Enayati, Mohammad Hossein; Raeissi, Keyvan; Imani, Reihane Faghih [Isfahan Univ. of Technology, Isfahan (Iran, Islamic Republic of). Dept. of Materials Engineering; Ngan, Alfonso Hing Wan [The Univ. of Hong Kong (China). Dept. of Mechanical Engineering

    2017-07-15

    The corrosion resistance of austenitic stainless steels is known to be hampered by the loss of chromium available for passive surface layer formation as a result of chromium carbide precipitation at austenite grain boundaries during annealing treatments. Although high-temperature annealing can promote carbide dissolution leading to better corrosion resistance, grain coarsening also results, which would lead to poorer mechanical properties. Processing methods to achieve both good corrosion resistance and mechanical properties are thus highly desirable for austenitic stainless steels. In the present study, we show that the corrosion resistance of AISI 304L stainless steel can be improved by grain refinement into the ultrafine-grained regime. Specifically, samples with different austenite grain sizes in the range of 0.65-12 μm were studied by potentiodynamic polarization and electrochemical impedance spectroscopy tests in a 3.5 wt.% NaCl solution. All samples showed a typical passive behavior with similar corrosion potential, but the corrosion current density decreased significantly with decreasing grain size. The results show that the sample with the finest grain size had the best corrosion resistance due to a higher resistance of the passive layer to pitting attacks. This study indicates that grain refinement which improves mechanical properties can also significantly improve the corrosion resistance of AISI 304L stainless steel.

  2. Effect of electromagnetic stirring on solidification structure of austenitic stainless steel in horizontal continuous casting

    Directory of Open Access Journals (Sweden)

    ZHOU Shu-cai

    2007-08-01

    Full Text Available An investigation on the influence of low frequency rotary electromagnetic stirring on solidification structure of austenitic stainless steel in horizontal continuous casting was experimentally conducted and carried out on an industrial trial basis. The results show that application of appropriate electromagnetic stirring parameters can obviously improve the macrostructure of austenitic stainless steel, in which both columnar and equiaxed grains can be greatly refined and shrinkage porosity or cavity zone along centerline can be remarkably decreased due to eliminating intracrystalline and enlarging equiaxed grains zone. The industrial trials verify that the electromagnetic stirring intensity of austenitic stainless steel should be higher than that of plain carbon steel. Electromagnetic stirring has somewhat affected the macrostructure of austenitic stainless steel even if the magnetic flux density of the electromagnetic stirring reaches 90 mT (amplitude reaches 141 mT in average at frequency f=3-4Hz, which provides a reference for the optimization of design and process parameters when applying the rotary electromagnetic stirrer.

  3. Modeling of Ni Diffusion Induced Austenite Formation in Ferritic Stainless Steel Interconnects

    DEFF Research Database (Denmark)

    Chen, Ming; Molin, Sebastian; Zhang, L.

    2015-01-01

    of the ferritic phase into an austenitic phase in the interface region. This is accompanied with changes in volume and in mechanical and corrosion properties of the IC plates. In this work, kinetic modeling of the inter-diffusion between Ni and FeCr based ferritic stainless steel was conducted, using the CALPHAD......Ferritic stainless steel interconnect plates are widely used in planar solid oxide fuel cell (SOFC) or electrolysis cell (SOEC) stacks. During stack production and operation, nickel from the Ni/YSZ fuel electrode or from the Ni contact component diffuses into the IC plate, causing transformation...... approach with the DICTRA software. The kinetics of inter-diffusion and austenite formation was explored in full detail, as functions of layer thickness, temperature, time, and steel composition. The simulation was further validated by comparing with experimental results. Growth of the austenite phase...

  4. Effect of Chemical Composition on Susceptibility to Weld Solidification Cracking in Austenitic Weld Metal

    Science.gov (United States)

    Kadoi, Kota; Shinozaki, Kenji

    2017-09-01

    The influence of the chemical composition, especially the niobium content, chromium equivalent Creq, and nickel equivalent Nieq, on the weld solidification cracking susceptibility in the austenite single-phase region in the Schaeffler diagram was investigated. Specimens were fabricated using the hot-wire laser welding process with widely different compositions of Creq, Nieq, and niobium in the region. The distributions of the susceptibility, such as the crack length and brittle temperature range (BTR), in the Schaeffler diagram revealed a region with high susceptibility to solidification cracking. Addition of niobium enhanced the susceptibility and changed the distribution of the susceptibility in the diagram. The BTR distribution was in good agreement with the distribution of the temperature range of solidification (ΔT) calculated by solidification simulation based on Scheil model. ΔT increased with increasing content of alloying elements such as niobium. The distribution of ΔT was dependent on the type of alloying element owing to the change of the partitioning behavior. Thus, the solidification cracking susceptibility in the austenite single-phase region depends on whether the alloy contains elements. The distribution of the susceptibility in the region is controlled by the change in ΔT and the segregation behavior of niobium with the chemical composition.

  5. Effect of Chemical Composition on Susceptibility to Weld Solidification Cracking in Austenitic Weld Metal

    Science.gov (United States)

    Kadoi, Kota; Shinozaki, Kenji

    2017-12-01

    The influence of the chemical composition, especially the niobium content, chromium equivalent Creq, and nickel equivalent Nieq, on the weld solidification cracking susceptibility in the austenite single-phase region in the Schaeffler diagram was investigated. Specimens were fabricated using the hot-wire laser welding process with widely different compositions of Creq, Nieq, and niobium in the region. The distributions of the susceptibility, such as the crack length and brittle temperature range (BTR), in the Schaeffler diagram revealed a region with high susceptibility to solidification cracking. Addition of niobium enhanced the susceptibility and changed the distribution of the susceptibility in the diagram. The BTR distribution was in good agreement with the distribution of the temperature range of solidification (Δ T) calculated by solidification simulation based on Scheil model. Δ T increased with increasing content of alloying elements such as niobium. The distribution of Δ T was dependent on the type of alloying element owing to the change of the partitioning behavior. Thus, the solidification cracking susceptibility in the austenite single-phase region depends on whether the alloy contains elements. The distribution of the susceptibility in the region is controlled by the change in Δ T and the segregation behavior of niobium with the chemical composition.

  6. Analysis of features of stainless steels in dissimilar welded joints in chloride inducted corrosion

    Science.gov (United States)

    Topolska, S.; Łabanowski, J.

    2017-08-01

    Stainless steels of femtic-austenitic microstructure that means the duplex Cr-Ni-Mo steels, in comparison with austenitic steel includes less expensive nickel and has much better mechanical properties with good formability and corrosion resistance, even in environments containing chloride ions. Similar share of high chromium ferrite and austenite, which is characterized by high ductility, determines that the duplex steels have good crack resistance at temperatures up to approximately -40°C. The steels containing approximately 22% Cr, 5% Ni, 3% Mo and 0.2% N crystallizes as a solid solution δ, partially transforming from the temperature of about 1200°C to 850°C into the phase α. The stable structure of considered steels, at temperatures above 850°C, is ferrite, and at lower temperatures the mixture of phase γ+α +σ. The two-phase structure α+γ the duplex steel obtains after hyperquenching at the temperature of stability of the mixture of α+γ phases, and the share of the phases depends on the hyper quenching attributes. Hyperquenching in water, with a temperature close to 1200°C, ensures the instance in the microstructure of the steel a large share of ferrite and a small share of the high chromium austenite. This causes the increase of strength properties and reducing the plasticity of the steel and its resistance ability to cracking and corrosion. Slower cooling from the mentioned temperature, for example in the air, enables the partial transformation of the a phase into the γ one (α → γ) and increasing the share of austenite in the steel structure. It leads to improvement of plasticity properties. In the paper are presented the results of investigations of heteronymous welded joints of duplex steel and austenitic one. The results include the relation between the chemical composition of steels and their weldability.

  7. Influence of the post-weld surface treatment on the corrosion resistance of the duplex stainless steel 1.4062

    Science.gov (United States)

    Rosemann, P.; Müller, C.; Baumann, O.; Modersohn, W.; Halle, T.

    2017-03-01

    The duplex stainless steel 1.4062 (X2CrNiN22-2) is used as alternative material to austenitic stainless steels in the construction industry. The corrosion resistance of welded seams is influenced by the base material, the weld filler material, the welding process and also by the final surface treatment. The scale layer next to the weld seam can be removed by grinding, pickling, electro-polished or blasting depending on the application and the requested corrosion resistance. Blasted surfaces are often used in industrial practice due to the easier and cheaper manufacturing process compared to pickled or electro-polished surfaces. Furthermore blasting with corundum-grain is more effective than blasting with glass-beads which also lower the process costs. In recent years, stainless steel surfaces showed an unusually high susceptibility to pitting corrosion after grinding with corundum. For this reason, it is now also questioned critically whether the corrosion resistance is influenced by the applied blasting agent. This question was specifically investigated by comparing grinded, pickled, corundum-grain- and glass-bead-blasted welding seams. Results of the SEM analyses of the blasting agents and the blasted surfaces will be presented and correlated with the different performed corrosion tests (potential measurement, KorroPad-test and pitting potential) on welding seams with different surface treatments.

  8. effects of metal inert gas welding parameters on some mechanical ...

    African Journals Online (AJOL)

    HOD

    MIG) welding parameters on the mechanical properties (hardness, tensile and impact) of type 304 austenitic stainless steel (ASS) immersed in 0.5M hydrochloric acid at ambient temperature. The MIG welding was applied to 3mm thick ASS.

  9. EFFECTS OF METAL INERT GAS WELDING PARAMETERS ON ...

    African Journals Online (AJOL)

    MIG) welding parameters on the mechanical properties (hardness, tensile and impact) of type 304 austenitic stainless steel (ASS) immersed in 0.5M hydrochloric acid at ambient temperature. The MIG welding was applied to 3mm thick ASS.

  10. Influence of delta ferrite on corrosion susceptibility of AISI 304 austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Lawrence O. Osoba

    2016-12-01

    Full Text Available In the current study, the influence of delta (δ ferrite on the corrosion susceptibility of AISI 304 austenitic stainless steel was evaluated in 1Molar concentration of sulphuric acid (H2SO4 and 1Molar concentration of sodium chloride (NaCl. The study was performed at ambient temperature using electrochemical technique—Tafel plots to evaluate the corrosive tendencies of the austenitic stainless steel sample. The as-received (stainless steel specimen and 60% cold-worked (stainless steel specimens were isothermally annealed at 1,100°C for 2 h and 1 h, respectively, and quenched in water. The results obtained show that the heat-treated specimen and the 60% cold-worked plus heat-treated specimen exhibited higher corrosion susceptibility than the as-received specimen, which invariably contained the highest fraction of δ ferrite particles. The finding shows that the presence of δ ferrite, in which chromium (Cr, the main corrosion inhibitor segregates, does not degrade and or reduces the resistance to aqueous corrosion of the austenitic stainless steel material.

  11. Eddy-Current Testing of Welded Stainless Steel Storage Containers to Verify Integrity and Identity

    Energy Technology Data Exchange (ETDEWEB)

    Tolk, Keith M.; Stoker, Gerald C.

    1999-07-20

    An eddy-current scanning system is being developed to allow the International Atomic Energy Agency (IAEA) to verify the integrity of nuclear material storage containers. Such a system is necessary to detect attempts to remove material from the containers in facilities where continuous surveillance of the containers is not practical. Initial tests have shown that the eddy-current system is also capable of verifying the identity of each container using the electromagnetic signature of its welds. The DOE-3013 containers proposed for use in some US facilities are made of an austenitic stainless steel alloy, which is nonmagnetic in its normal condition. When the material is cold worked by forming or by local stresses experienced in welding, it loses its austenitic grain structure and its magnetic permeability increases. This change in magnetic permeability can be measured using an eddy-current probe specifically designed for this purpose. Initial tests have shown that variations of magnetic permeability and material conductivity in and around welds can be detected, and form a pattern unique to the container. The changes in conductivity that are present around a mechanically inserted plug can also be detected. Further development of the system is currently underway to adapt the system to verifying the integrity and identity of sealable, tamper-indicating enclosures designed to prevent unauthorized access to measurement equipment used to verify international agreements.

  12. Influence of the solution temperature on the corrosion behavior of an austenitic stainless steel in phosphoric acid medium

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez-Ferrandiz, M.V.; Blasco-Tamarit, E.; Garcia-Garcia, D.M.; Garcia-Anton, J. [Valencia Univ. Politecnica, Dept. de Ingenieria Quimica y Nuclear. ETSI Industriales, Valencia (Spain); Guenbour, A.; Bakour, S.; Benckokroun, A. [University Mohammed V-Agdal, Lab. Corrosion-Electrochimie, Faculty of Sciences, Rabat (Morocco)

    2009-07-01

    The objective of the present work is to study the effect of the solution temperature on the corrosion resistance of a highly alloyed austenitic stainless steel (UNS N08031) used as base metal, the welded metal obtained by TIG (Tungsten Inert Gas) welding using a Nickel-base alloy (UNS N06059) as filler metal, and the Heat Affected Zone (HAZ) of the base metal. The materials were tested in 5.5 M phosphoric acid solution at 25 C, 40 C, 60 C and 80 C. Open Circuit Potential tests and potentiodynamic anodic polarization curves have been carried out to obtain information about the electrochemical behavior of the materials. Corrosion potentials and corrosion current densities were obtained from Tafel analysis. The critic potentials and passivation current densities of the studied materials were also analyzed. The galvanic corrosion generated by the electrical contact between the welded metal, the base metal and the HAZ, was estimated from the polarisation diagrams according to the Mixed Potential Theory. The samples were etched to study their microstructure by Optical Microscopy. Results demonstrated that the corrosion potential values shift to more anodic potentials as temperature increases. The corrosion current densities and the passive current densities increased with temperature. Open circuit potential values were located in the passive zone of the potentiodynamic curves, which means that the materials passivated spontaneously. (authors)

  13. Use of the Mass-Spying Lattice Model for Simulation of Ultrasonic Waves in Austenitic Welds

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Eun Sol; Yim, Hyun June [Hongik University, Seoul (Korea, Republic of)

    2006-02-15

    Feasibility is studied for an application of the mass-spring lattice model (MSLM), a numerical model previously developed for unidirectional composites, to the numerical simulation of ultrasonic inspection of austenitic welds modeled as transversely isotropic. Fundamental wave processes, such as propagation, reflection, refraction, and diffraction of ultrasonic waves in such an inspection are simulated using the MSLM. All numerical results show excellent agreement with the analytical results. Further, a simplified model of austenitic weld inspection has been successfully simulated using the MSLM. In conclusion, a great potential of the MSLM in numerically simulating ultrasonic inspections of austenitic welds has been manifested in this work, though significant further efforts will be required to develop a model with field practicality

  14. Effect of Grain Refinement on Deformation Mechanism and Mechanical Properties of Austenitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    WAN Xiang-liang

    2016-08-01

    Full Text Available The concept of phase reversion involving cold deformation of metastable austenite to generate strain-induced martensite, followed by temperature-time annealing sequence, was used to obtain grain size of nanograined/ultrafine-grained and coarse-grained austenitic stainless steels. The mechanical properties of austenitic stainless steels with different grain sizes were obtained by tensile testing, the deformation microstructure and fracture surface were analyzed by TEM and SEM observations, respectively. The results indicate that deformation twins contribute to excellent ductility in high yield strength nanograined/ultrafine-grained steel, while in the low yield strength coarse-grained steel, the high ductility is due to strain-induced martensite transformation. Interestingly, the tensile fracture of the two austensite stainless steels with different deformation mechanism is ductile fracture. The deformation mechanism from deformation twins to strain-induced martensite in the coarse-grained structure in nanograined/ultrafine-grained structures is owing to the increased stability of austenite with grain refining.

  15. 75 FR 53714 - Stainless Steel Butt-Weld Pipe Fittings From Japan, Korea, and Taiwan

    Science.gov (United States)

    2010-09-01

    ... 564 (Third Review)] Stainless Steel Butt-Weld Pipe Fittings From Japan, Korea, and Taiwan AGENCY... antidumping duty orders on stainless steel butt-weld pipe fittings from Japan, Korea, and Taiwan. SUMMARY: The... stainless steel butt-weld pipe fittings from Japan, Korea, and Taiwan would be likely to lead to...

  16. Responses of the corroded surface layer of austenitic stainless steel to different corrosive conditions under cavitation

    Energy Technology Data Exchange (ETDEWEB)

    Yong, Xingyue, E-mail: yongxy@mail.buct.edu.cn; Xiao, Ning; Shen, Hanjie; Song, Yili

    2016-08-01

    Nanoindentation was used to measure the nano-mechanical properties of the corroded surface layer of austenitic stainless steel after cavitation corrosion tests. The phase structures and chemical compositions of the corroded surface layer were analysed using X-ray diffraction and X-ray Photoelectron Spectroscopy. The results show that corrosion caused a decrement of the nano-mechanical properties of the corroded surface layer. Once corrosion was weakened, the formation of a work-hardened layer resulted from the transformation of austenite into martensite. The synergistic effect caused the more rapid dissolution of Fe hydroxides, resulting in the enrichment of Cr and property changes of the corroded surface layer under cavitation.

  17. Hydrogen Absorption Induced Slow Crack Growth in Austenitic Stainless Steels for Petrochemical Pressure Vessel Industries

    Directory of Open Access Journals (Sweden)

    Ronnie Rusli

    2011-05-01

    Full Text Available Type 304Land type 309 austenitic stainless steels were tested either by exposed to gaseous hydrogen or undergoing polarized cathodic charging. Slow crack growth by straining was observed in type 304L, and the formation of α‘ martensite was indicated to be precursor for such cracking. Gross plastic deformation was observed at the tip of the notch, and a single crack grew slowly from this region in a direction approximately perpendicular to the tensile axis. Martensite formation is not a necessary condition for hydrogen embrittlement in the austenitic phase.

  18. STUDY AND ANALYSIS OF THE EFFECT OF WELDING PROCESS ON DISTORTION WITH 304L STAINLESS STEEL WELD JOINTS

    OpenAIRE

    Dhananjay Kumar*, Dharamvir mangal

    2017-01-01

    The effect of welding process on the distortion with 304L stainless steel 12thk weld joints made by TIG (tungsten inert gas) and SMAW (Shielded metal arc welding) welding process involving different type joint configuration have been studied. The joint configurations employed were double V-groove edge preparation for double side SMAW welding and square – butt preparation for double side TIG welding. All weld joints passed by radiographic. Distortion measurements were carried out using height ...

  19. Irradiation effects on austenitic stainless steels for structural materials of IFMIF components

    Energy Technology Data Exchange (ETDEWEB)

    Jitsukawa, S.; Suzuki, K. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Zinkle, S. [Oak Ridge National Laboratory, Materials Science and Technology Div., AK TN (United States); Hirose, T. [Blanket Engineering Group, Japan Atomic Energy Agency, Naka, Ibaraki (Japan)

    2007-07-01

    Full text of publication follows: Austenitic stainless steel, such as 316 stainless steel is one of the candidate structural materials for the target component and test modules of the International Fusion Materials Irradiation Facility IFMIF, as well as that for ITER shield blanket. Anticipated displacement damage levels for the ITER shield blanket are as large as 3 displacements per atom (dpa), while those for the IFMIF target components and test modules will attain a high damage level of 50 dpa or even higher, depending on the service period. The anticipated operating temperature of the components is lower than 400 deg. C; therefore irradiation will cause hardening and reduction of elongation, as well as degradation of fracture toughness. This paper reviews the degradation of mechanical properties of austenitic stainless steels introduced by irradiation to some tens of dpa level; degradation of fatigue properties, fracture toughness and ductility, as well as irradiation induced creep. Additional data, especially those at temperatures lower than 300 deg. C, are also introduced. The results have been obtained during the collaborative irradiation experiment between JAEA and US-DOE using HFIR. Irradiation causes degradation in mechanical properties of the austenitic stainless steels. However, residual ductility and fracture toughness still seem to be large enough for the application as structural materials. This, however, does not assure that the current design criterion is applicable for the component engineering. A dedicated effort to develop engineering design criteria also needs to be accomplished. (authors)

  20. Evaluation of the fabricability of advanced iron aluminide-clad austenitic stainless steel tubing

    Energy Technology Data Exchange (ETDEWEB)

    Mohn, W.R.; Topolski, M.J. [Babcock and Wilcox Co., Alliance, OH (United States). Research and Development Div.

    1993-07-01

    Researchers at Babcock & Wilcox Alliance Research Center have investigated methods to produce bimetallic tubing consisting of iron aluminide-clad austenitic stainless steel for practical use in fossil fueled energy equipment. In the course of this work, the compatibility of iron aluminide with four candidate austenitic stainless steel substrates was first evaluated using diffusion couples. Based on these results, a combination of iron aluminide and 304 stainless steel was selected for further development. Two composite billets of this combination were then prepared and extruded in separate trails at 2200F and 2000F. Both extrusions yielded 2-inch OD clad tubes, each approximately 18 feet long. Results of the evaluation show that the tube extruded at 2000F had a sound, integrally bonded clad layer throughout its entire length. However, the tube extruded at 2200F exhibited regions of disbonding between the clad layer and the substrate. In supplement to this work, an assessment of the technical and economic merits of iron aluminide-clad austenitic stainless steel components in power generation systems was conducted by B&W Fossil Power Division. Future activities should include an investigation of lower extrusion processing temperatures to optimize the fabrication of high quality iron-aluminide clad tubing.

  1. Application Feasibility of PRE 50 grade Super Austenitic Stainless Steel as a Steam Generator Tubing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yong Soo [Yonsei University, Seoul (Korea, Republic of); Kim, Young sik [Andong National University, Andong (Korea, Republic of); Kim, Taek Jun; Kim, Sun Tae; Park, Hui Sang [Yonsei University, Seoul (Korea, Republic of)

    1997-07-01

    The aim of this study is to evaluate the properties of the super austenitic stainless steel, SR-50A for application as steam generator tubing material. The microstructure, mechanical properties, corrosion properties, were analyzed and the results were compared between super austenitic stainless steel and Alloy 600 and Alloy 690. Super austenitic stainless steel, SR-50A is superior to Alloy 600, Alloy 690 and Alloy 800 in the mechanical properties(tensile strength, yield strength, and elongation). It was investigated that thermal conductivity of SR-50A was higher than Alloy 600. As a result of thermal treatment on super stainless steel, SR-50A, caustic SCC resistance was increased and its resistance was as much as Alloy 600TT and Alloy 690TT. In this study, optimum thermal treatment condition to improve the caustic corrosion properties was considered as 650 deg C or 550 deg C 15 hours. However, it is necessary to verify the corrosion mechanism and to prove the above results in the various corrosive environments. 27 refs., 6 tabs., 59 figs. (author)

  2. Comprehensive Deformation Analysis of a Newly Designed Ni-Free Duplex Stainless Steel with Enhanced Plasticity by Optimizing Austenite Stability

    DEFF Research Database (Denmark)

    Moallemi, Mohammad; Zarei-Hanzaki, Abbas; Eskandari, Mostafa

    2017-01-01

    A new metastable Ni-free duplex stainless steel has been designed with superior plasticity by optimizing austenite stability using thermodynamic calculations of stacking fault energy and with reference to literature findings. Several characterization methods comprising optical microscopy, magneti...

  3. Laser cladding crack repair of austenitic stainless steel

    CSIR Research Space (South Africa)

    Van Rooyen, C

    2009-06-01

    Full Text Available @ 2 bar pressure Fig. 6: Crack sealing and overlay of 6.0mm plate 4 Typical hardness of the 316L crack seal layers is 160 HV1kg. Crack sealing can be performed with more noble Ni-base alloys to improved... of surface compressive stresses will avoid initiation of SCC. Due to primary austenitic solidification of laser cladded 316L, no delta ferrite is present in the microstructure. Although the susceptibility...

  4. Influence of Plastic Deformation on Low Temperature Surface Hardening of Austenitic and Precipitation Hardening Stainless Steels by Gaseous Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of three commercial austenitic stainless steels: AISI 304, EN 1.4369 and Sandvik Nanoflex® with various degrees of austenite stability. The materials were...

  5. In-situ investigation of strain-induced martensitic transformation kinetics in an austenitic stainless steel by inductive measurements

    NARCIS (Netherlands)

    Alonso de Celada Casero, C.; Kooiker, Harm; Groen, Manso; Post, J; San Martin, D

    2017-01-01

    An inductive sensor developed by Philips ATC has been used to study in-situ the austenite (γ) to martensite (α′) phase transformation kinetics during tensile testing in an AISI 301 austenitic stainless steel. A correlation between the sensor output signal and the volume fraction of α′-martensite

  6. Extended X-Ray Absorption Fine Structure Investigation of Carbon Stabilized Expanded Austenite and Carbides in Stainless Steel AISI 316

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny

    2011-01-01

    Low temperature carburized AISI 316 stainless steel - carbon expanded austenite - was investigated with EXAFS and synchrotron diffraction together with synthesized carbides of the type M3C2, M7C3 and M23C6. It was found that the chemical environment of carbon expanded austenite is not associated ...

  7. Phenomena Elucidation of High Brightness Fiber Laser Welding of Stainless Steel

    Science.gov (United States)

    Kawahito, Yousuke; Mizutani, Masami; Katayama, Seiji

    A high-brigthness fiber laser can produce an ultra-high peak power density of MW/mm2 level corresponding to a focused electron beam, and is promising as one of the desirable heat sources for deep-penetration welding. The objectives of this research are to elucidate the factors affecting weld penetration and defects formation mechanisms, to obtain a fundamental knowledge of interaction between a fiber laser beam and the laser-induced plume, and to assess laser absorption with water-calorimetric method in bead-on-plate welding of Type 304 austenitic stainless steel plates with a 10 kW fiber laser beam. Concerning the weldablity and defects, the penetration depth reached 18 mm at the maximum. At 50 mm/s or lower welding speeds, porosity was generated under the conventionally-focused and tightly-focused conditions. X-ray transmission in-site observation images demonstrated that pores were formed not only at the tip of the keyhole but also near the upper part. The keyhole behavior was stabilized by using nitrogen shielding gas, which led to the porosity prevention. As for the interaction under the normal Ar shielding gas conditions, the temperature and ionization degree of the laser-induced plumes were calculated to be 6,000 K and 0.02, respectively, by the Bolzman plots and Saha's equation. It was also found that the attenuation and the refraction between the 10-kW fiber laser beam and the short weakly-ionized plume were too small to exert the reduction in weld penetration. The laser absorption of the stainless steel plate was approximately 85 % high at 10 kW laser power and 50 mm/s welding speed. Compared X-ray transmission observation images of the keyhole with the focusing feature of the fiber laser beam, most of the incident laser passed through the keyhole inlet, and the center part of the beam was delivered directly to the tip of the deep keyhole. Consequently, as far as the adquate welding procedures were utilized on the basis of eclucidation of the welding

  8. Unraveling the Effect of Thermomechanical Treatment on the Dissolution of Delta Ferrite in Austenitic Stainless Steels

    Science.gov (United States)

    Rezayat, Mohammad; Mirzadeh, Hamed; Namdar, Masih; Parsa, Mohammad Habibi

    2016-02-01

    Considering the detrimental effects of delta ferrite stringers in austenitic stainless steels and the industrial considerations regarding energy consumption, investigating, and optimizing the kinetics of delta ferrite removal is of vital importance. In the current study, a model alloy prone to the formation of austenite/delta ferrite dual phase microstructure was subjected to thermomechanical treatment using the wedge rolling test aiming to dissolve delta ferrite. The effect of introducing lattice defects and occurrence of dynamic recrystallization (DRX) were investigated. It was revealed that pipe diffusion is responsible for delta ferrite removal during thermomechanical process, whereas when the DRX is dominant, the kinetics of delta ferrite dissolution tends toward that of the static homogenization treatment for delta ferrite removal that is based on the lattice diffusion of Cr and Ni in austenite. It was concluded that the optimum condition for dissolution of delta ferrite can be defined by the highest rolling temperature and strain in which DRX is not pronounced.

  9. Review of environmental effects on fatigue crack growth of austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Shack, W.J.; Kassner, T.F. [Argonne National Lab., IL (United States)

    1994-05-01

    Fatigue and environmentally assisted cracking of piping, pressure vessel cladding, and core components in light water reactors are potential concerns to the nuclear industry and regulatory agencies. The degradation processes include intergranular stress corrosion cracking of austenitic stainless steel (SS) piping in boiling water reactors (BWRs), and propagation of fatigue or stress corrosion cracks (which initiate in sensitized SS cladding) into low-alloy ferritic steels in BWR pressure vessels. Crack growth data for wrought and cast austenitic SSs in simulated BWR water, developed at Argonne National Laboratory under US Nuclear Regulatory Commission sponsorship over the past 10 years, have been compiled into a data base along with similar data obtained from the open literature. The data were analyzed to develop corrosion-fatigue curves for austenitic SSs in aqueous environments corresponding to normal BWR water chemistries, for BWRs that add hydrogen to the feedwater, and for pressurized water reactor primary-system-coolant chemistry.

  10. Effect of A-TIG Welding Process on the Weld Attributes of Type 304LN and 316LN Stainless Steels

    Science.gov (United States)

    Vasudevan, M.

    2017-03-01

    The specific activated flux has been developed for enhancing the penetration performance of TIG welding process for autogenous welding of type 304LN and 316LN stainless steels through systematic study. Initially single-component fluxes were used to study their effect on depth of penetration and tensile properties. Then multi-component activated flux was developed which was found to produce a significant increase in penetration of 10-12 mm in single-pass TIG welding of type 304LN and 316LN stainless steels. The significant improvement in penetration achieved using the activated flux developed in the present work has been attributed to the constriction of the arc and as well as reversal of Marangoni flow in the molten weld pool. The use of activated flux has been found to overcome the variable weld penetration observed in 316LN stainless steel with TIG welds compared to that of the welds produced by conventional TIG welding on the contrary the transverse strength properties of the 304LN and 316LN stainless steel welds produced by A-TIG welding exceeded the minimum specified strength values of the base metals. Improvement in toughness values were observed in 316LN stainless steel produced by A-TIG welding due to refinement in the weld microstructure in the region close to the weld center. Thus, activated flux developed in the present work has greater potential for use during the TIG welding of structural components made of type 304LN and 316LN stainless steels.

  11. Modeling of Ni Diffusion Induced Austenite Formation in Ferritic Stainless Steel Interconnects

    DEFF Research Database (Denmark)

    Chen, Ming; Alimadadi, Hossein; Molin, Sebastian

    2017-01-01

    stainless steel was conducted, using the CALPHAD (CALculation of PHAse Diagrams) approach with the DICTRA (DIffusion Controlled TRAnsformation) software. The kinetics of inter-diffusion and austenite formation was explored in detail. The simulation was further validated by comparing with experiments......Ferritic stainless steel interconnect plates are widely used in planar solid oxide fuel cell and electrolysis cell stacks. During stack production and operation, nickel from the Ni/yttria stabilized zirconia fuel electrode or from the Ni contact component layer diffuses into the interconnect plate......, causing transformation of the ferritic phase into an austenitic phase in the interface region. This is accompanied with changes in volume, and in mechanical and corrosion properties of the interconnect plates. In this work, kinetic modeling of the inter-diffusion between Ni and FeCr based ferritic...

  12. Diffusion of nitrogen in austenitic phase: Application to nitriding of stainless steels

    Directory of Open Access Journals (Sweden)

    Torchane Lazhar

    2014-04-01

    Full Text Available The nitriding treatment of the martensitic stainless steels aims to harden and to introduce compressive stresses on the surface of steel. Hardening is resulting of the martensitic transformation of the austenitic matrix enriched into nitrogen during cooling and of the germination and the nitride growth. In order to preserve the stainless character of the nitrided layer, it is imperative to control precipitation within the zone affected by the treatment. Our task consists in showing that is possible to control the composition of the gas atmosphere containing ammonia and argon and to carry out on the surface of nitrided samples at 1050°C two types of configuration of layers : a single phase layer made up by martensite enriched in nitrogen α’N and or a two phase layer made up by austenite γN and martensite α’N enriched in nitrogen.

  13. Hydrogen Environment Embrittlement on Austenitic Stainless Steels from Room Temperature to Low Temperatures

    Science.gov (United States)

    Ogata, Toshio

    2015-12-01

    Hydrogen environment embrittlement (HEE) on austenitic stainless steels SUS304, 304L, and 316L in the high pressure hydrogen gas was evaluated from ambient temperature to 20 K using a very simple mechanical properties testing procedure. In the method, the high- pressure hydrogen environment is produced just inside the hole in the specimen and the specimen is cooled in a cooled-alcohol dewar and a cryostat with a GM refrigerator. The effect of HEE was observed in tensile properties, especially at lower temperatures, and fatigue properties at higher stress level but almost no effect around the stress level of yield strength where almost no strain-induced martensite was produced. So, no effect of HEE on austenitic stainless steels unless the amount of the ferrite phase is small.

  14. Size-separated particle fractions of stainless steel welding fume particles - A multi-analytical characterization focusing on surface oxide speciation and release of hexavalent chromium.

    Science.gov (United States)

    Mei, N; Belleville, L; Cha, Y; Olofsson, U; Odnevall Wallinder, I; Persson, K-A; Hedberg, Y S

    2018-01-15

    Welding fume of stainless steels is potentially health hazardous. The aim of this study was to investigate the manganese (Mn) and chromium (Cr) speciation of welding fume particles and their extent of metal release relevant for an inhalation scenario, as a function of particle size, welding method (manual metal arc welding, metal arc welding using an active shielding gas), different electrodes (solid wires and flux-cored wires) and shielding gases, and base alloy (austenitic AISI 304L and duplex stainless steel LDX2101). Metal release investigations were performed in phosphate buffered saline (PBS), pH 7.3, 37°, 24h. The particles were characterized by means of microscopic, spectroscopic, and electroanalytical methods. Cr was predominantly released from particles of the welding fume when exposed in PBS [3-96% of the total amount of Cr, of which up to 70% as Cr(VI)], followed by Mn, nickel, and iron. Duplex stainless steel welded with a flux-cored wire generated a welding fume that released most Cr(VI). Nano-sized particles released a significantly higher amount of nickel compared with micron-sized particle fractions. The welding fume did not contain any solitary known chromate compounds, but multi-elemental highly oxidized oxide(s) (iron, Cr, and Mn, possibly bismuth and silicon). Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  15. Fatigue strength improvement of the AISI 316Ti austenitic stainless steel by shot peening

    Directory of Open Access Journals (Sweden)

    František Nový

    2014-10-01

    Full Text Available Stainless steels are structural materials used for a wide range of applications. One of the fields of application of these highly corrosion resistant materials is for various medical applications. Different methods of mechanical property improvement have been studied in recent years to increase the durability of components manufactured from these materials. The main goal of this study was an analysis of fatigue strength improvement of the AISI 316Ti austenitic stainless steel by shot peening. A significant improvement of surface hardness, yield strength and fatigue limit by shot peening was observed in this study. This is despite increasing the surface roughness which usually degrades material’s fatigue strength.

  16. Fracture toughness of irradiated wrought and cast austenitic stainless steels in BWR environment.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Gruber, E. E.; Shack, W. J.

    2007-01-01

    In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. Exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). We look at the results of a study of simulated light-water reactor coolants, material chemistry, and irradiation damage and their effects on the susceptibility to stress-corrosion cracking of various commercially available and laboratory-melted stainless steels.

  17. Nitriding Process Characterization of Cold Worked AISI 304 and 316 Austenitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Waldemar Alfredo Monteiro

    2017-01-01

    Full Text Available The nitriding behavior of austenitic stainless steels (AISI 304 and 316 was studied by different cold work degree (0% (after heat treated, 10%, 20%, 30%, and 40% before nitride processing. The microstructure, layer thickness, hardness, and chemical microcomposition were evaluated employing optical microscopy, Vickers hardness, and scanning electron microscopy techniques (WDS microanalysis. The initial cold work (previous plastic deformations in both AISI 304 and 306 austenitic stainless steels does not show special influence in all applied nitriding kinetics (in layer thicknesses. The nitriding processes have formed two layers, one external layer formed by expanded austenite with high nitrogen content, followed by another thinner layer just below formed by expanded austenite with a high presence of carbon (back diffusion. An enhanced diffusion can be observed on AISI 304 steel comparing with AISI 316 steel (a nitrided layer thicker can be noticed in the AISI 304 steel. The mechanical strength of both steels after nitriding processes reveals significant hardness values, almost 1100 HV, on the nitrided layers.

  18. Very high cycle regime fatigue of thin walled tubes made from austenitic stainless steel

    DEFF Research Database (Denmark)

    Carstensen, J.V.; Mayer, H.; Brøndsted, P.

    2002-01-01

    Fatigue life data of cold worked tubes (diameter 4 mm, wall thicknesses 0.25 and 0.30 mm) of an austenitic stainless steel, AISI 904 L, were measured in the regime ranging from 2 × 105 to 1010 cycles to failure. The influence of the loading frequency was investigated as data were obtained...... scanning electron microscopy. Fatigue cracks initiate at the surface and no significant influence from frequency or from loading modes on fatigue crack initiation and growth is visible....

  19. Use of Direct Current Resistivity Measurements to Assess AISI 304 Austenitic Stainless Steel Sensitization

    OpenAIRE

    Mesquita, Ramaiany Carneiro; Mecury, José Manoel Rivas; Tanaka, Auro Atsumi; Sousa, Regina Célia de

    2015-01-01

    This paper describes the feasibility of using direct current electrical resistivity measurements to evaluate AISI 304 austenitic stainless steel sensitization. ASTM A262 – Practice A and double loop electrochemical potentiodynamic reactivation (DL-EPR) tests were performed to assess the degree of sensitization (DoS) qualitatively and quantitatively, and electrical resistivity (ER) was measured by the four-point direct-current potential drop method. The results indicate that the DoS incr...

  20. Improving hardness and wear resistance of austenitic stainless steel; Harte und verschleissfeste Randschicht auf korrosionsbestaendigen Staehlen

    Energy Technology Data Exchange (ETDEWEB)

    Guempel, Paul [Hochschule Konstanz (Germany). Werkstoffprueflabor; Waegner, Martina [Bodycote Hardiff GmbH, Huerth (Germany). S3P-Gruppe

    2010-09-15

    Nowadays more stainless steels are used in the field of automotive technology. These austenitic or ferritic steels have a high corrosion resistance but they are not hardenable and therefore they are susceptible to gallig / fretting during mechanical / tribological loading, for example in connecting rods. With a new surface hardening treatment these detrimental effects can be avoided. Hochschule Konstanz and Bodycote jointly develop this process further to open up new market areas. (orig.)

  1. A Short review on wrought austenitic stainless steels at high temperatures: processing, microstructure, properties and performance

    Directory of Open Access Journals (Sweden)

    Ronald Lesley Plaut

    2007-12-01

    Full Text Available Wrought austenitic stainless steels are widely used in high temperature applications. This short review discusses initially the processing of this class of steels, with emphasis on solidification and hot working behavior. Following, a brief summary is made on the precipitation behavior and the numerous phases that may appear in their microstructures. Creep and oxidation resistance are, then, briefly discussed, and finalizing their performance is compared with other high temperature metallic materials.

  2. Multiobjective optimization of friction welding of UNS S32205 duplex stainless steel

    Directory of Open Access Journals (Sweden)

    P.M. Ajith

    2015-06-01

    Full Text Available The present study is to optimize the process parameters for friction welding of duplex stainless steel (DSS UNS S32205. Experiments were conducted according to central composite design. Process variables, as inputs of the neural network, included friction pressure, upsetting pressure, speed and burn-off length. Tensile strength and microhardness were selected as the outputs of the neural networks. The weld metals had higher hardness and tensile strength than the base material due to grain refinement which caused failures away from the joint interface during tensile testing. Due to shorter heating time, no secondary phase intermetallic precipitation was observed in the weld joint. A multi-layer perceptron neural network was established for modeling purpose. Five various training algorithms, belonging to three classes, namely gradient descent, genetic algorithm and Levenberg–Marquardt, were used to train artificial neural network. The optimization was carried out by using particle swarm optimization method. Confirmation test was carried out by setting the optimized parameters. In conformation test, maximum tensile strength and maximum hardness obtained are 822 MPa and 322 Hv, respectively. The metallurgical investigations revealed that base metal, partially deformed zone and weld zone maintain austenite/ferrite proportion of 50:50.

  3. Imposed potential measurement to evaluate the pitting corrosion resistance and the galvanic behaviour of a highly alloyed austenitic stainless steel and its weldment in a LiBr solution at temperatures up to 150ºC

    OpenAIRE

    Blasco Tamarit, María Encarnación; García García, Dionisio Miguel; García Antón, José

    2011-01-01

    Pitting corrosion resistance and galvanic behaviour of Alloy 31, a highly alloyed austenitic stainless steel (UNS N08031), and its weldment were studied in a heavy brine LiBr solution 1080 g/l at different temperatures (75–150 °C) using electrochemical techniques. The Mixed Potential Theory was used to evaluate the galvanic corrosion between the base and welded metals. Cyclic potentiodynamic curves indicate that high temperatures make passivation and repassivation of pits difficult, because t...

  4. The Influence of Porosity on Corrosion Attack of Austenitic Stainless Steel

    Science.gov (United States)

    Abdullah, Z.; Ismail, A.; Ahmad, S.

    2017-10-01

    Porous metals also known as metal foams is a metallic body having spaces orpores through which liquid or air may pass. Porous metals get an attention from researchers nowadays due to their unique combination of properties includes excellent mechanical and electrical, high energy absorption, good thermal and sound insulation and water and gas permeability. Porous metals have been applied in numerous applications such as in automotive, aerospace and also in biomedical applications. This research reveals the influence of corrosion attack in porous austenitic stainless steel 316L. The cyclic polarization potential analysis was performed on the porous austenitic stainless steel 316L in 3.5% NaCl solution. The morphology and the element presence on the samples before and after corrosion attack was examined using scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) respectively to determine the corrosion mechanism structure. The cyclic polarization potential analysis showed the result of (E corr ) for porous austenitic stainless steel type 316L in the range of -0.40v to -0.60v and breakdown potential (E b ) is -0.3v to -0.4v in NaCl solution.

  5. Development of a robust modeling tool for radiation-induced segregation in austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Allen, Todd R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Busby, Jeremy T [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels in Light Water Reactor (LWR) components has been linked to changes in grain boundary composition due to irradiation induced segregation (RIS). This work developed a robust RIS modeling tool to account for thermodynamics and kinetics of the atom and defect transportation under combined thermal and radiation conditions. The diffusion flux equations were based on the Perks model formulated through the linear theory of the thermodynamics of irreversible processes. Both cross and non-cross phenomenological diffusion coefficients in the flux equations were considered and correlated to tracer diffusion coefficients through Manning’s relation. The preferential atomvacancy coupling was described by the mobility model, whereas the preferential atom-interstitial coupling was described by the interstitial binding model. The composition dependence of the thermodynamic factor was modeled using the CALPHAD approach. Detailed analysis on the diffusion fluxes near and at grain boundaries of irradiated austenitic stainless steels suggested the dominant diffusion mechanism for chromium and iron is via vacancy, while that for nickel can swing from the vacancy to the interstitial dominant mechanism. The diffusion flux in the vicinity of a grain boundary was found to be greatly influenced by the composition gradient formed from the transient state, leading to the oscillatory behavior of alloy compositions in this region. This work confirms that both vacancy and interstitial diffusion, and segregation itself, have important roles in determining the microchemistry of Fe, Cr, and Ni at irradiated grain boundaries in austenitic stainless steels.

  6. Detailed Microstructural Characterization and Restoration Mechanisms of Duplex and Superduplex Stainless Steel Friction-Stir-Welded Joints

    Science.gov (United States)

    Santos, T. F. A.; Torres, E. A.; Lippold, J. C.; Ramirez, A. J.

    2016-12-01

    Duplex stainless steels are successfully used in a wide variety of applications in areas such as the food industry, petrochemical installations, and sea water desalination plants, where high corrosion resistance and high mechanical strength are required. However, during fusion welding operations, there can be changes to the favorable microstructure of these materials that compromise their performance. Friction stir welding with a non-consumable pin enables welded joints to be obtained in the solid state, which avoids typical problems associated with solidification of the molten pool, such as segregation of alloying elements and the formation of solidification and liquefaction cracks. In the case of superduplex stainless steels, use of the technique can avoid unbalanced proportions of ferrite and austenite, formation of deleterious second phases, or growth of ferritic grains in the heat-affected zone. Consolidated joints with full penetration were obtained for 6-mm-thick plates of UNS S32101 and S32205 duplex stainless steels, and S32750 and S32760 superduplex steels. The welding heat cycles employed avoided the conditions required for formation of deleterious phases, except in the case of the welded joint of the S32760 steel, where SEM images indicated the formation of secondary phases, as corroborated by decreased mechanical performance. Analysis using EBSD and transmission electron microscopy revealed continuous dynamic recrystallization by the formation of cellular arrays of dislocations in the ferrite and discontinuous dynamic recrystallization in the austenite. Microtexture evaluation indicated the presence of fibers typical of shear in the thermomechanically affected zone. These fibers were not obviously present in the stir zone, probably due to the intensity of microstructural reformulation to which this region was subjected.

  7. Effects of active flux on plasma behavior and weld shape in laser welding of X5CrNi189 stainless steel

    Science.gov (United States)

    Dai, Hongbin; Peng, Jun

    2016-11-01

    In this paper, stainless steel was welded by active flux-aided laser welding method. The effects of single active flux (Cr2O3, SiO2 and TiO2) and composite active flux on laser welding were studied. In the welding process, laser plasma behavior was recorded by a high-speed imaging system. The results show that, with the addition of active flux, the absorption of laser energy and melting efficiency increase. In the laser power of 750 W, effects of active flux on weld depth to width ratio are given by the order: composite active flux > SiO2 > Cr2O3 > TiO2. The effect of composite active flux is the most significant and it can increase the weld depth to width ratio to 85%. Active flux can restrict the laser plasma. With the addition of composite active flux, the projected area of laser plasma obtained obviously reduced, and it can be reduced by 41.39%. Active flux cannot obviously change the main components in weld zone, but can change the grains of austenite and ferrite.

  8. Surface analysis of localized corrosion of austenitic 316L and duplex 2205 stainless steels in simulated body solutions

    NARCIS (Netherlands)

    Conradi, Marjetka; Schön, Peter Manfred; Kocijan, Aleksandra; Jenko, M.; Vancso, Gyula J.

    2011-01-01

    We report on cyclic voltammetry and in situ electrochemical atomic force microscopy (EC-AFM) studies of localized corrosion of duplex 2205 stainless steel (DSS 2205) and austenitic stainless steel of the type AISI 316L in two model solutions, including artificial saliva (AS) and a simulated

  9. Characterization of Microstructure and Texture of 13Cr4Ni Martensitic Stainless Steel Weld Before and After Tempering =

    Science.gov (United States)

    Mokhtabad Amrei, Mohsen

    13Cr4Ni martensitic stainless steels are known for their outstanding performances in the hydroelectric industry, where they are mainly used in the construction of turbine components. Considering the size and geometry of turbine runners and blades, multi-pass welding procedures are commonly used in the fabrication and repair of such turbines. The final microstructure and mechanical properties of the weld are sensitive to the welding process parameters and thermal history. In the case of 13Cr4Ni steel, the thermal cycles imposed by the multi-pass welding operation have significant effects on the complex weld microstructure. Additionally, post-weld heat treatments are commonly used to reduce weld heterogeneity and improve the material's mechanical properties by tempering the microstructure and by forming a "room-temperature-stable austenite." In the first phase of this research, the microstructures and crystallographic textures of aswelded single-pass and double-pass welds were studied as a basis to studying the more complex multi-pass weld microstructure. This study found that the maximum hardness is obtained in high temperature heat affected zone inside the base metal. In particular, the results showed that the heat cycle exposed by the second pass increases the hardness of the previous pass because it produces a finer martensite microstructure. In areas of heat affected zone, a tempering effect is reported from 3 up to 6 millimeters far from the fusion line. Finding austenite phase in these areas are matter of interest and it can be indicative of the microstructure complexity of multi-pass welds. In the second phase of research, the microstructure of multi-pass welds was found to be more heterogeneous than that of single- and double-pass welds. Any individual pass in a multi-pass weld consists of several regions formed by adjacent weld passes heat cycle. Results showed that former austenite grains modification occurred in areas close to the subsequent weld passes

  10. Ultrasonic Testing of Thick Walled Austenitic Welds: Modelling and Experimental Verification

    Science.gov (United States)

    Köhler, B.; Müller, W.; Spies, M.; Schmitz, V.; Zimmer, A.; Langenberg, K.-J.; Mletzko, U.

    2006-03-01

    The testing of austenitic welds is difficult due to the elastically anisotropic properties of the weld grains. Therefore the normal rules for the selection of testing conditions as appropriate wave modes, frequencies and incident angles cannot be applied in the usual way. In last years several tools for simulation of the wave propagation in such testing situations were developed. In the paper these tools are applied to a austenitic weld containing a crack grown by intergranular stress corrosion cracking (IGSCC). It is demonstrated that by the combined application of several simulation tools a stepwise narrowing of the parameter space can be achieved. Eventually an optimized testing configuration is defined. The approach is validated experimentally.

  11. Corrosion Behavior of the Stressed Sensitized Austenitic Stainless Steels of High Nitrogen Content in Seawater

    Directory of Open Access Journals (Sweden)

    A. Almubarak

    2013-01-01

    Full Text Available The purpose of this paper is to study the effect of high nitrogen content on corrosion behavior of austenitic stainless steels in seawater under severe conditions such as tensile stresses and existence of sensitization in the structure. A constant tensile stress has been applied to sensitized specimens types 304, 316L, 304LN, 304NH, and 316NH stainless steels. Microstructure investigation revealed various degrees of stress corrosion cracking. SCC was severe in type 304, moderate in types 316L and 304LN, and very slight in types 304NH and 316NH. The electrochemical polarization curves showed an obvious second current peak for the sensitized alloys which indicated the existence of second phase in the structure and the presence of intergranular stress corrosion cracking. EPR test provided a rapid and efficient nondestructive testing method for showing passivity, degree of sensitization and determining IGSCC for stainless steels in seawater. A significant conclusion was obtained that austenitic stainless steels of high nitrogen content corrode at a much slower rate increase pitting resistance and offer an excellent resistance to stress corrosion cracking in seawater.

  12. Effect of solidification conditions on the solidification mode in austenitic stainless steels

    Science.gov (United States)

    Suutala, N.

    1983-02-01

    The effect of the solidification conditions on the solidification mode in the composition range in which the primary austenitic and ferritic modes compete is studied by varying the welding parameters in gas tungsten arc (GTA) welding and by comparing the results with those obtained from other laboratory experiments. A good agreement holds if the effect of the composition is described by the ratio Creq/Nieq (Creq = pct Cr + 1.37 × pct Mo + 1.5 × pct Si + 2 × pct Nb + 3 × pct Ti and Nieq = pct Ni + 0.31 × pct Mn + 22 × pct C + 14.2 × pct N + pct Cu) and the effect of the solidification conditions by the growth rate. The critical value of the ratio Creq/Nieq corresponding to the transition from primary austenitic to ferritic solidification increases from 1.43 to 1.55 with increasing growth rate. The upper limit is valid in GTA welding at high welding speeds, while the lower limit corresponds to the practical conditions which exist in ingot and shaped casting. The validity and applicability of this solidification model are discussed.

  13. Corrosion behavior of a welded stainless-steel orthopedic implant.

    Science.gov (United States)

    Reclaru, L; Lerf, R; Eschler, P Y; Meyer, J M

    2001-02-01

    The corrosion behavior of combinations of materials used in an orthopedic implant: the spherical part (forged or forged and annealed) constituting the head, the weld (tungsten inert gas (TIG) or electron beam (EB) techniques), and the cylindrical part (annealed) constituting the shaft of a femoral prosthesis - has been investigated. Open-circuit potentials, potentiodynamic curves, Tafel slope, mixed potential theory and susceptibility to intergranular attack are electrochemical and chemical procedures selected for this work. Electrochemical measurements using a microelectrode have been made in the following zones: spherical part, cylindrical part, weld, and weld/sphere, and weld/shaft interfaces. To detect intergranular attack, the Strauss test has been used. At the interfaces, corrosion currents, measured (Icorr) and predicted (Icouple) are low, in the order of the pico- to nanoampere. The electrochemical behavior of the electron beam (EB) weld is better than that of the tungsten inert gas (TIG). Welds at interfaces can behave either anodically or cathodically. It is better if welds, which are sensitive parts of the femoral prosthesis, behave cathodically. In this way, the risk of starting localized corrosion (pitting, crevice or intergranular corrosion) from a galvanic couple, remains low. From this point of view, the sample with the EB weld offers the best behavior. All the other samples containing a TIG type of weld exhibit a less favorable behavior. The mechanical treatments (forged, and forged and annealed) of the steel sphere did not show any difference in the corrosion behavior. No intergranular corrosion has been observed at the weld/steel interface for unsensitized samples. With sensitized samples, however, a TIG sample has exhibited some localized intergranular corrosion at a distance of 500 microm along the weld/stainless steel (sphere) interface.

  14. Arc characteristics of submerged arc welding with stainless steel wire

    Science.gov (United States)

    Li, Ke; Wu, Zhi-sheng; Liu, Cui-rong; Chen, Feng-hua

    2014-08-01

    The arc characteristics of submerged arc welding (SAW) with stainless steel wire were studied by using Analysator Hannover (AH). The tests were carried out under the same preset arc voltage combined with different welding currents. By comparing the probability density distribution (PDD) curves of arc voltage and welding current, the changes were analyzed, the metal transfer mode in SAW was deduced, and the characteristics of a stable arc were summarized. The analysis results show that, with an increase of welding parameters, the short-circuiting peak in the PDD curves of arc voltage decreases gradually until it disappears, and the dominant metal transfer mode changes from flux-wall guided transfer to projected transfer and then to streaming transfer. Moreover, when the PDD curves of arc voltage are both unimodal and generally symmetrical, the greater the peak probability and the smaller the peak span, the more stable the arc becomes.

  15. Effect of continuous and pulsed currents on microstructural evolution of stainless steel joined by TIG welding; Einfluss des Einsatzes von Dauerstrom und Impulsstrom auf die Mikrostrukturentwicklung bei durch das WIG-Schweissverfahren gefuegtem rostfreiem Stahl

    Energy Technology Data Exchange (ETDEWEB)

    Durgutlu, Ahmet; Findik, Tayfun; Guelenc, Behcet [Gazi Univ., Ankara (Turkey). Dept. of Metallurgy and Materials Engineering; Cevik, Bekir [Duezce Univ. (Turkey). Dept. of Welding Technology; Kaya, Yakup; Kahraman, Nizamettin [Karabuek Univ. (Turkey). Dept. of Manufacturing Engineering

    2015-07-01

    In this study, AISI 316L series austenitic stainless steel sheets were joined by tungsten inert gas welding method in continuous and pulsed currents. Regarding microstructural investigation and hardness values of weld metal, samples were welded to investigate the effect of current type on grain structures of weld metal. Results showed that samples welded by using pulsed current had considerable different properties compared to the samples welded by using continuous current. While the weld metals of joinings obtained by using continuous current displayed a coarse-grained and columnar structure, weld metals obtained by using pulsed current had a finer-grained structure. It was also found that hardness values of samples, which were welded with continuous and pulsed current, were quite different.

  16. Heat input effect on the microstructural transformation and mechanical properties in GTAW welds of a 409L ferritic stainless steel

    Directory of Open Access Journals (Sweden)

    Delgado, Jorge A.

    2016-06-01

    Full Text Available Welds without filler metal and welds using a conventional austenitic stainless steel filler metal (ER308L were performed to join a ferritic stainless steel with Gas Tungsten Arc Welding process (GTAW. Welding parameters were adjusted to obtain three different heat input values. Microstructure reveals the presence of coarse ferritic matrix and martensite laths in the Heat Affected Zone (HAZ. Dilution between filler and base metal was correlated with the presence of austenite, martensite and ferrite in the weld metal. Weld thermal cycles were measured to correlate the microstructural transformation in the HAZ. Microhardness measurements (maps and profiles allow to identify the different zones of the welded joints (weld metal, HAZ, and base metal. Comparing the base metal with the weld metal and the HAZ, a hardness increment (~172 HV0.5 to ~350 HV0.5 and ~310 HV0.5, respectively was observed, which has been attributed to the martensite formation. Tensile strength of the welded joints without filler metal increased moderately with respect to base metal. In contrast, ductility was approximately 25% higher than base metal, which provided a toughness improvement of the welded joints.Se llevaron a cabo soldaduras sin material de aporte y empleando un electrodo convencional (ER308L para unir un acero inoxidable ferrítico, empleando el proceso de soldadura de arco con electrodo de tungsteno (GTAW. Los parámetros de soldadura fueron ajustados para obtener tres valores diferentes de calor de aporte. La microestructura revela la presencia de una matriz ferrítica gruesa y placas de martensita en la Zona Afectada por el Calor (ZAC. La dilución entre el metal base y de aporte fue correlacionada con la presencia de austenita, martensita y ferrita en el metal de soldadura. Los ciclos térmicos de la soldadura fueron medidos para correlacionar la transformación microestrutural en la ZAC. Mediciones de microdureza (mapas y perfiles, permitieron identificar las

  17. Hydrogen Susceptibility of Pre-strained Type 316L Austenitic Stainless Steels in Aqueous Solutions

    Science.gov (United States)

    Mati, D.; Takasaki, A.; Uematsu, S.

    2017-09-01

    This paper presents the observations made as a result of hydrogen effects in austenitic stainless steels which led to reduction of its original mechanical properties. This paper therefore seeks to understand the mechanisms and effects induced by hydrogen leading to embrittlement. The samples of Type 316L austenitic stainless steel with 20% pre-strain were charged with hydrogen through galvanostastic cathodic loading for 12, 24, 36, and 48 hours respectively, with sample as Cathode and the platinum wire as Anode. Afterwards, they were fractured under tensile test at a slow strain rates. The loss of ductility was evident as observed by the brittle nature of fracture. Small pieces were cut-off near the fracture region and examined through XRD and SEM analysis. The peak widening and slight shifting of the peak positions was observed. The surface cracking was also observed, an indication of surface-induced stresses. The severity of the effects increased with the hydrogen loading time, which is predictive of a real service conditions for austenite steels in aqueous environments.

  18. Surface modification of AISI 304 austenitic stainless steel by plasma nitriding

    Science.gov (United States)

    Liang, Wang

    2003-04-01

    Plasma nitriding of austenitic stainless steel samples has been carried out using pulse dc glow discharge plasma of NH 3 gas at substrate temperature ranging from 350 to 520 °C. A nitriding time of only 4 h has been found to produce a compact surface nitride layer composed of γN' phase with a thickness of around 7-12 μm as processing temperature remained between 420 and 450 °C. The thickness of γN phase was found to be very thin only about 2 μm after plasma nitriding at temperature below 400 °C. Microhardness measurements showed significant increase in the hardness from 240 HV (for untreated samples) up to 1700 HV (for nitrided samples at temperature of 460 °C). For nitriding at higher temperature, i.e. above 460 °C, the chromium nitrides precipitated in the nitrided layer and caused austenite phase transform into ferrite phase or iron nitrides ( γ' or ɛ). The consequent result of chromium nitride precipitation is the reduction of corrosion resistance of nitrided layer. Compressive residual stresses existed in the nitrided layer due to nitrogen diffusion into austenitic stainless steel.

  19. Welding of AA1050 aluminum with AISI 304 stainless steel by rotary friction welding process

    OpenAIRE

    Chen Ying An; Francisco Piorino Neto; Eder Paduan Alves

    2010-01-01

    Abstract: The purpose of this work was to assess the development of solid state joints of dissimilar material AA1050 aluminum and AISI 304 stainless steel, which can be used in pipes of tanks of liquid propellants and other components of the Satellite Launch Vehicle. The joints were obtained by rotary friction welding process (RFW), which combines the heat generated from friction between two surfaces and plastic deformation. Tests were conducted with different welding process parameters. The ...

  20. Transformation and Precipitation Reactions by Metal Active Gas Pulsed Welded Joints from X2CrNiMoN22-5-3 Duplex Stainless Steels

    Science.gov (United States)

    Utu, Ion-Dragos; Mitelea, Ion; Urlan, Sorin Dumitru; Crăciunescu, Corneliu Marius

    2016-01-01

    The high alloying degree of Duplex stainless steels makes them susceptible to the formation of intermetallic phases during their exposure to high temperatures. Precipitation of these phases can lead to a decreasing of the corrosion resistance and sometimes of the toughness. Starting from the advantages of the synergic Metal Active Gas (MAG) pulsed welding process, this paper analyses the structure formation particularities of homogeneous welded joints from Duplex stainless steel. The effect of linear welding energy on the structure morphology of the welded joints was revealed by macro- and micrographic examinations, X-ray energy dispersion analyses, measurements of ferrite proportion and X-ray diffraction analysis. The results obtained showed that the transformation of ferrite into austenite is associated with the chromium, nickel, molybdenum and nitrogen distribution between these two phases and their redistribution degree is closely linked to the overall heat cycle of the welding process. The adequate control of the energy inserted in the welded components provides an optimal balance between the two microstructural constituents (Austenite and Ferrite) and avoids the formation of undesirable intermetallic phases. PMID:28773727

  1. Influence of Austenitizing Heat Treatment on the Properties of the Tempered Type 410-1Mo Stainless Steel

    Science.gov (United States)

    Mabruri, E.; Syahlan, Z. A.; Sahlan; Prifiharni, S.; Anwar, M. S.; Chandra, S. A.; Romijarso, T. B.; Adjiantoro, B.

    2017-05-01

    The modified 410-1Mo stainless steel has been developed with higher tensile strength and elongation compared to the standard 410 stainless steel. This paper reports the influence of austenitizing temperature on the microstructure, hardness, impact resistance and corrosion resistance of the modified 410-1Mo steel. The steel samples were prepared by a process sequence of induction melting, hot forging, annealing, hardening, and tempering. The microstructure of the tempered steels revealed additional phase of delta ferrite at pre-austenitizing temperatures of 950 to 1050 °C and disappeared at a temperature of 1100 °C. The steels which underwent pre-austenitizing at 1100 °C showed the largest sized lath martensite and the largest amount of retained austenite. The tempered steels maintained hardness at austenitizing temperatures of 950 °C to 1000 °C and showed an increasing hardness at austenitizing temperatures from 1000 to 1100 °C. At a range of austenitizing temperatures, it was investigated that the steels exhibited higher impact resistance at 1050 °C. The tempered steels that were pre-austenitized at 950 °C and 1100 °C showed the lowest pitting potential due to the existence of carbides and coarse-high carbon martensite, respectively.

  2. Detrimental Cr-rich Phases Precipitation on SAF 2205 Duplex Stainless Steels Welds After Heat Treatment

    Directory of Open Access Journals (Sweden)

    Argelia Fabiola Miranda Pérez

    Full Text Available Abstract The austeno-ferritic Stainless Steels are commonly employed in various applications requiring structural performances with enhanced corrosion resistance. Their characteristics can be worsened if the material is exposed to thermal cycles, since the high-temperature decomposition of ferrite causes the formation of detrimental secondary phases. The Submerged Arc Welding (SAW process is currently adopted for joining DSS owing to its relatively simple execution, cost savings, and using molten slag and granular flux from protecting the seam of atmospheric gases. However, since it produces high contents of δ-ferrite in the heat affected zone and low content of γ-austenite in the weld, high-Ni filler materials must be employed, to avoid excessive ferritization of the joint. The present work is aimed to study the effect of 3 and 6 hours isothermal heat treatments at 850°C and 900°C in a SAF 2205 DSS welded joint in terms of phases precipitation. The results showed the presence of σ-phase at any time-temperature combination, precipitating at the δ/γ interphases and often accompanied by the presence of χ-phase. However, certain differences in secondary phases amounts were revealed among the different zones constituting the joint, ascribable both to peculiar elements partitioning and to the different morphology pertaining to each microstructure.

  3. Microstructural Study of 17-4PH Stainless Steel after Plasma-Transferred Arc Welding.

    Science.gov (United States)

    Deng, Dewei; Chen, Rui; Sun, Qi; Li, Xiaona

    2015-01-29

    The improvement of the surface qualities and surface hardening of precipitation hardened martensitic stainless steel 17-4PH was achieved by the plasma-transferred arc welding (PTAW) process deposited with Co-based alloy. The microstructure of the heat affected zone (HAZ) and base metal were characterized by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that there are obvious microstructural differences between the base metal and HAZ. For example, base material is transformed from lath martensite to austenite due to the heateffect of the welding process. On the other hand, the precipitate in the matrix (bar-like shape Cr₇C₃ phase with a width of about one hundred nanometres and a length of hundreds of nanometres) grows to a rectangular appearance with a width of about two hundred nanometres and a length of about one micron. Stacking fault could also be observed in the Cr₇C₃ after PTAW. The above means that welding can obviously improve the surface qualities.

  4. Microstructural Study of 17-4PH Stainless Steel after Plasma-Transferred Arc Welding

    Directory of Open Access Journals (Sweden)

    Dewei Deng

    2015-01-01

    Full Text Available The improvement of the surface qualities and surface hardening of precipitation hardened martensitic stainless steel 17-4PH was achieved by the plasma-transferred arc welding (PTAW process deposited with Co-based alloy. The microstructure of the heat affected zone (HAZ and base metal were characterized by optical microscope (OM, scanning electron microscope (SEM and transmission electron microscope (TEM. The results show that there are obvious microstructural differences between the base metal and HAZ. For example, base material is transformed from lath martensite to austenite due to the heateffect of the welding process. On the other hand, the precipitate in the matrix (bar-like shape Cr7C3 phase with a width of about one hundred nanometres and a length of hundreds of nanometres grows to a rectangular appearance with a width of about two hundred nanometres and a length of about one micron. Stacking fault could also be observed in the Cr7C3 after PTAW. The above means that welding can obviously improve the surface qualities.

  5. Handbook for tensile properties of austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D. W.; Ryu, W. S.; Jang, J. S.; Kim, S. H.; Kim, W. G.; Chung, M. K.; Han, C. H. [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2000-03-01

    Database system of nuclear materials has not been developed and the physical and mechanical properties of materials used in nuclear power plant are not summarized systematically in Korea. Although Korea designs nuclear power plant, many materials used in nuclear power plant are imported because we do not have database system of nuclear material yet and it was hard to select a proper material for the structural materials of nuclear power plant. To develop database system of nuclear materials, data of mechanical, corrosion, irradiation properties are needed. Of theses properties, tensile properties are tested and summarized in this report. Tensile properties of stainless steel used in nuclear reactor internal were investigated. Data between Korea Atomic Energy Research Institute and foreign laboratory were compared to determine the precision of the result. To develope database system, materials, chemical composition, heat treatment, manufacturing process, and grain size were classified. Tensile properties were tested and summarized to use input data of database system. 9 figs., 9 tabs. (Author)

  6. Microstructural changes of a thermally aged stainless steel submerged arc weld overlay cladding of nuclear reactor pressure vessels

    Science.gov (United States)

    Takeuchi, T.; Kameda, J.; Nagai, Y.; Toyama, T.; Matsukawa, Y.; Nishiyama, Y.; Onizawa, K.

    2012-06-01

    The effect of thermal aging on microstructural changes in stainless steel submerged arc weld-overlay cladding of reactor pressure vessels was investigated using atom probe tomography (APT). In as-received materials subjected to post-welding heat treatments (PWHTs), with a subsequent furnace cooling, a slight fluctuation of the Cr concentration was observed due to spinodal decomposition in the δ-ferrite phase but not in the austenitic phase. Thermal aging at 400 °C for 10,000 h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn = 16:7:6 in the δ-ferrite phase. The degree of the spinodal decomposition in the submerged arc weld sample was similar to that in the electroslag weld one reported previously. We also observed a carbide on the γ-austenite and δ-ferrite interface. There were no Cr depleted zones around the carbide.

  7. Patterning of magnetic structures on austenitic stainless steel by local ion beam nitriding

    Energy Technology Data Exchange (ETDEWEB)

    Menendez, E. [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)], E-mail: enric.menendez@uab.es; Martinavicius, A.; Liedke, M.O.; Abrasonis, G.; Fassbender, J. [Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Sommerlatte, J. [Max Planck Institute of Microstructure Physics, Weinberg 2, D-06120 Halle (Germany); Nielsch, K. [Institut fuer Angewandte Physik, Universitaet Hamburg, Jungiusstrasse 11, D-20355 Hamburg (Germany); Surinach, S.; Baro, M.D. [Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Nogues, J. [Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Institut Catala de Nanotecnologia, Edifici CM7, Campus Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Sort, J. [Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)

    2008-10-15

    Periodic arrays of ferromagnetic structures with micrometer and submicrometer lateral sizes have been prepared at the surface of a paramagnetic austenitic stainless steel by means of ion beam nitriding through different types of shadow masks (such as transmission electron microscopy grids or self-assembled porous alumina membranes). This method takes advantage of the formation of the ferromagnetic supersaturated nitrogen solid solution {gamma}{sub N} phase (i.e., expanded austenite) upon nitriding at moderate temperatures. The local character of the induced ferromagnetism is confirmed by magneto-optical Kerr effect measurements together with magnetic force microscopy imaging. Furthermore, the influence of the nitriding temperature and time on the induced ferromagnetic and structural properties has been analyzed.

  8. Correlation Between Microstructure and Mechanical Properties Before and After Reversion of Metastable Austenitic Stainless Steels

    Science.gov (United States)

    Fargas, Gemma; Zapata, Ana; Roa, Joan Josep; Sapezanskaia, Ina; Mateo, Antonio

    2015-12-01

    Reversion treatments are a way to improve the mechanical response of metastable austenitic stainless steels by means of grain refinement. To effectively apply those treatments, the steel must be previously deformed to induce a significant amount of martensitic transformation. In this work, the effect of reversion treatments was studied on a commercial AISI 301LN grade subjected to an industrial cold rolling process, with thickness reductions not higher than 40 pct. Microstructural changes and evolution of both monotonic and cyclic mechanical properties were investigated after cold rolling and upon reversion treatments. Results revealed that the finer austenitic microstructure obtained after reversion leads to an interesting combination of properties, with strong increments in hardness and yield strength, and also fatigue limit improvement, as compared to the initial annealed condition.

  9. Development of Creep-Resistant and Oxidation-Resistant Austenitic Stainless Steels for High Temperature Applications

    Science.gov (United States)

    Maziasz, Philip J.

    2017-11-01

    Austenitic stainless steels are cost-effective materials for high-temperature applications if they have the oxidation and creep resistance to withstand prolonged exposure at such conditions. Since 1990, Oak Ridge National Laboratory (ORNL) has developed advanced austenitic stainless steels with creep resistance comparable to Ni-based superalloy 617 at 800-900°C based on specially designed "engineered microstructures" utilizing a microstructure/composition database derived from about 20 years of radiation effect data on steels. The wrought high temperature-ultrafine precipitate strengthened (HT-UPS) steels with outstanding creep resistance at 700-800°C were developed for supercritical boiler and superheater tubing for fossil power plants in the early 1990s, the cast CF8C-Plus steels were developed in 1999-2001 for land-based gas turbine casing and diesel engine exhaust manifold and turbocharger applications at 700-900°C, and, in 2015-2017, new Al-modified cast stainless steels with oxidation and creep resistance capabilities up to 950-1000°C were developed for automotive exhaust manifold and turbocharger applications. This article reviews and summarizes their development and their properties and applications.

  10. Development of Creep-Resistant and Oxidation-Resistant Austenitic Stainless Steels for High Temperature Applications

    Science.gov (United States)

    Maziasz, Philip J.

    2018-01-01

    Austenitic stainless steels are cost-effective materials for high-temperature applications if they have the oxidation and creep resistance to withstand prolonged exposure at such conditions. Since 1990, Oak Ridge National Laboratory (ORNL) has developed advanced austenitic stainless steels with creep resistance comparable to Ni-based superalloy 617 at 800-900°C based on specially designed "engineered microstructures" utilizing a microstructure/composition database derived from about 20 years of radiation effect data on steels. The wrought high temperature-ultrafine precipitate strengthened (HT-UPS) steels with outstanding creep resistance at 700-800°C were developed for supercritical boiler and superheater tubing for fossil power plants in the early 1990s, the cast CF8C-Plus steels were developed in 1999-2001 for land-based gas turbine casing and diesel engine exhaust manifold and turbocharger applications at 700-900°C, and, in 2015-2017, new Al-modified cast stainless steels with oxidation and creep resistance capabilities up to 950-1000°C were developed for automotive exhaust manifold and turbocharger applications. This article reviews and summarizes their development and their properties and applications.

  11. Hydrogen permeation characteristics of welded 316 stainless steel using nickel welding filler

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, T.; Ikeshoji, T.T.; Suzumura, A.; Kobayashi, D.; Naito, T. [Tokyo Inst. of Technology, Tokyo (Japan)

    2007-07-01

    Low carbon stainless steel of 316L has been utilized for an ultra high vacuum chamber assembled by welding, and it contains 12-15% nickel. We investigate the work of nickel element with hydrogen atoms as the hydrogen catalysis near heat affected zone. Hydrogen permeation tests for welded specimens using nickel filler were performed to prevent from hydrogen embrittlement cracking in the heat affected zone. In this study, the hydrogen permeation technique using an orifice and a quadrupole mass spectrometer (QMS) is utilized to measure the hydrogen gas flux in the stainless steel. A stationary hydrogen flux from the stainless steel surface was measured by using a system with an orifice. The hydrogen pressure difference which applied to the specimen was enabled us to maintain constant by constant gas flow rate from the orifice in low pressure vessel. The value of hydrogen permeability, K, at 620K for welded specimen using the nickel filler is 3.62 times 10{sup -12} m{sup 2}s{sup -1}Pa{sup 1/2}. It is 1.9 times grater than that of normal non-welded 316 stainless steel substrate. The value at 520 K for the welded specimen is 7.31 times 10{sup -14} m{sup 2}s{sup -1}Pa{sup 1/2}. It is as same as that of the non-welded substrate. It is considered that the role of nickel at high temperature near 620K is to release hydrogen atom, and the role of nickel at temperature below 520K is to trap hydrogen atoms, and that the weld metal become hydrogen diffusion path. (orig.)

  12. An improved method to identify grain boundary creep cavitation in 316H austenitic stainless steel.

    Science.gov (United States)

    Chen, B; Flewitt, P E J; Smith, D J; Jones, C P

    2011-04-01

    Inter-granular creep cavitation damage has been observed in an ex-service 316H austenitic stainless steel thick section weldment. Focused ion beam cross-section milling combined with ion channelling contrast imaging is used to identify the cavitation damage, which is usually associated with the grain boundary carbide precipitates in this material. The results demonstrate that this technique can identify, in particular, the early stage of grain boundary creep cavitation unambiguously in materials with complex phase constituents. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Influence of Plastic Deformation on Low Temperature Surface Hardening of Austenitic Stainless Steel by Gaseous Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of two commercial austenitic stainless steels: AISI 304 and EN 1.4369. The materials were plastically deformed to different equivalent strains by uniaxial...... tension. Gaseous nitriding of the strained material was performed in ammonia gas at atmospheric pressure at 703 K. Microstructural characterization of the as-deformed states and the nitrided case produced included X-ray diffraction analysis, reflected light microscopy, microhardness testing. The results...

  14. Formability and fracture studies of austenitic stainless steel 316 at different temperatures

    OpenAIRE

    Hussaini, Syed Mujahed; Singh, Swadesh Kumar; Gupta, Amit Kumar

    2014-01-01

    Deep drawing is one of the most important sheet metal forming processes in automotive, aerospace and nuclear industries. In this process, the sheet metal blank is formed into a cup shape by an application of punch into the die. The present work is aimed at studying the formability and the nature of fracture for one of the important materials in industrial applications, austenitic stainless steel 316 at different temperatures. Circular blanks were deep drawn at room temperature, 150 and 300 °C...

  15. Metallographic screening of grain boundary engineered type 304 austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Hanning, F., E-mail: Fabian.Hanning@googlemail.com; Engelberg, D.L., E-mail: Dirk.engelberg@manchester.ac.uk

    2014-08-15

    An electrochemical etching method for the identification of grain boundary engineered type 304 austenitic stainless steel microstructures is described. The method can be applied for rapid microstructure screening to complement electron backscatter diffraction analysis. A threshold parameter to identify grain boundary engineered microstructure is proposed, and the application of metallographic etching for characterising the degree of grain boundary engineering discussed. - Highlights: • As-received (annealed) and grain boundary engineered microstructures were compared. • Electro-chemical polarisation in nitric acid solutions was carried out. • A metallographic screening method has been developed. • The screening method complements EBSD analysis for microstructure identification.

  16. Effect of plastic deformation on the magnetic properties of selected austenitic stainless steels

    Directory of Open Access Journals (Sweden)

    Tatiana Oršulová

    2017-04-01

    Full Text Available Austenitic stainless steels are materials, that are widely used in various fields of industry, architecture and biomedicine. Their specific composition of alloying elements has got influence on their deformation behavior. The main goal of this study was evaluation of magnetic properties of selected steels, caused by plastic deformation. The samples were heat treated in different intervals of temperature before measuring. Then the magnetic properties were measured on device designed for measuring of magnetism. From tested specimens, only AISI 304 confirmed effect of plastic deformation on the magnetic properties. Magnetic properties changed with increasing temperature.

  17. Post irradiation tensile and fatigue behavior of austenitic PCA stainless steels irradiated in HFIR

    Science.gov (United States)

    Tanaka, M. P.; Hamada, S.; Hishinuma, A.; Grossbeck, M. L.

    1988-07-01

    Mechanical properties were determined on solution annealed (SA) and cold worked (CW) JPCA (Ti-modified austenitic stainless steel) irradiated in the High Flux Isotope Reactor (HFIR) at temperatures ranging from 300 to 600°C. The irradiation produced damage levels from 16 to 56 dpa and helium concentration from 1020 to 4100 appm. The improved stability of MC precipitates which formed in the matrix during irradiation prevent loss of ductility at 500°C and below. Application of solution annealed JPCA is recommended for structural components of fusion reactors to be operated at 500°C and below.

  18. Comparison of Hydrogen Embrittlement Resistance between 2205 Duplex Stainless Steels and type 316L Austenitic Stainless Steels Under the Cathodic Applied Potential

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Dong-Il; Lee, Jae-Bong [Kookmin University, Seoul (Korea, Republic of)

    2016-10-15

    2205 duplex stainless steels have been used for the construction of the marine environment, because of their excellent corrosion resistance and high strength. However, the resistance to hydrogen embrittlement (HE) may be less than that of 316L austenitic stainless steel. The reason why 316L stainless steels have better resistance to HE is associated with crystal structure (FCC, face centered cubic) and the higher stacking faults energy than 2205 duplex stainless steels. Furthermore 2205 stainless steels with or without tungsten were also examined in terms of HE. 2205 stainless steels containing tungsten is less resistible to HE. It is because dislocation tangle was formed in 2205 duplex stainless steels. Slow strain-rate tensile test (SSRT) was conducted to measure the resistance to HE under the cathodic applied potential. Hydrogen embrittlement index (HEI) was used to evaluate HE resistance through the quantitative calculation.

  19. Quantification of retained austenite by X-ray diffraction and saturation magnetization in a supermartensitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Sicupira, Felipe Lucas [Departamento de Engenharia Metalúrgica e de Materiais - Escola de Engenharia da UFMG, 31270–901 Belo Horizonte, MG (Brazil); Sandim, Maria José R.; Sandim, Hugo R.Z. [Escola de Engenharia de Lorena – USP, 12600–970 Lorena, SP (Brazil); Santos, Dagoberto Brandão [Departamento de Engenharia Metalúrgica e de Materiais - Escola de Engenharia da UFMG, 31270–901 Belo Horizonte, MG (Brazil); Renzetti, Reny Angela, E-mail: renzetti.ra@gmail.com [Universidade Federal de Itajubá - UNIFEI, 35903–087 Itabira, MG (Brazil)

    2016-05-15

    The good performance of supermartensitic stainless steels is strongly dependent on the volume fraction of retained austenite at room temperature. The present work investigates the effect of secondary tempering temperatures on this phase transformation and quantifies the amount of retained austenite by X-ray diffraction and saturation magnetization. The steel samples were tempered for 1 h within a temperature range of 600–800 °C. The microstructure was characterized using scanning electron microscopy and electron backscatter diffraction. Results show that the amount of retained austenite decreased with increasing secondary tempering temperature in both quantification methods. - Highlights: • The phase transformation during secondary tempering temperatures was observed. • Phases were quantified by X-ray diffraction and DC-saturation magnetization. • More retained austenite forms with increasing secondary tempering temperature. • The retained austenite is mainly located at the grain and lath boundaries.

  20. Elemental distribution inside a heat treated stainless steel weld.

    CERN Multimedia

    2017-01-01

    The video shows the elemental distribution of Molybdenum (red), Manganese (green) and Chromium (blue) within a 20 μm × 20 μm × 20 μm region of a heat treated stainless steel weld. This data has been collected using 3D Focused Ion Beam Milling and Energy Dispersive X-ray Spectroscopy, an elemental characterisation analysis technique. High resolution (75 nm voxel size) mapping is necessary to gain insight into the distribution of regions with distinct elemental composition (phases), which are shown in purple (sigma) and yellow (delta ferrite) in the video. These features have important implications for the toughness and the magnetic properties of the weld, especially at cryogenic temperatures. The video shows the individual slices which were collected in a direction perpendicular to the weld bead direction, followed by a 3D representation of the gauge volume.

  1. Effect of Water Depth on the Underwater Wet Welding of Ferritic Steels Using Austenitic Ni-Based Alloy Electrodes

    National Research Council Canada - National Science Library

    Sheakley, Brian

    2000-01-01

    ...), slag inclusions, oxide inclusions, and porosity. To avoid underbead cracking three weld samples were made using an austenitic nickel weld metal with an Oxylance coating at 10 feet of salt water, 25 feet of salt water, and 33 feet of salt water...

  2. Performance evaluation of vegetable-based oils in drilling austenitic stainless steel

    DEFF Research Database (Denmark)

    Belluco, Walter; De Chiffre, Leonardo

    2004-01-01

    The efficiency of six cutting oils was evaluated in drilling AISI 316L austenitic stainless steel using conventional HSS-Co tools by measurements of tool life, tool wear, cutting forces and chip formation. Seven tools were tested with each fluid to catastrophic failure. Cutting forces and chip...... that a performing fluid produces longer tool life, better chip breaking, lower wear and cutting forces. In particular, good correlation was found between tool life and cutting forces. Differences in cutting forces due to the fluid could be measured with a higher repeatability than tool life, thus resulting...... in a measurement capability comparable to that obtained using tool life as a performance criterion. As a consequence, it is suggested that drilling thrust can be used to assess the performance of cutting fluids in drilling stainless steel, resulting in considerable time savings and cost reduction with respect...

  3. The Cold Gas-Dynamic Spray and Characterization of Microcrystalline Austenitic Stainless Steel

    Science.gov (United States)

    2014-09-01

    such as zinc and magnesium, which occur during traditional thermal spray techniques and welding [1]. Because of these benefits, cold spray can be...coating on magnesium alloys [2, 15], aluminum components [22], and biomedical implants [5, 23]. A number of investigators have demonstrated successful...stainless steel powders have been successfully deposited onto magnesium alloys [2, 15], aluminum components [22], and biomedical implants [5, 23]. These

  4. Selecting Processes to Minimize Hexavalent Chromium from Stainless Steel Welding

    Science.gov (United States)

    KEANE, M.; SIERT, A.; STONE, S.; CHEN, B.; SLAVEN, J.; CUMPSTON, A.; ANTONINI, J.

    2015-01-01

    Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium (Cr6+) in stainless steel welding fumes. The processes examined were gas metal arc welding (GMAW) (axial spray, short circuit, and pulsed spray modes), flux cored arc welding (FCAW), and shielded metal arc welding (SMAW). The Cr6+ fractions were measured in the fumes; fume generation rates, Cr6+ generation rates, and Cr6+ generation rates per unit mass of welding wire were determined. A limited controlled comparison study was done in a welding shop including SMAW, FCAW, and three GMAW methods. The processes studied were compared for costs, including relative labor costs. Results indicate the Cr6+ in the fume varied widely, from a low of 2800 to a high of 34,000 ppm. Generation rates of Cr6+ ranged from 69 to 7800 μg/min, and Cr6+ generation rates per unit of wire ranged from 1 to 270 μg/g. The results of field study were similar to the findings in the laboratory. The Cr6+ (ppm) in the fume did not necessarily correlate with the Cr6+ generation rate. Physical properties were similar for the processes, with mass median aerodynamic diameters ranging from 250 to 336 nm, while the FCAW and SMAW fumes were larger (360 and 670 nm, respectively). Conclusion: The pulsed axial spray method was the best choice of the processes studied based on minimal fume generation, minimal Cr6+ generation, and cost per weld. This method is usable in any position, has a high metal deposition rate, and is relatively simple to learn and use. PMID:26690276

  5. Microstructural, Mechanical, and Electrochemical Analysis of Duplex and Superduplex Stainless Steels Welded with the Autogenous TIG Process Using Different Heat Input

    Directory of Open Access Journals (Sweden)

    Gláucio Soares da Fonseca

    2017-12-01

    Full Text Available Duplex Stainless Steels (DSS and Superduplex Stainless Steels (SDSS have a strong appeal in the petrochemical industry. These steels have excellent properties, such as corrosion resistance and good toughness besides good weldability. Welding techniques take into account the loss of alloying elements during the process, so this loss is usually compensated by the addition of a filler metal rich in alloying elements. A possible problem would be during the welding of these materials in adverse conditions in service, where the operator could have difficulties in welding with the filler metal. Therefore, in this work, two DSS and one SDSS were welded, by autogenous Tungsten Inert Gas (TIG, i.e., without addition of a filler metal, by three different heat inputs. After welding, microstructural, mechanical, and electrochemical analysis was performed. The microstructures were characterized for each welding condition, with the aid of optical microscopy (OM. Vickers hardness, Charpy-V, and cyclic polarization tests were also performed. After the electrochemical tests, the samples were analyzed by scanning electron microscopy (SEM. The SDSS welded with high heat input kept the balance of the austenite and ferrite, and toughness above the limit value. The hardness values remain constant in the weld regions and SDSS is the most resistant to corrosion.

  6. Effect of Heat Treatment on Low Temperature Toughness of Reduced Pressure Electron Beam Weld Metal of Type 316L Stainless Steel

    Science.gov (United States)

    Nakagawa, H.; Fujii, H.; Tamura, M.

    2006-03-01

    Austenitic stainless steels are considered to be the candidate materials for liquid hydrogen vessels and the related equipments, and those welding parts that require high toughness at cryogenic temperature. The authors have found that the weld metal of Type 316L stainless steel processed by reduced pressure electron beam (RPEB) welding has high toughness at cryogenic temperature, which is considered to be due to the single-pass welding process without reheating effect accompanied by multi-pass welding process. In this work, the effect of heat treatment on low temperature toughness of the RPEB weld metal of Type 316L was investigated by Charpy impact test at 77K. The absorbed energy decreased with higher temperature and longer holding time of heat treatment. The remarkable drop in the absorbed energy was found with heat treatment at 1073K for 2 hours, which is as low as that of conventional multi-pass weld metal such as tungsten inert gas welding. The observations of fracture surface and microstructure revealed that the decrease in the absorbed energy with heat treatment resulted from the precipitation of intermetallic compounds near delta-ferrite phase.

  7. Stainless steel welding and semen quality

    DEFF Research Database (Denmark)

    Jelnes, J E; Knudsen, Lisbeth E.

    1988-01-01

    Questionnaire studies of patients from fertility clinics suggest that welders may have an increased risk of reduced semen quality. In this study, welders and nonwelders from the same plants were asked to provide blood, urine, and semen samples. Urine was analyzed for chromium and nickel, and for ...... and nonwelders. Because the metal dust exposure of nonwelders in the plant may be higher than that in the general population, welders were also compared to referents not working in the metal industry. Again, no decrease in semen quality associated with welding was demonstrated....

  8. Estimation of embrittlement during aging of AISI 316 stainless steel ...

    Indian Academy of Sciences (India)

    Unknown

    Stainless steel; TIG welds; aging; Charpy impact; lower shelf energy; embrittlement. 1. Introduction. Austenitic stainless steels have high ductility, low yield strength, high tensile strength, are easy to fabricate and have good corrosion resistance (Harvey 1979). In welding of these steels there are some difficulties including hot.

  9. High Nb, Ta, and Al creep- and oxidation-resistant austenitic stainless steel

    Science.gov (United States)

    Brady, Michael P [Oak Ridge, TN; Santella, Michael L [Knoxville, TN; Yamamoto, Yukinori [Oak Ridge, TN; Liu, Chain-tsuan [Oak Ridge, TN

    2010-07-13

    An austenitic stainless steel HTUPS alloy includes, in weight percent: 15 to 30 Ni; 10 to 15 Cr; 2 to 5 Al; 0.6 to 5 total of at least one of Nb and Ta; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1 W; up to 0.5 Cu; up to 4 Mn; up to 1 Si; 0.05 to 0.15 C; up to 0.15 B; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni wherein said alloy forms an external continuous scale comprising alumina, nanometer scale sized particles distributed throughout the microstructure, said particles comprising at least one composition selected from the group consisting of NbC and TaC, and a stable essentially single phase fcc austenitic matrix microstructure, said austenitic matrix being essentially delta-ferrite-free and essentially BCC-phase-free.

  10. Effect of material heat treatment on fatigue crack initiation in austenitic stainless steels in LWR environments.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Alexandreanu, B.; Shack, W. J.; Energy Technology

    2005-07-31

    The ASME Boiler and Pressure Vessel Code provides rules for the design of Class 1 components of nuclear power plants. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify design curves for applicable structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. The existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. Under certain environmental and loading conditions, fatigue lives of austenitic stainless steels (SSs) can be a factor of 20 lower in water than in air. This report presents experimental data on the effect of heat treatment on fatigue crack initiation in austenitic Type 304 SS in LWR coolant environments. A detailed metallographic examination of fatigue test specimens was performed to characterize the crack morphology and fracture morphology. The key material, loading, and environmental parameters and their effect on the fatigue life of these steels are also described. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic SSs as a function of material, loading, and environmental parameters. Two methods for incorporating the effects of LWR coolant environments into the ASME Code fatigue evaluations are presented.

  11. Review of environmental effects on fatigue crack growth of austenitic stainless steels.

    Energy Technology Data Exchange (ETDEWEB)

    Shack, W. J.; Kassner, T. F.; Energy Technology

    1994-07-11

    Fatigue and environmentally assisted cracking of piping, pressure vessel cladding, and core components in light water reactors are potential concerns to the nuclear industry and regulatory agencies. The degradation processes include intergranular stress corrosion cracking of austenitic stainless steel (SS) piping in boiling water reactors (BWRs), and propagation of fatigue or stress corrosion cracks (which initiate in sensitized SS cladding) into low-alloy ferritic steels in BWR pressure vessels. Crack growth data for wrought and cast austenitic SSs in simulated BWR water, developed at Argonne National Laboratory under US Nuclear Regulatory Commission sponsorship over the past 10 years, have been compiled into a data base along with similar data obtained from the open literature. The data were analyzed to develop corrosion-fatigue curves for austenitic SSs in aqueous environments corresponding to normal BWR water chemistries, for BWRs that add hydrogen to the feedwater, and for pressurized water reactor primary-system-coolant chemistry. The corrosion-fatigue data and curves in water were compared with the air line in Section XI of the ASME Code.

  12. Cutting Properties of Austenitic Stainless Steel by Using Laser Cutting Process without Assist Gas

    Directory of Open Access Journals (Sweden)

    Hitoshi Ozaki

    2012-01-01

    Full Text Available Recently, laser cutting is used in many industries. Generally, in laser cutting of metallic materials, suitable assist gas and its nozzle are needed to remove the molten metal. However, because of the gas nozzle should be set closer to the surface of a workpiece, existence of the nozzle seems to prevent laser cutting from being used flexible. Therefore, the new cutting process, Assist Gas Free laser cutting or AGF laser cutting, has been developed. In this process, the pressure at the bottom side of a workpiece is reduced by a vacuum pump, and the molten metal can be removed by the air flow caused by the pressure difference between both sides of the specimen. In this study, cutting properties of austenitic stainless steel by using AGF laser cutting with 2 kW CO2 laser were investigated. Laser power and cutting speed were varied in order to study the effect of these parameters on cutting properties. As a result, austenitic stainless steel could be cut with dross-free by AGF laser cutting. When laser power was 2.0 kW, cutting speed could be increased up to 100 mm/s, and kerf width at specimen surface was 0.28 mm.

  13. Equi-biaxial loading effect on austenitic stainless steel fatigue life

    Directory of Open Access Journals (Sweden)

    C. Gourdin

    2016-10-01

    Full Text Available Fatigue lifetime assessment is essential in the design of structures. Under-estimated predictions may result in unnecessary in service inspections. Conversely, over-estimated predictions may have serious consequences on the integrity of structures. In some nuclear power plant components, the fatigue loading may be equibiaxial because of thermal fatigue. So the potential impact of multiaxial loading on the fatigue life of components is a major concern. Meanwhile, few experimental data are available on austenitic stainless steels. It is essential to improve the fatigue assessment methodologies to take into account the potential equi-biaxial fatigue damage. Hence this requires obtaining experimental data on the considered material with a strain tensor in equibiaxial tension. Two calibration tests (with strain gauges and image correlation were used to obtain the relationship between the imposed deflection and the radial strain on the FABIME2 specimen. A numerical study has confirmed this relationship. Biaxial fatigue tests are carried out on two austenitic stainless steels for different values of the maximum deflection, and with a load ratio equal to -1. The interpretation of the experimental results requires the use of an appropriate definition of strain equivalent. In nuclear industry, two kinds of definition are used: von Mises and TRESCA strain equivalent. These results have permitted to estimate the impact of the equibiaxiality on the fatigue life of components

  14. Corrosion fatigue crack growth behaviour of austenitic stainless steels under light water reactor conditions

    Energy Technology Data Exchange (ETDEWEB)

    Seifert, H.P., E-mail: hans-peter.seifert@psi.ch [Paul Scherrer Institute (PSI), Nuclear Energy and Safety Research Department, Laboratory for Nuclear Materials, 5232 Villigen PSI (Switzerland); Ritter, S.; Leber, H.J. [Paul Scherrer Institute (PSI), Nuclear Energy and Safety Research Department, Laboratory for Nuclear Materials, 5232 Villigen PSI (Switzerland)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Corrosion fatigue in austenitic stainless steels under light water reactor conditions. Black-Right-Pointing-Pointer Identification of major parameters of influence. Black-Right-Pointing-Pointer Critical system conditions for environmental acceleration of fatigue crack growth. Black-Right-Pointing-Pointer Proposal for new code fatigue curves, which consider environmental effects. - Abstract: The corrosion fatigue crack growth behaviour of different wrought low-carbon and stabilised austenitic stainless steels was characterised under simulated boiling water and primary pressurised water reactor conditions by cyclic fatigue tests with pre-cracked fracture mechanics specimens in the temperature range from 70 to 320 Degree-Sign C. The major parameter effects and critical conjoint threshold conditions, which result in relevant environmental acceleration of fatigue crack growth are discussed and summarised. Furthermore, the observed corrosion fatigue behaviour is compared with the corresponding (corrosion) fatigue curves in the ASME and JSME boiler and pressure vessel code or open literature and conclusions with regard to their adequacy and conservatism are given.

  15. Formability and fracture studies of austenitic stainless steel 316 at different temperatures

    Directory of Open Access Journals (Sweden)

    Syed Mujahed Hussaini

    2014-07-01

    Full Text Available Deep drawing is one of the most important sheet metal forming processes in automotive, aerospace and nuclear industries. In this process, the sheet metal blank is formed into a cup shape by an application of punch into the die. The present work is aimed at studying the formability and the nature of fracture for one of the important materials in industrial applications, austenitic stainless steel 316 at different temperatures. Circular blanks were deep drawn at room temperature, 150 and 300 °C using a 20 Ton hydraulic press coupled with a furnace and found that formability of the austenitic stainless steel 316 increased as the temperature was increased. This material underwent dynamic strain aging between 350 and 550 °C. Fractured surface of the broken tensile test specimen at different regions were studied and analyzed using scanning electron microscope. It was observed that the nature of the fracture was brittle in dynamic strain aging region.

  16. High corrosion resistance of austenitic stainless steel alloyed with nitrogen in an acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Metikos-Hukovic, M., E-mail: mmetik@fkit.h [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Babic, R. [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Grubac, Z. [Department of General and Inorganic Chemistry, Faculty of Chemistry and Technology, University of Split, 21000 Split (Croatia); Petrovic, Z. [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Lajci, N. [Faculty of Mine and Metallurgy, University of Prishtina, 10000 Prishtina, Kosovo (Country Unknown)

    2011-06-15

    Highlights: {yields} ASS alloyed with nitrogen treated at 1150 {sup o}C exhibits microstructure homogeneity. {yields} Passivation peak of ASS corresponds to oxidation of metal and absorbed hydrogen. {yields} Transfer phenomena and conductivity depend on the film formation potential. {yields} Electronic structure of the passive film and its corrosion resistance correlate well. {yields} Passive film on ASS with nitrogen is low disordered and high corrosion resistant. - Abstract: Passivity of austenitic stainless steel containing nitrogen (ASS N25) was investigated in comparison with AISI 316L in deareated acid solution, pH 0.4. A peculiar nature of the passivation peak in a potentiodynamic curve and the kinetic parameters of formation and growth of the oxide film have been discussed. The electronic-semiconducting properties of the passive films have been correlated with their corrosion resistance. Alloying austenitic stainless steel with nitrogen increases its microstructure homogeneity and decreases the concentration of charge carriers, which beneficially affects the protecting and electronic properties of the passive oxide film.

  17. On the constitutive model of nitrogen-containing austenitic stainless steel 316LN at elevated temperature.

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    Full Text Available The nitrogen-containing austenitic stainless steel 316LN has been chosen as the material for nuclear main-pipe, which is one of the key parts in 3rd generation nuclear power plants. In this research, a constitutive model of nitrogen-containing austenitic stainless steel is developed. The true stress-true strain curves obtained from isothermal hot compression tests over a wide range of temperatures (900-1250°C and strain rates (10(-3-10 s(-1, were employed to study the dynamic deformational behavior of and recrystallization in 316LN steels. The constitutive model is developed through multiple linear regressions performed on the experimental data and based on an Arrhenius-type equation and Zener-Hollomon theory. The influence of strain was incorporated in the developed constitutive equation by considering the effect of strain on the various material constants. The reliability and accuracy of the model is verified through the comparison of predicted flow stress curves and experimental curves. Possible reasons for deviation are also discussed based on the characteristics of modeling process.

  18. Mechanism and estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Energy Technology

    2002-08-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of fatigue crack initiation in austenitic stainless steels in LWR coolant environments. The existing fatigue {var_epsilon}-N data have been evaluated to establish the effects of key material, loading, and environmental parameters (such as steel type, strain range, strain rate, temperature, dissolved-oxygen level in water, and flow rate) on the fatigue lives of these steels. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic stainless steels as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are presented. The influence of reactor environments on the mechanism of fatigue crack initiation in these steels is also discussed.

  19. Hydrogen embrittlement in superaustenitic stainless steels welded unions in sulfuric acid; Fragilizacao por hidrogenio em juntas soldadas de acos inoxidaveis superausteniticos em acido sulfurico

    Energy Technology Data Exchange (ETDEWEB)

    Berthier, T. [Parana Univ., Curitiba, PR (Brazil). Lab. de Materiais e Tratamento de Superficies (LaMaTS)]. E-mail: thiana@demec.ufpr.br; Kuromoto, N.K. [Parana Univ., Curitiba, PR (Brazil). Lab. de Nanopropriedades Mecanicas; Paredes, R.S.C. [Instituto de Tecnologia para o Desenvolvimento (LACTEC), Curitiba, PR (Brazil)

    2003-07-01

    The embrittlement of the austenitic stainless steel by hydrogen has been known for more than four decades. Researches done into the behavior of the hydrogenated homogeneous structures, under cathodic charging at room temperature, have shown that the hydrogen induces phase transformations and nucleation of retarded superficial cracks during the outgassing which is followed by the end of the hydrogenation. The results obtained upon austenitic and superaustenitic stainless steels are few considering the changes produced in welded unions. The aim of this work is to evaluate mechanical properties of material and its relation to the nucleation of the cracks in the austenitic steels welds type AISI 904L submitted to hydrogenated solutions. The samples have been welded through the process MIG/MAG; the hydrogenation has been made catholically in a sulfuric acid solution of 1N, with variable time of 1 to 4 hours at the room temperature. An anode of platinum in and density of current 1000 A/m{sup 2} has been used. The outgassing has occurred at the room temperature. Many retarded superficial cracks with different morphologies have been observed. Regarding the hardness measure, major alterations in all the regions of the sample have not been noticed. (author)

  20. Tailoring plasticity of austenitic stainless steels for nuclear applications: Review of mechanisms controlling plasticity of austenitic steels below 400 °C

    Energy Technology Data Exchange (ETDEWEB)

    Meric de Bellefon, G., E-mail: mericdebelle@wisc.edu [University of Wisconsin-Madison (United States); Duysen, J.C. van [EDF R& D (France); University of Tennessee-Knoxville (United States); Unité Matériaux et Transformation (UMET) CNRS, Université de Lille (France)

    2016-07-15

    AISI 304 and 316 austenitic stainless steels were invented in the early 1900s and are still trusted by materials and mechanical engineers in numerous sectors because of their good combination of strength, ductility, and corrosion resistance, and thanks to decades of experience and data. This article is part of an effort focusing on tailoring the plasticity of both types of steels to nuclear applications. It provides a synthetic and comprehensive review of the plasticity mechanisms in austenitic steels during tensile tests below 400 °C. In particular, formation of twins, extended stacking faults, and martensite, as well as irradiation effects and grain rotation are discussed in details. - Highlights: • This article is part of an effort to tailor the plasticity of 304L and 316L steels for nuclear applications. • It reviews mechanisms controlling plasticity of austenitic steels during tensile tests. • Formation of twins, extended stacking faults, and martensite, grain rotation, and irradiation effects are discussed.

  1. Synergistic Computational and Microstructural Design of Next- Generation High-Temperature Austenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Karaman, Ibrahim [Texas A& M Engineering Experiment Station, College Station, TX (United States); Arroyave, Raymundo [Texas A& M Engineering Experiment Station, College Station, TX (United States)

    2015-07-31

    The purpose of this project was to: 1) study deformation twinning, its evolution, thermal stability, and the contribution on mechanical response of the new advanced stainless steels, especially at elevated temperatures; 2) study alumina-scale formation on the surface, as an alternative for conventional chromium oxide, that shows better oxidation resistance, through alloy design; and 3) design new generation of high temperature stainless steels that form alumina scale and have thermally stable nano-twins. The work involved few baseline alloys for investigating the twin formation under tensile loading, thermal stability of these twins, and the role of deformation twins on the mechanical response of the alloys. These baseline alloys included Hadfield Steel (Fe-13Mn-1C), 316, 316L and 316N stainless steels. Another baseline alloy was studied for alumina-scale formation investigations. Hadfield steel showed twinning but undesired second phases formed at higher temperatures. 316N stainless steel did not show signs of deformation twinning. Conventional 316 stainless steel demonstrated extensive deformation twinning at room temperature. Investigations on this alloy, both in single crystalline and polycrystalline forms, showed that deformation twins evolve in a hierarchical manner, consisting of micron–sized bundles of nano-twins. The width of nano-twins stays almost constant as the extent of strain increases, but the width and number of the bundles increase with increasing strain. A systematic thermomechanical cycling study showed that the twins were stable at temperatures as high as 900°C, after the dislocations are annealed out. Using such cycles, volume fraction of the thermally stable deformation twins were increased up to 40% in 316 stainless steel. Using computational thermodynamics and kinetics calculations, we designed two generations of advanced austenitic stainless steels. In the first generation, Alloy 1, which had been proposed as an alumina

  2. Stainless steel welding and semen quality

    Energy Technology Data Exchange (ETDEWEB)

    Jelnes, J.E.; Knudsen, L.E. (Department of Biology and Toxicology, Danish National Institute of Occupational Health, Copenhagen (Denmark))

    1988-01-01

    Questionnaire studies of patients from fertility clinics suggest that welders may have an increased risk of reduced semen quality. In this study, welders and nonwelders from the same plants were asked to provide blood, urine, and semen samples. Urine was analyzed for chromium and nickel, and for mutagenic activity and metal concentration; blood for metal concentrations, immunoglobulin G, total protein, and measures of genotoxicity in lymphocytes; and semen was evaluated by standard semen analysis. Results of the semen evaluation, presented here, showed no difference in semen quality between welders and nonwelders. Because the metal dust exposure of nonwelders in the plant may be higher than that in the general population, welders were also compared to referents not working in the metal industry. Again, no decrease in semen quality associated with welding was demonstrated.

  3. Development of Ultra-Fine-Grained Structure in AISI 321 Austenitic Stainless Steel

    Science.gov (United States)

    Tiamiyu, A. A.; Szpunar, J. A.; Odeshi, A. G.; Oguocha, I.; Eskandari, M.

    2017-12-01

    Ultra-fine-grained (UFG) structure was developed in AISI 321 austenitic stainless steel (ASS) using cryogenic rolling followed by annealing treatments at 923 K, 973 K, 1023 K, and 1073 K (650 °C, 700 °C, 750 °C, and 800 °C) for different lengths of time. The α'-martensite to γ-austenite reversion behavior and the associated texture development were analyzed in the cryo-rolled specimens after annealing. The activation energy, Q, required for the reversion of α'-martensite to γ-austenite in the steel was estimated to be 80 kJ mol-1. TiC precipitates and unreversed triple junction α'-martensite played major roles in the development of UFG structure through the Zener pinning of grain boundaries. The optimum annealing temperature and time for the development of UFG structure in the cryo-rolled AISI 321 steel are (a) 923 K (650 °C) for approximately 28800 seconds and (b) 1023 K (750 °C) for 600 seconds, with average grain sizes of 0.22 and 0.31 µm, respectively. Annealing at 1023 K (750 °C) is considered a better alternative since the volume fraction of precipitated carbides in specimens annealed at 1023 K (750 °C) are less than those annealed at 923 K (650 °C). More so, the energy consumption during prolonged annealing time to achieve an UFG structure at 923 K (650 °C) is higher due to low phase reversion rate. The hardness of the UFG specimens is 195 pct greater than that of the as-received steel. The higher volume fraction of TiC precipitates in the UFG structure may be an additional source of hardening. Micro and macrotexture analysis indicated {110}〈uvw〉 as the major texture component of the austenite grains in the UFG structure. Its intensity is stronger in the specimen annealed at low temperatures.

  4. Round Robin Analyses on Stress Intensity Factors of Inner Surface Cracks in Welded Stainless Steel Pipes

    Directory of Open Access Journals (Sweden)

    Chang-Gi Han

    2016-12-01

    Full Text Available Austenitic stainless steels (ASSs are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  5. Round robin analysis on stress intensity factor of inner surface cracks in welded stainless steel pipes

    Energy Technology Data Exchange (ETDEWEB)

    Han, Chang Gi; Chang, Yoon Suk [Dept. of Nuclear Engineering, College of Engineering, Kyung Hee University, Yongin (Korea, Republic of); Kim, Jong Sung [Dept. of Mechanical Engineering, Sunchon National University, Sunchon (Korea, Republic of); Kim, Maan Won [Central Research Institute, Korea Hydro and Nuclear Power Company, Daejeon (Korea, Republic of)

    2016-12-15

    Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.

  6. Prediction of solidification and phase transformation in weld metals for welding of high performance stainless steels; Kotaishoku kotainetsu stainless koyo yosetsu kinzoku no gyoko hentai no yosoku gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Koseki, T.; Inoue, H.; Morimoto, H.; Okita, S. [Nippon Steel Corp., Tokyo (Japan)

    1995-02-28

    Prediction technology is introduced on the solidification and transformation of weld metals used for high performance stainless steel. A model has been developed which uses Thermo Calc, a multiple balanced calculation program, as a means to analyze the solidification of multi-component alloys including the polyphase solidification such as eutectic and peritectic. Verification has been in progress concerning the adequacy of this model and the adaptability as a practical steel. The following are the prediction technologies for solidification and transformation which have been derived from experiments and applied to welding techniques: the effects of nitrogen on the solidification mode and residual {gamma}quantity of a welding metal that is required for controlling the welding/solidification of high nitrogen content {gamma}system stainless steel; the structural control of weld metal for high corrosion resistance high Mo stainless steel, in which high Ni and high Mo contents are indispensable for attaining the optimum structure; the structural control of weld metal for two-phase stainless steel containing Mo and N, in which it is essential to secure a high nitrogen content and a {delta}/{gamma}phase balance in a weld metal; and the precipitation prediction of intermetallic compound in a high alloy weld metal for a high alloy stainless steel, for which an explanation is there by Cieslak et al. based on the phase stability theory. 22 refs., 16 figs.

  7. Heterogeneities in local plastic flow behavior in a dissimilar weld between low-alloy steel and stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Mas, Fanny [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Martin, Guilhem, E-mail: guilhem.martin@simap.grenoble-inp.fr [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Lhuissier, Pierre; Bréchet, Yves; Tassin, Catherine [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Roch, François [Areva NP, Tour Areva, 92084 Paris La Défense (France); Todeschini, Patrick [EDF R& D, Avenue des Renardières, 77250 Moret-sur-Loing (France); Simar, Aude [Institute of Mechanics, Materials and Civil Engineering (iMMC), Université catholique de Louvain, 1348 Louvain-la-Neuve (Belgium)

    2016-06-14

    In dissimilar welds between low-alloy steel and stainless steel, the post-weld heat-treatment results in a high variety of microstructures coexisting around the fusion line, due to carbon diffusion and carbides dissolution/precipitation. The local constitutive laws in the vicinity of the fusion zone were identified by micro tensile specimens for the sub-millimeter sized zones, equivalent bulk materials representing the decarburized layer using both wet H{sub 2} atmosphere and diffusion couple, and nano-indentation for the carburized regions (i.e. the martensitic band and the austenitic region). The decarburized zone presents only 50% of the yield strength of the low-alloy steel heat affected zone and a ductility doubled. The carburized zones have a yield strength 3–5 times higher than that of the low-alloy steel heat affected zone and have almost no strain hardening capacity. These properties result in heterogeneous plastic deformation happening over only millimeters when the weld is loaded perpendicularly to the weld line, affecting its overall behavior. The constitutive laws experimentally identified were introduced as inputs into a finite elements model of the transverse tensile test performed on the whole dissimilar weld. A good agreement between experiments and simulations was achieved on the global stress-strain curve. The model also well predicts the local strain field measured by microscale DIC. A large out-of-plane deformation due to the hard carburized regions has also been identified.

  8. 78 FR 63517 - Control of Ferrite Content in Stainless Steel Weld Metal

    Science.gov (United States)

    2013-10-24

    ... to remove an appendix that has been incorporated into relevant specifications. ADDRESSES: Please... procedure for the control of ferrite content in stainless steel weld metal. This guide provides methods that..., Safety Guide 31, ``Control of Stainless Steel Welding,'' issued August 1972, provided guidance to test...

  9. 77 FR 60478 - Control of Ferrite Content in Stainless Steel Weld Metal

    Science.gov (United States)

    2012-10-03

    ... Ferrite Content in Stainless Steel Weld Metal.'' This guide describes a method that the NRC staff... guide describes a method that the staff of the U.S. Nuclear Regulatory Commission (NRC) considers... COMMISSION Control of Ferrite Content in Stainless Steel Weld Metal AGENCY: Nuclear Regulatory Commission...

  10. 78 FR 45271 - Welded Stainless Steel Pressure Pipe From Malaysia, Thailand, and Vietnam

    Science.gov (United States)

    2013-07-26

    ... COMMISSION Welded Stainless Steel Pressure Pipe From Malaysia, Thailand, and Vietnam Determination On the... injured by reason of imports from Malaysia, Thailand, and Vietnam of welded stainless steel pressure pipe... the Department of Commerce (Commerce) of affirmative preliminary determinations in these...

  11. 78 FR 31574 - Welded Stainless Steel Pressure Pipe From Malaysia, Thailand, and Vietnam; Institution of...

    Science.gov (United States)

    2013-05-24

    ...)] Welded Stainless Steel Pressure Pipe From Malaysia, Thailand, and Vietnam; Institution of Antidumping... materially retarded, by reason of imports from Malaysia, Thailand, and Vietnam of welded stainless steel... value. Unless the Department of Commerce extends the time for initiation pursuant to section 732(c)(1)(B...

  12. Statistical model of water environment effects on the fatigue behavior of austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Wilhelm, Paul [AREVA GmbH, Erlangen (Germany); Erlangen-Nuernberg Univ., Erlangen (Germany). Chair of Applied Mechanics; Steinmann, Paul [Erlangen-Nuernberg Univ., Erlangen (Germany). Chair of Applied Mechanics; Rudolph, Juergen [AREVA GmbH, Erlangen (Germany)

    2014-07-01

    Many studies on the effects of elevated temperature environments on the cycle fatigue performance of austenitic stainless steels typically used for boiling and light water reactor components have been performed. The key parameters (e. g. strain rate, and temperature) that influence the fatigue life were identified and the range of these key parameters where environmental effects become pronounced were defined. The two major efforts to characterize environmentally assisted fatigue (EAF) are by Argonne National Laboratory (U. S.) and EFD (Japan). Since each nation considers only domestic fatigue data, the widely applied titanium and niobium stabilized austenitic stainless steels in Germany are not included by any data points in these models. Based on a review of past and current research reports about EAF a database for wrought Types 304, 304L, 316, 316NG, 321, 347, and 348 stainless steels was compiled. Only specimen tests under strain control with a fully reversed uniaxial loading were included. The modified Langer equation was used to develop the room temperature in air curve to the collected data, which serves as the basis for the discussion of the EAF database. Besides the key variables that influence fatigue life in light and boiling water reactor environments additional parameters like, for example, the strain amplitude, which pronounces environmental effects more at low than at high strain amplitudes, can reduce the fatigue life by a factor of about two and should not be neglected in the current fatigue approach. A statistical model is evolved to address EAF in fatigue usage calculation by a fatigue life correction factor (F{sub en}), which is defined as the ratio of life in air at room temperature to that in water at elevated temperature. Compared to the current ANL statistical prediction model, a different functional form is used and additional variables are considered, too.

  13. 76 FR 79651 - Stainless Steel Butt-Weld Pipe Fittings From Italy: Preliminary Results of Antidumping Duty...

    Science.gov (United States)

    2011-12-22

    ... International Trade Administration Stainless Steel Butt-Weld Pipe Fittings From Italy: Preliminary Results of... antidumping duty order on stainless steel butt-weld pipe fittings (SSBW pipe fittings) from Italy. The review... results of the review to no later than December 15, 2011. See Stainless Steel Butt-Weld Pipe Fittings From...

  14. 77 FR 24459 - Stainless Steel Butt-Weld Pipe Fittings From Italy: Final Results of Antidumping Duty...

    Science.gov (United States)

    2012-04-24

    ... International Trade Administration Stainless Steel Butt-Weld Pipe Fittings From Italy: Final Results of... stainless steel butt-weld pipe fittings (SSBW pipe fittings) from Italy.\\1\\ This review covers two... results remain unchanged from the preliminary results of review. \\1\\ See Stainless Steel Butt-Weld Pipe...

  15. 76 FR 78614 - Welded ASTM A-312 Stainless Steel Pipe From South Korea and Taiwan: Continuation of Antidumping...

    Science.gov (United States)

    2011-12-19

    ... International Trade Administration Welded ASTM A-312 Stainless Steel Pipe From South Korea and Taiwan... welded ASTM A-312 stainless steel pipe from South Korea (Korea) and Taiwan would likely lead to... published the antidumping duty orders on welded ASTM A-312 stainless steel pipe from Korea and Taiwan.\\1\\ On...

  16. 76 FR 67673 - Welded ASTM A-312 Stainless Steel Pipe From South Korea and Taiwan: Final Results of Expedited...

    Science.gov (United States)

    2011-11-02

    ... International Trade Administration Welded ASTM A-312 Stainless Steel Pipe From South Korea and Taiwan: Final... (the Department) initiated sunset reviews of the antidumping duty orders on welded ASTM A-312 stainless... the antidumping duty orders on welded ASTM A-312 stainless steel pipe from South Korea and Taiwan...

  17. An ultrasonic non-destructive testing method for the measurement of weld width in laser welding of stainless steel

    Science.gov (United States)

    Zhang, Bo; Liu, Fang; Liu, Chang; Li, Jingming; Zhang, Baojun; Zhou, Qingxiang; Han, Xiaohui; Zhao, Yang

    2017-10-01

    In order to inspect welding defects of the laser welding of stainless steel, the piezoelectric bimorph focusing method is presented, the non-destructive testing system is setup. The cutting part of the laser weld sample is used to measure the welding width by metallography and the non-destructive testing system. The results show that the welding width is unevenly distributed, the relation between the ultrasonic signal amplitude and metallography is showed a good linearity, which means the ultrasonic signal amplitude can be used to measure the welding width.

  18. Measured resolved shear stresses and Bishop-Hill stress states in individual grains of austenitic stainless steel

    DEFF Research Database (Denmark)

    Juul, Nicolai Ytterdal; Oddershede, Jette; Beaudoin, Armand

    2017-01-01

    The full three-dimensional stress state of 172 individual bulk grains in austenitic stainless steel 316L at 0.1 and 1% sample elongation has been determined with sufficient accuracy to allow comparison with the theoretical Bishop-Hill stress states for plastically deforming grains as well as calc...

  19. Stability of grain-refined reversed structures in a 301LN austenitic stainless steel under cyclic loading

    Czech Academy of Sciences Publication Activity Database

    Järvenpää, A.; Jaskari, M.; Man, Jiří; Karjalalinen, L.P.

    2017-01-01

    Roč. 703, č. 4 (2017), s. 280-292 ISSN 0921-5093 R&D Projects: GA ČR GA13-32665S Institutional support: RVO:68081723 Keywords : austenitic stainless steel * reversion treatment * grain size * deformation induced martensite * strain-controlled fatigue Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 3.094, year: 2016

  20. Material property evaluations of bimetallic welds, stainless steel saw fusion lines, and materials affected by dynamic strain aging

    Energy Technology Data Exchange (ETDEWEB)

    Rudland, D.; Scott, P.; Marschall, C.; Wilkowski, G. [Battelle Memorial Institute, Columbus, OH (United States)

    1997-04-01

    Pipe fracture analyses can often reasonably predict the behavior of flawed piping. However, there are material applications with uncertainties in fracture behavior. This paper summarizes work on three such cases. First, the fracture behavior of bimetallic welds are discussed. The purpose of the study was to determine if current fracture analyses can predict the response of pipe with flaws in bimetallic welds. The weld joined sections of A516 Grade 70 carbon steel to F316 stainless steel. The crack was along the carbon steel base metal to Inconel 182 weld metal fusion line. Material properties from tensile and C(T) specimens were used to predict large pipe response. The major conclusion from the work is that fracture behavior of the weld could be evaluated with reasonable accuracy using properties of the carbon steel pipe and conventional J-estimation analyses. However, results may not be generally true for all bimetallic welds. Second, the toughness of austenitic steel submerged-arc weld (SAW) fusion lines is discussed. During large-scale pipe tests with flaws in the center of the SAW, the crack tended to grow into the fusion line. The fracture toughness of the base metal, the SAW, and the fusion line were determined and compared. The major conclusion reached is that although the fusion line had a higher initiation toughness than the weld metal, the fusion-line J-R curve reached a steady-state value while the SAW J-R curve increased. Last, carbon steel fracture experiments containing circumferential flaws with periods of unstable crack jumps during steady ductile tearing are discussed. These instabilities are believed to be due to dynamic strain aging (DSA). The paper discusses DSA, a screening criteria developed to predict DSA, and the ability of the current J-based methodologies to assess the effect of these crack instabilities. The effect of loading rate on the strength and toughness of several different carbon steel pipes at LWR temperatures is also discussed.

  1. Novel Approach for Welding Stainless Steel Using Cr-Free Welding Consumables

    Science.gov (United States)

    2004-12-31

    chromium in the 6+ oxidation state and is commonly referred to as chromate). Fumes containing Cr(VI) can cause lung cancer . Shielded Metal Arc...Fumes containing Cr(VI) can cause lung cancer .1,4. In shipbuilding operations, manual Shielded Metal Arc Welding (SMAW) of stainless steel is...Service, Canberra 1990. 6. E. Zumelzu and C. Cabezas , J. Mat. Proc. Tech. 57 (1996): p. 249. 7. S. A. Campbell, G. J. W. Radford, C. D. S. Tuck, and B

  2. Swelling behavior of welded type 316 stainless steel and its improvement

    Science.gov (United States)

    Sawai, T.; Fukai, K.; Kodaira, T.; Nishida, T.; Nayama, M.; Hishinuma, A.

    1988-07-01

    Type 316 stainless steel was electron beam welded with titanium foil insertion. The concentration of introduced titanium in the weld metal was 0.1, 0.3 and 0.6 wt% corresponding to the inserted foil thickness of 10, 30 and 60 μm, respectively. All the weld joint showed good mechanical performance. The swelling resistance of the weld metal is effectively improved by the introduced titanium. Although inhomogeneous distribution of titanium makes it difficult to estimate the extent of the improvement quantitatively, the results suggest the applicability of this method to Ti-modified 316 stainless steel, where weld metal is already reported to show reduced swelling resistance.

  3. Environmental cracking behavior of submerged arc-welded supermartensitic stainless steel weldments

    Science.gov (United States)

    Srinivasan, P. Bala; Sharkawy, S. W.; Dietzel, W.

    2004-04-01

    Supermartensitic stainless steel welds produced by submerged are welding were assessed for their microstructure and properties. Slow strain rate tests conducted on these specimens revealed that both the parent material and the weld metals are susceptible to cracking under conditions of hydrogen (H) charging.

  4. Influence of the austenitic stainless steel microstructure on the void swelling under ion irradiation

    Directory of Open Access Journals (Sweden)

    Rouxel Baptiste

    2016-01-01

    Full Text Available To understand the role of different metallurgical parameters on the void formation mechanisms, various austenitic stainless steels were elaborated and irradiated with heavy ions. Two alloys, in several metallurgical conditions (15Cr/15Ni–Ti and 15Cr/25Ni–Ti, were irradiated in the JANNUS-Saclay facility at 600 °C with 2 MeV Fe2+ ions up to 150 dpa. Resulting microstructures were observed by Transmission Electron Microscopy (TEM. Different effects on void swelling are highlighted. Only the pre-aged samples, which were consequently solute and especially titanium depleted, show cavities. The nickel-enriched matrix shows more voids with a smaller size. Finally, the presence of nano-precipitates combined with a dense dislocation network decreases strongly the number of cavities.

  5. Effect of Carbon and Nitrogen Content on Deformation and Fracture of AISI 304 Austenitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    C. Menapace

    2008-04-01

    Full Text Available The effect of small differences in the content of carbon and nitrogen on the room temperature tensile deformation and fracture behaviour of an AISI 304 stainless steel was studied. In the steel containing the lower amount of carbon and nitrogen, a higher amount of strain induced alfa’ martensite is formed, which increases strain hardening rate and both uniform and total elongation at fracture. The presence of large martensitic areas in the cross section causes strain localization at the austenite/martensite interface, which promotes the nucleation of cracks and their propagation along the interface. This results in a decrease of Ultimate Tensile Strength. Strain induced transformation slightly reduces strain rate sensitivity, as well.

  6. Effects of low temperature neutron irradiation on deformation behavior of austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, J.E.; Rowcliffe, A.F.; Alexander, D.J.; Grossbeck, M.L. [Oak Ridge National Laboratory, TN (United States); Shiba, K.

    1996-04-01

    An austenitic stainless steel, designated 316LN-IG, has been chosen for the first wall/shield (FW/S) structure for the International Thermonuclear Experimental Reactor (ITER). The proposed operational temperature range for the structure (100 to 250{degree}C) is below the temperature regimes for void swelling (400-600{degree}C) and for helium embrittlement (500-700{degree}C). However, the proposed neutron dose is such that large changes in yield strength, deformation mode, and strain hardening capacity could be encountered which could significantly affect fracture properties. Definition of the irradiation regimes in which this phenomenon occurs is essential to the establishment of design rules to protect against various modes of failure.

  7. Hardness variation in a cathodic hydrogen-charged austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Iost, A. [Univ. de Lille 1, Villeneuve d`Ascq (France). Lab. de Metallurgie Physique]|[Ecole Nationale Superieure d`Arts et Metiers, Lille (France); Vogt, J.B. [Univ. de Lille 1, Villeneuve d`Ascq (France). Lab. de Metallurgie Physique

    1997-11-15

    Hydrogen embrittlement has been studied for a long time but the mechanism has not been yet explained clearly. The difficulty lies in the fact that the cause of embrittlement can change from one alloy to another. In addition, a large part of the reactions take place at the surface, especially at the beginning of the process. Thus, analysis of the surface should provide useful information about the role of hydrogen in this process. While X-ray diffraction is commonly used, microhardness seems to be less developed. The primary objective of this paper is to study the hydrogen-enriched surface of an austenitic stainless steel with the microhardness test, and to show that reliable conclusions can be drawn provided a detailed analysis of the results is taken into account.

  8. Relative merits of duplex and austenitic stainless steels for applications in the oil and gas industry

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Elisabeth; Wegrelius, Lena; Pettersson, Rachel [Outokumpu Stainless AB, Avesta (Sweden)

    2012-07-01

    The broad range of available stainless steel grades means that these materials can fulfil a wide variety of requirements within the oil and gas industry. The duplex grades have the advantage of higher strength than standard austenitic grades, while the superaustenitic grades provide a cost-effective alternative to nickel-base alloys in a number of cases. The paper presents the results of various types of laboratory testing to rank the grades in terms of resistance to pitting, crevice corrosion and stress corrosion cracking. Results from field testing in actual or simulated service conditions are discussed and a number of application examples, including process piping flexible, heat exchangers and topside equipment are presented. (author)

  9. Tool Wear Analysis due to Machining In Super Austenitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    Polishetty Ashwin

    2017-01-01

    Full Text Available This paper presents tool wear study when a machinability test was applied using milling on Super Austenitic Stainless Steel AL6XN alloy. Eight milling trials were performed under two cutting speeds, 100 m/min and 150 m/min, combined with two feed rates at 0.1mm/tooth and 0.15 mm/tooth and two depth of cuts at 2 mm and 3 mm. An Alicona 3D optical surface profilometer was used to scan cutting inserts flank and rake face areas for wear. Readings such as maximum and minimum deviations were extracted and used to analyse the outcomes. Results showed various types of wear were generated on the tool rake and flank faces. The common formed wear was the crater wear. The formation of the build-up edge was observed on the rake face of the cutting tool.

  10. Inhibition Effect of N, N'-Dimethylaminoethanol on the Pitting Corrosion Austenitic Stainless Steel Type 304

    Directory of Open Access Journals (Sweden)

    Roland Tolulope LOTO

    2015-11-01

    Full Text Available The electrochemical influence and corrosion inhibition of N, N'-dimethylaminoethanol on the pitting corrosion resistance of austenitic stainless steel (type 304 in dilute sulphuric acid solution with sodium chloride addition was investigated using potentiodynamic polarization technique. Corrosion potential, pitting potential, repassivation potential, nucleation resistance, passivation range and repassivation capacity measurements and potentiodynamic analysis were used to evaluate the steel’s pitting resistance characteristics. The potentiodynamic experiments revealed that pitting potential increased with increase in concentration of the inhibiting compound coupled with an increase in the passivation range hence increased resistance to pittinggcorrosion.  DOI: http://dx.doi.org/10.5755/j01.ms.21.4.8977

  11. Crack initiation in smooth fatigue specimens of austenitic stainless steel in light water reactor environments.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Smith, J. L.

    1999-04-08

    The fatigue design curves for structural materials specified in Section III of the ASME Boiler and Pressure Vessel Code are based on tests of smooth polished specimens at room temperature in air. The effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves; however, recent test data illustrate the detrimental effects of LWR coolant environments on the fatigue resistance of austenitic stainless steels (SSs). Certain loading and environmental conditions have led to test specimen fatigue lives that are significantly shorter than those obtained in air. Results of fatigue tests that examine the influence of reactor environments on crack initiation and crack growth of austenitic SSs are presented. Block loading was used to mark the fracture surface to determine crack length as a function of fatigue cycles in water environments, Crack lengths were measured by scanning electron microscopy. The mechanism for decreased fatigue life in LWR environments is discussed, and crack growth rates in the smooth fatigue specimens are compared with existing data from studies of crack growth rates.

  12. Flow Softening Index for Assessment of Dynamic Recrystallization in an Austenitic Stainless Steel

    Science.gov (United States)

    Aashranth, B.; Samantaray, Dipti; Kumar, Santosh; Dasgupta, Arup; Borah, Utpal; Albert, Shaju K.; Bhaduri, A. K.

    2017-07-01

    The present study proposes a novel technique to assess dynamic recrystallization (DRX) and related microstructural phenomena during hot deformation of austenite. A `Flow Softening Index (FSI)' has been identified on the basis of investigations on elevated temperature deformation behaviour of austenitic stainless steel. This index corresponds to dominant microstructural phenomena at different deformation conditions. For this investigation, experimental results obtained from isothermal, constant true strain rate compression tests in a temperature range of 1173 (900)-1473 K (1200 °C) and strain rate range of 0.01-100 s-1 have been used. Resultant microstructures have been quantified using average grain size and grain size distributions. The dominant microstructural phenomena have been identified at different conditions using electron backscatter diffraction. Low FSI values are associated with the grain growth, intermediate values with DRX, and high values with the work-hardening and flow localisation phenomena. FSI also quantitatively indexes the average grain size and grain size distributions at different temperature-strain rate combinations. Analysis of the specific deformation conditions, particularly where 3.4 < FSI < 3.5, indicates a common thermo-mechanical origin of flow localisation and DRX. The potential technological implications thereof are discussed and a semi-empirical model of microstructural evolution is developed for the studied material.

  13. IASCC susceptibility of austenitic stainless steels and alloy 690 in high dissolved oxygen water environment

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Chopra, O.K.; Soppet, W.K. [Argonne National Lab., Nuclear Engineering Div., Argonne, Illinois (United States); Dietz Rago, N.L. [Argonne National Lab., Chemical Engineering Div., Argonne, Illinois (United States); Shack, W.J. [Argonne National Lab., Nuclear Engineering Div., Argonne, Illinois (United States)

    2007-07-01

    The influences of grain boundary engineering, alloying elements, and neutron dose on irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels and Alloy 690 were investigated. Flat dog-bone specimens irradiated in the Halden boiling heavy water reactor to {approx}2 dpa were tested in slow strain rate tensile tests in high dissolved oxygen water at 289 {sup o}C. The area fractions of intergranular or transgranular fracture were measured using a scanning electron microscope. All tested materials showed significant hardening and loss of ductility after irradiation. The area fractions of the intergranular cracking decreased with increase of uniform elongation, and were used to rank IASCC susceptibility. The grain boundary engineering treatment employed in this study does not have a significant impact on IASCC susceptibility for austenitic SSs at {approx}2 dpa, but does affect the cracking behavior of Alloy 690. High-sulfur and low-carbon SSs are more susceptible to IASCC. Oxygen content also contributes to the IASCC susceptibility in high-purity Type 304L SS. (author)

  14. The role of dislocation channeling in IASCC initiation of neutron irradiated austenitic stainless steel

    Science.gov (United States)

    Stephenson, Kale Jennings

    The objective of this study was to understand the role of dislocation channeling in the initiation of irradiation-assisted stress corrosion cracking (IASCC) of neutron irradiated austenitic stainless steel using a novel four-point bend test. Stainless steels used in this study were irradiated in the BOR-60 fast reactor at 320 °C, and included a commercial purity 304L stainless steel irradiated to 5.5, 10.2, and 47.5 dpa, and two high purity stainless steels, Fe-18Cr-12Ni and Fe-18Cr-25Ni, irradiated to ~10 dpa. The four-point bend test produced the same relative IASCC susceptibility as constant extension rate tensile (CERT) experiments performed on the same irradiated alloys in boiling water reactor normal water chemistry. The cracking susceptibility of the CP 304L alloy was high at all irradiation dose levels, enhanced by the presence of MnS inclusions in the alloy microstructure, which dissolve in the NWC environment. Dissolution of the MnS inclusion results in formation of an oxide cap that occludes the inclusion site, creating a crevice condition with a high propensity for crack initiation. Crack initiation at these locations was induced by stress concentration at the intersecting grain boundary, resulting from the intersection of a discontinuous dislocation channels (DC). Stress to initiate an IASCC crack decreased with dose due earlier DC initiation. The HP Fe-18Cr-12Ni alloy had low susceptibility to IASCC, while the high Ni alloy exhibited no cracking susceptibility. The difference in susceptibility among these conditions was attributed to the propensity for DCs to transmit across grain boundaries, which controls stress accumulation at DC -- grain boundary intersections.

  15. Stainless steel submerged arc weld fusion line toughness

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfield, A.R.; Held, P.R.; Wilkowski, G.M. [Battelle, Columbus, OH (United States)

    1995-04-01

    This effort evaluated the fracture toughness of austenitic steel submerged-arc weld (SAW) fusion lines. The incentive was to explain why cracks grow into the fusion line in many pipe tests conducted with cracks initially centered in SAWS. The concern was that the fusion line may have a lower toughness than the SAW. It was found that the fusion line, Ji. was greater than the SAW toughness but much less than the base metal. Of greater importance may be that the crack growth resistance (JD-R) of the fusion line appeared to reach a steady-state value, while the SAW had a continually increasing JD-R curve. This explains why the cracks eventually turn to the fusion line in the pipe experiments. A method of incorporating these results would be to use the weld metal J-R curve up to the fusion-line steady-state J value. These results may be more important to LBB analyses than the ASME flaw evaluation procedures, since there is more crack growth with through-wall cracks in LBB analyses than for surface cracks in pipe flaw evaluations.

  16. Hybrid/Tandem Laser-Arc Welding of Thick Low Carbon Martensitic Stainless Steel Plates =

    Science.gov (United States)

    Mirakhorli, Fatemeh

    High efficiency and long-term life of hydraulic turbines and their assemblies are of utmost importance for the hydropower industry. Usually, hydroelectric turbine components are made of thick-walled low carbon martensitic stainless steels. The assembly of large hydroelectric turbine components has been a great challenge. The use of conventional welding processes involves typical large groove design and multi-pass welding to fill the groove which exposes the weld to a high heat input creating relatively large fusion zone and heat affected zone. The newly-developed hybrid/tandem laser-arc welding technique is believed to offer a highly competitive solution to improve the overall hydro-turbine performance by combining the high energy density and fast welding speed of the laser welding technology with the good gap bridging and feeding ability of the gas metal arc welding process to increase the productivity and reduce the consumable material. The main objective of this research work is to understand different challenges appearing during hybrid laser-arc welding (HLAW) of thick gauge assemblies of low carbon 13%Cr- 4%Ni martensitic stainless steel and find a practical solution by adapting and optimizing this relatively new welding process in order to reduce the number of welding passes necessary to fill the groove gap. The joint integrity was evaluated in terms of microstructure, defects and mechanical properties in both as-welded and post-welded conditions. A special focus was given to the hybrid and tandem laser-arc welding technique for the root pass. Based on the thickness of the low carbon martensitic stainless steel plates, this work is mainly focused on the following two tasks: • Single pass hybrid laser-arc welding of 10-mm thick low carbon martensitic stainless steel. • Multi-pass hybrid/tandem laser-arc welding of 25-mm thick martensitic stainless steel.

  17. Evolution of microstructures and mechanical properties during dissimilar electron beam welding of titanium alloy to stainless steel via copper interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Tomashchuk, I., E-mail: iryna.tomashchuk@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 12 rue de la Fonderie, F-71200 Le Creusot (France); Sallamand, P. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 12 rue de la Fonderie, F-71200 Le Creusot (France); Belyavina, N. [Department of Physics, Taras Shevchenko University, 2, Glushkov Avenue, 03022 Kiev (Ukraine); Pilloz, M. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 12 rue de la Fonderie, F-71200 Le Creusot (France)

    2013-11-15

    The influence of operational parameters on the local phase composition and mechanical stability of the electron beam welds between titanium alloy and AISI 316L austenitic stainless steel with a copper foil as an intermediate layer has been studied. It was shown that two types of weld morphologies could be obtained depending on beam offset from the center line. Beam shift toward the titanium alloy side results in formation of a large amount of the brittle TiFe{sub 2} phase, which is located at the steel/melted zone interface and leads to reducing the mechanical resistance of the weld. Beam shift toward the steel side inhibits the melting of titanium alloy and, so, the formation of brittle intermetallics at the titanium alloy/melted zone interface. Mechanical stability of the obtained junctions was shown to depend on the thickness of this intermetallic layer. The fracture zone of the weld was found to be a mixture of TiCu (3–42 wt%), TiCu{sub 1−x}Fe{sub x} (x=0.72–0.84) (22–68 wt%) and TiCu{sub 1−x}Fe{sub x} (x=0.09–0.034) (0–22 wt%). In order to achieve the maximal ultimate tensile strength (350 MPa), the diffusion path length of Ti in the melted zone should be equal to 40–80 µm.

  18. The application of neutron diffraction to a study of phases in type 316 stainless steel weld metals

    Science.gov (United States)

    Slattery, G. F.; Windsor, C. G.

    1983-10-01

    Neutron diffraction techniques have been utilised to study the phases in type 316 austenitic stainless steel weld metal, both in the as-welded condition and after stress-relieving and ageing heat-treatments. The amounts of the principal crystallographic phases present in bulk specimens have been measured. Two compositions of weld metal were selected to provide a "low" (6%) and "high" (16%) initial ferrite level and the subsequent volume fractions of transformation products were measured after heat-treatment. Some retained ferrite was observed in all the heat-treated specimens, ranging from 4% for specimens of both initial ferrite levels treated at 625°C for 1000 h, to around 1% for the specimens treated at 850°C for 6 h. The high initial ferrite specimen produced 0.9% of sigma phase after the 850°C treatment and 0.2% sigma after the 625°C treatment. The low initial ferrite specimen produced 1.5% M 23C 6 carbide after both heat-treatments. The results compare well with previous findings on similar samples of weld metal using optical and electron microscopy.

  19. Welding of stainless and nickel based materials in the chemical industry. Consumables and procedures. Soldadura de aceros inoxidables y de materiales de base niquel en la industria quimica. Consumibles y procedimientos

    Energy Technology Data Exchange (ETDEWEB)

    Stromberg, J.; Budgifvars, S. (The ESA Grouo, Geoteborg (Sweden))

    1994-01-01

    In the chemical and petrochemical process industry a large range of various stainless and nickel based materials are used to meet high demands on corrosion resistance for optimum service performance. These materials include standard stainless steels, duplex and super duplex steels, super austenitic steels and nickel based alloys. Many components are being welded in the construction stage or may later on have to be repaired by welding. The design of components also often calls for joining or cladding of dissimilar materials to optimize the use of the material properties and for economical reasons to reduce the amount of expensive materials. Consumables and procedures have been developed to give weld metals to match the corrosion and strength requirements of the materials. There is a wide selection of MM electrodes with different coatings available and new types of stainless flux cored wires are being introduced. Especially for cladding of large surfaces the submerged arc strip cladding process offer high productivity solutions. (Author) 6 ref.

  20. Influence of electrical Field on Pulsed Laser beam welding of Stainless Steel (304)

    OpenAIRE

    FAWZİ, Salah A. H.; ARİF, RAZ N.

    1999-01-01

    Pulsed laser beam welding experiment were carried out on stainless steel (SUS 304), using vertical and horizontal electric fields of different intensities to study its effectiveness on the welding process, regarding depth and weld quality. Pulsed Nd: YAG laser emitting 10 ms pulses in the TEM00 mode at 1.06 m m wave length was employed, microstructure of welded zone and defect were investigated using optical and scanning electron microscopes. Tensile test and microhardness measuremen...

  1. Conduction mechanism in passive films on austenitic stainless steels in sulphate solutions

    Directory of Open Access Journals (Sweden)

    Iva Betova

    2015-08-01

    Full Text Available The passive state of three commercial highly alloyed austenitic stainless steels is studied by voltammetric, contact electric resistance and impedance measurements in 0.5 M sulphate solutions (pH 2-7. The three materials self-passivate and are susceptible to transpassive dissolution. The electric properties of the passive films formed are only slightly dependent on alloy composition. The impedance response can be interpreted as due to both the electronic properties of a thin semiconductor film of variable stoichiometry and the ionic defect migration through that film limiting the metal dissolution rate in the passive state. A range of kinetic, transport and structural parameters characterising the passive film and its interfaces with the underlying alloys and the electrolyte solution are determined by a quantitative comparison of the Mixed-Conduction Model to the experimental steady-state current and impedance data in a wide potential range. The relevance of the parameter values and the prospects of using the proposed approach to predict the steady-state metal dissolution rate and thus the general corrosion behaviour of stainless steels are discussed.

  2. Partial transient liquid phase diffusion bonding of Zircaloy-4 to stabilized austenitic stainless steel 321

    Energy Technology Data Exchange (ETDEWEB)

    Atabaki, M. Mazar, E-mail: m.mazaratabaki@gmail.com [Department of Materials Engineering, Faculty of Mechanical Engineering, University Technology Malaysia, 81310 (Malaysia); Hanzaei, A. Talebi [Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Tehran (Iran, Islamic Republic of)

    2010-10-15

    An innovative method was applied for bonding Zircaloy-4 to stabilized austenitic stainless steel 321 using an active titanium interlayer. Specimens were joined by a partial transient liquid phase diffusion bonding method in a vacuum furnace at different temperatures under 1 MPa dynamic pressure of contact. The influence of different bonding temperatures on the microstructure, microindentation hardness, joint strength and interlayer thickness has been studied. The diffusion of Fe, Cr, Ni and Zr has been investigated by scanning electron microscopy and energy dispersive spectroscopy elemental analyses. Results showed that control of the heating and cooling rate and 20 min soaking at 1223 K produces a perfect joint. However, solid-state diffusion of the melting point depressant elements into the joint metal causes the solid/liquid interface to advance until the joint is solidified. The tensile strength of all the bonded specimens was found around 480-670 MPa. Energy dispersive spectroscopy studies indicated that the melting occurred along the interface of the bonded specimens as a result of the transfer of atoms between the interlayer and the matrix during bonding. This technique provides a reliable method of bonding zirconium alloy to stainless steel.

  3. Recent Developments in Niobium Containing Austenitic Stainless Steels for Thermal Power Plants

    Science.gov (United States)

    de Oliveira, Mariana Perez; Zhang, Wei; Yu, Hongyao; Bao, Hansheng; Xie, Xishan

    The challenge of growing continuously in a sustainable way is the main driver to improve efficiency in the use of natural resources. The increasing demand for energy has made thermal power based countries to set audacious programs to increase efficiency of thermal power generation. In China, coal-burning accounts nowadays for approximately 65% of the total primary energy supply being responsible for around 25% of the countries' CO2 emission, this coal-based energy supply scenario is believed to continue until 2020. Therefore, the country has invested strongly in the last years in the construction of more efficient power plants. To attend higher operating temperatures and steam pressures, the application of higher performance materials is mandatory, presenting improved mechanical resistance — to stand the higher pressures applied — and having sufficient high temperature and corrosion resistance with the best cost-benefit relation possible. The present work addresses some research developments made in niobium containing austenitic stainless steels for super heaters and re-heater tubes in the past years as a joint effort between industry and academia to understand mechanisms and optimize the steel chemical composition, improving its performance. Niobium role has been studied in detail in heat resistant stainless steels TP347H, Super 304 and HR3C, a summary of such studies is presented in this paper. Niobium improves high temperature properties as it precipitates as nano-size MX and NbCrN, well dispersed in the matrix, hindering dislocation movement, increasing precipitation strengthening and creep resistance.

  4. Estimation of the kinetics of martensitic transformation in austenitic stainless steels by conventional and novel approaches

    Energy Technology Data Exchange (ETDEWEB)

    Shirdel, M., E-mail: mshirdel1989@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Mirzadeh, H., E-mail: hmirzadeh@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Parsa, M.H., E-mail: mhparsa@ut.ac.ir [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of); Center of Excellence for High Performance Materials, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Advanced Metalforming and Thermomechanical Processing Laboratory, School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-01-29

    A comparative study was carried out on the kinetics of the martensitic transformation in a 304L stainless steel during cold rolling by conventional and novel approaches. The phase analysis based on X-ray diffraction patterns and metallography and also magnetic measurements based on ferritescope readings were utilized to elucidate the kinetics of the martensitic transformation. A straightforward magnetic measurement approach for evaluating the amount of strain-induced martensite in metastable austenitic stainless steels has been introduced in this study. This technique collects the data throughout the bulk of the material to give a realistic estimate of the amount of ferromagnetic martensite. This is an advantage over the surface collecting methods such as ferritescope readings, which overestimates the amount of martensite due to its inhomogeneous distribution through the thickness based on the frictional effects between the rolls and the specimen surface. The proposed approach can be applied in various designs for static/continuous magnetic measurement of bulk materials that is advantageous compared with the conventional vibrating sample magnetometer technique which is useful for static measurement of bulk materials with specific shapes. Moreover, in analogy to ferritescope, the output data of the developed device is directly related to the amount of martensite.

  5. Study of ultrasonic characterization and propagation in austenitic welds: The MOSAICS project

    Science.gov (United States)

    Chassignole, Bertrand; Recolin, Patrick; Leymarie, Nicolas; Gueudré, Cécile; Guy, Philippe; Elbaz, Deborah

    2015-03-01

    Regulatory requirements enforce a volumetric inspection of welded components of nuclear equipments. However, the multi-pass austenitic welds are characterized by anisotropic and heterogeneous structures which lead to numerous disturbances of the ultrasonic beam. The MOSAICS project supported by the ANR (French National Research Agency) aims at matching various approaches to improve the prediction of the ultrasonic testing in those welds. The first stage consists in characterizing the weld structure (determination of the columnar grain orientation and measurements of elastic constants and attenuation coefficients). The techniques of characterization provide input data for the modeling codes developed in another task of the project. For example, a 3D version of the finite elements code ATHENA is developed by EDF R&D to take into account anisotropic texture in any direction. Semi-analytical models included in CIVA software are also improved to better predict the ultrasonic propagation in highly anisotropic and heterogeneous structures. The last stage deals with modeling codes validation based on experimental inspections on representative mock-ups containing calibrated defects. The objective of this paper is to give an overview of the MOSAICS project and to present specific results illustrating the various tasks.

  6. The Prediction of Long-Term Thermal Aging in Cast Austenitic Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Byun, Thak Sang; Yang, Ying; Lach, Timothy G.

    2017-02-15

    Cast austenitic stainless steel (CASS) materials are extensively used for many massive primary coolant system components of light water reactors (LWRs) including coolant piping, valve bodies, pump casings, and piping elbows. Many of these components are operated in complex and persistently damaging environments of elevated temperature, high pressure, corrosive environment, and sometimes radiation for long periods of time. Since a large number of CASS components are installed in every nuclear power plant and replacing such massive components is prohibitively expensive, any significant degradation in mechanical properties that affects structural integrity, cracking resistance in particular, of CASS components will raise a serious concern on the performance of entire power plant. The CASS materials for nuclear components are highly corrosion-resistant Fe-Cr-Ni alloys with 300 series stainless steel compositions and mostly austenite (γ)–ferrite (δ) duplex structures, which result from the casting processes consisting of alloy melting and pouring or injecting liquid metal into a static or spinning mold. Although the commonly used static and centrifugal casting processes enable the fabrication of massive components with proper resistance to environmental attacks, the alloying and microstructural conditions are not highly controllable in actual fabrication, especially in the casting processes of massive components. In the corrosion-resistant Fe-Cr-Ni alloy system, the minor phase (i.e., the δ-ferrite phase) is inevitably formed during the casting process, and is in a non-equilibrium state subject to detrimental changes during exposure to elevated temperature and/or radiation. In general, relatively few critical degradation modes are expected within the current design lifetime of 40 years, given that the CASS components have been processed properly. It has been well known, however, that both the thermal aging and the neutron irradiation can cause degradation of static

  7. Influence of electrical Field on Pulsed Laser beam welding of Stainless Steel (304)

    Science.gov (United States)

    Fawzý, Salah A. H.; Arýf, Raz N.

    1999-06-01

    Pulsed laser beam welding experiment were carried out on stainless steel (SUS 304), using vertical and horizontal electric fields of different intensities to study its effectiveness on the welding process, regarding depth and weld quality. Pulsed Nd: YAG laser emitting 10 ms pulses in the TEM00 mode at 1.06 m m wave length was employed, microstructure of welded zone and defect were investigated using optical and scanning electron microscopes. Tensile test and microhardness measurements were carried out to evaluate the weld quality. Welding by this method increased the efficiency tremendously and a depth increase of 85% was achieved.

  8. On the Carbon Solubility in Expanded Austenite and Formation of Hägg Carbide in AISI 316 Stainless Steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Ståhl, Kenny; Brink, Bastian

    2016-01-01

    –420 °C and 465–470 °C, respectively. Hägg carbide (x-M5C2)develops when the carbon content in the expanded austenite exceeds the metastable solubility limit; the transformation of carbon expanded austenite into Hägg carbide occurs irrespective of carburizing temperature in the investigated temperature......The carbon solubility in expanded austenite is investigated by controlled low temperaturegaseous through-carburizing of AISI 316 stainless steel thin foils with thermogravimetry and synchrotron powder diffraction analysis. Carburizing is carried out in C2H2–H2–N2 and CO–H2–N2 atmospheres at 380...

  9. Effect of heat treatment on an AISI 304 austenitic stainless steel evaluated by the ultrasonic attenuation coefficient

    Energy Technology Data Exchange (ETDEWEB)

    Moghanizadeh, Abbas; Farzi, Abolfazl [Islamic Azad Univ., Esfarayen (Iran, Islamic Republic of). Dept. of Civil Engineering

    2016-07-01

    The properties of metals can be substantially changed by various methods, one of them is using heat treatment processes. Moreover, ultrasonic testing is the most preferred and effective, nondestructive testing technique for characterization of mechanical material properties. Austenitic stainless steel AISI 304 serves in many applications due to high strength and corrosion resistance. In certain applications, it is important to evaluate the mechanical properties of AISI 304 stainless steel. In this study, the ultrasonic method (attenuation measurement technique) is used to evaluate the hardness of AISI 304 stainless steel samples which were heat treated at different levels. Due to the heat treatment process, each sample has its specific microstructure and hardness which attenuate ultrasonic waves appropriately. The ultrasonic and hardness test show that it is possible to evaluate the hardness of AISI 304 stainless steel by ultrasonic attenuation coefficient. In addition, the relationship between ultrasonic attenuation coefficients and time of heat treatment is investigated.

  10. Microbial corrosion in weld zone of stainless steel. Stainless ko yosetsubu no biseibutsu fushoku

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, E. (National Chemical Laboratory for Industry, Tsukuba (Japan)); Nishimura, M. (Mitsubishi Kakoki Kaisha, Ltd., Tokyo (Japan))

    1992-10-15

    Microbial corrosion may happen wherever water is treated in many kinds of practical metal except titan, such as common steel, copper alloy, stainless steel, and high-nickel alloy. Although microbes causing microbial corrosion are not limited to specified microbes, specially affecting microbes are iron bacteria, iron-oxidizing bacteria, and sulfate-reducing bacteria. mechanism in these microbial corrosion, which is fundamentally caused through formation of oxygen concentration cells and production of metabolites, is complex and different by each microbe. In the case of stainless steel, the corrosion is located mainly in weld zones or heat affected zones, the shape of corrosion is like a pot, and the pattern is a type of pitting corrosion. Microbes are apt to adhere to the surface near weld zones, then oxygen becomes consequently insufficient beneath the surface, where the self-mending capacity of passive films is deprived, resulting in occurrence of pitting corrosion. For protection of microbial corrosion, it is essential to control water so that habitation of microbes is not formed. 9 refs., 3 figs.

  11. submitter Physical Properties of a High-Strength Austenitic Stainless Steel for the Precompression Structure of the ITER Central Solenoid

    CERN Document Server

    Sgobba, Stefano; Arauzo, Ana; Roussel, Pascal; Libeyre, Paul

    2016-01-01

    The ITER central solenoid (CS) consists of six independent coils kept together by a precompression support structure that must react vertical tensile loads and provide sufficient preload to maintain coil-to-coil contact when the solenoid is energized. The CS precompression system includes tie plates, lower and upper key blocks, load distribution and isolation plates and other attachment, support and insulating hardware. The tie plates operating at 4 K are manufactured starting from forgings in a high-strength austenitic stainless steel (FXM-19) with a stringent specification. Moreover, forged components for the lower and upper key blocks have to be provided in the same FXM-19 grade with comparably strict requirements. FXM-19 is a high-nitrogen austenitic stainless steel, featuring high strength and toughness, ready weldability, and forgeability. It features as well higher integral thermal contraction down to 4 K compared with the very high Mn steel grade selected for the CS coil jackets, hence providing an ad...

  12. The influence of fire exposure on austenitic stainless steel for pressure vessel fitness-for-service assessment: Experimental research

    Science.gov (United States)

    Li, Bo; Shu, Wenhua; Zuo, Yantian

    2017-04-01

    The austenitic stainless steels are widely applied to pressure vessel manufacturing. The fire accident risk exists in almost all the industrial chemical plants. It is necessary to make safety evaluation on the chemical equipment including pressure vessels after fire. Therefore, the present research was conducted on the influences of fire exposure testing under different thermal conditions on the mechanical performance evolution of S30408 austenitic stainless steel for pressure vessel equipment. The metallurgical analysis described typical appearances in micro-structure observed in the material suffered by fire exposure. Moreover, the quantitative degradation of mechanical properties was investigated. The material thermal degradation mechanism and fitness-for-service assessment process of fire damage were further discussed.

  13. Crack growth behavior of warm-rolled 316L austenitic stainless steel in high-temperature hydrogenated water

    Science.gov (United States)

    Choi, Kyoung Joon; Yoo, Seung Chang; Jin, Hyung-Ha; Kwon, Junhyun; Choi, Min-Jae; Hwang, Seong Sik; Kim, Ji Hyun

    2016-08-01

    To investigate the effects of warm rolling on the crack growth of 316L austenitic stainless steel, the crack growth rate was measured and the oxide structure was characterized in high-temperature hydrogenated water. The warm-rolled specimens showed a higher crack growth rate compared to the as-received specimens because the slip bands and dislocations produced during warm rolling served as paths for corrosion and cracking. The crack growth rate increased with the dissolved hydrogen concentration. This may be attributed to the decrease in performance and stability of the protective oxide layer formed on the surface of stainless steel in high-temperature water.

  14. Microstructure and mechanical properties of 2024-T3 and 7075-T6 aluminum alloys and austenitic stainless steel 304 after being exposed to hydrogen peroxide

    Science.gov (United States)

    Sofyan, Nofrijon Bin Imam

    The effect of hydrogen peroxide used as a decontaminant agent on selected aircraft metallic materials has been investigated. The work is divided into three sections; bacterial attachment behavior onto an austenitic stainless steel 304 surface; effect of decontamination process on the microstructure and mechanical properties of aircraft metallic structural materials of two aluminum alloys, i.e. 2024-T3 and 7075-T6, and an austenitic stainless steel 304 as used in galley and lavatory surfaces; and copper dissolution rate into hydrogen peroxide. With respect to bacterial attachment, the results show that surface roughness plays a role in the attachment of bacteria onto metallic surfaces at certain extent. However, when the contact angle of the liquid on a surface increased to a certain degree, detachment of bacteria on that surface became more difficult. In its relation to the decontamination process, the results show that a corrosion site, especially on the austenitic stainless steel 304 weld and its surrounding HAZ area, needs more attention because it could become a source or a harborage of bio-contaminant agent after either incidental or intentional bio-contaminant delivery. On the effect of the decontamination process on the microstructure and mechanical properties of aircraft metallic structural materials, the results show that microstructural effects are both relatively small in magnitude and confined to a region immediately adjacent to the exposed surface. No systematic effect is found on the tensile properties of the three alloys under the conditions examined. The results of this investigation are promising with respect to the application of vapor phase hydrogen peroxide as a decontaminant agent to civilian aircraft, in that even under the most severe circumstances that could occur; only very limited damage was observed. The results from the dissolution of copper by concentrated liquid hydrogen peroxide showed that the rate of copper dissolution increased for

  15. Hydrogen-Induced Delayed Cracking in TRIP-Aided Lean-Alloyed Ferritic-Austenitic Stainless Steels.

    Science.gov (United States)

    Papula, Suvi; Sarikka, Teemu; Anttila, Severi; Talonen, Juho; Virkkunen, Iikka; Hänninen, Hannu

    2017-06-03

    Susceptibility of three lean-alloyed ferritic-austenitic stainless steels to hydrogen-induced delayed cracking was examined, concentrating on internal hydrogen contained in the materials after production operations. The aim was to study the role of strain-induced austenite to martensite transformation in the delayed cracking susceptibility. According to the conducted deep drawing tests and constant load tensile testing, the studied materials seem not to be particularly susceptible to delayed cracking. Delayed cracks were only occasionally initiated in two of the materials at high local stress levels. However, if a delayed crack initiated in a highly stressed location, strain-induced martensite transformation decreased the crack arrest tendency of the austenite phase in a duplex microstructure. According to electron microscopy examination and electron backscattering diffraction analysis, the fracture mode was predominantly cleavage, and cracks propagated along the body-centered cubic (BCC) phases ferrite and α'-martensite. The BCC crystal structure enables fast diffusion of hydrogen to the crack tip area. No delayed cracking was observed in the stainless steel that had high austenite stability. Thus, it can be concluded that the presence of α'-martensite increases the hydrogen-induced cracking susceptibility.

  16. Hydrogen-Induced Delayed Cracking in TRIP-Aided Lean-Alloyed Ferritic-Austenitic Stainless Steels

    Directory of Open Access Journals (Sweden)

    Suvi Papula

    2017-06-01

    Full Text Available Susceptibility of three lean-alloyed ferritic-austenitic stainless steels to hydrogen-induced delayed cracking was examined, concentrating on internal hydrogen contained in the materials after production operations. The aim was to study the role of strain-induced austenite to martensite transformation in the delayed cracking susceptibility. According to the conducted deep drawing tests and constant load tensile testing, the studied materials seem not to be particularly susceptible to delayed cracking. Delayed cracks were only occasionally initiated in two of the materials at high local stress levels. However, if a delayed crack initiated in a highly stressed location, strain-induced martensite transformation decreased the crack arrest tendency of the austenite phase in a duplex microstructure. According to electron microscopy examination and electron backscattering diffraction analysis, the fracture mode was predominantly cleavage, and cracks propagated along the body-centered cubic (BCC phases ferrite and α’-martensite. The BCC crystal structure enables fast diffusion of hydrogen to the crack tip area. No delayed cracking was observed in the stainless steel that had high austenite stability. Thus, it can be concluded that the presence of α’-martensite increases the hydrogen-induced cracking susceptibility.

  17. Effect of strain rate and temperature on the susceptibility of 304 austenitic stainless steel to hydrogen embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    El Shawesh, F. [Petroleum Research Center, Tripoli (Libyan Arab Jamahiriya)

    1998-12-31

    Cathodic charging of notched 304 austenitic stainless steel specimens was carried out in aqueous solution of 1N H{sub 2}SO{sub 4}, containing 250 mg/l NaAsO{sub 2}, at room temperature and 70 {+-} 2 C while undergoing tensile straining over a wide range of crosshead speed (833 {micro}m/s, 83 {micro}m/s, 8.3 {micro}m/s, 833 nm/s, 83 nm/s and 9.8 nm/s). Test at room temperature 22 {+-} 2 C resulted in a marked reduction in the elongation to fracture ratio (Esol/Eair) by reducing the crosshead speed. However, little reduction was observed in the stress to fracture ratio ({sigma}sol/{sigma}air). Quasi cleavage and intergranular fractures where the predominant failure modes when tests were carried out at low crosshead speeds, The extent of these modes of fracture was observed to increase by reducing the crosshead speed. Cathodic charging of 304 austenitic stainless steel at 70 {+-} 2 C caused less reduction in the elongation to fracture ratio compared to the tests carried out at room temperature. Consistent with the room temperature test results, the reduction in the elongation to fracture ratio was found to increase with reduced crosshead speed. However, restoration in the elongation to fracture ratio was exhibited by 304 austenitic stainless steel specimens tested at the lowest crosshead speed (9.8 nm/s). These results are in good agreement with the finding that hydrogen embrittlement is temperature and strain dependent. Quasi cleavage fracture associated with the plastic deformation was the predominant failure mode exhibited by 304 austenitic stainless steel specimens tested at 70 {+-} 2 C at low crosshead speeds.

  18. 75 FR 76025 - Stainless Steel Butt-Weld Pipe Fittings From Japan, Korea, and Taiwan

    Science.gov (United States)

    2010-12-07

    ... stainless steel butt-weld pipe fittings from Japan, Korea, and Taiwan would be likely to lead to... can be obtained by contacting the Commission's TDD terminal on 202-205-1810. Persons with mobility...

  19. 78 FR 62583 - Welded Stainless Pressure Pipe From Malaysia, Thailand, and the Socialist Republic of Vietnam...

    Science.gov (United States)

    2013-10-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Welded Stainless Pressure Pipe From Malaysia, Thailand, and the Socialist...: Import Administration, International Trade Administration, Department of Commerce. DATES: October 22...

  20. An evaluation of creep rupture strength of ferritic/austenitic dissimilar weld interfaces using cohesive zone modelling

    OpenAIRE

    Hu, Jia-nan; Fukahori, Takuya; Igari, Toshihide; Chuman, Yasuharu; Cocks, Alan C.F.

    2016-01-01

    Dissimilar metal welds between ferritic and austenitic alloys are used extensively in power generation plants. Failure of such welds can occur in the base metal, the heat-affected zone (HAZ), or the interface between the two materials, depending on the operating stress and temperature. Evaluation of the creep rupture properties of dissimilar weld joints of 2.25Cr-1Mo (P22) and 9Cr-1MoVNb (P91) ferritic steels with INCONEL 82 filler metal are described, with the primary focus on failure at the...

  1. Ultrasonic Phased Array Evaluations Of Implanted And In-Situ Grown Flaws In Cast Austenitic Stainless Steel Pressurizer Surge Line Piping

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Susan L.; Cinson, Anthony D.; Moran, Traci L.; Prowant, Matthew S.; Diaz, Aaron A.; Anderson, Michael T.

    2011-07-31

    A set of circumferentially oriented thermal fatigue cracks (TFCs) were implanted into three cast austenitic stainless steel (CASS) pressurizer (PZR) surge-line specimen welds (pipe-to-elbow configuration) that were salvaged from a U.S. commercial nuclear power plant that had not been operated. Thus, these welds were fabricated using vintage CASS materials that were formed in the 1970s. Additionally, in-situ grown TFCs were placed in the adjacent CASS base material of one of these specimens. Ultrasonic phased-array responses from both types of flaws (implanted and in-situ grown) were analyzed for detection and characterization based on sizing and signal-to-noise determination. Multiple probes were employed covering the 0.8 to 2.0 MHz frequency range. To further validate the Pacific Northwest National Laboratory (PNNL) findings, an independent in-service inspection (ISI) supplier evaluated the flaws with their American Society of Mechanical Engineers (ASME) Code, Section XI, Appendix VIII-qualified procedure. The results obtained by PNNL personnel compared favorably to the ISI supplier results. All examined flaws were detected and sized within the ASME Code-allowable limits.

  2. Adhesion of Salmonella Enteritidis and Listeria monocytogenes on stainless steel welds.

    Science.gov (United States)

    Casarin, Letícia Sopeña; Brandelli, Adriano; de Oliveira Casarin, Fabrício; Soave, Paulo Azevedo; Wanke, Cesar Henrique; Tondo, Eduardo Cesar

    2014-11-17

    Pathogenic microorganisms are able to adhere on equipment surfaces, being possible to contaminate food during processing. Salmonella spp. and Listeria monocytogenes are important pathogens that can be transmitted by food, causing severe foodborne diseases. Most surfaces of food processing industry are made of stainless steel joined by welds. However currently, there are few studies evaluating the influence of welds in the microorganism's adhesion. Therefore the purpose of the present study was to investigate the adhesion of Salmonella Enteritidis and L. monocytogenes on surface of metal inert gas (MIG), and tungsten inert gas (TIG) welding, as well as to evaluate the cell and surface hydrophobicities. Results demonstrated that both bacteria adhered to the surface of welds and stainless steel at same levels. Despite this, bacteria and surfaces demonstrated different levels of hydrophobicity/hydrophilicity, results indicated that there was no correlation between adhesion to welds and stainless steel and the hydrophobicity. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. On the Carbon Solubility in Expanded Austenite and Formation of Hägg Carbide in AISI 316 Stainless Steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Ståhl, Kenny; Brink, Bastian

    2016-01-01

    The carbon solubility in expanded austenite is investigated by controlled low temperaturegaseous through-carburizing of AISI 316 stainless steel thin foils with thermogravimetry and synchrotron powder diffraction analysis. Carburizing is carried out in C2H2–H2–N2 and CO–H2–N2 atmospheres at 380......–420 °C and 465–470 °C, respectively. Hägg carbide (x-M5C2)develops when the carbon content in the expanded austenite exceeds the metastable solubility limit; the transformation of carbon expanded austenite into Hägg carbide occurs irrespective of carburizing temperature in the investigated temperature...... range (380–470 °C). The maximum solubility of carbon in expanded austenite (380 °C) is found to correspond to an occupancy (yC) of 0.220 of the interstitial octahedral sites of the austenite lattice (i.e., 4.74wt%C). Decomposition of Hägg carbide into M7C3 occurs upon prolonged carburizing treatment...

  4. Investigation on cracking mechanism of austenite stainless steel during in situ tension in transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Peng; Hu Hongyan; Liu Yuanyuan [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Zhang Yue [College of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Fang, Yuan [Advanced Technology Institute, Technology Center of Baoshan Iron and Steel company, Shanghai 201900 (China); Ren Xuejun [School of Engineering, Liverpool John Moores University, Liverpool L3 3AF (United Kingdom); Liao Bo [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Yang Qingxiang, E-mail: qxyang@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

    2011-01-25

    Research highlights: {yields} During the initial stage of loading process, at the crack tip, the dislocations slip from center to around zone and the density of dislocation is increased at local zone. With the increase of load, around center, an oval-shaped dislocation free zone (DFZ) forms. When the displacement keeps constant, the dislocations continue moving. The DFZ become thinner and the nano-cracks initiate gradually, then, propagate abruptly along the direction vertical to the tensile force. {yields} The cracks may propagate in continuous propagation way. The micro-cracks initiate ahead of the main crack firstly, then propagate, grow and connect with the main crack finally, which results in that the main crack propagates too. The initiation direction of micro-crack has a certain angle with the tensile force direction. However, the direction of the main crack propagation is always along the direction vertical to the tensile force. {yields} The cracks may propagate in discontinuous way too. The dislocations pile up inversely in front of the crack tip. The propagation process of crack is that the crack tip is blunt at first. Then, with the increase of load, the new crack tip forms in the blunt crack firstly, then propagates and is blunt again. So back and forth, the cracks propagate forward continuously. - Abstract: Twin-roll strip casting technology is a new one to produce austenite stainless steel strip directly. However, during this process, the cracking occurs usually on the surface of the steel strip. The technique of in situ tension in transmission electron microscope was used to observe and analyze the crack initiation and propagation in austenite stainless steel produced by twin-roll strip casting technology in this work. The results show that the crack initiates in dislocation free-zone firstly and then propagates along the direction vertical to the tensile force. The crack may propagate in continuous propagation way and discontinuous one respectively

  5. The numerical simulation of Lamb wave propagation in laser welding of stainless steel

    Science.gov (United States)

    Zhang, Bo; Liu, Fang; Liu, Chang; Li, Jingming; Zhang, Baojun; Zhou, Qingxiang; Han, Xiaohui; Zhao, Yang

    2017-12-01

    In order to explore the Lamb wave propagation in laser welding of stainless steel, the numerical simulation is used to show the feature of Lamb wave. In this paper, according to Lamb dispersion equation, excites the Lamb wave on the edge of thin stainless steel plate, and presents the reflection coefficient for quantizing the Lamb wave energy, the results show that the reflection coefficient is increased with the welding width increasing,

  6. In-situ kinetics study on the growth of expanded austenite in AISI 316L stainless steels by XRD

    Science.gov (United States)

    Balogh-Michels, Zoltán; Faeht, Alexander; Kleiner, Simon; von Känel, Adrian; Rufer, Jean-Martin; Dommann, Alex; Margraf, Patrick; Tschopp, Gerhard; Neels, Antonia

    2017-07-01

    The formation of expanded austenite in Cr-Ni austenitic stainless steels like AISI 316L is not completely understood despite its technological relevance. In this work, we present an in-situ X-ray diffraction study on the growth kinetics of the expanded austenite. We applied a low-temperature nitrocarburizing treatment using a mixture of NH3, N2, H2, and C2H4 gases at atmospheric pressures in a novel and custom built chamber attached to a Bruker D8 Advance diffractometer. The nitrocarburizing temperature was varied between 340 and 440 °C, and the possible effects of the gas amount were also tested. The thickness of the growing layer was determined from the shrinkage of the unmodified austenite peak. The growth rate coefficient was calculated using the linear-parabolic equation. The resulting coefficients follow the Arrhenius law with the activation energy of 165 ± 12 kJ/mol. This value is in good agreement with the diffusion activation energy for heavy interstitials like carbon and nitrogen. The expanded austenite peak was modelled by a multilayer approach, where each 0.5 μm sublayer has a constant lattice parameter. The lattice expansion is analyzed as a function of the Boltzmann-variable (η = 0.5 × t-1/2). The expanded austenite layer in this metric has a constant width. Furthermore by rescaling with the lattice expansion of the first sublayer, it is possible to create a scale-independent master curve. These findings indicate that thickening of the expanded austenite is purely diffusion controlled, while the extent of strain is set by the uptake rate of the gas atoms.

  7. Microstructure, Mechanical and Corrosion Properties of Friction Stir Welding High Nitrogen Martensitic Stainless Steel 30Cr15Mo1N

    Directory of Open Access Journals (Sweden)

    Xin Geng

    2016-11-01

    Full Text Available High nitrogen martensitic stainless steel 30Cr15Mo1N plates were successfully welded by friction stir welding (FSW at a tool rotation speed of 300 rpm with a welding speed of 100 mm/min, using W-Re tool. The sound joint with no significant nitrogen loss was successfully produced. Microstructure, mechanical and corrosion properties of an FSW joint were investigated. The results suggest that the grain size of the stir zone (SZ is larger than the base metal (BM and is much larger the case in SZ-top. Some carbides and nitrides rich in chromium were found in BM while not observed in SZ. The martensitic phase in SZ could transform to austenite phase during the FSW process and the higher peak temperature, the greater degree of transformation. The hardness of SZ is significantly lower than that of the BM. An abrupt change of hardness defined as hard zone (HZ was found in the thermo-mechanically affected zone (TMAZ on the advancing side (AS, and the HZ is attributed to a combination result of temperature, deformation, and material flow behavior. The corrosion resistance of SZ is superior to that of BM, which can be attributed to less precipitation and lower angle boundaries (LABs. The corrosion resistance of SZ-bottom is slight higher than that of SZ-top because of the finer grained structure.

  8. Qualification of electron-beam welded joints between copper and stainless steel for cryogenic application

    Science.gov (United States)

    Lusch, C.; Borsch, M.; Heidt, C.; Magginetti, N.; Sas, J.; Weiss, K.-P.; Grohmann, S.

    2015-12-01

    Joints between copper and stainless steel are commonly applied in cryogenic systems. A relatively new and increasingly important method to combine these materials is electron-beam (EB) welding. Typically, welds in cryogenic applications need to withstand a temperature range from 300K down to 4K, and pressures of several MPa. However, few data are available for classifying EB welds between OFHC copper and 316L stainless steel. A broad test program was conducted in order to qualify this kind of weld. The experiments started with the measurement of the hardness in the weld area. To verify the leak-tightness of the joints, integral helium leak tests at operating pressures of 16 MPa were carried out at room- and at liquid nitrogen temperature. The tests were followed by destructive tensile tests at room temperature, at liquid nitrogen and at liquid helium temperatures, yielding information on the yield strength and the ultimate tensile strength of the welds at these temperatures. Moreover, nondestructive tensile tests up to the yield strength, i.e. the range in which the weld can be stressed during operation, were performed. Also, the behavior of the weld upon temperature fluctuations between room- and liquid nitrogen temperature was tested. The results of the qualification indicate that EB welded joints between OFHC copper and 316L stainless steel are reliable and present an interesting alternative to other technologies such as vacuum brazing or friction welding.

  9. Evaluation of weld defects in stainless steel 316L pipe using guided wave

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joon Hyun [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of); Lee, Jin Kyung [Dept. of Mechanical Engineering, Dongeui University, Busan (Korea, Republic of)

    2015-02-15

    Stainless steel is a popular structural materials for liquid-hydrogen storage containers and piping components for transporting high-temperature fluids because of its superior material properties such as high strength and high corrosion resistance at elevated temperatures. In general, tungsten inert gas (TIG) arc welding is used for bonding stainless steel. However, it is often reported that the thermal fatigue cracks or initial defects in stainless steel after welding decreases the reliability of the material. The objective of this paper is to clarify the characteristics of ultrasonic guided wave propagation in relation to a change in the initial crack length in the welding zone of stainless steel. For this purpose, three specimens with different artificial defects of 5 mm, 10 mm, and 20 mm in stainless steel welds were prepared. By considering the thickness of s stainless steel pipe, special attention was given to both the L(0,1) mode and L(0,2) mode in this study. It was clearly found that the L(0,2) mode was more sensitive to defects than the L(0,1) mode. Based on the results of the L(0,1) and L(0,2) mode analyses, the magnitude ratio of the two modes was more effective than studying each mode when evaluating defects near the welded zone of stainless steel because of its linear relationship with the length of the artificial defect.

  10. A low-temperature study to examine the role of epsilon-martensite during strain-induced transformations in metastable austenitic stainless steels

    NARCIS (Netherlands)

    Datta, K.; Delhez, R.; Bronsveld, P. M.; Beyer, J.; Geijselaers, H. J. M.; Post, J.

    A low-temperature study of the mechanical behaviour of a metastable semi-austenitic stainless steel was carried out. This class of stainless steels is found to show a characteristic hump followed by softening in their stress-strain curves, especially at low temperatures, much like dynamically

  11. A low-temperature study to examine the role of epsilon-martensite during strain-induced transformations in metastable austenitic stainless steels

    NARCIS (Netherlands)

    Datta, K.; Delhez, R; Bronsveld, P.M.; Beyer, J.; Geijselaers, Hubertus J.M.; Post, J.

    2009-01-01

    A low-temperature study of the mechanical behaviour of a metastable semi-austenitic stainless steel was carried out. This class of stainless steels is found to show a characteristic hump followed by softening in their stress–strain curves, especially at low temperatures, much like dynamically

  12. Formation of Inclusions in Ti-Stabilized 17Cr Austenitic Stainless Steel

    Science.gov (United States)

    Yin, Xue; Sun, Yanhui; Yang, Yindong; Bai, Xuefeng; Barati, Mansoor; Mclean, Alex

    2016-12-01

    The behavior and formation mechanisms of inclusions in Ti-stabilized, 17Cr Austenitic Stainless Steel produced by the ingot casting route were investigated through systematic sampling of liquid steel and rolled products. Analysis methods included total oxygen and nitrogen contents, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicate that the composition of inclusions was strongly dependent on the types of added alloying agents. During the AOD refining process, after the addition of ferrosilicon alloy and electrolytic manganese, followed by aluminum, the composition of inclusions changed from manganese silicate-rich inclusions to alumina-rich inclusions. After tapping and titanium wire feeding, pure TiN particles and complex inclusions with Al2O3-MgO-TiO x cores containing TiN were found to be the dominant inclusions when [pct Ti] was 0.307 mass pct in the molten steel. These findings were confirmed by thermodynamic calculations which indicated that there was a driving force for TiN inclusions to be formed in the liquid phase due to the high contents of [Ti] and [N] in the molten steel. From the start of casting through to the rolled bar, there was no further change in the composition of inclusions compared to the titanium addition stage. Stringer-shaped TiN inclusions were observed in the rolled bar. These inclusions were elongated along the rolling direction with lengths varying from 17 to 84 µm and could have a detrimental impact on the corrosion resistance as well as the mechanical properties of the stainless steel products.

  13. Impact of the nanostructuration on the corrosion resistance and hardness of irradiated 316 austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Hug, E., E-mail: eric.hug@ensicaen.fr [Laboratoire de Cristallographie et Sciences des Matériaux, Normandie Université, CNRS UMR 6508, 6 Bd Maréchal Juin, 14050 Caen (France); Prasath Babu, R. [School of Materials, University of Manchester, M13 9PL (United Kingdom); Groupe de Physique des Matériaux, UMR CNRS 6634, Université et INSA de Rouen, Normandie Université, Saint-Etienne du Rouvray Cedex (France); Monnet, I. [Centre de recherches sur les Ions, les Matériaux et la Photonique CEA-CNRS, Normandie Université, 6 Bd Maréchal Juin, 14050 Caen (France); Etienne, A. [Groupe de Physique des Matériaux, UMR CNRS 6634, Université et INSA de Rouen, Normandie Université, Saint-Etienne du Rouvray Cedex (France); Moisy, F. [Centre de recherches sur les Ions, les Matériaux et la Photonique CEA-CNRS, Normandie Université, 6 Bd Maréchal Juin, 14050 Caen (France); Pralong, V. [Laboratoire de Cristallographie et Sciences des Matériaux, Normandie Université, CNRS UMR 6508, 6 Bd Maréchal Juin, 14050 Caen (France); Enikeev, N. [Institute of Physics of Advanced Materials, Ufa (Russian Federation); Saint Petersburg State University, Laboratory of the Mechanics of Bulk Nanostructured Materials, 198504 St. Petersburg (Russian Federation); Abramova, M. [Institute of Physics of Advanced Materials, Ufa (Russian Federation); and others

    2017-01-15

    Highlights: • Impacts of nanostructuration and irradiation on the properties of 316 stainless steels are reported. • Irradiation of nanostructured samples implies chromium depletion as than depicted in coarse grain specimens. • Hardness of nanocrystalline steels is only weakly affected by irradiation. • Corrosion resistance of the nanostructured and irradiated samples is less affected by the chromium depletion. - Abstract: The influence of grain size and irradiation defects on the mechanical behavior and the corrosion resistance of a 316 stainless steel have been investigated. Nanostructured samples were obtained by severe plastic deformation using high pressure torsion. Both coarse grain and nanostructured samples were irradiated with 10 MeV {sup 56}Fe{sup 5+} ions. Microstructures were characterized using transmission electron microscopy and atom probe tomography. Surface mechanical properties were evaluated thanks to hardness measurements and the corrosion resistance was studied in chloride environment. Nanostructuration by high pressure torsion followed by annealing leads to enrichment in chromium at grain boundaries. However, irradiation of nanostructured samples implies a chromium depletion of the same order than depicted in coarse grain specimens but without metallurgical damage like segregated dislocation loops or clusters. Potentiodynamic polarization tests highlight a definitive deterioration of the corrosion resistance of coarse grain steel with irradiation. Downsizing the grain to a few hundred of nanometers enhances the corrosion resistance of irradiated samples, despite the fact that the hardness of nanocrystalline austenitic steel is only weakly affected by irradiation. These new experimental results are discussed in the basis of couplings between mechanical and electrical properties of the passivated layer thanks to impedance spectroscopy measurements, hardness properties of the surfaces and local microstructure evolutions.

  14. THE INFLUENCE OF POSTHEAT TREATMENT ON FERRITE REDISTRIBUTION IN DUPLEX STEELS ELECTRON BEAM WELDS

    Directory of Open Access Journals (Sweden)

    Zita Iždinská

    2009-04-01

    Full Text Available The duplex stainless steel is two-phase steel with the structure composed of austenite and ferrite with optimum austenite/ferrite proportion 50%. At present, classical arc processes for welding duplex steels are generally regarded as acceptable. On the other hand electron and laser beam welding is up to now considered less suitable for welding duplex steels. The submitted work presents the results of testing various thermal conditions at welding duplex stainless steel with electron beam. It was shown, that application of suitable postheat made possible to reduce the ferrite content in weld metal.

  15. 49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

    Science.gov (United States)

    2010-10-01

    ... procedure. A heat of steel made under the specifications in table 1 in this paragraph (b), check chemical... abrupt change in wall thickness is permitted. Welding procedures and operators must be qualified in... 49 Transportation 2 2010-10-01 2010-10-01 false Specification 4DS welded stainless steel cylinders...

  16. Serrated Flow Behavior of Aisi 316l Austenitic Stainless Steel for Nuclear Reactors

    Science.gov (United States)

    Li, Qingshan; Shen, Yinzhong; Han, Pengcheng

    2017-10-01

    AISI 316L austenitic stainless steel is a candidate material for Generation IV reactors. In order to investigate the influence of temperature on serrated flow behavior, tensile tests were performed at temperatures ranging from 300 to 700 °C at an initial strain rate of 2×10-4 s-1. Another group of tensile tests were carried out at strain rates ranging from 1×10-4 to 1×10-2 s-1 at 600 °C to examine the influence of strain rates on serrated flow behavior. The steel exhibited serrated flow, suggesting the occurrence of dynamic strain ageing at 450-650°C. No plateau of yield stresses of the steel was observed at an initial strain rate of 2×10-4 s-1. The effective activation energy for serrated flow occurrence was calculated to be about 254.72 kJ/mol-1. Cr, Mn, Ni and Mo solute atoms are expected to be responsible for dynamic strain ageing at high temperatures of 450-650 °C in the steel.

  17. Microstructural evolution in austenitic stainless steel irradiated with triple-beam

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Shozo; Miwa, Yukio; Yamaki, Daiju [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Zhang Yichuan

    1997-03-01

    An austenitic stainless steel was simultaneously irradiated with nickel, helium and hydrogen ions at the temperature range of 573-673 K. The damage level and injected concentration of He and H ions in the triple-beam irradiated region are 57 dpa, 19000 and 18000 at.ppm, respectively. Following to irradiation, the cross sectional observation normal to the incident surface of the specimen was carried out with a transmission electron microscope. Two bands parallel to the incident surface were observed in the irradiated specimen, which consist of dislocation loops and lines of high number density. These locate in the range of the depth of 0.4 to 1.3 {mu}m and 1.8 to 2.4 {mu}m from the incident surface, respectively. The region between two bands, which corresponds to the triple beam irradiated region, shows very low number density of dislocations than that in each band. Observation with higher magnification of this region shows that fine cavities with high number density uniformly distribute in the matrix. (author)

  18. Comparability and accuracy of nitrogen depth profiling in nitrided austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Manova, D. [Leibniz-Institut für Oberflächenmodifizierung, 04318 Leipzig (Germany); Díaz, C. [AIN Centro de Ingeniería Avanzada de Superficies, 31191 Cordovilla, Pamplona (Spain); Pichon, L. [Institut P' , UPR3346 CNRS-Université de Poitiers-ISAE-ENSMA, Bat. SP2MI, Téléport 2, Boulevard Marie et Pierre Curie, BP30179, 86962 Chasseneuil Futuroscope Cedex (France); Abrasonis, G. [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany); Mändl, S., E-mail: stephan.maendl@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung, 04318 Leipzig (Germany)

    2015-04-15

    A comparative study of nitrogen depth profiles in low energy ion implantation nitrided austenitic stainless steel 1.4301 by glow discharge optical emission spectroscopy (GDOES), secondary ion mass spectrometry (SIMS) and nuclear reaction analysis (NRA) is presented. All methods require calibration either from reference samples or known scattering or reaction cross sections for the nitrogen concentration, while the methods producing a sputter crater – SIMS and GDOES – need additional conversion from sputter time to depth. NRA requires an assumption of material density for a correct conversion from the ‘natural’ units inherent to all ion beam analysis methods into ‘conventional’ depth units. It is shown that a reasonable agreement of the absolute concentrations and very good agreement of the layer thickness is obtained. The observed differences in broadening between the nitrogen distribution near the surface and the deeper region of the nitrided layer–steel interface are discussed on the basis of surface contaminations, surface roughening and energy straggling effects.

  19. Improved Accident Tolerance of Austenitic Stainless Steel Cladding through Colossal Supersaturation with Interstitial Solutes

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, Frank [Case Western Reserve Univ., Cleveland, OH (United States)

    2016-10-13

    We proposed a program-supporting research project in the area of fuel-cycle R&D, specifically on the topic of advanced fuels. Our goal was to investigate whether SECIS (surface engineering by concentrated interstitial solute – carbon, nitrogen) can improve the properties of austenitic stainless steels and related structural alloys such that they can be used for nuclear fuel cladding in LWRs (light-water reactors) and significantly excel currently used alloys with regard to performance, safety, service life, and accident tolerance. We intended to demonstrate that SECIS can be adapted for post-processing of clad tubing to significantly enhance mechanical properties (hardness, wear resistance, and fatigue life), corrosion resistance, resistance to stress–corrosion cracking (hydrogen-induced embrittlement), and – potentially – radiation resistance (against electron-, neutron-, or ion-radiation damage). To test this hypothesis, we measured various relevant properties of the surface-engineered alloys and compared them with corresponding properties of the non–treated, as-received alloys. In particular, we studied the impact of heat exposure corresponding to BWR (boiling-water reactor) working and accident (loss-of-coolant) conditions and the effect of ion irradiation.

  20. Strengthening of σ phase in a Fe20Cr9Ni cast austenite stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.Q., E-mail: yqwang@ahut.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); School of Materials Science and Engineering, Anhui University of Technology, Maanshan, Anhui, 243002 (China); Han, J. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Yang, B., E-mail: byang@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Wang, X.T. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2013-10-15

    The strengthening mechanism of σ phase in a Fe20Cr9Ni cast austenite stainless steel used for primary coolant pipes of nuclear power plants has been investigated. The yield and ultimate tensile strengths of aged specimens increased comparing with those of the unaged ones. It was found that the increase of strengths is due to the hard and brittle (σ + γ{sub 2}) structure which decomposed from α phase in the steel. Fracture surfaces of specimens after in situ tensile test showed that the inhibition of (σ + γ{sub 2}) structure on the dislocation movements was more significant than ferrite although cracks started predominately at σ/γ{sub 2} interfaces. The (σ + γ{sub 2}) structure behaves like a fiber reinforced composite material. - Highlights: • The strengthening mechanism of σ phase in a Fe20Cr9Ni CASS is investigated. • The yield and ultimate tensile strengths increase with increasing of σ phase. • The increase of strengths is due to hard and brittle (σ + γ{sub 2}) structure. • The (σ + γ{sub 2}) structure in CASS behaves like a fibre reinforced composite material. • The σ/γ{sub 2} and α/σ/γ{sub 2} boundaries hinder the movement of dislocation.

  1. Correlation between locally deformed structure and oxide film properties in austenitic stainless steel irradiated with neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Chimi, Yasuhiro, E-mail: chimi.yasuhiro@jaea.go.jp [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Kitsunai, Yuji [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Kasahara, Shigeki [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Chatani, Kazuhiro; Koshiishi, Masato [Nippon Nuclear Fuel Development, 2163 Narita-cho, Oarai-machi, Higashi-ibaraki-gun, Ibaraki 311-1313 (Japan); Nishiyama, Yutaka [Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2016-07-15

    To elucidate the mechanism of irradiation-assisted stress corrosion cracking (IASCC) in high-temperature water for neutron-irradiated austenitic stainless steels (SSs), the locally deformed structures, the oxide films formed on the deformed areas, and their correlation were investigated. Tensile specimens made of irradiated 316L SSs were strained 0.1%–2% at room temperature or at 563 K, and the surface structures and crystal misorientation among grains were evaluated. The strained specimens were immersed in high-temperature water, and the microstructures of the oxide films on the locally deformed areas were observed. The appearance of visible step structures on the specimens' surface depended on the neutron dose and the applied strain. The surface oxides were observed to be prone to increase in thickness around grain boundaries (GBs) with increasing neutron dose and increasing local strain at the GBs. No penetrative oxidation was observed along GBs or along surface steps. - Highlights: • Visible step structures depend on the neutron dose and the applied strain. • Local strain at grain boundaries was accumulated with the neutron dose. • Oxide thickness increases with neutron dose and local strain at grain boundaries. • No penetrative oxidation was observed along grain boundaries or surface steps.

  2. The mechanical properties of austenite stainless steel 304 after structural deformation through cold work

    Energy Technology Data Exchange (ETDEWEB)

    Mubarok, Naila; Manaf, Azwar, E-mail: azwar@ui.ac.id [PPS Materials Science, FMIPA-Universitas Indonesia, Depok 16424 (Indonesia); Notonegoro, Hamdan Akbar [Mechanical Engineering Dept., FT-Universitas Sultan Ageng Tirtayasa,Cilegon 42435 (Indonesia); Thosin, Kemas Ahmad Zaini [Pusat Penelitian Fisika,LIPI, Serpong (Indonesia)

    2016-06-17

    The 304 stainless steel (SS) type is widely used in oil and gas operations due to its excellent corrosion resistance. However, the presence of the fine sand particles and H{sub 2}S gas contained in crude oil could lead the erosion and abrasion in steel. In this study, cold rolled treatments were conducted to the 304 SS in order to increase the wear resistance of the steel. The cold work has resulted in thickness reduction to 20%, 40% and 60% of the original. Various microstructural characterizations were used to analyze the effect of deformation. The hardness characterization showed that the initial hardness value increased from 145 HVC to 395 HVC as the level of deformation increase. Further, the wear resistance increased with the deformation rate from 0% to 40% and subsequently decreased from 40% to 60% deformation rate. Microstructural characterization shows that the boundary change to coincide by 56 µm, 49 µm, 45 µm, and 43 µm width and the grain go to flatten and being folded like needles. The effect of deformation on the grain morphology and structure was also studied by optical metallography and X-Ray Diffraction. It is shown that the deformation by means of a cold rolled process has transformed the austenite structure into martensitic structure.

  3. Influence of Localized Plasticity on IASCC Sensitivity of Austenitic Stainless Steels under PWR Primary Water

    Science.gov (United States)

    Cissé, Sarata; Tanguy, Benoit; Laffont, Lydia; Lafont, Marie-Christine; Guerre, Catherine; Andrieu, Eric

    The sensibility of precipitation-strengthened A286 austenitic stainless steel to Stress Corrosion Cracking (SCC) is studied by means of Slow Strain Rate Tests (SSRT). First, alloy cold working by Low Cycle Fatigue (LCF) is investigated. Fatigue tests under plastic strain control are performed at different strain levels (Δ ɛp/2=0.2%, 0.5% and 0.8%) in order to establish correlation between stress softening and deformation microstructure resulting from LCF tests. Deformed microstructures have been identified through TEM investigations. Three states of cyclic behaviour for precipitation-strengthened A286 have been identified: hardening, cyclic softening and finally saturation of softening. It is shown that the A286 alloy cyclic softening is due to microstructural features such as defects — free deformation bands resulting from dislocations motion along family plans , that swept defects or γ' precipitates and lead to deformation localization. In order to quantify effects of plastic localized deformation on intergranular stress corrosion cracking (IGSCC) of the A286 alloy in PWR primary water, slow strain rate tests are conducted. For each cycling conditions, two specimens at a similar stress level are tested: the first containing free precipitate deformation bands, the other not significant of a localized deformation state. SSRT tests are still in progress.

  4. Impact of the nanostructuration on the corrosion resistance and hardness of irradiated 316 austenitic stainless steels

    Science.gov (United States)

    Hug, E.; Prasath Babu, R.; Monnet, I.; Etienne, A.; Moisy, F.; Pralong, V.; Enikeev, N.; Abramova, M.; Sauvage, X.; Radiguet, B.

    2017-01-01

    The influence of grain size and irradiation defects on the mechanical behavior and the corrosion resistance of a 316 stainless steel have been investigated. Nanostructured samples were obtained by severe plastic deformation using high pressure torsion. Both coarse grain and nanostructured samples were irradiated with 10 MeV 56Fe5+ ions. Microstructures were characterized using transmission electron microscopy and atom probe tomography. Surface mechanical properties were evaluated thanks to hardness measurements and the corrosion resistance was studied in chloride environment. Nanostructuration by high pressure torsion followed by annealing leads to enrichment in chromium at grain boundaries. However, irradiation of nanostructured samples implies a chromium depletion of the same order than depicted in coarse grain specimens but without metallurgical damage like segregated dislocation loops or clusters. Potentiodynamic polarization tests highlight a definitive deterioration of the corrosion resistance of coarse grain steel with irradiation. Downsizing the grain to a few hundred of nanometers enhances the corrosion resistance of irradiated samples, despite the fact that the hardness of nanocrystalline austenitic steel is only weakly affected by irradiation. These new experimental results are discussed in the basis of couplings between mechanical and electrical properties of the passivated layer thanks to impedance spectroscopy measurements, hardness properties of the surfaces and local microstructure evolutions.

  5. Methods for the In-Situ Characterization of Cast Austenitic Stainless Steel Microstructures

    Science.gov (United States)

    Ramuhalli, P.; Good, M. S.; Harris, R. J.; Bond, L. J.; Ruud, C. O.; Diaz, A. A.; Anderson, M. T.

    2011-06-01

    Cast austenitic stainless steel (CASS) that was commonly used in U.S. nuclear power plants is a coarse-grained, elastically anisotropic material. Its engineering properties made it a material of choice for selected designs of nuclear power reactor systems. However, the material manufacturing and fabrication processes result in a variety of coarse-grain microstructures that make current ultrasonic in-service inspection of components quite challenging. To address inspection needs, new ultrasonic inspection approaches are being sought. However, overcoming the deleterious and variable effects of the microstructure on the interrogating ultrasonic beam may require knowledge of the microstructure, for potential optimization of inspection parameters to enhance the probability of detection (POD). The ability to classify microstructure type (e.g. polycrystalline or columnar) has the potential to guide selection of optimal NDE approaches. This paper discusses the application of ultrasonic and electromagnetic methods for classifying CASS microstructures, when making measurements from the outside surface of the component. Results to date demonstrate the potential of these measurements to discriminate between two consistent microstructures—equiaxed-grain material versus columnar-grain material. The potential for fusion of ultrasonic and electromagnetic measurements for in-situ microstructure characterization in CASS materials will be explored.

  6. Thermomechanical processing optimization for 304 austenitic stainless steel using artificial neural network and genetic algorithm

    Science.gov (United States)

    Feng, Wen; Yang, Sen

    2016-12-01

    Thermomechanical processing has an important effect on the grain boundary character distribution. To obtain the optimal thermomechanical processing parameters is the key of grain boundary engineering. In this study, genetic algorithm (GA) based on artificial neural network model was proposed to optimize the thermomechanical processing parameters. In this model, a back-propagation neural network (BPNN) was established to map the relationship between thermomechanical processing parameters and the fraction of low-Σ CSL boundaries, and GA integrated with BPNN (BPNN/GA) was applied to optimize the thermomechanical processing parameters. The validation of the optimal thermomechanical processing parameters was verified by an experiment. Moreover, the microstructures and the intergranular corrosion resistance of the base material (BM) and the materials produced by the optimal thermomechanical processing parameters (termed as the GBEM) were studied. Compared to the BM specimen, the fraction of low-Σ CSL boundaries was increased from 56.8 to 77.9% and the random boundary network was interrupted by the low-Σ CSL boundaries, and the intergranular corrosion resistance was improved in the GBEM specimen. The results indicated that the BPNN/GA model was an effective and reliable means for the thermomechanical processing parameters optimization, which resulted in improving the intergranular corrosion resistance in 304 austenitic stainless steel.

  7. Improved austenitic stainless steel for high temperature applications. [Improved stress-rupture properties

    Science.gov (United States)

    Not Available

    This invention describes a composition for an austenitic stainless steel which has been found to exhibit improved high temperature stress rupture properties. The composition of this alloy is about (in wt. %): 12.5 to 14.5 Cr; 14.5 to 16.5 Ni; 1.5 to 2.5 Mo; 1.5 to 2.5 Mn; 0.1 to 0.4 Ti; 0.02 to 0.08 C; 0.5 to 1.0 Si; 0.01 maximum, N; 0.02 to 0.08 P; 0.002 to 0.008 B; 0.004-0.010 S; 0.02-0.05 Nb; .01-.05 V; 0.005-0.02 Ta; 0.02-0.05 Al; 0.01-0.04 Cu; 0.02-0.05 Co; .03 maximum, As; 0.01 maximum, 0; 0.01 maximum, Zr; and with the balance of the alloy being essentially iron. The carbon content of the alloy is adjusted such that wt. % Ti/(wt. % C+wt. % N) is between 4 and 6, and most preferably about 5. In addition the sum of the wt. % P + wt. % B + wt. % S is at least 0.03 wt. %. This alloy is believed to be particularly well suited for use as fast breeder reactor fuel element cladding.

  8. Parametric optimization during machining of AISI 304 Austenitic Stainless Steel using CVD coated DURATOMIC cutting insert

    Directory of Open Access Journals (Sweden)

    M. Kaladhar

    2012-08-01

    Full Text Available In this work, Taguchi method is applied to determine the optimum process parameters for turning of AISI 304 austenitic stainless steel on CNC lathe. A Chemical vapour deposition (CVD coated cemented carbide cutting insert is used which is produced by DuratomicTM technology of 0.4 and 0.8 mm nose radii. The tests are conducted at four levels of Cutting speed, feed and depth of cut. The influence of these parameters are investigated on the surface roughness and material removal rate (MRR. The Analysis Of Variance (ANOVA is also used to analyze the influence of cutting parameters during machining. The results revealed that cutting speed significantly (46.05% affected the machined surface roughness values followed by nose radius (23.7%. The influence of the depth of cut (61.31% in affecting material removal rate (MRR is significantly large. The cutting speed (20.40% is the next significant factor. Optimal range and optimal level of parameters are also predicted for responses.

  9. The Investigation of Strain-Induced Martensite Reverse Transformation in AISI 304 Austenitic Stainless Steel

    Science.gov (United States)

    Cios, G.; Tokarski, T.; Żywczak, A.; Dziurka, R.; Stępień, M.; Gondek, Ł.; Marciszko, M.; Pawłowski, B.; Wieczerzak, K.; Bała, P.

    2017-10-01

    This paper presents a comprehensive study on the strain-induced martensitic transformation and reversion transformation of the strain-induced martensite in AISI 304 stainless steel using a number of complementary techniques such as dilatometry, calorimetry, magnetometry, and in-situ X-ray diffraction, coupled with high-resolution microstructural transmission Kikuchi diffraction analysis. Tensile deformation was applied at temperatures between room temperature and 213 K (-60 °C) in order to obtain a different volume fraction of strain-induced martensite (up to 70 pct). The volume fraction of the strain-induced martensite, measured by the magnetometric method, was correlated with the total elongation, hardness, and linear thermal expansion coefficient. The thermal expansion coefficient, as well as the hardness of the strain-induced martensitic phase was evaluated. The in-situ thermal treatment experiments showed unusual changes in the kinetics of the reverse transformation (α' → γ). The X-ray diffraction analysis revealed that the reverse transformation may be stress assisted—strains inherited from the martensitic transformation may increase its kinetics at the lower annealing temperature range. More importantly, the transmission Kikuchi diffraction measurements showed that the reverse transformation of the strain-induced martensite proceeds through a displacive, diffusionless mechanism, maintaining the Kurdjumov-Sachs crystallographic relationship between the martensite and the reverted austenite. This finding is in contradiction to the results reported by other researchers for a similar alloy composition.

  10. Microstructural and Surface Texture Analysis due to Machining in Super Austenitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    Mohanad Alabdullah

    2016-01-01

    Full Text Available Inferior surface quality is a significant problem faced by machinist. The purpose of this study is to present a surface texture analysis undertaken as part of machinability assessment of Super Austenitic Stainless Steel alloy-AL6XN. The surface texture analysis includes measuring the surface roughness and investigating the microstructural behaviour of the machined surfaces. Eight milling trials were conducted using combination of cutting parameters under wet machining. An optical profilometer (noncontact was used to evaluate the surface texture at three positions. The surface texture was represented using the parameter, average surface roughness. Scanning Electron Microscope was utilised to inspect the machined surface microstructure and correlate the microstructure with the surface roughness. Results showed that maximum roughness values recorded at the three positions in the longitudinal direction (perpendicular to the machining grooves were 1.21 μm (trial 1, 1.63 μm (trial 6, and 1.68 μm (trial 7, respectively, whereas the roughness values were greatly reduced in the lateral direction. Also, results showed that the feed rate parameter significantly influences the roughness values compared to the other cutting parameters. The microstructure of the machined surfaces was distorted by the existence of cracks, deformed edges, and bands and wear deposition due to machining process.

  11. Effects of pre-creep on the dislocations of 316LN Austenite stainless steel

    Science.gov (United States)

    Pei, Hai-xiang; Hui, Jun; Hua, Hou; Feng, Zai-xin; Xu, Xiao-long

    2017-09-01

    The 316LN Austenite stainless steels (316LNASS) were pre-creep treated, the evolution of microstructure were investigated. The samples were pre-creep at 593 K and from 500 to 2000 h at 873 K with a stress in the range of 20 to 150 MPa, Then the evolution of microstructure and precipitation were investigated by optical microscope (OM), and transmission electron microscope (TEM). The results show that the crystal surface slipping resulted in dislocations and original dislocations decomposition during the pre-creep process, and generate quadrilateral or hexagonal dislocation network was obviously. The sub-grain boundary gradually became narrow with the increasing of pre-creep treatment time and temperature. When the pre-creep temperature was 593 K and 873 K, dislocation network gradually disappear with the increasing of pre-creep time and load. When the pre-creep temperature was 873 K under 120 MPa, and the treatment time was 2000 h, the hexagonal dislocation network (HDN) would completely disappeared. When the pre-creep temperature was 593 K under 20 MPa, and the treatment time was 500 h, the quadrilateral dislocation network (QDN) would completely disappeared.

  12. Processing nickel free high nitrogen austenitic stainless steels through conventional electroslag remelting process

    Energy Technology Data Exchange (ETDEWEB)

    Balanchandran, G.

    2000-05-01

    Nickel free high nitrogen austenitic stainless steels, made through air-induction melting were processed using conventional electroslag remelting (ESR) process without application of nitrogen gas pressure over the melt. It was found possible to retain the high nitrogen contents of the original steel. The loss in nitrogen content during ESR was found to increase with increasing melt rate. Electroslag remelting was carted out on eleven steels with a base composition at around 18wt%Cr-18wt%Mn- 0.1 to 0.6wt%C-0.53 to 0.9wt%N. While the air-induction melted steel had extensive porosity, the ESR ingots were all sound and free from porosity. Thus, steels made in any other process route can be successfully remelted using conventional ESR. The cast structure analysis in a typical medium carbon high nitrogen steel showed that Cr and Mn has a tendency for microsegregation. The presence of microsegregation and residual carbides affect the ductility of the cast steel. (author)

  13. Experimental and numerical investigation of formability for austenitic stainless steel 316 at elevated temperatures

    Directory of Open Access Journals (Sweden)

    Syed Mujahed Hussaini

    2014-01-01

    Full Text Available Sheet metal forming at elevated temperature is not much used in industries but it is going to be a very important process in the future. The present work is aimed to investigate the formability of austenitic stainless steel 316 at elevated temperatures. Limiting drawing ratio and thickness of the drawn cup are the indicators of formability in deep drawing. In the present investigation circular blanks are deep drawn at room temperature, 150 °C and 300 °C using a 20 ton hydraulic press coupled with a furnace. Finite element simulations are carried out using Dynaform with LS-Dyna solver. Simulations and experimental results show an increase in the limiting drawing ration as the temperature increases and a decrease in the thickness of the drawn cup without any fracture. An artificial neural network model is developed for the prediction of the cup thickness at different locations. Based on the input variables, such as distance from the center of the cup, temperature and LDR, a back propagation neural network model to predict the thickness as output was develop. The comparison between these sets of results indicates the reliability of the predictions. It was found that there is a good agreement between the experimental and predicted values.

  14. Effect of initial grain size on dynamic recrystallization in high purity austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    El Wahabi, M. [Centre SMS, CNRS UMR 5146, Ecole Nationale Superieure des Mines de Saint-Etienne, 158, cours Fauriel-42023, Saint-Etienne Cedex 2 (France); Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB - Universidad Politecnica de Cataluna, Av. Diagonal 647, 08028-Barcelona (Spain); Gavard, L. [Centre SMS, CNRS UMR 5146, Ecole Nationale Superieure des Mines de Saint-Etienne, 158, cours Fauriel-42023, Saint-Etienne Cedex 2 (France); Montheillet, F. [Centre SMS, CNRS UMR 5146, Ecole Nationale Superieure des Mines de Saint-Etienne, 158, cours Fauriel-42023, Saint-Etienne Cedex 2 (France); Cabrera, J.M. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB - Universidad Politecnica de Cataluna, Av. Diagonal 647, 08028-Barcelona (Spain)]. E-mail: jose.maria.cabrera@upc.edu; Prado, J.M. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB - Universidad Politecnica de Cataluna, Av. Diagonal 647, 08028-Barcelona (Spain)

    2005-10-15

    The influence of initial microstructure on discontinuous dynamic recrystallization (DDRX) has been investigated by using high purity and ultra high purity austenitic stainless steels with various initial grain sizes. After uniaxial compression tests at constant strain rates and various temperatures, the steady state microstructure or the state corresponding to the maximum strain ({epsilon} = 1) attained in the test was analyzed by scanning electron microscopy aided with automated electron back scattering diffraction. Recrystallized grain size d {sub rec} and twin boundary fraction f {sub TB} measurements were carried out. The mechanical behavior was also investigated by comparing experimental stress-strain curves with various initial grain sizes. DDRX kinetics was described by the classical Avrami equation. It was concluded that larger initial grain sizes promoted a delay in the DDRX onset in the two alloys. It was also observed that the softening process progressed faster for smaller initial grain sizes. The effect of initial grain size is larger in the HP material and becomes more pronounced at low temperature.

  15. EBSD study of purity effects during hot working in austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    El Wahabi, M. [Centre SMS, CNRS UMR 5146, Ecole Nationale Superieure des Mines de Saint-Etienne, 158, cours Fauriel-42023, Saint-Etienne Cedex 2 (France) and Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB, Universidad Politecnica de Cataluna, Av. Diagonal 647, Barcelona 08028 (Spain)]. E-mail: elwahabi@emse.fr; Gavard, L. [Centre SMS, CNRS UMR 5146, Ecole Nationale Superieure des Mines de Saint-Etienne, 158, cours Fauriel-42023, Saint-Etienne Cedex 2 (France); Cabrera, J.M. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB, Universidad Politecnica de Cataluna, Av. Diagonal 647, Barcelona 08028 (Spain); Prado, J.M. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, ETSEIB, Universidad Politecnica de Cataluna, Av. Diagonal 647, Barcelona 08028 (Spain); Montheillet, F. [Centre SMS, CNRS UMR 5146, Ecole Nationale Superieure des Mines de Saint-Etienne, 158, cours Fauriel-42023, Saint-Etienne Cedex 2 (France)

    2005-02-25

    The technique of electron back scattering diffraction (EBSD) is considered as a powerful instrument for the study of the microstructural changes during hot forming processes and gives the possibility to present the information in different ways (OIM, misorientation diagram and pole figures). The present work is focused on the observation by EBSD of the microstructure evolution during deformation at high temperature of three austenitic stainless steels: AISI-304H, AISI-304L and a high purity steel HP. The difference between the three steels is the content carbon and the presence of residual elements. To this aim compression tests were carried out at a constant strain rate of 0.001 s{sup -1} and different temperatures. The study showed an increase of twin boundary fractions and a diminution of substructure (low angle densities boundaries) at increasing temperatures. On the other hand, increasing carbon content promotes lower twin boundary fractions and larger amounts of low angle boundaries. This effect can be explained by the reduction of grain boundary mobility caused by increasing carbon contents, which in turn reduces the migration rate and consequently the probability of twin boundary generation. Moreover, the increment of low angle boundaries with carbon content accelerates the twin character loss. It was also found that the dynamically recrystallized grain size decreased at increasing carbon content due to a typical drag effect. No important features on textures were found during DDRX.

  16. Study of stress relief cracking in titanium stabilized austenitic stainless steel; Etude de la fissuration differee par relaxation d'un acier inoxydable austenitique stabilise au titane

    Energy Technology Data Exchange (ETDEWEB)

    Chabaud-Reytier, M

    1999-07-01

    The heat affected zone (HAZ) of titanium stabilised austenitic stainless steel welds (AISI 321) may exhibit a serious form of intercrystalline cracking during service at high temperature. This type of cracking, called 'stress relief cracking', is known to be due to work hardening but also to ageing: a fine and abundant intragranular Ti(C,N) precipitation appears near the fusion line and modifies the mechanical behaviour of the HAZ. This study aims to better know the accused mechanism and to succeed in estimating the risk of such cracking in welded junctions of 321 stainless steel. To analyse this embrittlement mechanism, and to assess the lifetime of real components, different HAZ are simulated by heat treatments applied to the base material which is submitted to various cold rolling and ageing conditions in order to reproduce the HAZ microstructure. Then, we study the effects of work hardening and ageing on the titanium carbide precipitation, on the mechanical (tensile and creep) behaviour of the resulting material and on its stress relief cracking sensitivity. It is shown that work hardening is the main parameter of the mechanism and that ageing do not favour crack initiation although it leads to titanium carbide precipitation. The role of this precipitation is also discussed. Moreover, a creep damage model is identified by a local approach to fracture. Materials sensitive to stress relief cracking are selected. Then, creep tests are carried out on notched bars in order to quantify the intergranular damage of these different materials; afterwards, these measurements are combined with calculated mechanical fields. Finally, it is shown that the model gives good results to assess crack initiation for a compact tension (CT) specimen during relaxation tests, as well as for a notched tubular specimen tested at 600 deg. C under a steady torque. (author)

  17. High temperature oxidation of alumina forming cast austenitic stainless steels within an environment of pure steam

    Science.gov (United States)

    Prenzlow, Elmer A.

    Steam cracking of hydrocarbons in the petrochemical industry is a multibillion dollar industry. The processes performed in these plants create byproducts that negatively affect the integrity of stainless steel piping through high temperature corrosion. Alloys used presently in industry rely on the formation of chromium oxide (chromia) as a protective layer between the bulk metal pipe and chemical byproducts. However, chromia can become susceptible to attack from aggressive species such as carbon, water vapor, and sulfur compounds, thus creating a need for a better protection method. A new series of austenitic stainless steels have been developed in recent years that, rather than forming chromia, create a protective layer of aluminum oxide (alumina) under oxidative conditions. These alloys have high nickel content for the stabilization of the austenitic phase, and a more thermodynamically stable oxide layer relative to the traditional chromia formers. Consequently, alumina forming alloys have been proposed as replacements for chromia forming alloys in the petrochemical industry. General oxidation testing has been performed on alumina forming alloys under dry and 10% water vapor conditions. However, oxidation conditions in industry resemble a 100% steam environment. Therefore, test methods to mimic such conditions are needed so that alloys can be tested and developed further for these applications. Four alloys with aluminum contents ranging from 2.6 to 3.9 wt% were cut from centrifugally cast pipes and subjected to oxidation in an environment of pure steam for up to 30 hours, at temperatures of 800 °C and 950 °C. Samples were analyzed using Raman, SEM, and EDS and showed a continuous alumina layer free of cracks. The alumina layer thickness increased with time. Additionally, larger thicknesses were observed in samples oxidized at 950 °C from those of 800 °C. Thickness measurements were used to calculate parabolic and non-parabolic oxidation rate constants

  18. Welding of AA1050 aluminum with AISI 304 stainless steel by rotary friction welding process

    Directory of Open Access Journals (Sweden)

    Chen Ying An

    2010-09-01

    Full Text Available The purpose of this work was to assess the development of solid state joints of dissimilar material AA1050 aluminum and AISI 304 stainless steel, which can be used in pipes of tanks of liquid propellants and other components of the Satellite Launch Vehicle. The joints were obtained by rotary friction welding process (RFW, which combines the heat generated from friction between two surfaces and plastic deformation. Tests were conducted with different welding process parameters. The results were analyzed by means of tensile tests, Vickers microhardness, metallographic tests and SEM-EDX. The strength of the joints varied with increasing friction time and the use of different pressure values. Joints were obtained with superior mechanical properties of the AA1050 aluminum, with fracture occurring in the aluminum away from the bonding interface. The analysis by EDX at the interface of the junction showed that interdiffusion occurs between the main chemical components of the materials involved. The RFW proves to be a great method for obtaining joints between dissimilar materials, which is not possible by fusion welding processes.

  19. Influence of Mode of Metal Transfer on Microstructure and Mechanical Properties of Gas Metal Arc-Welded Modified Ferritic Stainless Steel

    Science.gov (United States)

    Mukherjee, Manidipto; Pal, Tapan Kumar

    2012-06-01

    This article describes in detail the effect of the modes of metal transfer on the microstructure and mechanical properties of gas metal arc-welded modified ferritic stainless steel (SSP 409M) sheets (as received) of 4 mm thickness. The welded joints were prepared under three modes of metal transfer, i.e., short-circuit (SC), spray (S), transfer, and mix (M) mode transfer using two different austenitic filler wires (308L and 316L) and shielding gas composition of Ar + 5 pct CO2. The welded joints were evaluated by means of microstructural, hardness, notched tensile strength, Charpy impact toughness, and high cycle fatigue. The dependence of weld metal microstructure on modes of metal transfer and filler wires has been determined by dilution calculation, WRC-1992 diagram, Creq/Nieq ratio, stacking fault energy (SFE), optical microscopy (OM), and transmission electron microscopy (TEM). It was observed that the microstructure as well as the tensile, Charpy impact, and high cycle fatigue of weld metal is significantly affected by the mode of metal transfer and filler wire used. However, the heat-affected zone (HAZ) is affected only by the modes of metal transfer. The results have been correlated with the microstructures of weld and HAZ developed under different modes of metal transfer.

  20. Biocompatibility studies of low temperature nitrided and collagen-I coated AISI 316L austenitic stainless steel.

    Science.gov (United States)

    Martinesi, M; Stio, M; Treves, C; Borgioli, F

    2013-06-01

    The biocompatibility of austenitic stainless steels can be improved by means of surface engineering techniques. In the present research it was investigated if low temperature nitrided AISI 316L austenitic stainless steel may be a suitable substrate for bioactive protein coating consisting of collagen-I. The biocompatibility of surface modified alloy was studied using as experimental model endothelial cells (human umbilical vein endothelial cells) in culture. Low temperature nitriding produces modified surface layers consisting mainly of S phase, the supersaturated interstitial solid solution of nitrogen in the austenite lattice, which allows to enhance surface microhardness and corrosion resistance in PBS solution. The nitriding treatment seems to promote the coating with collagen-I, without chemical coupling agents, in respect of the untreated alloy. For biocompatibility studies, proliferation, lactate dehydrogenase levels and secretion of two metalloproteinases (MMP-2 and MMP-9) were determined. Experimental results suggest that the collagen protection may be favourable for endothelial cell proliferation and for the control of MMP-2 release.

  1. Detection and sizing of stress corrosion cracks in austenitic components using ultrasonic testing and synthetic aperture focusing technique

    Energy Technology Data Exchange (ETDEWEB)

    Dugan, Sandra; Wagner, Sabine [Stuttgart Univ. (Germany). Materialpruefungsanstalt; Dillhoefer, Alexander [NDT Global GmbH and Co.KG, Stutensee (Germany); Rieder, Hans; Spies, Martin [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren (IZFP), Saarbruecken (Germany)

    2015-05-01

    Flaw detection and sizing using NDT techniques is an important factor for reliably assessing the integrity of components. In the case of dissimilar metal welds and austenitic stainless steel welds, the grain structure of the weld in combination with the elastic anisotropy of the material will present major challenges for UT. A study on austenitic base metal test blocks with artificially grown IGSCCs has shown that the Synthetic Aperture Focusing Technique (SAFT) can improve the signal-to-noise ratio, particularly for crack tip signals. In welded test blocks, the influence of the inhomogeneous, anisotropic weld has to be considered.

  2. Assessment of void swelling in austenitic stainless steel PWR core internals.

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H. M.; Energy Technology

    2006-01-31

    As many pressurized water reactors (PWRs) age and life extension of the aged plants is considered, void swelling behavior of austenitic stainless steel (SS) core internals has become the subject of increasing attention. In this report, the available database on void swelling and density change of austenitic SSs was critically reviewed. Irradiation conditions, test procedures, and microstructural characteristics were carefully examined, and key factors that are important to determine the relevance of the database to PWR conditions were evaluated. Most swelling data were obtained from steels irradiated in fast breeder reactors at temperatures >385 C and at dose rates that are orders of magnitude higher than PWR dose rates. Even for a given irradiation temperature and given steel, the integral effects of dose and dose rate on void swelling should not be separated. It is incorrect to extrapolate swelling data on the basis of 'progressive compounded multiplication' of separate effects of factors such as dose, dose rate, temperature, steel composition, and fabrication procedure. Therefore, the fast reactor data should not be extrapolated to determine credible void swelling behavior for PWR end-of-life (EOL) or life-extension conditions. Although the void swelling data extracted from fast reactor studies is extensive and conclusive, only limited amounts of swelling data and information have been obtained on microstructural characteristics from discharged PWR internals or steels irradiated at temperatures and at dose rates comparable to those of a PWR. Based on this relatively small amount of information, swelling in thin-walled tubes and baffle bolts in a PWR is not considered a concern. As additional data and relevant research becomes available, the newer results should be integrated with existing data, and the worthiness of this conclusion should continue to be scrutinized. PWR baffle reentrant corners are the most likely location to experience high swelling

  3. Material Characterization of Fatigue Specimens made from Meta-stable Austenitic Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Niffenegger, M.; Grosse, M.; Kalkhof, D.; Leber, H. [Paul Scherrer Institut Villigen (Switzerland); Vincent, A.; Pasco, L.; Morin, M. [Insa de Lyon (France)

    2003-07-01

    defects, - Metallographic investigations to determine shape and size of grains and martensite. Based on results from former investigations, main attention was paid to the content of martensitic phase as an indicator for fatigue. Since most NDT-methods are considered as indirect methods for the detection of martensite, neutron diffraction was applied as a reference method for a quantitative determination of martensite. Differences between the three investigated metastable austenitic stainless steels concerning their microstructure and affinity for martensitic transformation were observed. After a short description of the measuring methods some representative results are presented and discussed in this report. Finally, some conclusions in respect to the application of NDT-methods are summarised. (author)

  4. The effect of temperature on the SCC behavior of AISI301L stainless steel welded joints in 3.5% NaCl solution

    Science.gov (United States)

    Fu, Z. H.; Gou, G. Q.; Xiao, J.; Qiu, S. Y.; Wang, W. J.

    2017-07-01

    The stress corrosion cracking (SCC) behaviors at slow strain rate tensile (SSRT) test of AISI301L stainless steel laser-MIG welded joints in 3.5 wt.% NaCl solution at 20∘C, 40∘C and 60∘C were investigated. The results showed that the weld metal composed of as-cast with δ-Fe and austenite. The base metal (BM) and heat affected zone (HAZ) contained strain-induced M phase. The stress and strain decreased with the increasing temperature. The SCC cracks are initiated by anodic dissolution at 20∘C. Besides the anodic dissolution mechanism, hydrogen-induced SCC mechanism had appeared in 3.5 wt.% NaCl solution at 40∘C and 60∘C.

  5. Yb-fibre Laser Welding of 6 mm Duplex Stainless Steel 2205

    Science.gov (United States)

    Bolut, M.; Kong, C. Y.; Blackburn, J.; Cashell, K. A.; Hobson, P. R.

    Duplex stainless steel (DSS) is one of the materials of choice for structural and nuclear applications, having high strength and good corrosion resistance when compared with other grades of stainless steel. The welding process used to join these materials is critical as transformation of the microstructure during welding directly affects the material properties. High power laser welding has recently seen an increase in research interest as it offers both speed and flexibility. This paper presents an investigation into the important parameters affecting laser welding of DSS grade 2205, with particular focus given to the critical issue of phase transformation during welding. Bead-on-plate melt-run trials without filler material were performed on 6mm thick plates using a 5 kW Yb-fibre laser. The laser beam was characterized and a Design of Experiment approach was used to quantify the impact of the process parameters. Optical metallographic methods were used to examine the resulting microstructures.

  6. Pulsed Nd:YAG laser welding of AISI 304 to AISI 420 stainless steels

    Science.gov (United States)

    Berretta, José Roberto; de Rossi, Wagner; David Martins das Neves, Maurício; Alves de Almeida, Ivan; Dias Vieira Junior, Nilson

    2007-09-01

    The technique to weld AISI 304 stainless steel to AISI 420 stainless steel with a pulsed Nd:YAG laser has been investigated. The main objective of this study was to determine the influence of the laser beam position, with respect to the joint, on weld characteristics. Specimens were welded with the laser beam incident on the joint and moved 0.1 and 0.2 mm on either side of the joint. The joints were examined in an optical microscope for cracks, pores and to determine the weld geometry. The microstructure of the weld and the heat affected zones were observed in a scanning electron microscope. An energy dispersive spectrometer, coupled to the scanning electron microscope, was used to determine variations in (weight %) the main chemical elements across the fillet weld. Vickers microhardness testing and tensile testing were carried out to determine the mechanical properties of the weld. The results of the various tests and examinations enabled definition of the best position for the incident laser beam with respect to the joint, for welding together the two stainless steels.

  7. Elaboration of austenitic stainless steel samples with bimodal grain size distributions and investigation of their mechanical behavior

    Science.gov (United States)

    Flipon, B.; de la Cruz, L. Garcia; Hug, E.; Keller, C.; Barbe, F.

    2017-10-01

    Samples of 316L austenitic stainless steel with bimodal grain size distributions are elaborated using two distinct routes. The first one is based on powder metallurgy using spark plasma sintering of two powders with different particle sizes. The second route applies the reverse-annealing method: it consists in inducing martensitic phase transformation by plastic strain and further annealing in order to obtain two austenitic grain populations with different sizes. Microstructural analy ses reveal that both methods are suitable to generate significative grain size contrast and to control this contrast according to the elaboration conditions. Mechanical properties under tension are then characterized for different grain size distributions. Crystal plasticity finite element modelling is further applied in a configuration of bimodal distribution to analyse the role played by coarse grains within a matrix of fine grains, considering not only their volume fraction but also their spatial arrangement.

  8. In-Situ Investigation of Strain-Induced Martensitic Transformation Kinetics in an Austenitic Stainless Steel by Inductive Measurements

    Directory of Open Access Journals (Sweden)

    Carola Celada-Casero

    2017-07-01

    Full Text Available An inductive sensor developed by Philips ATC has been used to study in-situ the austenite (γ to martensite (α′ phase transformation kinetics during tensile testing in an AISI 301 austenitic stainless steel. A correlation between the sensor output signal and the volume fraction of α′-martensite has been found by comparing the results to the ex-situ characterization by magnetization measurements, light optical microscopy, and X-ray diffraction. The sensor has allowed for the observation of the stepwise transformation behavior, a not-well-understood phenomena that takes place in large regions of the bulk material and that so far had only been observed by synchrotron X-ray diffraction.

  9. A review of irradiation effects on LWR core internal materials - IASCC susceptibility and crack growth rates of austenitic stainless steels.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Roa, A. S.; Environmental Science Division; U.S. NRC

    2010-12-15

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of light water reactor (LWR) pressure vessels because of their relatively high strength, ductility, and fracture toughness. However, exposure to neutron irradiation for extended periods changes the microstructure (radiation hardening) and microchemistry (radiation-induced segregation) of these steels, and degrades their fracture properties. Irradiation-assisted stress corrosion cracking (IASCC) is another degradation process that affects LWR internal components exposed to neutron radiation. The existing data on irradiated austenitic SSs were reviewed to evaluate the effects of key parameters such as material composition, irradiation dose, and water chemistry on IASCC susceptibility and crack growth rates of these materials in LWR environments. The significance of microstructural and microchemistry changes in the material on IASCC susceptibility is also discussed. The results are used to determine (a) the threshold fluence for IASCC and (b) the disposition curves for cyclic and IASCC growth rates for irradiated SSs in LWR environments.

  10. A review of irradiation effects on LWR core internal materials - IASCC susceptibility and crack growth rates of austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O.K., E-mail: okc@anl.gov [Environmental Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Rao, A.S. [Division of Engineering, US Nuclear Regulatory Commission, Washington, DC 20555 (United States)

    2011-02-28

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of light water reactor (LWR) pressure vessels because of their relatively high strength, ductility, and fracture toughness. However, exposure to neutron irradiation for extended periods changes the microstructure (radiation hardening) and microchemistry (radiation-induced segregation) of these steels, and degrades their fracture properties. Irradiation-assisted stress corrosion cracking (IASCC) is another degradation process that affects LWR internal components exposed to neutron radiation. The existing data on irradiated austenitic SSs were reviewed to evaluate the effects of key parameters such as material composition, irradiation dose, and water chemistry on IASCC susceptibility and crack growth rates of these materials in LWR environments. The significance of microstructural and microchemistry changes in the material on IASCC susceptibility is also discussed. The results are used to determine (a) the threshold fluence for IASCC and (b) the disposition curves for cyclic and IASCC growth rates for irradiated SSs in LWR environments.

  11. Corrosion behavior of cold-worked austenitic stainless steels in liquid lead-bismuth eutectic

    Science.gov (United States)

    Kurata, Yuji

    2014-05-01

    The effect of cold working on the corrosion behavior of austenitic stainless steels in liquid lead-bismuth eutectic (LBE) was studied to develop accelerator-driven systems for the transmutation of long-lived radioactive wastes and lead-bismuth cooled fast reactors. Corrosion tests on solution-treated, 20% cold-worked and 50% cold-worked 316SS and JPCA (15Cr-15Ni-Ti) were conducted in oxygen-controlled LBE. Slight ferritization caused by Ni dissolution and Pb-Bi penetration were observed for all specimens in the corrosion test conducted at 500 °C for 1000 h in liquid LBE with an intermediate oxygen concentration (1.4 × 10-7 wt.%). In the corrosion test performed at 550 °C for 1000 h in liquid LBE with a low oxygen concentration (4.2 × 10-9 wt.%), the depth of the ferritization of 316SS and JPCA increased with the extent of cold working. Only oxidation was observed in the corrosion test that was performed at 550 °C for 1000 h in liquid LBE with a high oxygen concentration (approximately 10-5 wt.%). Cold working accelerated the formation of the double layer oxide and increased the thickness of the oxide layer slightly. In contrast, the ferritization accompanied by Pb-Bi penetration was widely observed with oxidation for all specimens corrosion tested at 550 °C for 3000 h under the high-oxygen condition. Cold working increased the depth of the ferritization of 316SS and JPCA. It is considered that cold working accelerated the ferritization and Pb-Bi penetration through the enhanced dissolution of Ni into LBE due to an increase in the dislocation density under conditions in which the protective oxide layer was not formed in liquid LBE.

  12. Pitting corrosion in austenitic stainless steel water tanks of hotel trains

    Directory of Open Access Journals (Sweden)

    Moreno, D. A.

    2011-12-01

    Full Text Available The water storage tanks of hotel trains suffered pitting corrosion. To identify the cause, the tanks were subjected to a detailed metallographic study and the chemical composition of the austenitic stainless steels used in their construction was determined. Both the tank water and the corrosion products were further examined by physicochemical and microbiological testing. Corrosion was shown to be related to an incompatibility between the chloride content of the water and the base and filler metals of the tanks. These findings formed the basis of recommendations aimed at the prevention and control of corrosion in such tanks.

    Se han detectado problemas de corrosión por picaduras en los depósitos de agua de trenes hotel. Para identificar las causas se llevó a cabo un detallado estudio metalográfico así como de la composición química de los aceros inoxidables austeníticos utilizados en su construcción. También se realizaron estudios fisicoquímicos y microbiológicos de los productos de corrosión. Se ha encontrado que los problemas de corrosión están relacionados con la incompatibilidad entre el contenido en cloruros del agua y los metales base y de aporte de la soldadura de los tanques. En base a estos hallazgos se proponen una serie de recomendaciones encaminadas a la prevención y control de la corrosión de dichos depósitos.

  13. Crack growth behavior of warm-rolled 316L austenitic stainless steel in high-temperature hydrogenated water

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Joon; Yoo, Seung Chang [Department of Nuclear Science and Engineering, School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919 (Korea, Republic of); Jin, Hyung-Ha; Kwon, Junhyun; Choi, Min-Jae; Hwang, Seong Sik [Nuclear Materials Safety Research Division, Korea Atomic Energy Research Institute (KAERI), 111, Daedeok-daero 989beon-gil, Yuseong-gu, Daejeon 34057 (Korea, Republic of); Kim, Ji Hyun, E-mail: kimjh@unist.ac.kr [Department of Nuclear Science and Engineering, School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919 (Korea, Republic of)

    2016-08-01

    To investigate the effects of warm rolling on the crack growth of 316L austenitic stainless steel, the crack growth rate was measured and the oxide structure was characterized in high-temperature hydrogenated water. The warm-rolled specimens showed a higher crack growth rate compared to the as-received specimens because the slip bands and dislocations produced during warm rolling served as paths for corrosion and cracking. The crack growth rate increased with the dissolved hydrogen concentration. This may be attributed to the decrease in performance and stability of the protective oxide layer formed on the surface of stainless steel in high-temperature water. - Highlights: • 316L Stainless steels were used for the study of crack growth behavior in PWR water. • Warm rolling was applied to simulate the irradiation hardening of stainless steels. • DH concentration was changed to see the effect on crack growth and oxide structure. • Warm-rolled stainless steels showed higher rates of corrosion and crack growth. • Higher DH concentration also promoted the rates of corrosion and crack growth.

  14. Acoustic emisson and ultrasonic wave characteristics in TIG-welded 316 stainless steel

    Science.gov (United States)

    Lee, Jin Kyung; Lee, Joon Hyun; Lee, Sang Pill; Son, In Su; Bae, Dong Su

    2014-05-01

    A TIG welded 316 stainless steel materials will have a large impact on the design and the maintenance of invessel components including pipes used in a nuclear power plant, and it is important to clear the dynamic behavior in the weld part of stainless steel. Therefore, nondestructive techniques of acoustic emission (AE) and ultrasonic wave were applied to investigate the damage behavior of welded stainless steel. The velocity and attenuation ratio of the ultrasonic wave at each zone were measured, and a 10 MHz sensor was used. We investigated the relationship between dynamic behavior and AE parameters analysis and derived the optimum parameters to evaluate the damage degree of the specimen. By measuring the velocity and the attenuation of an ultrasonic wave propagating each zone of the welded stainless steel, the relation of the ultrasonic wave and metal structure at the base metal, heat affected zone (HAZ) metal and weld metal is also discussed. The generating tendency of cumulated counts is similar to that of the load curve. The attenuation ratios from the ultrasonic test results were 0.2 dB/mm at the base zone, and 0.52 dB/mm and 0.61 dB/mm at the HAZ zone and weld zone, respectively.

  15. Grain-to-Grain Variations in NbC Particle Size Distributions in an Austenitic Stainless Steel

    DEFF Research Database (Denmark)

    Barlow, Claire; Ralph, B.; Silverman, B.

    1979-01-01

    Quantitative information has been obtained concerning the size distributions of NbC precipitate particles in different grains in a deformed and aged austenitic stainless steel specimen. The precipitate size distributions obtained differ from one grain to another. The average disparity measured...... between the mean precipitate sizes was a function of the distance betwen the grains compared. The results obtained are considered in terms of differences in precipitation behaviour due to variations in the levels of plastic strain in constituent grains of the deformed specimen....

  16. High temperature and stress corrosion cracking of 310S austenitic stainless steel in wet chloride corrosive environment

    Directory of Open Access Journals (Sweden)

    T. Pornpibunsompop

    2018-01-01

    Full Text Available High temperature corrosion and stress corrosion cracking of 310S austenitic stainless steel in wet chloride environment at a high temperature was investigated. The result showed that high temperature corrosion products mostly consisted of ferrous oxides and chromium oxides. Chloride ions attacked a chromium passive film and strongly reacted with iron and chromium. As a result of metal chlorides being volatized, tunnel of pores inside corrosion layer existed. Intergranular stress corrosion cracking was observed. The oxide originated on surface could act as a crack initiator and a crack propagation would progress along grain boundaries and particularly along tunnel of pores.

  17. Development of stress corrosion cracking resistant welds of 321 stainless steel by simple surface engineering

    Science.gov (United States)

    Mankari, Kamal; Acharyya, Swati Ghosh

    2017-12-01

    We hereby report a simple surface engineering technique to make AISI grade 321 stainless steel (SS) welds resistant to stress corrosion cracking (SCC) in chloride environment. Heat exchanger tubes of AISI 321 SS, welded either by (a) laser beam welding (LBW) or by (b) metal inert gas welding (MIG) were used for the study. The welds had high magnitude of tensile residual stresses and had undergone SCC in chloride environment while in service. The welds were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Subsequently, the welded surfaces were subjected to buffing operation followed by determination of residual stress distribution and surface roughness by XRD and surface profilometer measurements respectively. The susceptibility of the welds to SCC was tested in buffed and un-buffed condition as per ASTM G-36 in boiling MgCl2 for 5 h and 10 h, followed by microstructural characterization by using optical microscope and FESEM. The results showed that the buffed surfaces (both welds and base material) were resistant to SCC even after 10 h of exposure to boiling MgCl2 whereas the un-buffed surfaces underwent severe SCC for the same exposure time. Buffing imparted high magnitude of compressive stresses on the surface of stainless steel together with reduction in its surface roughness and reduction in plastic strain on the surface which made the welded surface, resistant to chloride assisted SCC. Buffing being a very simple, portable and economic technique can be easily adapted by the designers as the last step of component fabrication to make 321 stainless steel welds resistant to chloride assisted SCC.

  18. Temperature distribution of multipass TIG welded AISI 304L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Esme, Ugur; Guven, Onur [Mersin Univ., Tarsus (Turkey); Bayramoglu, Melih; Serin, Hasan [Cukurova Univ., Adana (Turkey); Aydin, Hakan [Uludag Unaiv., Bursa (Turkey); Kazancoglu, Yigit [Izmir Univ. of Economics (Turkey). Dept. of Business Administration

    2011-07-01

    Tungsten inert gas welding (TIG) is one of the most important material-joining processes widely used in industry. AISI type 304L stainless steel plates with 8 and 10 mm thicknesses are widely used in the fabrication of pressure vessels and other components. These plates are mostly joined together by multipass welding methods. The temperature distribution that occurs during multipass welding affects the material microstructure, hardness, mechanical properties, and the residual stresses that will be present in the welded material. Very limited experimental data regarding temperature distribution during multipass welding of plates is available in the literature. Experimental work was carried out to find out the temperature distribution during multipass welding of the AISI 304L stainless steel plates. The temperature distribution curves obtained during the experiments are presented. The average maximum temperature rise during each pass of welding is calculated and plotted against the distance from the weld pad centre line. From these plots, the maximum temperature rise expected in the base plate region during any pass of welding operation can be estimated. (orig.)

  19. Microstructure and Mechanical Properties of 21-6-9 Stainless Steel Electron Beam Welds

    Science.gov (United States)

    Elmer, John W.; Ellsworth, G. Fred; Florando, Jeffrey N.; Golosker, Ilya V.; Mulay, Rupalee P.

    2017-04-01

    Welds can either be stronger or weaker than the base metals that they join depending on the microstructures that form in the fusion and heat-affected zones of the weld. In this paper, weld strengthening in the fusion zone of annealed 21-6-9 stainless steel is investigated using cross-weld tensile samples, hardness testing, and microstructural characterization. Due to the stronger nature of the weld, the cross-weld tensile tests failed in the base metal and were not able to generate true fusion zone mechanical properties. Nanoindentation with a spherical indenter was instead used to predict the tensile behavior for the weld metal. Extrapolation of the nanoindentation results to higher strains was performed using the Steinberg-Guinan and Johnson-Cook strength models, and the results can be used for weld strength modeling purposes. The results illustrate how microstructural refinement and residual ferrite formation in the weld fusion zone can be an effective strengthener for 21-6-9 stainless steel.

  20. Kinetics analysis of two-stage austenitization in supermartensitic stainless steel

    DEFF Research Database (Denmark)

    Nießen, Frank; Villa, Matteo; Hald, John

    2017-01-01

    that the austenitization kinetics is governed by Ni-diffusion and that slow transformation kinetics separating the two stages is caused by soft impingement in the martensite phase. Increasing the lath width in the kinetics model had a similar effect on the austenitization kinetics as increasing the heating-rate....

  1. 77 FR 10773 - Stainless Steel Butt-Weld Pipe Fittings From Italy, Malaysia, and the Philippines; Scheduling of...

    Science.gov (United States)

    2012-02-23

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Stainless Steel Butt-Weld Pipe Fittings From Italy, Malaysia, and the Philippines; Scheduling of... antidumping duty orders on stainless steel butt-weld pipe fittings from Italy, Malaysia, and the Philippines...

  2. COMPETITION BEETWEN DYNAMIC RECUPERATION AND RECRYSTALLIZATION OF ASTM F 138 AUSTENITIC STAINLESS STEEL UTILIZED IN MEDICAL DEVICES

    Directory of Open Access Journals (Sweden)

    Fabio Henrique Casarini Geronimo

    2013-06-01

    Full Text Available ASTM F 138 austenitic stainless steel has being used in the manufacture of orthopedical devices by hot forging. In this work, the flow stress curves are determined by hot torsion tests in a wide range of temperatures and strain rates. With the observed microestrutural evolution by optical microscopy in different hot forming conditions in addiction with EBSD (Electron Backscatter Diffraction techniques it is possible to obtained the recrystallized volume fraction and the misorientation angles of the samples. Due to the intermediate level of stacking fault energy of this material, during the dynamic softening occurs a competition between recrystallization and recovery. The aim of this work is to identify the softening mechanisms in this stainless steel, as well as in which hot work conditions they become more active.

  3. Low-Temperature Nitriding of Deformed Austenitic Stainless Steels with Various Nitrogen Contents Obtained by Prior High-Temperature Solution Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin

    2016-01-01

    In the past decades, high nitrogen steels (HNS) have been regarded as substitutes for conventional austenitic stainless steels because of their superior mechanical and corrosion properties. However, the main limitation to their wider application is their expensive production process....... As an alternative, high-temperature solution nitriding has been applied to produce HNS from three commercially available stainless steel grades (AISI 304L, AISI 316, and EN 1.4369). The nitrogen content in each steel alloy is varied and its influence on the mechanical properties and the stability of the austenite...

  4. Heat transfer and fluid flow during laser spot welding of 304 stainless steel

    CERN Document Server

    He, X; Debroy, T

    2003-01-01

    The evolution of temperature and velocity fields during laser spot welding of 304 stainless steel was studied using a transient, heat transfer and fluid flow model based on the solution of the equations of conservation of mass, momentum and energy in the weld pool. The weld pool geometry, weld thermal cycles and various solidification parameters were calculated. The fusion zone geometry, calculated from the transient heat transfer and fluid flow model, was in good agreement with the corresponding experimentally measured values for various welding conditions. Dimensional analysis was used to understand the importance of heat transfer by conduction and convection and the roles of various driving forces for convection in the weld pool. During solidification, the mushy zone grew at a rapid rate and the maximum size of the mushy zone was reached when the pure liquid region vanished. The solidification rate of the mushy zone/liquid interface was shown to increase while the temperature gradient in the liquid zone at...

  5. Mechanical property degradation and microstructural evolution of cast austenitic stainless steels under short-term thermal aging

    Energy Technology Data Exchange (ETDEWEB)

    Lach, Timothy G.; Byun, Thak Sang; Leonard, Keith J.

    2017-12-01

    Mechanical testing and microstructural characterization were performed on short-term thermally aged cast austenitic stainless steels (CASS) to understand the severity and mechanisms of thermal-aging degradation experienced during extended operation of light water reactor (LWR) coolant systems. Four CASS materials – CF3, CF3M, CF8, and CF8M – were thermally aged for 1500 hours at 290 °C, 330 °C, 360 °C, and 400 °C. All four alloys experienced insignificant change in strength and ductility properties but a significant reduction in absorbed impact energy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/ α`, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ ferrite interphase boundary, and growth of M23C6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on chemical composition, particularly the concentration of C and Mo, and aging temperature. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation for predictive evaluations of LWR coolant system components.

  6. Comprehensive Deformation Analysis of a Newly Designed Ni-Free Duplex Stainless Steel with Enhanced Plasticity by Optimizing Austenite Stability

    Science.gov (United States)

    Moallemi, Mohammad; Zarei-Hanzaki, Abbas; Eskandari, Mostafa; Burrows, Andrew; Alimadadi, Hossein

    2017-08-01

    A new metastable Ni-free duplex stainless steel has been designed with superior plasticity by optimizing austenite stability using thermodynamic calculations of stacking fault energy and with reference to literature findings. Several characterization methods comprising optical microscopy, magnetic phase measurements, X-ray diffraction (XRD) and electron backscattered diffraction were employed to study the plastic deformation behavior and to identify the operating plasticity mechanisms. The results obtained show that the newly designed duplex alloy exhibits some extraordinary mechanical properties, including an ultimate tensile strength of 900 MPa and elongation to fracture of 94 pct due to the synergistic effects of transformation-induced plasticity and twinning-induced plasticity. The deformation mechanism of austenite is complex and includes deformation banding, strain-induced martensite formation, and deformation-induced twinning, while the ferrite phase mainly deforms by dislocation slip. Texture analysis indicates that the Copper and Rotated Brass textures in austenite (FCC phase) and {001} texture in ferrite and martensite (BCC phases) are the main active components during tensile deformation. The predominance of these components is logically related to the strain-induced martensite and/or twin formation.

  7. Effect of weld thermal cycle on helium bubble formation in stainless steel

    Science.gov (United States)

    Kano, F.; Nakahigashi, S.; Nakamura, H.; Uesugi, N.; Mitamura, T.; Terasawa, M.; Irie, H.; Fukuya, K.

    1998-10-01

    Helium bubble structure was examined on a helium-implanted stainless steel after applying two kinds of heat input. Helium ions were implanted on Type 304 stainless steel at 573 K from 2 to 200 appm to a peak depth of 0.5 μm from the surface. After that, weld thermal history was applied by an electron beam. The cooling rates were selected to be 370 and 680 K/s from 1023 to 773 K. TEM observation revealed that nucleation and growth of helium bubbles were strongly dependent on the cooling rate after welding and the helium concentration.

  8. Effects of Multiple Treatments of Low-Temperature Colossal Supersaturation on Tribological Characteristics of Austenitic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jun [ORNL; Blau, Peter Julian [ORNL; Zhang, Ligong [University of Central Florida; Xu, Hanbing [ORNL

    2008-01-01

    An alternative carburization process, low-temperature colossal supersaturation (LTCSS), has demonstrated significant improvement on both wear- and corrosion-resistance for austenitic stainless steel surfaces in recent literature. This study explores the effects of multiple treatments of LTCSS on tribological characteristics for Type 316 stainless steel. Thicker carburized layers were produced by multiple LTCSS treatments, with 30, 45, and 55 m for one, two, and four treatments, respectively. Although the hardness remains unchanged at low-load microindentation, multiple treatments have showed higher values in both microindentation and scratch hardness tests when deeper penetrations occurred under heavier loads. The friction and wear characteristics of Type 316 stainless steel with multiple LTCSS treatments were evaluated in non-lubricated unidirectional sliding (pin-on-disk) against Type 440C stainless steel. While little change was observed on friction behavior, substantial further improvement on wear-resistance has been achieved for the multiple treatments. In addition, the wear of the counterface was also largely reduced when rubbing against a multiple-treated surface.

  9. Linear Friction Welding Process Model for Carpenter Custom 465 Precipitation-Hardened Martensitic Stainless Steel

    Science.gov (United States)

    2014-04-11

    stainless steel (Ref 13). The work Fig. 1 A schematic of a single cycle of the Linear Friction Welding (LFW) process Fig. 2 First four phases of the LFW...have a small electronegativity difference. This is achieved by ensuring that the precipitate phase is of an intermetallic character (Ref 18). 2.1 Heat...thermodynamics and kinetics of various interacting and competing phase transformations which may take place within the weld region of this material. For example

  10. Laser/TIG Hybrid Welding of Pot for Induction Heater

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove; Sondrup, Lars de Caldas

    2004-01-01

    In this paper, systematic work is presented that shows the steps for realizing a hybrid welded tailored blank that is formed to a pot for induction heating. The bottom is made of ferritic stainless steel and the sides of austenitic stainless steel. Only the bottom will then interact directly...

  11. Microstructural characteristics on bead on plate welding of AISI 904 ...

    African Journals Online (AJOL)

    In the present work, bead-on -plate welds were carried out on AISI 904 L super austenitic stainless steel sheets using Gas Metal Arc Welding (GMAW) process. In this present investigation AISI 904 L solid wire having 1.2 mm diameter was used as an electrode with direct current electrode positive polarity. Argon was ...

  12. Microstructural characteristics on bead on plate welding of AISI 904 ...

    African Journals Online (AJOL)

    user

    Abstract. In the present work, bead-on -plate welds were carried out on AISI 904 L super austenitic stainless steel sheets using Gas. Metal Arc Welding (GMAW) process. In this present investigation AISI 904 L solid wire having 1.2 mm diameter was used as an electrode with direct current electrode positive polarity.

  13. Aspects and mechanisms of austenitic stainless steel corrosion in case of sodium leaks under mineral wool insulation

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, C.; Ardellier, A.

    1996-12-31

    Sodium pipe rupture tests representative of Fast Reactors Accidents have been carried out on austenitic stainless steel surfaces. These tests improve our knowledge of small sodium leakage propagation in mineral wool insulation. They explain the new and unexpected aspects of the crevice corrosion phenomenon which has been observed on austenitic stainless steel pipe surfaces. Experimental results show that corrosion is limited to a peripheral annular zone, which extends out in concentric waves. The diameter of this corrosion zone is practically constant. Tests show that sodium does not expand directly on the pipe surface. Sodium sprays through mineral wool insulation, where chemical reaction between silica fibers, occluded oxygen and water vapor occur at the same time. Simultaneously, there is a diffusion phenomenon of liquid Na droplets on the mineral wool fibers. The study allows to prove the electrochemical nature of the corrosion. The excess liquid Na, spraying as droplets induces an anodic dissolution mechanism by differential aeration. This phenomenon explains the random microscopic and macroscopic aspects of material removal. (authors). 1 ref., 16 figs.

  14. Aspects and mechanisms of austenitic stainless steel corrosion in case of sodium leaks under mineral wool insulation

    Energy Technology Data Exchange (ETDEWEB)

    Bertrand, C.; Ardellier, A. [Commissariat a l`Energie Atomique, Saint-Paul-Lez-Durance (France)

    1996-10-01

    Sodium pipe rupture tests representative of Fast Reactors accidents have been carried out on austenitic stainless steel surfaces. These tests improve the authors knowledge of small sodium leakage propagation in mineral wool insulation. Furthermore, they explain the new and unexpected aspects of the crevice corrosion phenomenon which has been observed on austenitic stainless steel external pipe surfaces. Experimental results show that the corrosion is limited to a peripheral annular zone, which extends out in concentric waves. The diameter of this corrosion zone is practically constant. Furthermore, the tests show that sodium does not expand directly on the pipe surface. The sodium sprays through the mineral wool insulation, where chemical reactions between silica fibers, occluded oxygen and water vapor occur at the same time. Simultaneously, there is a diffusion phenomenon of liquid sodium droplets on the mineral wool fibers. The study allows to prove the electrochemical nature of the corrosion. The excess liquid sodium, spraying as droplets on the pipe surface, induces an anodic dissolution mechanism by differential aeration. This phenomenon explains the random microscopic and macroscopic aspects of material removal.

  15. Effects of concentration of sodium chloride solution on the pitting corrosion behavior of AISI 304L austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Asaduzzaman M.D.

    2011-01-01

    Full Text Available The pitting corrosion behavior of the austenitic stainless steel in aqueous chloride solution was investigated using electrochemical technique. Corrosion potential (Ecorr measurement, potentiodynamic experiments, potential-hold experiments in the passive range, and microscopic examination were used for the evaluation of corrosion characteristics. The experimental parameters were chloride ion concentration, immersion time and anodic-hold potential. Ecorr measurements along with microscopic examinations suggest that in or above 3.5 % NaCl at pH 2 pitting took place on the surface in absence of applied potential after 6 hour immersion. The potentiodynamic experiment reveals that Ecorr and pitting potential (Epit decreased and current density in the passive region increased with the increase of chloride ion concentrations. A linear relationship between Epit and chloride ion concentrations was found in this investigation. The analysis of the results suggests that six chloride ions are involved for the dissolution of iron ion in the pitting corrosion process of austenitic stainless steel.

  16. Study of Creep of Alumina-Forming Austenitic Stainless Steel for High-Temperature Energy Applications

    Science.gov (United States)

    Afonina, Natalie Petrovna

    To withstand the high temperature (>700°C) and pressure demands of steam turbines and boilers used for energy applications, metal alloys must be economically viable and have the necessary material properties, such as high-temperature creep strength, oxidation and corrosion resistance, to withstand such conditions. One promising class of alloys potentially capable of withstanding the rigors of aggressive environments, are alumina-forming austenitic stainless steels (AFAs) alloyed with aluminum to improve corrosion and oxidation resistance. The effect of aging on the microstructure, high temperature constant-stress creep behavior and mechanical properties of the AFA-type alloy Fe-20Cr-30Ni-2Nb-5Al (at.%) were investigated in this study. The alloy's microstructural evolution with increased aging time was observed prior to creep testing. As aging time increased, the alloy exhibited increasing quantities of fine Fe2Nb Laves phase dispersions, with a precipitate-free zone appearing in samples with higher aging times. The presence of the L1 2 phase gamma'-Ni3Al precipitate was detected in the alloy's matrix at 760°C. A constant-stress creep rig was designed, built and its operation validated. Constant-stress creep tests were performed at 760°C and 35MPa, and the effects of different aging conditions on creep rate were investigated. Specimens aged for 240 h exhibited the highest creep rate by a factor of 5, with the homogenized sample having the second highest rate. Samples aged for 2.4 h and 24 h exhibited similar low secondary creep rates. Creep tests conducted at 700oC exhibited a significantly lower creep rate compared to those at 760oC. Microstructural analysis was performed on crept samples to explore high temperature straining properties. The quantity and size of Fe2Nb Laves phase and NiAl particles increased in the matrix and on grain boundaries with longer aging time. High temperature tensile tests were performed and compared to room temperature results. The

  17. Microstructure and pitting corrosion of shielded metal arc welded high nitrogen stainless steel

    Directory of Open Access Journals (Sweden)

    Raffi Mohammed

    2015-09-01

    Full Text Available The present work is aimed at studying the microstructure and pitting corrosion behaviour of shielded metal arc welded high nitrogen steel made of Cromang-N electrode. Basis for selecting this electrode is to increase the solubility of nitrogen in weld metal due to high chromium and manganese content. Microscopic studies were carried out using optical microscopy (OM and field emission scanning electron microscopy (FESEM. Energy back scattered diffraction (EBSD method was used to determine the phase analysis, grain size and orientation image mapping. Potentio-dynamic polarization testing was carried out to study the pitting corrosion resistance in aerated 3.5% NaCl environment using a GillAC electrochemical system. The investigation results showed that the selected Cr–Mn–N type electrode resulted in a maximum reduction in delta-ferrite and improvement in pitting corrosion resistance of the weld zone was attributed to the coarse austenite grains owing to the reduction in active sites of the austenite/delta ferrite interface and the decrease in galvanic interaction between austenite and delta-ferrite.

  18. Effect of Nb Addition to Ti-Bearing Super Martensitic Stainless Steel on Control of Austenite Grain Size and Strengthening

    Science.gov (United States)

    Ma, Xiaoping; Langelier, Brian; Gault, Baptiste; Subramanian, Sundaresa

    2017-05-01

    The role of Nb in normalized and tempered Ti-bearing 13Cr5Ni2Mo super martensitic stainless steel is investigated through in-depth characterization of the bimodal chemistry and size of Nb-rich precipitates/atomic clusters and Nb in solid solution. Transmission electron microscopy and atom probe tomography are used to analyze the samples and clarify precipitates/atom cluster interactions with dislocations and austenite grain boundaries. The effect of 0.1 wt pct Nb addition on the promotion of (Ti, Nb)N-Nb(C,N) composite precipitates, as well as the retention of Nb in solution after cooling to room temperature, are analyzed quantitatively. (Ti, Nb)N-Nb(C,N) composite precipitates with average diameters of approximately 24 ± 8 nm resulting from epitaxial growth of Nb(C,N) on pre-existing (Ti,Nb)N particles, with inter-particle spacing on the order of 205 ± 68 nm, are found to be associated with mean austenite grain size of 28 ± 10 µm in the sample normalized at 1323 K (1050 °C). The calculated Zener limiting austenite grain size of 38 ± 13 µm is in agreement with the experimentally observed austenite grain size distribution. 0.08 wt pct Nb is retained in the as-normalized condition, which is able to promote Nb(C, N) atomic clusters at dislocations during tempering at 873 K (600 °C) for 2 hours, and increases the yield strength by 160 MPa, which is predicted to be close to maximum increase in strengthening effect. Retention of solute Nb before tempering also leads to it preferentially combing with C and N to form Nb(C, N) atom clusters, which suppresses the occurrence of Cr- and Mo-rich carbides during tempering.

  19. Evaluation of Distortion in Welding Unions of 304 Stainless Steel with Elliptic Trajectory Using a Welding Robot

    Science.gov (United States)

    Carrasco-González, L. A.; Hurtado-Delgado, E.; Reyes-Valdés, F. A.

    The aim of this investigation is to evaluate the distortions generated in welding unions of stainless steel 304 by effect of the welding temperature and the microestructural changes. The joint design is a 100 × 100 mm steel plate of 3 mm thickness. The plate was joined to a tube of 50 mm diameter and 2 mm thickness, which has a defined angular cut; therefore, the trajectory followed by the seam has an elliptic form. Temperature data acquisition was developed by type K thermocouples, placed in pairs at 0°, 90°, 180° and 270° along the welding trajectory and connected to a data acquisition device yo obtain the measures to generate time-temperature plots. The welding process was executed by a KUKA ®; KR16 welding robot with an integrated GMAW (Gas metal arc welding) process where the input parameters of voltage, wire feed and travel speed are set to constant. The distortion of the work piece was measured using a laser scanning technique that generates a point cloud with the VXelements TM software for comparison between the pre and post-weld condition. Microstructural evaluation was performed on transversal sections of the seam, at the mentioned angles for correlation.

  20. Quantitative evaluation of ultrasonic wave propagation in inhomogeneous anisotropic austenitic welds using 3D ray tracing method. Numerical and experimental validation

    Energy Technology Data Exchange (ETDEWEB)

    Kolkoori, Sanjeevareddy

    2014-07-01

    Austenitic welds and dissimilar welds are extensively used in primary circuit pipes and pressure vessels in nuclear power plants, chemical industries and fossil fuelled power plants because of their high fracture toughness, resistance to corrosion and creep at elevated temperatures. However, cracks may initiate in these weld materials during fabrication process or stress operations in service. Thus, it is very important to evaluate the structural integrity of these materials using highly reliable non-destructive testing (NDT) methods. Ultrasonic non-destructive inspection of austenitic welds and dissimilar weld components is complicated because of anisotropic columnar grain structure leading to beam splitting and beam deflection. Simulation tools play an important role in developing advanced reliable ultrasonic testing (UT) techniques and optimizing experimental parameters for inspection of austenitic welds and dissimilar weld components. The main aim of the thesis is to develop a 3D ray tracing model for quantitative evaluation of ultrasonic wave propagation in an inhomogeneous anisotropic austenitic weld material. Inhomogenity in the anisotropic weld material is represented by discretizing into several homogeneous layers. According to ray tracing model, ultrasonic ray paths are traced during its energy propagation through various discretized layers of the material and at each interface the problem of reflection and transmission is solved. The influence of anisotropy on ultrasonic reflection and transmission behaviour in an anisotropic austenitic weld material are quantitatively analyzed in three dimensions. The ultrasonic beam directivity in columnar grained austenitic steel material is determined three dimensionally using Lamb's reciprocity theorem. The developed ray tracing model evaluates the transducer excited ultrasonic fields accurately by taking into account the directivity of the transducer, divergence of the ray bundle, density of rays and phase

  1. Intermetallic diffusion coatings for enhanced hot-salt oxidation resistance of nitrogen-containing austenitic stainless steels

    Science.gov (United States)

    Mudali, U. Kamachi; Bhuvaneswaran, N.; Shankar, P.; Khatak, H. S.; Raj, B.

    2004-06-01

    This article presents the preparation, characterization, and hot-salt oxidation behavior of nitrogen-containing type 316L stainless steel (SS), surface modified with intermetallic coatings. Three different types of intermetallic coating systems, containing aluminum, titanium, and titanium/aluminum multilayers, were formed by diffusion annealing of type 316L austenitic SS containing 0.015, 0.1, 0.2, and 0.56 pct nitrogen. Analysis by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and secondary ion mass spectroscopy (SIMS) confirmed the formation of various intermetallic phases such as AIN, Al13Fe4, FeAl2, FeTi, Ti2N, and Ti3Al in the coatings. Hot salt oxidation behavior of the uncoated and surface-modified stainless steels was assessed by periodic monitoring of the weight changes of NaCl salt-applied alloys kept in an air furnace at 1023 K up to 250 hours. The oxide scales formed were examined by XRD and stereomicroscopy. Among the various surface modifications investigated in the present study, the results indicate that the titanium-modified alloys show the best hot-salt oxidation resistance with the formation of an adherent, protective, thin, and continuous oxide layer. Among the four N-containing alloys investigated, the titanium and Ti/Al multilayer modified 0.56 pct N alloy showed the best hot-salt oxidation resistance as compared to uncoated alloys. The slower corrosion kinetics and adherent scale morphology indicate that the surface-modified titanium intermetallic coatings could provide high-temperature service applications up to 1073 K, particularly in chloride containing atmospheres, for austenitic stainless steels.

  2. Low-Temperature Nitriding of Deformed Austenitic Stainless Steels with Various Nitrogen Contents Obtained by Prior High-Temperature Solution Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin

    2016-01-01

    In the past decades, high nitrogen steels (HNS) have been regarded as substitutes for conventional austenitic stainless steels because of their superior mechanical and corrosion properties. However, the main limitation to their wider application is their expensive production process. As an altern...

  3. Effect of Plastic Pre-straining on Residual Stress and Composition Profiles in Low-Temperature Surface-Hardened Austenitic Stainless Steel

    DEFF Research Database (Denmark)

    Bottoli, Federico; Christiansen, Thomas Lundin; Winther, Grethe

    2016-01-01

    The present work deals with the evaluation of the residual stress profiles in expanded austenite by applying grazing incidence X-ray diffraction (GI-XRD) combined with successive sublayer removal. Annealed and deformed (εeq=0.5) samples of stable stainless steel EN 1.4369 were nitrided or nitroca...

  4. Modeling precipitation thermodynamics and kinetics in type 316 austenitic stainless steels with varying composition as an initial step toward predicting phase stability during irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Jae-Hyeok, E-mail: jhshim@kist.re.kr [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Povoden-Karadeniz, Erwin [Christian Doppler Laboratory for Early Stages of Precipitation, Vienna University of Technology, A-1040 Vienna (Austria); Kozeschnik, Ernst [Institute of Materials Science and Technology, Vienna University of Technology, A-1040 Vienna (Austria); Wirth, Brian D. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2015-07-15

    Highlights: • We model the precipitation kinetics in irradiated 316 austenitic stainless steels. • Radiation-induced phases are predicted to form at over 10 dpa segregation conditions. • The Si content is the most critical for the formation of radiation-induced phases. - Abstract: The long-term evolution of precipitates in type 316 austenitic stainless steels at 400 °C has been simulated using a numerical model based on classical nucleation theory and the thermodynamic extremum principle. Particular attention has been paid to the precipitation of radiation-induced phases such as γ′ and G phases. In addition to the original compositions, the compositions for radiation-induced segregation at a dose level of 5, 10 or 20 dpa have been used in the simulation. In a 316 austenitic stainless steel, γ′ appears as the main precipitate with a small amount of G phase forming at 10 and 20 dpa. On the other hand, G phase becomes relatively dominant over γ′ at the same dose levels in a Ti-stabilized 316 austenitic stainless steel, which tends to suppress the formation of γ′. Among the segregated alloying elements, the concentration of Si seems to be the most critical for the formation of radiation-induced phases. An increase in dislocation density as well as increased diffusivity of Mn and Si significantly enhances the precipitation kinetics of the radiation-induced phases within this model.

  5. A Plasma Control and Gas Protection System for Laser Welding of Stainless Steel

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther; Olsen, Flemming Ove

    1997-01-01

    A prototype shield gas box with different plasma control nozzles have been investigated for laser welding of stainless steel (AISI 316). Different gases for plasma control and gas protection of the weld seam have been used. The gas types, welding speed and gas flows show the impact on process...... stability and protection against oxidation. Also oxidation related to special conditions at the starting edge has been investigated. The interaction between coaxial and plasma gas flow show that the coaxial flow widens the band in which the plasma gas flow suppresses the metal plasma. In this band the welds...... are oxide free. With 2.7 kW power welds have been performed at 4000 mm/min with Ar / He (70%/30%) as coaxial, plasma and shield gas....

  6. Plasma Control and Gas Protection System for Laser Welding of Stainless Steel

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther; Olsen, Flemming Ove; Petersen, Kaj

    1997-01-01

    An integrated plasma nozzle and a shield gas box have been investigated for laser welding of 2 mm stainless steel sheets. Different gases for plasma control and gas protection of the weld seam have been used. The gas types, welding speed and coaxial and plasma flow show the impact on process...... stability and protection against oxidation. Also oxidation related to special conditions at the starting edge has been investigated. The interaction between coaxial and plasma gas flow show that the coaxial flow widens the band in which the plasma gas flow suppresses the metal plasma. In this band the welds...... are oxide free. With 2.7 kW power welds have been performed at 3000 mm/min with Ar / He (70%/30%) as coaxial, plasma and shield gas....

  7. 77 FR 39735 - Stainless Steel Butt-Weld Pipe Fittings From Italy, Malaysia, and the Philippines

    Science.gov (United States)

    2012-07-05

    ...)] Stainless Steel Butt-Weld Pipe Fittings From Italy, Malaysia, and the Philippines Determination On the basis..., Malaysia, and the Philippines would be likely to lead to continuation or recurrence of material injury to... Pipe Fittings from Italy, Malaysia, and the Philippines: Inv. Nos. 731-TA-865-867 (Second Review...

  8. 78 FR 35253 - Welded Stainless Pressure Pipe From Malaysia, Thailand, and the Socialist Republic of Vietnam...

    Science.gov (United States)

    2013-06-12

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE...-3931, (202) 482-5075, or at (202) 482-2924, respectively, AD/CVD Operations, Office 7, Import... Initiation Checklist: Welded Stainless Pressure Pipe from Malaysia (Malaysia Checklist), Antidumping Duty...

  9. Delta-Ferrite Distribution in a Continuous Casting Slab of Fe-Cr-Mn Austenitic Stainless Steel

    Science.gov (United States)

    Chen, Chao; Cheng, Guoguang

    2017-10-01

    The delta-ferrite distribution in a continuous casting slab of Fe-Cr-Mn stainless steel grade (200 series J4) was analyzed. The results showed that the ferrite fraction was less than 3 pct. The "M" type distribution was observed in the thickness direction. For the distribution at the centerline, the maximum ferrite content was found in the triangular zone of the macrostructure. In addition, in this zone, the carbon and sulfur were severely segregated. Furthermore, an equilibrium solidification calculation by Thermo-Calc® software indicates that the solidification mode of the composition in this triangular zone is the same as the solidification mode of the averaged composition, i.e., the FA (ferrite-austenite) mode. None of the nickel-chromium equivalent formulas combined with the Schaeffler-type diagram could predict the ferrite fraction of the Cr-Mn stainless steel grade in a reasonable manner. The authors propose that more attention should be paid to the development of prediction models for the ferrite fraction of stainless steels under continuous casting conditions.

  10. On the Stress Corrosion Cracking and Hydrogen Embrittlement Behavior of Austenitic Stainless Steels in Boiling Saturated Magnesium Chloride Solutions

    Directory of Open Access Journals (Sweden)

    Osama M. Alyousif

    2012-01-01

    Full Text Available The stress corrosion cracking (SCC and hydrogen embrittlement (HE behaviors for types 304, 310, and 316 austenitic stainless steels were investigated in boiling saturated magnesium chloride solutions using a constant load method under different conditions including test temperature, applied stress, and sensitization. Both of type 304 and type 316 stainless steels showed quite similar behavior characteristics, whereas type 310 stainless steel showed a different behavior. The time to failure (tf parameter was used among other parameters to characterize the materials behavior in the test solution and to develop a mathematical model for predicting the time to failure in the chloride solution. The combination of corrosion curve parameters and fracture surface micrographs gave some explanation for the cracking modes as well as an indication for the cracking mechanisms. On the basis of the results obtained, it was estimated that intergranular cracking was resulted from hydrogen embrittlement due to strain-induced formation of martensite along the grain boundaries, while transgranular cracking took place by propagating cracks nucleated at slip steps by dissolution.

  11. Structural stability and hardness of carburized surfaces of 316 stainless steel after welding and after neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, K. [Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, MS-6151, Oak Ridge, TN 37831 (United States)]. E-mail: p-k-f@comcast.net; Byun, T.S. [Metals and Ceramics Division, Oak Ridge National Laboratory, P.O. Box 2008, MS-6151, Oak Ridge, TN 37831 (United States)

    2006-09-15

    Surface hardening treatments offer promise of mitigating the threat of liquid cavitation pitting erosion at the interior surfaces of the austenitic 316 stainless steel vessel that will hold the liquid mercury target of the Spallation Neutron Source. One treatment is a commercial carburization process in which carbon is impregnated at low temperature at concentrations up to 6 wt% in supersaturated solid solution to depths of about 33 {mu}m. The surface hardness of 316L steel is raised from 150 to 200HV{sub 0.05} (micro-Vickers hardness number at a 50 g load) to 1000-1200HV{sub 0.05}. It is shown that during subsequent electron beam welding the supersaturated carburized layer in the heat affected zone decomposes to a tiered microstructure of carbide phases in austenite. The hardness of this complex decomposition microstructure is in the range 530-1200HV{sub 0.05}, depending on the exposure temperature, the local carbon level, and the size of the carbide particles. To test whether the carburized solid solution layer would break down under atomic displacements from proton and neutron irradiation in service, specimens of annealed and 20% cold-rolled 316LN steel were neutron irradiated to 1 dpa at 60-100 deg. C. No softening of the layer was detected. Rather, the hardness of the layers was increased by 2-12%, compared to increases of 81% and 43% for the annealed and 20% cold rolled substrate materials, respectively. Optical microscopy examinations of the surfaces of the as-carburized-and-irradiated specimens revealed no sign of decomposition attributable to irradiation.

  12. Thermal fatigue cracking of austenitic stainless steels; Fissuration en fatigue thermique des aciers inoxydables austenitiques

    Energy Technology Data Exchange (ETDEWEB)

    Fissolo, A

    2001-07-01

    This report deals with the thermal fatigue cracking of austenitic stainless steels as AISI 316 LN and 304 L. Such damage has been clearly observed for some components used in Fast Breeder reactors (FBR) and Pressure Water Reactor (PWR). In order to investigate thermal fatigue, quasi-structural specimen have been used. In this frame, facilities enforcing temperature variations similar to those found under the operation conditions have been progressively developed. As for components, loading results from impeded dilatation. In the SPLASH facility, the purpose was to establish accurate crack initiation conditions in order to check the relevance of the usual component design methodology. The tested specimen is continuously heated by the passage of an electrical DC current, and submitted to cyclic thermal down shock (up to 1000 deg C/s) by means of periodical spraying of water on two opposite specimen faces. The number of cycles to crack initiation N{sub i} is deduced from periodic examinations of the quenched surfaces, by means of optical microscopy. It is considered that initiation occurs when at least one 50{mu}m to 150{open_square}m long crack is observed. Additional SPLASH tests were performed for N >> N{sub i}, with a view to investigate the evolution of a surface multiple cracking network with the number of cycles N. The CYTHIA test was mainly developed for the purpose of assessing crack growth dynamics of one isolated crack in thermal fatigue conditions. Specimens consist of thick walled tubes with a 1 mm circular groove is spark-machined at the specimen centre. During the test, the external wall of the tube is periodically heated by using a HF induction coil (1 MHz), while its internal wall is permanently cooled by flowing water. Total crack growth is derived from post-mortem examinations, whereby the thermal fatigue final rupture surface is oxidized at the end of the test. The specimen is broken afterwards under mechanical fatigue at room temperature. All the

  13. Discontinuous precipitation in a nickel-free high nitrogen austenitic stainless steel on solution nitriding

    DEFF Research Database (Denmark)

    Mohammadzadeh, Roghayeh; Akbari, Alireza; Grumsen, Flemming Bjerg

    2017-01-01

    elements between austenite and nitrides, with chromium contents of about 80 wt.% in the precipitates. XRD analysis indicated that the Chromium-rich nitride precipitates are hexagonal (Cr, Mo)2N. Based on the TEM studies, (Cr, Mo)2N precipitates presented a (1 1 1)γ//(0 0 2)(Cr, Mo)2N, (Formula presented......, morphology and crystallographic orientation between the resulted austenite and precipitates were investigated using optical microscopy, X-ray Diffraction (XRD), Scanning and Transmission Electron Microscopy (TEM) and Electron Back Scatter Diffraction (EBSD). On prolonged nitriding, Chromium-rich nitride...

  14. Friction Stir Welding of Stainless Steel to Al Alloy: Effect of Thermal Condition on Weld Nugget Microstructure

    Science.gov (United States)

    Ghosh, M.; Gupta, R. K.; Husain, M. M.

    2014-02-01

    Joining of dissimilar materials is always a global challenge. Sometimes it is unavoidable to execute multifarious activities by a single component. In the present investigation, 6061 aluminum alloy and 304 stainless steel were joined by friction stir welding (FSW) at different tool rotational rates. Welded joints were characterized in optical and scanning electron microscopes. Reaction products in the stirring zone (SZ) were confirmed through X-ray diffraction. Joint strength was evaluated by tensile testing. It was found that the increment in average heat input and temperature at the weld nugget (WN) facilitated iron enrichment near the interface. Enhancement in the concentration of iron shifted the nature of intermetallics from the Fe2Al5 to Fe-rich end of the Fe-Al binary phase diagram. The peak microhardness and ultimate tensile strength were found to be maxima at the intermediate tool rotational rate, where Fe3Al and FeAl2 appeared along with Fe2Al5.

  15. Mehanical Properties of Electron Beam Welded Joints in Thick Gage CA6NM Stainless Steel

    Science.gov (United States)

    Sarafan, Sheida; Wanjara, Priti; Gholipour, Javad; Champliaud, Henri; Mathieu, Louis

    2017-10-01

    Design of hydroelectric turbine components requires high integrity welds (without detectable volumetric defects) in heavy gage sections of stainless steel materials, such as ASTM A743 grade CA6NM—a low carbon 13% Cr-4% Ni martensitic stainless steel that is manufactured in cast form. In this work, 90-mm-thick plates of CA6NM were joined using a single-pass autogenous electron beam (EB) welding process and the mechanical properties were evaluated in the as-welded condition to characterize the performance of the joints. The static tensile properties that were evaluated in two directions—transverse and longitudinal to the EB weld seam—demonstrated conformance of the joints with the requirements of the ASME Section IX standard. The Charpy impact energies of the EB welds—measured at -18 °C on samples with V-notch roots located in the fusion and heat-affected zones—met the minimum requirements of 27 J specified in ASME Section VIII standard. In addition, bend tests that were conducted on the entire weld cross section displayed no discontinuities on the tension side of the bent joints. Hence, the developed EB welding process was demonstrated to render high-performance joints and promises key advantages for industrialization, such as cost savings through reductions in consumable material, production time and labor intensity.

  16. Mehanical Properties of Electron Beam Welded Joints in Thick Gage CA6NM Stainless Steel

    Science.gov (United States)

    Sarafan, Sheida; Wanjara, Priti; Gholipour, Javad; Champliaud, Henri; Mathieu, Louis

    2017-09-01

    Design of hydroelectric turbine components requires high integrity welds (without detectable volumetric defects) in heavy gage sections of stainless steel materials, such as ASTM A743 grade CA6NM—a low carbon 13% Cr-4% Ni martensitic stainless steel that is manufactured in cast form. In this work, 90-mm-thick plates of CA6NM were joined using a single-pass autogenous electron beam (EB) welding process and the mechanical properties were evaluated in the as-welded condition to characterize the performance of the joints. The static tensile properties that were evaluated in two directions—transverse and longitudinal to the EB weld seam—demonstrated conformance of the joints with the requirements of the ASME Section IX standard. The Charpy impact energies of the EB welds—measured at -18 °C on samples with V-notch roots located in the fusion and heat-affected zones—met the minimum requirements of 27 J specified in ASME Section VIII standard. In addition, bend tests that were conducted on the entire weld cross section displayed no discontinuities on the tension side of the bent joints. Hence, the developed EB welding process was demonstrated to render high-performance joints and promises key advantages for industrialization, such as cost savings through reductions in consumable material, production time and labor intensity.

  17. Microbially influenced corrosion of stainless steel welds; Stainless ko yosetsubu no biseibutsu yuki fushoku no kisoteki kento

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Y.; Tomoto, K.; Okayama, C.; Matsuda, F. [Osaka University, Osaka (Japan). Joining and Welding Research Institute; Nishimura, M. [Mitsubishi Kakoki Kaisha Ltd., Tokyo (Japan); Sakane, T. [Institute for Fermentation, Osaka (Japan); Kaneko, Y. [Osaka University, Osaka (Japan). Faculty of Engineering

    1997-06-20

    This paper describes sensitivities of microbiologically influenced corrosion (MIC) for various stainless steels. The failure in the weld joint of SUS steel pipes occurred in about 60 days from the start-up of the sewage treatment plant. Any welding defects were not found, and the corrosion rate of welds was estimated to be 18 mm per year which was too fast. The corrosion was reproduced using the residual liquid from effluent treatment plant in laboratory. Corrosion pits and bacteria adhering around these were observed at the same time. For the experiments using boiled and sterilized waste water, corrosion did not occur. As a result, MIC was confirmed. Seven kinds of bacteria were separated and identified from the waste water. Among individual bacteria separated and incubated, Methylobacterium sp. and Arthrobacter sp. showed the most strong corrosion properties. It was estimated that these bacteria produced organic acid and its concentration became high locally at the site adhered by bacteria to generate the corrosion. The MIC was observed for several kinds of stainless steels used. There was not a significant difference in anti-corrosion due to the kind of steel. 19 refs., 10 figs., 4 tabs.

  18. Effect of Composition on the Formation of Delta Ferrite in 304L Austenitic Stainless Steels During Hot Deformation

    Science.gov (United States)

    Soleymani, S.; Ojo, O. A.; Richards, N.

    2015-01-01

    Four different AISI 304L austenitic stainless steels with chromium equivalent-to-nickel equivalent (Creq/Nieq) ratios of 1.57, 1.59, 1.62, and 1.81 were chosen for this study. The influence of chemical composition on solid-state formation of delta ferrite phase during hot deformation was investigated. Compression tests were performed at temperature, strain, and strain rate ranges of 1200 to 1300 °C, 10 to 70%, and 0.1 to 10 s-1, respectively. Increasing the temperature, strain, and strain rate led to increased formation of delta ferrite. The results show that the formation of delta ferrite during hot deformation is also strongly dependent on chemical composition. The higher the Creq/Nieq ratio, the higher the tendency for the formation of delta ferrite. The observed behavior may be attributed to plastic deformation-induced formation of crystallographic defects such as dislocations affecting the diffusion rate.

  19. Effect of Grain Size on Void Formation during High-Energy Electron Irradiation of Austenitic Stainless Steel

    DEFF Research Database (Denmark)

    Singh, Bachu Narain

    1974-01-01

    ’ model based on the property of grain boundaries as neutral and unsaturable sinks for vacancies and self-interstitials. It is suggested that even in the presence of sufficiently large amount of impurity gas atoms, a critical level of vacancy supersaturation is necessary to produce critically sized......Thin foils of an ‘ experimental ’ austenitic stainless steel, with and without dispersions of aluminium oxide particles, are irradiated with 1 MeV electrons in a High Voltage Electron Microscope at 600°C. Evidence of grain size dependent void nucleation, void concentration, and void volume swelling...... are presented for grains in the size range 0°45 to 50 μ. In both undoped and helium-doped samples the void nucleation is delayed, void concentration is lowered, and void volume swelling is reduced by decreasing the size of the grain under irradiation. The results are discussed in terms of a ‘ defect depletion...

  20. Kinetics of dynamic recrystallization in Ti-modified 15Cr-15Ni-2Mo austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, A. [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Marchattiwar, A. [Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai 400 076 (India); Chakravartty, J.K., E-mail: jayanta@barc.gov.in [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kashyap, B.P. [Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai 400 076 (India)

    2013-01-15

    The hot working behaviour of Ti-modified 15Cr-15Ni-2Mo austenitic stainless steel (Alloy D9) was studied by hot compression test at temperatures of 900-1200 Degree-Sign C and at strain rates of 0.002-1 s{sup -1}. The progress of dynamic recrystallization (DRX) was modelled by the Avarmi kinetics equation. The flow softening was directly related to the DRX volume fraction and the DRX time was determined by strain rate. For quantification of recrystallization rate, the time corresponding to the DRX fraction of 50% was used. Analysis of the sigmoid-shaped recrystallization curves revealed that the rate of DRX increases with increasing deformation temperature and strain rate. Results of the Avrami analysis were used to predict the DRX flow curves.

  1. Kinetics and critical conditions for initiation of dynamic recrystallization during hot compression deformation of AISI 321 austenitic stainless steel

    Science.gov (United States)

    Ghazani, Mehdi Shaban; Eghbali, Beitallah; Ebrahimi, Gholamreza

    2017-09-01

    Dynamic recrystallization behavior of AISI 321 austenitic stainless steel were studied using hot compression tests over the range of temperatures from 900 °C to 1200 °C and strain rates from 0.001 s-1 to 1 s-1. The critical strain and stress for initiation of dynamic recrystallization were determined by plotting strain hardening rate vs. stress curves and a constitutive equation describing the flow stress at strains lower than peak strain. Also, the strain at maximum flow softening was obtained and the effect of deformation conditions (Z parameter) on the critical strain and stress were analyzed. Finally, the volume fraction of dynamic recrystallization was calculated at different deformation conditions using these critical values. Results showed that the model used for predicting the kinetics of dynamic recrystallization has a great consistency with the data, in the form of θ-ɛ curves, directly acquired from experimental flow curves.

  2. Nitriding using cathodic cage technique of austenitic stainless steel AISI 316 with addition of CH{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, R.R.M. de [Centro Federal de Educacao Tecnologica do Piaui, Departamento de Mecanica, Teresina, PI (Brazil); Araujo, F.O. de [Universidade Federal Rural do Semi-Arido, Departamento de Ciencias Ambientais, Mossoro, RN (Brazil)], E-mail: odolbert@yahoo.com.br; Barbosa, J.C.P.; Ribeiro, K.J.B. [Labplasma, Departamento de Fisica - UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Costa, J.A.P. da [Departamento de Fisica - UFC, Fortaleza, CE (Brazil); Alves, C. [Labplasma, Departamento de Fisica - UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)

    2008-07-25

    Samples of austenitic stainless steel AISI 316 were nitrided using the cathodic cage technique with the addition of methane in the nitriding atmosphere. The aim was to study the influence of this technique in reducing the precipitation of chromium nitrite and in improving the wear resistance. The results show that there was a significant improvement in such properties when compared to the results of ionic plasma nitriding. Formation of a double layer, one more internal composed of carbon and another with high nitrogen content, was confirmed by Scanning Electron Microscopy (SEM). The microhardness profile of the layer showed an increase in hardness values and a larger uniformity, while X-ray analysis showed less chromium nitriding precipitation when compared with results obtained for samples treated using ionic plasma nitriding.

  3. Stress Corrosion Behavior of Low-temperature Liquid-Nitrided 316 Austenitic Stainless Steel in a Sour Environment

    Science.gov (United States)

    Zhang, Xiangfeng; Wang, Jun; Fan, Hongyuan; Yan, Jing; Duan, Lian; Gu, Tan; Xian, Guang; Sun, Lan; Wang, Danqi

    2017-10-01

    Low-temperature nitridation is a widely used surface heat treatment. Low-temperature liquid nitridation was applied to 316 austenitic stainless steel and an S-phase (expanded austenite) layer was achieved on the alloy surface. The effect of the S-phase layer on corrosion resistance and stress corrosion cracking was investigated in a sour environment. When a bending stress of 164 MPa (80 pct yield stress, YS) was applied, no macroscopic corrosion cracking and pits were observed on the nitrided samples and the S-phase layer stayed intact. Although no macroscopic corrosion cracking was observed on the non-nitrided samples under 205 MPa (100 pct YS), some pits were formed on the alloy surface. This could be attributed to the high stresses and hardness, and the excellent corrosion resistance of the S-phase layer introduced by low-temperature nitridation. Supersaturated nitrogen atoms in the S-phase layer can effectively prevent the decrease in pH of the corrosive medium and accelerate the alloy repassivation kinetics. However, when the bending stress was increased to 205 and 246 MPa (100 pct YS, 120 pct YS), macroscopic cracks were observed in the presence of both tensile stress and a corrosive medium.

  4. Stress Corrosion Behavior of Low-temperature Liquid-Nitrided 316 Austenitic Stainless Steel in a Sour Environment

    Science.gov (United States)

    Zhang, Xiangfeng; Wang, Jun; Fan, Hongyuan; Yan, Jing; Duan, Lian; Gu, Tan; Xian, Guang; Sun, Lan; Wang, Danqi

    2018-01-01

    Low-temperature nitridation is a widely used surface heat treatment. Low-temperature liquid nitridation was applied to 316 austenitic stainless steel and an S-phase (expanded austenite) layer was achieved on the alloy surface. The effect of the S-phase layer on corrosion resistance and stress corrosion cracking was investigated in a sour environment. When a bending stress of 164 MPa (80 pct yield stress, YS) was applied, no macroscopic corrosion cracking and pits were observed on the nitrided samples and the S-phase layer stayed intact. Although no macroscopic corrosion cracking was observed on the non-nitrided samples under 205 MPa (100 pct YS), some pits were formed on the alloy surface. This could be attributed to the high stresses and hardness, and the excellent corrosion resistance of the S-phase layer introduced by low-temperature nitridation. Supersaturated nitrogen atoms in the S-phase layer can effectively prevent the decrease in pH of the corrosive medium and accelerate the alloy repassivation kinetics. However, when the bending stress was increased to 205 and 246 MPa (100 pct YS, 120 pct YS), macroscopic cracks were observed in the presence of both tensile stress and a corrosive medium.

  5. Elastic interaction between twins during tensile deformation of austenitic stainless steel

    DEFF Research Database (Denmark)

    Juul, Nicolai Ytterdal; Winther, Grethe; Dale, Darren

    2016-01-01

    In austenite, the twin boundary normal is a common elastically stiff direction shared by the two twins, which may induce special interactions. By means of three-dimensional X-ray diffraction this elastic interaction has been analysed and compared to grains separated by conventional grain boundari...

  6. Modeling of the Austenite-Martensite Transformation in Stainless and TRIP Steels

    NARCIS (Netherlands)

    Geijselaers, Hubertus J.M.; Hilkhuijsen, P.; Bor, Teunis Cornelis; Perdahcioglu, Emin Semih; van den Boogaard, Antonius H.; Zhang, S.-H.; Liu, X.-H.; Gheng, M.; Li, J.

    2013-01-01

    The transformation of austenite to martensite is a dominant factor in the description of the constitutive behavior during forming of TRIP assisted steels. To predict this transformation different models are currently available. In this paper the transformation is regarded as a stress induced process

  7. Quantitative analysis of retained austenite in laser melted martensitic stainless steel

    CSIR Research Space (South Africa)

    Seleka, T

    2007-11-01

    Full Text Available of this study was to determine if X-ray diffraction (XRD) was sufficient for quantifying the volume percentage of retained austenite. After a preliminary qualitative analysis, a Rietveld full pattern refinement program was used to quantify the volume percentage...

  8. Characteristics of oxide scale formed on Cu-bearing austenitic stainless steel during early stages of high temperature oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Swaminathan, Srinivasan, E-mail: swaminathan@kist.re.kr [Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 136 791 (Korea, Republic of); Krishna, Nanda Gopala [Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kim, Dong-Ik, E-mail: dongikkim@kist.re.kr [High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 136 791 (Korea, Republic of)

    2015-10-30

    Highlights: • Initial oxidation characteristics of Cu-bearing austenitic stainless steel at 650 °C were studied. • Strong segregation and oxidation of Mn and Nb were found in the entire oxide scale. • Surface coverage by metallic Cu-rich precipitates increases with exposure time. • Chemical heterogeneity of oxide scale revealed initial oxidation to be non-selective. • Fe-Cr and Mn-Cr mixed oxides were realized along with binary oxides of Fe, Cr and Mn. - Abstract: Oxide scale evolution on Cu-bearing austenitic stainless steel 304H at 650 °C, in ambient air, for exposure times 100, 300, 500 and 1000 h, has been investigated. Surface morphology and chemistry of the oxide scale grown were examined using SEM/EDX and XPS. The oxidation kinetics was determined by measuring the weight change using an electronic balance. At the initial stage, up to 500 h of exposure time, the oxidation rate was rapid due to surface reactions governed primarily by oxygen ingress, and then, dropped to a low rate after prolonged oxidation for 1000 h. The diffusion of reactants through the initially formed oxide scale limits the oxidation rate at longer times, thus, the progress of reaction followed the parabolic kinetics. The formed oxide scale was enriched significantly with segregation and subsequent oxidation of Nb, and finely dispersed metallic Cu particles. Within the time frame of oxidation, the oxide scale was mainly composed of mixed oxides such as FeCr{sub 2}O{sub 4} and MnCr{sub 2}O{sub 4} along with the binary oxides of Fe, Cr and Mn. Moreover, the precipitation fraction of Cu-rich particles on the oxide scale increased markedly with increase of exposure times. The chemical heterogeneity of oxide scale suggests that the oxidation occurred in a non-selective manner.

  9. Interpretation of experimental data on austenitic and dissimilar welds using SAFT; Interpretation von Messdaten mit SAFT an Austenit- und Mischnaehten

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, W.; Schmitz, V. [Fraunhofer Inst. fuer Zerstoerungsfreie Pruefverfahren, Saarbruecken (Germany); Mletzko, U. [Materialpruefungsanstalt, Univ. Stuttgart (Germany)

    2004-07-01

    Measurements had been carried out at the PWR-nozzle no. 92 of the full scale pressure vessel at the MPA at Stuttgart using the synthetic aperture focusing technique SAFT to detect and analyze longitudinal cracks. Longitudinal wave probes were used having insonification angles of 45 , 60 and 70 . The defect detectibility could be clearly increased by the SAFT-reconstruction compared to conventional B-, C- and D-scan imaging techniques. All cracklife defects could be detected and sized. With the aid of imaging the geometry of specimen (counterbore) and weld the exact defect-position could be determined relative to the weld. According to MPA statements, the SAFT-sizing is in good agreement with the intended defect sizes. Difficulties occurred in imaging a KTA-notch (20 mm x 3 mm) at the interface between counterwelding and buttering. This notch could be detected only with a SNR of 6 dB with insonification from the ferritic side of the weld and 3 dB from the opposite direction. (orig.)

  10. Comparison of stainless and mild steel welding fumes in generation of reactive oxygen species

    Directory of Open Access Journals (Sweden)

    Frazer David

    2010-11-01

    Full Text Available Abstract Background Welding fumes consist of a wide range of complex metal oxide particles which can be deposited in all regions of the respiratory tract. The welding aerosol is not homogeneous and is generated mostly from the electrode/wire. Over 390,000 welders were reported in the U.S. in 2008 while over 1 million full-time welders were working worldwide. Many health effects are presently under investigation from exposure to welding fumes. Welding fume pulmonary effects have been associated with bronchitis, metal fume fever, cancer and functional changes in the lung. Our investigation focused on the generation of free radicals and reactive oxygen species from stainless and mild steel welding fumes generated by a gas metal arc robotic welder. An inhalation exposure chamber located at NIOSH was used to collect the welding fume particles. Results Our results show that hydroxyl radicals (.OH were generated from reactions with H2O2 and after exposure to cells. Catalase reduced the generation of .OH from exposed cells indicating the involvement of H2O2. The welding fume suspension also showed the ability to cause lipid peroxidation, effect O2 consumption, induce H2O2 generation in cells, and cause DNA damage. Conclusion Increase in oxidative damage observed in the cellular exposures correlated well with .OH generation in size and type of welding fumes, indicating the influence of metal type and transition state on radical production as well as associated damage. Our results demonstrate that both types of welding fumes are able to generate ROS and ROS-related damage over a range of particle sizes; however, the stainless steel fumes consistently showed a significantly higher reactivity and radical generation capacity. The chemical composition of the steel had a significant impact on the ROS generation capacity with the stainless steel containing Cr and Ni causing more damage than the mild steel. Our results suggest that welding fumes may cause acute

  11. Comparison of stainless and mild steel welding fumes in generation of reactive oxygen species.

    Science.gov (United States)

    Leonard, Stephen S; Chen, Bean T; Stone, Samuel G; Schwegler-Berry, Diane; Kenyon, Allison J; Frazer, David; Antonini, James M

    2010-11-03

    Welding fumes consist of a wide range of complex metal oxide particles which can be deposited in all regions of the respiratory tract. The welding aerosol is not homogeneous and is generated mostly from the electrode/wire. Over 390,000 welders were reported in the U.S. in 2008 while over 1 million full-time welders were working worldwide. Many health effects are presently under investigation from exposure to welding fumes. Welding fume pulmonary effects have been associated with bronchitis, metal fume fever, cancer and functional changes in the lung. Our investigation focused on the generation of free radicals and reactive oxygen species from stainless and mild steel welding fumes generated by a gas metal arc robotic welder. An inhalation exposure chamber located at NIOSH was used to collect the welding fume particles. Our results show that hydroxyl radicals (.OH) were generated from reactions with H2O2 and after exposure to cells. Catalase reduced the generation of .OH from exposed cells indicating the involvement of H2O2. The welding fume suspension also showed the ability to cause lipid peroxidation, effect O2 consumption, induce H2O2 generation in cells, and cause DNA damage. Increase in oxidative damage observed in the cellular exposures correlated well with .OH generation in size and type of welding fumes, indicating the influence of metal type and transition state on radical production as well as associated damage. Our results demonstrate that both types of welding fumes are able to generate ROS and ROS-related damage over a range of particle sizes; however, the stainless steel fumes consistently showed a significantly higher reactivity and radical generation capacity. The chemical composition of the steel had a significant impact on the ROS generation capacity with the stainless steel containing Cr and Ni causing more damage than the mild steel. Our results suggest that welding fumes may cause acute lung injury. Since type of fume generated, particle size

  12. Risk of lung cancer according to mild steel and stainless steel welding

    DEFF Research Database (Denmark)

    Sørensen, Anita Rath; Thulstrup, Ane Marie; Hansen, Johnni

    2007-01-01

    OBJECTIVES: Whether the elevated risk of lung cancer observed among welders is caused by welding emissions or by confounding from smoking or asbestos exposure is still not resolved. This question was addressed in a cohort with a long follow-up and quantified estimates of individual exposure...... to welding fume particulates. METHODS: Male metal workers employed at least 1 year at one or more Danish stainless or mild steel industrial companies from 1964 through 1984 were enrolled in a cohort. Data on occupational and smoking history were obtained by questionnaire in 1986. Welders in the cohort who...... started welding in 1960 or later (N=4539) were followed from April 1968 until December 2003, when information on cancer diagnosis was obtained from the Danish Cancer Registry. During the follow-up, 75 cases of primary lung cancer were identified. Lifetime accumulated exposure to welding fume particulates...

  13. Finite element modelling and characterization of friction welding on UNS S31803 duplex stainless steel joints

    Directory of Open Access Journals (Sweden)

    Mohammed Asif. M

    2015-12-01

    Full Text Available Solid state joining techniques are increasingly employed in joining duplex stainless steel materials due to their high integrity. Continuous drive friction welding is a solid state welding technique which is used to join similar and dissimilar materials. This joining technique is characterized by short cycle time, low heat input and narrow heat affected zones. The simulation becomes an important tool in friction welding because of short welding cycle. In the present work, a three dimensional non-linear finite element model was developed. The thermal history and axial shortening profiles were predicted using ANSYS, a software tool. This numerical model was validated using experimental results. The results show that the frictional heating stage of the process has more influence on temperature and upsetting stage has more impact on axial shortening. The knowledge of these parameters would lead to optimization of input parameters and improvement of design and machine tools.

  14. 77 FR 14002 - Stainless Steel Butt-Weld Pipe Fittings From Italy, Malaysia, and the Philippines: Final Results...

    Science.gov (United States)

    2012-03-08

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Stainless Steel Butt-Weld Pipe Fittings From Italy, Malaysia, and the... AGENCY: Import Administration, International Trade Administration, Department of Commerce. SUMMARY: On...

  15. 77 FR 18266 - Stainless Steel Butt-Weld Pipe Fittings From Italy, Malaysia, and the Philippines; Revised...

    Science.gov (United States)

    2012-03-27

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Stainless Steel Butt-Weld Pipe Fittings From Italy, Malaysia, and the Philippines; Revised Schedule for the Subject Reviews AGENCY: United States International Trade Commission. ACTION: Notice...

  16. Efeito da densidade do fluxo e da presença de aditivos na soldagem ATIG de aço inoxidável austenítico Effect of flux density and addictive presence on ATIG welding of austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Paulo J. Modenesi

    2013-06-01

    Full Text Available A soldagem ATIG é uma variante simples do processo TIG convencional que permite aumentar a penetração da solda e, por exemplo, possibilitar a soldagem em um passe, com penetração total e sem abertura de chanfro, para juntas com espessura de 5 mm ou mais. Diferentes mecanismos foram propostos para explicar este efeito com destaque para o da contração do arco pela presença de íons negativos e o da alteração no movimento de metal líquido na poça de fusão associada com variações da tensão superficial em função da temperatura. O presente trabalho avalia o efeito da quantidade de um fluxo de um componente (óxido de cromo III, Cr2O3 colocado na superfície da peça e de adições de KClO4 e Al2O3 no formato do cordão de solda. Foram realizados três conjuntos de experimentos consistindo na deposição de cordões sobre chapa de aço inoxidável austenítico ABNT 304 com 5 mm de espessura. No primeiro conjunto, variou-se a quantidade de fluxo usada, no segundo, estudou-se o efeito de adições de KClO4 e, no terceiro, de Al2O3. Foram medidos os sinais elétricos (corrente e tensão durante a soldagem e, em seções transversais dos cordões, a largura, a penetração e a área do cordão. Os resultados indicaram uma pequena variação na tensão de soldagem (aumento inferior a 1 V na passagem da soldagem TIG para a ATIG. A concentração superficial de fluxo afetou a penetração da solda, ocorrendo um aumento brusco de penetração e área do cordão para concentrações entre 7,5 e 15 g/m², seguido por uma variação mais suave para concentrações maiores (até 120 g/m². Por outro lado, enquanto a adição de KClO4, claramente reduziu o aumento de penetração causado pelo fluxo, a adição de Al2O3 teve um efeito menos significativo no processo.Active flux TIG (ATIG welding is a simple variant of conventional TIG welding that allows a major improvement in weld bead penetration. Different mechanisms have been proposed to

  17. Dynamical recrystallization of high purity austenitic stainless steels; Recristallisation dynamique d'aciers inoxydables austenitiques de haute purete

    Energy Technology Data Exchange (ETDEWEB)

    Gavard, L

    2001-01-01

    The aim of this work is to optimize the performance of structural materials. The elementary mechanisms (strain hardening and dynamical regeneration, germination and growth of new grains) occurring during the hot working of metals and low pile defect energy alloys have been studied for austenitic stainless steels. In particular, the influence of the main experimental parameters (temperature, deformation velocity, initial grain size, impurities amount, deformation way) on the process of discontinuous dynamical recrystallization has been studied. Alloys with composition equal to those of the industrial stainless steel-304L have been fabricated from ultra-pure iron, chromium and nickel. Tests carried out in hot compression and torsion in order to cover a wide range of deformations, deformation velocities and temperatures for two very different deformation ways have allowed to determine the rheological characteristics (sensitivity to the deformation velocity, apparent activation energy) of materials as well as to characterize their microstructural deformations by optical metallography and electron back-scattered diffraction. The influence of the initial grain size and the influence of the purity of the material on the dynamical recrystallization kinetics have been determined. An analytical model for the determination of the apparent mobility of grain boundaries, a semi-analytical model for the dynamical recrystallization and at last an analytical model for the stationary state of dynamical recrystallization are proposed as well as a new criteria for the transition between the refinement state and the state of grain growth. (O.M.)

  18. Effect of ferrite transformation on the tensile and stress corrosion properties of type 316 L stainless steel weld metal thermally aged at 873 K

    Science.gov (United States)

    Shaikh, H.; Khatak, H. S.; Seshadri, S. K.; Gnanamoorthy, J. B.; Rodriguez, P.

    1995-07-01

    This article deals with the effect of the microstructural changes, due to transformation of delta ferrite, on the associated variations that take place in the tensile and stress corrosion properties of type 316 L stainless steel weld deposits when subjected to postweld heat treatment at 873 K for prolonged periods (up to 2000 hours). On aging for short durations (up to 20 hours), carbide/ carbonitride was the dominant transformation product, whereas sigma phase was dominant at longer aging times. The changes in the tensile and stress corrosion behavior of the aged weld metal have been attributed to the two competitive processes of matrix softening and hardening. Yield strength (YS) was found to depend predominantly on matrix softening only, while sig-nificant changes in the ultimate tensile strength (UTS) and the work-hardening exponent, n, occurred due to matrix hardening. Ductility and stress corrosion properties were considerably affected by both factors. Fractographic observations on the weld metal tested for stress-corrosion cracking (SCC) indicated a combination of transgranular cracking of the austenite and interface cracking.

  19. Plasma plume oscillations monitoring during laser welding of stainless steel by discrete wavelet transform application.

    Science.gov (United States)

    Sibillano, Teresa; Ancona, Antonio; Rizzi, Domenico; Lupo, Valentina; Tricarico, Luigi; Lugarà, Pietro Mario

    2010-01-01

    The plasma optical radiation emitted during CO2 laser welding of stainless steel samples has been detected with a Si-PIN photodiode and analyzed under different process conditions. The discrete wavelet transform (DWT) has been used to decompose the optical signal into various discrete series of sequences over different frequency bands. The results show that changes of the process settings may yield different signal features in the range of frequencies between 200 Hz and 30 kHz. Potential applications of this method to monitor in real time the laser welding processes are also discussed.

  20. Plasma Plume Oscillations Monitoring during Laser Welding of Stainless Steel by Discrete Wavelet Transform Application

    Directory of Open Access Journals (Sweden)

    Teresa Sibillano

    2010-04-01

    Full Text Available The plasma optical radiation emitted during CO2 laser welding of stainless steel samples has been detected with a Si-PIN photodiode and analyzed under different process conditions. The discrete wavelet transform (DWT has been used to decompose the optical signal into various discrete series of sequences over different frequency bands. The results show that changes of the process settings may yield different signal features in the range of frequencies between 200 Hz and 30 kHz. Potential applications of this method to monitor in real time the laser welding processes are also discussed.