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Sample records for weld line mechanical

  1. Mechanical properties of the weld line defect in micro injection molding for various nano filled polypropylene composites

    International Nuclear Information System (INIS)

    Xie Lei; Ziegmann, Gerhard

    2011-01-01

    Research highlights: → PP/CNFs and PP/TiO 2 composites with relative high loading fractions (10, 20, 30 and 35 wt%) were fabricated by inner melt mixing process. Micro tensile test samples were formed by injection molding combined with variotherm process for all composites. → The morphological properties of all nano composites were characterized by WXRD, whose results imply the adding nano fillers did not change the crystal form of PP, but the crystallites size and distance between lattices of crystals were changed with various nano fillers and loading fractions. → DSC analysis show that due to the nucleating function of nano fillers, the peak temperature of crystallization was increased and the peak temperature of crystallization melting was decreased by adding the nanofillers. → The flow ability of nano composites was tested by high pressure single capillary rheometer and the results demonstrate that nano fillers increased the viscosity of PP matrix. → Based on these significant information and analysis foundation of the nano filled composites, the micro weld line samples were formed by injection molding process and characterized by tensile test method. From the achieved results, it can be found that in general, for functional nano filled polymer composites, the mechanical property of micro weld lines were obviously influenced by nano fillers' shape and loading fractions. → The E modulus of micro weld line was increased due to loading CNFs in PP matrix, while the elongation of the micro tensile samples with weld line is considerably decreased comparing with those of unfilled PP samples. The detrimental tensile strength of micro weld lines were observed when CNFs contents increasing, except for at a 10 wt%. → For TiO 2 nano particles filled PP, due to the poor dispersion of nano particles, at low loading fraction of 10 wt%, the E modulus and tensile strength of micro weld lines were decreased by filling nano particles, but when the loading fraction

  2. Mechanized hyperbaric welding by robots

    International Nuclear Information System (INIS)

    Aust, E.; Santos, J.F. dos; Bohm, K.H.; Hensel, H.D.

    1988-01-01

    At the GKSS-Forschungszentrum investigations are carried out on mechanized welded test plates produced under working pressure between 10 to 110 bar in breathable TRIMIX-5-atmosphere. The welds are performed by a modified industrial robot, which was adapted in its components to withstand these severe conditions. Variations on the welding parameters were made to maintain a stable arc as well as to provide on indication of the effect of the variables on the mechanical properties of the welded joint. During all tests the robot showed a very good function. Good reliable welds were achieved meeting the requirements according API II04 or BS 4515-1984. (orig.) [de

  3. Effects of cavity surface temperature on mechanical properties of specimens with and without a weld line in rapid heat cycle molding

    International Nuclear Information System (INIS)

    Wang, Guilong; Zhao, Guoqun; Wang, Xiaoxin

    2013-01-01

    Highlights: ► Higher cavity surface temperature reduces tensile strength of non-weldline part. ► Higher cavity surface temperature increases weldline tensile strength for PS and PP. ► Higher cavity surface temperature reduces weldline tensile strength for ABS, ABS/PMMA, ABS/PMMA/nano-C a CO 3 and FRPP. ► Tensile strength is reduced more by the weldline than impact strength. ► FRPP has the lowest weld line factor than other plastics without reinforced fibers. - Abstract: Rapid heat cycle molding (RHCM) is a recently developed injection molding technology to enhance surface esthetic of the parts. By rapid heating and cooling of mold cavity surfaces in molding process, it can greatly alleviate or even eliminate the surface defects such as flow mark, weld line, glass fiber rich surface, silver mark, jetting mark, and swirl mark, and also improve gloss finish and dimensional accuracy without prolonging the molding cycle. Besides surface esthetic, mechanical property is also a very import issue for the molded plastic part. The aim of this study is focusing on the effects of the cavity surface temperature just before filling, T cs , in RHCM on the mechanical strength of the specimen with and without weld line. Six kinds of typical plastics including polystyrene (PS), polypropylene (PP), acrylonitrile butadiene styrene (ABS), acrylonitrile butadiene styrene/polymethylmethacrylate (ABS/PMMA), ABS/PMMA/nano-C a CO 3 and glass fiber reinforced polypropylene (FRPP) are used in experiments. The specimens with and without a weld line are produced with the different T cs on the developed electric-heating RHCM system. Tensile tests and notched Izod impact tests are conducted to characterize the mechanical strength of the specimens molded with different cavity surface temperatures. Simulations, differential scanning calorimetry (DSC), scanning electron microscope (SEM) and optical microscope are implemented to explain the impact mechanism of T cs on mechanical properties

  4. Mechanics Model of Plug Welding

    Science.gov (United States)

    Zuo, Q. K.; Nunes, A. C., Jr.

    2015-01-01

    An analytical model has been developed for the mechanics of friction plug welding. The model accounts for coupling of plastic deformation (material flow) and thermal response (plastic heating). The model predictions of the torque, energy, and pull force on the plug were compared to the data of a recent experiment, and the agreements between predictions and data are encouraging.

  5. Influence of process parameters on the weld lines of a micro injection molded component

    DEFF Research Database (Denmark)

    Tosello, Guido; Gava, Alberto; Hansen, Hans Nørgaard

    2007-01-01

    The insufficient entanglement of the molecular chains and the stress amplification at the v-notch of a weld line compromise the mechanical strength of a plastic product, also in the micro scale. To investigate the influence of process parameters on the weld lines formation, a special micro cavity...... was designed and manufactured by µEDM (Electro Discharge Machining). Weld lines were quantitatively characterized both in the two-dimensional (direction and position) and three-dimensional range (surface topography characterization). Results showed that shape and position of weld lines are mainly influenced...

  6. Effect of weld morphology on mechanical response and failure of friction stir welds in a naturally aged aluminium alloy

    International Nuclear Information System (INIS)

    Imam, Murshid; Biswas, Kajal; Racherla, Vikranth

    2013-01-01

    Highlights: ► Friction stir welds of AA 6063-T4 are obtained using three tool pin profiles. ► Signature of weld defects in mechanical response of welds is investigated. ► Correlation between peak temperatures in HAZs and their hardness is studied. ► Reasons for strengthening of WNZ and softening of HAZs are found using TEM and XRD. ► A FEM model for the weld zone is developed and validated. -- Abstract: Friction stir butt welds in 6063-T4 aluminium alloy were obtained using square and two tapered tool pin profiles. Tensile tests at 0°, 45°, and 90° to the weld line, hardness contours in the weld cross-section, temperatures in the heat affected zones, cross-sectional macrographs, transmission electron micrographs, and X-ray diffraction studies were used to characterize the welds. In transverse weld specimen, tunnel defects appearing at higher weld speeds for tapered pin profiles, were found to result in mechanical instabilities, i.e. sharp drops in load–displacement curves, much before macroscopic necking occured. Further, in comparison to the base metal, a marked reduction in ductility was observed even in transverse specimen with defect free welds. Hardness contours in the weld cross-section suggest that loss in ductility is due to significant softening in heat affected zone on the retreating side. Transmission electron microscopy images demonstrate that while recovery and overaging are responsible for softening in the heat affected zone, grain size refinement from dynamic recrystallization is responsible for strengthening of the weld nugget zone. X-ray diffraction studies in the three weld zones: weld nugget zone, heat affected zone, and the base metal corroborate these findings. A weld zone model, for use in forming simulations on friction stir welded plates of naturally aged aluminium alloys, was proposed based on mechanical characterization tests. The model was validated using finite element analysis.

  7. Mechanical Properties of Plug Welds after Micro-Jet Cooling

    Directory of Open Access Journals (Sweden)

    Hadryś D.

    2016-12-01

    Full Text Available New technology of micro-jet welding could be regarded as a new way to improve mechanical properties of plug welds. The main purpose of that paper was analyzing of mechanical properties of plug welds made by MIG welding method with micro-jet cooling. The main way for it was comparison of plug welds made by MIG welding method with micro-jet cooling and plug welds made by ordinary MIG welding method. It is interesting for steel because higher amount of acicular ferrite (AF in weld metal deposit (WMD is obtained in MIG welding method with micro-jet cooling in relation to ordinary MIG welding method. This article presents the influence of the cooling medium and the number of micro-jet streams on mechanical properties of the welded joint. Mechanical properties were described by force which is necessary to destroy weld joint.

  8. Mechanical Properties of Plug Welds after Micro-Jet Cooling

    OpenAIRE

    Hadryś D.

    2016-01-01

    New technology of micro-jet welding could be regarded as a new way to improve mechanical properties of plug welds. The main purpose of that paper was analyzing of mechanical properties of plug welds made by MIG welding method with micro-jet cooling. The main way for it was comparison of plug welds made by MIG welding method with micro-jet cooling and plug welds made by ordinary MIG welding method. It is interesting for steel because higher amount of acicular ferrite (AF) in weld metal deposit...

  9. Mechanical Behaviour Investigation Of Aluminium Alloy Tailor Welded Blank Developed By Using Friction Stir Welding Technique

    Science.gov (United States)

    Dwi Anggono, Agus; Sugito, Bibit; Hariyanto, Agus; Subroto; Sarjito

    2017-10-01

    The objective on the research was to investigate the mechanical properties and microstructure of tailor welded blank (TWB) made from AA6061-T6 and AA1100 using friction stir welding (FSW) process. Due to the dissimilar mechanical properties of the two aluminium alloys, microhardness test was conducted to measure the hardness distribution across the weld nugget. The mixing of two distinct materials was influenced by tool rotation speed. Therefore, microstructure analysis was carried out to investigate the grain size and shape. The grain size of AA6061-T6 has increased in the heat affected zone (HAZ) while for AA1100 has decreased. In the weld nugget, it has found a hook defects in the dissimilar aluminium joining. By using monotonic tensile load, the different weld line direction was observed with the expansion in tool rotation. The joints failure were consistently on the area of AA1100 series. Furthermore, two specimens were investigated, one through the dissimilar aluminium and the other through similiar material. Inspection of the weld nugget hardness was shown that nonhomogen material intermixing during the stiring process as confirmed by microhardness measurement.

  10. Investigation on mechanical properties of welded material under different types of welding filler (shielded metal arc welding)

    Science.gov (United States)

    Tahir, Abdullah Mohd; Lair, Noor Ajian Mohd; Wei, Foo Jun

    2018-05-01

    The Shielded Metal Arc Welding (SMAW) is (or the Stick welding) defined as a welding process, which melts and joins metals with an arc between a welding filler (electrode rod) and the workpieces. The main objective was to study the mechanical properties of welded metal under different types of welding fillers and current for SMAW. This project utilized the Design of Experiment (DOE) by adopting the Full Factorial Design. The independent variables were the types of welding filler and welding current, whereas the other welding parameters were fixed at the optimum value. The levels for types of welding filler were by the models of welding filler (E6013, E7016 and E7018) used and the levels for welding current were 80A and 90A. The responses were the mechanical properties of welded material, which include tensile strength and hardness. The experiment was analyzed using the two way ANOVA. The results prove that there are significant effects of welding filler types and current levels on the tensile strength and hardness of the welded metal. At the same time, the ANOVA results and interaction plot indicate that there are significant interactions between the welding filler types and the welding current on both the hardness and tensile strength of the welded metals, which has never been reported before. This project found that when the amount of heat input with increase, the mechanical properties such as tensile strength and hardness decrease. The optimum tensile strength for welded metal is produced by the welding filler E7016 and the optimum of hardness of welded metal is produced by the welding filler E7018 at welding current of 80A.

  11. Effect of weld line shape on material flow during friction stir welding of aluminum and steel

    International Nuclear Information System (INIS)

    Yasui, Toshiaki; Ando, Naoyuki; Morinaka, Shinpei; Mizushima, Hiroki; Fukumoto, Masahiro

    2014-01-01

    The effect of weld line shape on material flow during the friction stir welding of aluminum and steel was investigated. The material flow velocity was evaluated with simulated experiments using plasticine as the simulant material. The validity of the simulated experiments was verified by the marker material experiments on aluminum. The circumferential velocity of material around the probe increased with the depth from the weld surface. The effect is significant in cases where the advancing side is located on the outside of curve and those with higher curvature. Thus, there is an influence of weld line shape on material flow

  12. Study of verification and validation of standard welding procedure specifications guidelines for API 5L X-70 grade line pipe welding

    Directory of Open Access Journals (Sweden)

    Qazi H. A. A.

    2017-12-01

    Full Text Available Verification and validation of welding procedure specifications for X-70 grade line pipe welding was performed as per clause 8.2, Annexure B and D of API 5L, 45th Edition to check weld integrity in its future application conditions. Hot rolled coils were imported from China, de-coiling, strip edge milling, three roller bending to from pipe, inside and outside submerged arc welding of pipe, online ultrasonic testing of weld, HAZ and pipe body, cutting at fixed random length of pipe, visual inspection of pipe, Fluoroscopic inspection of pipe, welding procedure qualification test pieces marking at weld portion of the pipe, tensile testing, guided bend testing, CVN Impact testing were performed. Detailed study was conducted to explore possible explanations and variation in mechanical properties, WPS is examined and qualified as per API 5L 45th Edition.

  13. Identification of Mechanical parameters for Resistance Welding Machines

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    2003-01-01

    Mechanical dynamic responses of resistance welding machine have a significant influence on weld quality and electrode service life, it must be considered when the real welding production is carried out or the welding process is simulated. The mathematical models for characterizing the mechanical...

  14. Numerical aspects for efficient welding computational mechanics

    Directory of Open Access Journals (Sweden)

    Aburuga Tarek Kh.S.

    2014-01-01

    Full Text Available The effect of the residual stresses and strains is one of the most important parameter in the structure integrity assessment. A finite element model is constructed in order to simulate the multi passes mismatched submerged arc welding SAW which used in the welded tensile test specimen. Sequentially coupled thermal mechanical analysis is done by using ABAQUS software for calculating the residual stresses and distortion due to welding. In this work, three main issues were studied in order to reduce the time consuming during welding simulation which is the major problem in the computational welding mechanics (CWM. The first issue is dimensionality of the problem. Both two- and three-dimensional models are constructed for the same analysis type, shell element for two dimension simulation shows good performance comparing with brick element. The conventional method to calculate residual stress is by using implicit scheme that because of the welding and cooling time is relatively high. In this work, the author shows that it could use the explicit scheme with the mass scaling technique, and time consuming during the analysis will be reduced very efficiently. By using this new technique, it will be possible to simulate relatively large three dimensional structures.

  15. EFFECT OF PRE-HEAT TREATMENT ON MECHANICAL PROPERTIES OF Ti-6Al-4V WELDS

    Directory of Open Access Journals (Sweden)

    Gnofam Jacques TCHEIN

    2016-11-01

    Full Text Available The work presented here is related to the optimization of the Friction Stir Welding (FSW process. The objective is to study the influence of some parameters used in the production of welded joints by FSW. The most important parameters are the welding speed and the rotational speed of the tool. The effect of pre-heat treatment on the plates to be welded is also studied by the design of experimental methods. These pre-heat treatments result not only in a change of mechanical properties of plates to be welded, but also of their microstructure. The experiments were performed following a 16 lines fractional Taguchi table.

  16. Wave forming mechanisms in explosive welding

    NARCIS (Netherlands)

    Carton, E.P.

    2004-01-01

    Experimental results of wavy metal interfaces obtained by explosive welding are presented and used to determine which wave forming mechanism occurred. It was found that for small collision angles (smaller than about 20°) the Von Karman or jet indentation mechanism occurs, while for large collision

  17. Mechanical and electrochemical characteristics with welding materials in robotic MIG welding of dissimilar Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Jong; Han, Min Su; Woo, Yong Bin [Mokpo Maritime Univ., Mokpo (Korea, Republic of)

    2013-05-15

    In this study, mechanical and electrochemical characteristics with welding material in MIG welded with ROBOT for dissimilar Al alloys were investigated using various experiment methods. The MIG welding by ROBOT with ER5183 and ER5556 for the 5456-H116 and 6061-T6 Al alloy were carried out. The hardness of welding zone was lower than that of base metal. In electrochemical experiment, ER5183 welding material presented excellent characteristics. The yield strength and maximum tensile strength in welding with welding material of ER5183 presented lower value than those of ER5556. The elongation and time-to-fracture showed the opposite results.

  18. Mechanical properties of welded joints of duplex steels

    International Nuclear Information System (INIS)

    Kawiak, M.; Nowacki, J.

    2003-01-01

    The paper presents the study results of mechanical properties of duplex steels UNS S31803 welded joints as well as duplex and NV A36 steels welded joints. They have ben welded by FCAW method in CO 2 using FCW 2205-H flux-cored wire. The joints have been subjected: tensile tests, impact tests, bending tests, hardness tests and metallographic investigations. The influence of welding parameters and mechanical properties of the joints was appreciated. The welding method assured high tensile strength of the joints (approximately 770 MPa) and high impact strength of the welds (approximately 770 J). All samples were broken outside of welds. (author)

  19. Recognition and automatic tracking of weld line in fringe welding by autonomous mobile robot with visual sensor

    International Nuclear Information System (INIS)

    Suga, Yasuo; Saito, Keishin; Ishii, Hideaki.

    1994-01-01

    An autonomous mobile robot with visual sensor and four driving axes for welding of pipe and fringe was constructed. The robot can move along a pipe, and detect the weld line to be welded by visual sensor. Moreover, in order to perform welding automatically, the tip of welding torch can track the weld line of the joint by rotating the robot head. In the case of welding of pipe and fringe, the robot can detect the contact angle between the two base metals to be welded, and the torch angle changes according to the contact angle. As the result of tracking test by the robot system, it was made clear that the recognition of geometry of the joint by the laser lighting method and automatic tracking of weld line were possible. The average tracking error was ±0.3 mm approximately and the torch angle could be always kept at the optimum angle. (author)

  20. FineLine{sup TM} welding process for power plant applications

    Energy Technology Data Exchange (ETDEWEB)

    Offer, H.; Chapman, T.; Grycko, L.; Mahoney, P. [GE Nuclear Energy, San Jose, CA (United States)

    1996-12-31

    This paper discusses the technical development and current applications of the FineLine{sup TM} Welding (FLW) process. FineLine Welding is a modified Gas Tungsten-Arc Welding mechanized process recently developed by GE Nuclear Energy for a thin-wall piping application. Based on its unique combination of high thermal and volumetric efficiencies, the FLW process offers significant technical and productivity improvements over both standard orbital V-groove and narrow-gap welding procedures. The FLW process is suitable for many common structural materials, and has been successfully applied to unstabilized and stabilized grades of austenitic stainless steels, martensitic stainless steels, nickel-base (Inconel) alloys, carbon steels, as well as ferritic higher alloy steels. (orig./MM)

  1. Cold pressure welding - the mechanisms governing bonding

    DEFF Research Database (Denmark)

    Bay, Niels

    1979-01-01

    Investigations of the bonding surface in scanning electron microscope after fracture confirm the mechanisms of bond formation in cold pressure welding to be: fracture of work-hardened surface layer, surface expansion increasing the area of virgin surface, extrusion of virgin material through cracks...... of the original surface layer, and establishment of real contact and bonding between virgin material. This implies that normal pressure as well as surface expansion are basic parameters governing the bond strength. Experimental investigations of pressure welding Al-Al under plane strain compression in a specially...

  2. Effect of weld spacing on microstructure and mechanical properties of CLAM electron beam welding joints

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Yutao; Huang, Bo, E-mail: aufa0007@163.com; Zhang, Junyu; Zhang, Baoren; Liu, Shaojun; Huang, Qunying

    2016-11-15

    Highlights: • The welded joints of CLAM steel with different weld spacings have been fabricated with electron beam welding, and a simplified model of CLAM sheet was proposed. • The microstructure and mechanical properties such as microhardness, impact and tensile were investigated at different welding spacing for both conditions of as-welded and post weld heat treatment (PWHT). • The effect of the welding thermal cycle was significantly when the weld spacings were smaller than 4 mm. • When the weld spacing was small enough, the original microstructures would be fragmented with the high heat input. - Abstract: China low activation martensitic (CLAM) steel has been chosen as the primary structural material in the designs of dual function lithium-lead (DFLL) blanket for fusion reactors, China helium cooled ceramic breeder (HCCB) test blanket module (TBM) for ITER and China fusion engineering test reactor (CFETR) blanket. The cooling components of the blankets are designed with high density cooling channels (HDCCs) to remove the high nuclear thermal effectively. Hence, the welding spacing among the channels are small. In this paper, the welded joints of CLAM steel with different weld spacings have been fabricated with electron beam welding (EBW). The weld spacing was designed to be 2 mm, 3 mm, 4 mm, 6 mm and 8 mm. The microstructure and mechanical properties such as microhardness, impact and tensile were investigated at different welding spacing for both conditions of as-welded and post weld heat treatment (PWHT). The PWHT is tempering at 740 °C for 120 min. The results showed that the grain size in the heat affected zone (HAZ) increased with the increasing weld spacing, and the joint with small weld spacing had a better performance after PWHT. This work would give useful guidance to improve the preparation of the cooling components of blanket.

  3. Effect of process parameters on microstructure and mechanical properties of friction stir welded joints: A review

    Science.gov (United States)

    Wanare, S. P.; Kalyankar, V. D.

    2018-04-01

    Friction stir welding is emerging as a promising technique for joining of lighter metal alloys due to its several advantages over conventional fusion welding processes such as low thermal distortion, good mechanical properties, fine weld joint microstructure, etc. This review article mainly focuses on analysis of microstructure and mechanical properties of friction stir welded joints. Various microstructure characterization techniques used by previous researchers such as optical microscopes, x-ray diffraction, electron probe microscope, transmission electron microscope, scanning electron microscopes with electron back scattered diffraction, electron dispersive microscopy, etc. are thoroughly overviewed and their results are discussed. The effects of friction stir welding process parameters such as tool rotational speed, welding speed, tool plunge depth, axial force, tool shoulder diameter to tool pin diameter ratio, tool geometry etc. on microstructure and mechanical properties of welded joints are studied and critical observations are noted down. The microstructure examination carried out by previous researchers on various zones of welded joints such as weld zone, heat affected zone and base metal are studied and critical remarks have been presented. Mechanical performances of friction stir welded joints based on tensile test, micro-hardness test, etc. are discussed. This article includes exhaustive literature review of standard research articles which may become ready information for subsequent researchers to establish their line of action.

  4. Effects of post weld heat treatment and weld overlay on the residual stress and mechanical properties in dissimilar metal weld

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Wagner R.C.; Ribeiro, Vladimir S.; Vilela, Alisson H.F.; Almeida, Camila R.O.; Rabello, Emerson G., E-mail: wrcc@cdtn.br, E-mail: camilarezende.cr@gmail.com, E-mail: egr@cdtn.br, E-mail: vladimirsoler@hotmail.com, E-mail: ahfv02@outlook.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-07-01

    The object of this work is a dissimilar metal weld (DMW) pipe joint between carbon steel (A-106 Gr B) and stainless steel (A-312 TP316L) pipes and filler metals of Nickel alloy (82/182), which find wide application in the field of chemical, oil, petroleum industries, fossil fuel and nuclear power plant. A lot of the failures that have occurred in dissimilar metal welded are affected greatly by residual stresses. Residual stress is often a cause of premature failure of critical components under normal operation of welded components. Several methods have been tested and developed for removing the tensile residual stresses. The aim of the methods is to reduce the tensile stress state or to create compressive stresses at a predefined area, such as the inner surface of a welded pipe joint. Post weld heat treatment (PWHT) and weld overlay (WOL) are two of the residual stress mitigation methods which reduce the tensile residual stress, create compressive stresses and arrest crack initiation and crack growth. The technique used to substantially minimized or eliminated this failure development in the root weld is the post weld heat treatments (stress relief heat treatment) or the weld overlay. In this work was studied the effectiveness in reducing internal residual stress in dissimilar metal welded pipe joints subjected to post weld heat treatment and weld overlay, measurement by hole-drilling strain-gage method of stress relaxation. Also held was mechanical characterization of the welded pipe joint itself. (author)

  5. Effects of post weld heat treatment and weld overlay on the residual stress and mechanical properties in dissimilar metal weld

    International Nuclear Information System (INIS)

    Campos, Wagner R.C.; Ribeiro, Vladimir S.; Vilela, Alisson H.F.; Almeida, Camila R.O.; Rabello, Emerson G.

    2017-01-01

    The object of this work is a dissimilar metal weld (DMW) pipe joint between carbon steel (A-106 Gr B) and stainless steel (A-312 TP316L) pipes and filler metals of Nickel alloy (82/182), which find wide application in the field of chemical, oil, petroleum industries, fossil fuel and nuclear power plant. A lot of the failures that have occurred in dissimilar metal welded are affected greatly by residual stresses. Residual stress is often a cause of premature failure of critical components under normal operation of welded components. Several methods have been tested and developed for removing the tensile residual stresses. The aim of the methods is to reduce the tensile stress state or to create compressive stresses at a predefined area, such as the inner surface of a welded pipe joint. Post weld heat treatment (PWHT) and weld overlay (WOL) are two of the residual stress mitigation methods which reduce the tensile residual stress, create compressive stresses and arrest crack initiation and crack growth. The technique used to substantially minimized or eliminated this failure development in the root weld is the post weld heat treatments (stress relief heat treatment) or the weld overlay. In this work was studied the effectiveness in reducing internal residual stress in dissimilar metal welded pipe joints subjected to post weld heat treatment and weld overlay, measurement by hole-drilling strain-gage method of stress relaxation. Also held was mechanical characterization of the welded pipe joint itself. (author)

  6. Mechanical Behaviour of Lined Pipe

    NARCIS (Netherlands)

    Hilberink, A.

    2011-01-01

    Installing lined pipe by means of the reeling installation method seems to be an attractive combination, because it provides the opportunity of eliminating the demanding welds from the critical time offshore and instead preparing them onshore. However, reeling of lined pipe is not yet proven

  7. Effects of multi-pass arc welding on mechanical properties of carbon steel C25 plate

    International Nuclear Information System (INIS)

    Adedayo, S.M.; Babatunde, A.S.

    2013-01-01

    The effects of multi-pass welding on mechanical properties of C25 carbon steel plate were examined. Mild steel plate workpieces of 90 x 55 mm 2 area and 10 mm thickness with a 30 degrees vee weld-grooves were subjected to single and multi-pass welding. Toughness, hardness and tensile tests of single and multi-pass welds were conducted. Toughness values of the welds under double pass welds were higher than both single pass and unwelded alloy, at respective maximum values of 2464, 2342 and 2170 kN/m. Hardness values were reduced under double pass relative to single pass welding with both being lower than the value for unwelded alloy; the values were 40.5, 43.2 and 48.5 Rs respectively at 12 mm from the weld line. The tensile strength of 347 N/mm 2 under multi-pass weld was higher than single pass weld with value of 314 N/mm 2 . Therefore, the temperature distribution and apparent pre-heating during multi-pass welding increased the toughness and tensile strength of the weldments, but reduced the hardness. (au)

  8. Investigate The Effect Of Welding Parameters On Mechanical Properties During The Welding Of Al-6061 Alloy

    Directory of Open Access Journals (Sweden)

    Rajendra Prasad

    2017-10-01

    Full Text Available Friction welding is a solid state welding technique which is being used in recent times to weld similar as well as dissimilar metals for getting defect free weld. Many combinations like low carbon to stainless steel austenitic to ferrite stainless steel aluminium to copper and titanium to aluminium or steel have been tried out by various solid state welding processes with quite good results. In the present work the 3 level full factorial design has been employed to investigate the effect of welding parameters on tensile strength toughness and heat generation during the welding of Al-6061 alloy. Mathematical relationships between friction welding parameters and mechanical properties like heat generation tensile strength and toughness have also been developed. An attempt has also been made to examine the fracture surfaces of test specimens using SEM. It has been found that welding speed is the most significant parameter thats affect the heat generation tensile strength and toughness. it has been found that tensile strength and toughness during welding increases with increased in welding speed while tensile strength and toughness initially increased as the welding time increases after that it decreased with increase in welding time. The difference in weight of alloying elements can be clearly seen by analyzing spectrum of elements.

  9. Mechanical behaviour of Astm A 297 grade Hp joints welded using different processes

    International Nuclear Information System (INIS)

    Emygdio, Paulo Roberto Oliveira; Zeemann, Annelise; Almeida, Luiz Henrique de

    1996-01-01

    The influence of different arc welding processes on mechanical behaviour was studied for cast heat resistant stainless steel welded joints, in the as welded conditions. ASTM A 297 grade HP with niobium and niobium/titanium additions were welded following three different welding procedures, using shielded metal arc welding gas tungsten arc welding and plasma arc welding, in six welded joints. The welded joint mechanical behaviour was evaluated by ambient temperature and 870 deg C tensile tests; and creep tests at 900 deg C and 50 MPa. Mechanical test results showed that the welding procedure qualification following welding codes is not suitable for high temperature service applications. (author)

  10. Mechanical tunnel excavation in welded tuff

    International Nuclear Information System (INIS)

    Sperry, P.E.

    1991-01-01

    The Technical Review Board for the US high-level radioactive waste facility at Yucca Mountain has recommended maximum use of open-quotes the most modern mechanical excavation techniques...in order to reduce disturbance to the rock walls and to achieve greater economy of time and cost.close quotes Tunnels for the waste repository at Yucca Mountain can be economically constructed with mechanical excavation equipment. This paper presents the results of mechanical excavation of a tunnel in welded tuff, similar to the tuffs of Yucca Mountain. These results are projected to excavation of emplacement drifts in Yucca Mountain using a current state-of-the-art tunnel boring machine (TBM)

  11. Characterization and analysis of weld lines on micro-injection moulded parts using atomic force microscopy (AFM)

    DEFF Research Database (Denmark)

    Tosello, Guido; Gava, Alberto; Hansen, Hans Nørgaard

    2009-01-01

    In recent years plastic moulding techniques, such as injection moulding, have been developed to fulfil the needs of micro-components fabrication. Micro-injection moulding (SLIM) is the process which enables the mass production of polymer micro-systems such as micro-mechanical parts, micro...... the two original flows will generate and a weld line is formed on the surface of the micro-moulded part. This phenomenon has to be avoided or at least reduced, since in the weld line area the mechanical properties are poorer than in the bulk part, creating strength problems on the final part. Although...... injection moulding parameters on the weld lines' dimensions is presented, using an atomic force microscope (AFM). Depth and width of weld lines were chosen as parameters to be optimized....

  12. Weld-Windsor 115-kV Transmission Line Project, Weld County, Colorado

    International Nuclear Information System (INIS)

    1996-05-01

    The Western Area Power Administration is proposing to rebuild a 3.0 mile segment of the existing Flatiron-Weld 115-kV transmission line in Weld County. The line would be reconductored with new conductor on new wood pole double circuit structures. The new structures would support a double circuit transmission line configuration. The first circuit would be owned by Western and the second by Public Service Company of Colorado (PSCO). Alternatives considered included no action, constructing PSCO's circuit on new right-of-way, and reconductoring Western's existing line on the same structures. The proposed action was selected because it provided an opportunity to share structures with PSCO and, overall, would minimize costs and environmental impacts. The environmental assessment identifies minor effects on existing natural or human resources and minor benefits for agricultural operations

  13. Effect of multiple repairs in girth welds of pipelines on the mechanical properties

    International Nuclear Information System (INIS)

    Vega, O.E.; Hallen, J.M.; Villagomez, A.; Contreras, A.

    2008-01-01

    This work presents the results of multiple weld repairs in the same area in seamless API X-52 microalloyed steel pipe. Four conditions of shielded metal arc welding repairs and one as-welded specimen of the girth weld were characterized to determine changes in the microstructure, grain size in the heat affected zone, and to evaluate their effect on the mechanical properties of the weld joints. The mechanical properties by means of tension tests, Charpy-V impact resistance and Vickers hardness of the welds were analyzed. The results indicate that significant changes are not generated in the microstructural constituents of the heat affected zone. Grain growth in the heat affected zone at the specimen mid-thickness with the number of repairs was observed. Tensile strength of the weld joints meets the requirement of the API 1104 standard even after the fourth weld repair. Significant reduction in Charpy-V impact resistance with the number of weld repairs was found when the notch location was in the intersection of the fusion line with the specimen mid-thickness. A significant increase in the Vickers hardness of the heat affected zone occurred after the first repair and a gradual decrease in the Vickers hardness occurred as the number of repairs increases

  14. Fracture mechanics evaluation of heavy welded structures

    International Nuclear Information System (INIS)

    Sprung, I.; Ericksson, C.W.; Zilberstein, V.A.

    1982-01-01

    This paper describes some applications of nondestructive examination (NDE) and engineering fracture mechanics to evaluation of flaws in heavy welded structures. The paper discusses not only widely recognized linear elastic fracture mechanics (LEFM) analysis, but also methods of the elastic-plastic fracture mechanics (EPFM), such as COD, J-integral, and Failure Assessment Diagram. Examples are given to highlight the importance of interaction between specialists providing input and the specialists performing the analysis. The paper points out that the critical parameters for as-welded structures when calculated by these methods are conservative since they are based on two pessimistic assumptions: that the magnitude of residual stress is always at the yield strength level, and that the residual stress always acts in the same direction as the applied (mechanical) stress. The suggestion is made that it would be prudent to use the COD or the FAD design curves for a conservative design. The appendix examines a J-design curve modified to include residual stresses

  15. The Mechanism of Ultrasonic Vibration on Grain Refining and Degassing in GTA Spot Welding of Copper Joints.

    Science.gov (United States)

    Al-Ezzi, Salih; Quan, Gaofeng; Elrayah, Adil

    2018-05-07

    This paper examines the effect of ultrasonic vibration (USV) on grain size and interrupted porosity in Gas Tungsten Arc (GTA) spot-welded copper. Grain size was refined by perpendicularly attaching a transducer to the welded sheet and applying USV to the weld pool for a short time (0, 2, 4, and 6 s) in addition improvements to the degassing process. Results illustrate a significant reduction of grain size (57%). Notably, USV provided interaction between reformations (fragmentation) and provided nucleation points (detaching particles from the fusion line) for grains in the nugget zone and the elimination of porosity in the nugget zone. The GTA spot welding process, in conjunction with USV, demonstrated an improvement in the corrosion potential for a copper spot-welded joint in comparison to the joint welded without assistance of USV. Finally, welding of copper by GTA spot welding in conjunction with ultrasound for 2 s presented significant mechanical properties.

  16. Microstructure and Mechanical Properties of an Ultrasonic Spot Welded Aluminum Alloy: The Effect of Welding Energy

    Directory of Open Access Journals (Sweden)

    He Peng

    2017-04-01

    Full Text Available The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique–ultrasonic spot welding (USW–at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with “river-flow” patterns and characteristic fatigue striations.

  17. Testing and Modeling of Mechanical Characteristics of Resistance Welding Machines

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    2003-01-01

    for both upper and lower electrode systems. This has laid a foundation for modeling the welding process and selecting the welding parameters considering the machine factors. The method is straightforward and easy to be applied in industry since the whole procedure is based on tests with no requirements......The dynamic mechanical response of resistance welding machine is very important to the weld quality in resistance welding especially in projection welding when collapse or deformation of work piece occurs. It is mainly governed by the mechanical parameters of machine. In this paper, a mathematical...... model for characterizing the dynamic mechanical responses of machine and a special test set-up called breaking test set-up are developed. Based on the model and the test results, the mechanical parameters of machine are determined, including the equivalent mass, damping coefficient, and stiffness...

  18. Residual stresses and their mechanisms of production at circumferential weld by heat-sink welding

    International Nuclear Information System (INIS)

    Ueda, Yukio; Nakacho, Keiji; Ohkubo, Katsumi; Shimizu, Tsubasa.

    1983-01-01

    In the previous report, the authors showed effectiveness of the heat-sink welding (water cooling) to accomplish this end by conducting theoretical analysis and an experiment on residual stresses in the 4B pipe of SUS 304 by the conventional welding and the heat-sink welding at a certain standard heat-input condition. In this research, different pipe sizes and varied heat-input are applied. The welding residual stresses by the conventional welding and the heat-sink welding are obtained by the theoretical analysis and their production mechanisms are clarified. Hence the influence of the above changes of conditions on effectiveness of the heat-sink welding is investigated. The main results are summarized as follow. (1) In case of this pipes such as 2B and 4B pipes, it is important to minimize heat-input per one pass (especially for latter half passes) in order to improve the effectiveness of the heat-sink welding. The effectiveness can be predicted either by theoretical analysis of the temperature distribution history with consideration of the characteristic of heat transfer under spray-watering or by experimental measurement. (2) In case of 24B pipes, thick pipes, it is desirable to minimize heat-input for the first half passes, by which the heat-sink welding becomes more effective. In addition, no matter whether the conventional welding or the heat-sink welding, it is important to prevent angular distorsion which produces tensile axial stresses on the inner surface of the pipe in the weld zone. Possible measures to meet these requirements are to apply restraining jigs, to minimize the section area of the groove (ex. application of the narrow gap arc welding), and to change continuous welding to skip one. (J.P.N.)

  19. Evaluating mechanical properties of hybrid laser arc girth welds

    Energy Technology Data Exchange (ETDEWEB)

    Pussegoda, L. N.; Begg, D.; Holdstock, R.; Jodoin, A. [BMT Fleet Technology Ltd Techonology, Kanata, ON, (Canada); Ligh, K.; Rondeau, D. [Appliead Thermal Sciences Inc., Sanford, ME, (United States); Hansen, E. [ESAB, Florence, SC, (United States)

    2010-07-01

    Hybrid laser arc welding (HLAW) is a promising new process for making girth welds on steel pipelines. This study investigated the mechanical properties of overmatched X80 and X100 pipeline steel girth welds made using the HLAW process. The testing of this process was conducted on NPS36 pipes of 10.4 mm and 14.3 mm thickness, respectively. Various weld positions were produced on X80 and X100 pipes. Laser inspection data were collected during the whole welding process. Also standard tests for girth welds, Charpy V-notch impact tests, CTOD tests, all weld metal (AWM) tension tests, were carried out. The results showed that the fracture transition temperature is higher at the 3 and 9 o'clock positions than at the 9 and 12 o'clock positions. The effect of clock position on fracture toughness is currently being explored; a modified CTOD has been developed to reduce the possibility of crack deviation.

  20. Real weld geometry determining mechanical properties of high power laser welded medium plates

    Science.gov (United States)

    Liu, Sang; Mi, Gaoyang; Yan, Fei; Wang, Chunming; Li, Peigen

    2018-06-01

    Weld width is commonly used as one of main factors to assess joint performances in laser welding. However, it changes significantly through the thickness direction in conditions of medium or thick plates. In this study, high-power autogenous laser welding was conducted on 7 mm thickness 201 stainless steel to elucidate the factor of whole weld transverse shape critically affecting the mechanical properties with the aim of predicting the performance visually through the weld appearance. The results show that single variation of welding parameters could result in great changes of weld pool figures and subsequently weld transverse shapes. All the obtained welds are composed of austenite containing small amount of cellular dendritic δ-Ferrite. The 0.2% proof stresses of Nail- and Peanut-shaped joint reach 458 MPa and 454 MPa, 88.2% and 87.5% of the base material respectively, while that of Wedge-shaped joint only comes to 371 MPa, 71.5% of the base material. The deterioration effect is believed to be caused by the axial grain zone in the weld center. The fatigue strength of joint P is a bit lower than N, but much better than W. Significant deformation incompatibility through the whole thickness and microstructure resistance to crack initiation should be responsible for the poor performance of W-shaped joints.

  1. Stainless steel submerged arc weld fusion line toughness

    International Nuclear Information System (INIS)

    Rosenfield, A.R.; Held, P.R.; Wilkowski, G.M.

    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

  2. Effect of welding speed on microstructural and mechanical properties of friction stir welded Inconel 600

    International Nuclear Information System (INIS)

    Song, K.H.; Fujii, H.; Nakata, K.

    2009-01-01

    In order to evaluate the properties of a friction stir welded Ni base alloy, Inconel 600 (single phase type) was selected. Sound friction stir welds without weld defect were obtained at 150 and 200 mm/min in welding speed, however, a groove like defect occurred at 250 mm/min. The electron back scattered diffraction (EBSD) method was used to analyze the grain boundary character distribution. As a result, dynamic recrystallization was observed at all conditions, and the grain refinement was achieved in the stir zone, and it was gradually accelerated from 19 μm in average grain size of the base material to 3.4 μm in the stir zone with increasing the welding speed. It also has an effect on the mechanical properties so that friction stir welded zone showed 20% higher microhardness and 10% higher tensile strength than those of base material.

  3. Mechanism for Self-Reacted Friction Stir Welding

    Science.gov (United States)

    Venable, Richard; Bucher, Joseph

    2004-01-01

    A mechanism has been designed to apply the loads (the stirring and the resection forces and torques) in self-reacted friction stir welding. This mechanism differs somewhat from mechanisms used in conventional friction stir welding, as described below. The tooling needed to apply the large reaction loads in conventional friction stir welding can be complex. Self-reacted friction stir welding has become popular in the solid-state welding community as a means of reducing the complexity of tooling and to reduce costs. The main problems inherent in self-reacted friction stir welding originate in the high stresses encountered by the pin-and-shoulder assembly that produces the weld. The design of the present mechanism solves the problems. The mechanism includes a redesigned pin-and-shoulder assembly. The welding torque is transmitted into the welding pin by a square pin that fits into a square bushing with set-screws. The opposite or back shoulder is held in place by a Woodruff key and high-strength nut on a threaded shaft. The Woodruff key reacts the torque, while the nut reacts the tensile load on the shaft.

  4. Simulation of Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    Science.gov (United States)

    2015-11-01

    Memorandum Simulation of Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes...Weld Mechanical Behavior to Include Welding-Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes by Charles R. Fisher...Welding- Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes 5a. CONTRACT NUMBER N/A 5b. GRANT NUMBER N/A 5c

  5. Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

    OpenAIRE

    Chetan Aneja; Amit Handa

    2016-01-01

    In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW) process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases w...

  6. Review of techniques for on-line monitoring and inspection of laser welding

    International Nuclear Information System (INIS)

    Shao, J; Yan, Y

    2005-01-01

    Laser welding has been applied to various industries, in particular, automotive, aerospace and microelectronics. However, traditional off-line testing of the welds is costly and inefficient. Therefore, on-line inspection systems with low cost have being developed to increase productivity and maintain high welding quality. This paper presents the applications of acoustic, optical, visual, thermal and ultrasonic techniques and latest development of laser welding monitoring. The advantages and limitations of these techniques are also discussed

  7. Laser welding of polymers, compatibility and mechanical properties

    DEFF Research Database (Denmark)

    Nielsen, Steen Erik; Strange, Marianne; Kristensen, Jens Klæstrup

    2013-01-01

    for research and development. This paper presents some research results related to laser welding of various polymer materials, including weld compatibility investigations related to the joining of different polymers. Theory for bonding mechanisms, strength development, mechanical properties testing and other......Laser welding of polymers is today a commonly used industrial technology. It has shown obvious advantages compared to e.g. adhesive bonding in terms of higher productivity, better quality and easiness for automation. The ongoing development of lasers tailored for polymer welding in coordination...

  8. Microstructural evolution and mechanical performance of resistance spot welded DP1000 steel with single and double pulse welding

    NARCIS (Netherlands)

    Chabok, Ali; van der Aa, Ellen; De Hosson, Jeff; Pei, Yutao T.

    2017-01-01

    Two welding schemes of single and double pulse were used for the resistance spot welding of DP1000 dual phase steel. The changes in the mechanical performance and variant pairing of martensite under two different welding conditions were scrutinized. It is demonstrated that, although both welds fail

  9. Microstructure and Mechanical Properties of Welds of Al - Mg - Si Alloys After Different Modes of Impulse Friction Stir Welding

    Science.gov (United States)

    Kondrat'ev, S. Yu.; Morozova, Yu. N.; Golubev, Yu. A.; Hantelmann, C.; Naumov, A. A.; Mikhailov, V. G.

    2018-03-01

    Welded joints of aluminum alloy 6082-T6 formed by the method of impulse friction stir welding are studied. The effect of the power and frequency of the pulses on the microstructure and mechanical properties of the welded joints is determined. Application of an additional pulse during the welding affects the surface quality and the shape of the weld, the distribution of the oxide layer and of particles of the hardening phase, and the grain size in the zone of dynamic recrystallization.

  10. Automatization and mechanization of welding in nuclear engineering

    Energy Technology Data Exchange (ETDEWEB)

    Shul' ma, I E; Kupin, N V

    1986-02-01

    The state of welding and cladding works, which constitute more than 12% of total labour content of NPP equipment production, is described. Special attention is paid to a considerable part of manual labour in the processes of thermal cutting and welding of joints inside the vessels. The necessity of perspective technology introduction is pointed out. It means, in particular, the introduction of technological complex robotics for automatic welding of pipes with tube plates in heat exchanger, the mechanization of cladding processes for sealing surfaces of locking equipment, facility equipment for the welding of steam generator vessels to bottoms by means of preliminary and concomitant heating devices.

  11. Automatization and mechanization of welding in nuclear engineering

    International Nuclear Information System (INIS)

    Shul'ma, I.E.; Kupin, N.V.

    1986-01-01

    The state of welding and cladding works, which constitute more than 12% of total labour content of NPP equipment production, is described. Special attention is paid to a considerable part of manual labour in the processes of thermal cutting and welding of joints inside the vessels. The necessity of perspective technology introduction is pointed out. It means, in particular, the introduction of technological complex robotics for automatic welding of pipes with tube plates in heat exchanger, the mechanization of cladding processes for sealing surfaces of locking equipment, facility equipment for the welding of steam generator vessels to bottoms by means of preliminary and concomitant heating devices

  12. Mechanical and Microstructural Evaluation of DMAG Welding of Structural Steel

    Directory of Open Access Journals (Sweden)

    Tolga Mert

    2015-01-01

    Full Text Available Double channel torch, which allows concentric flow of two different shielding gases, was designed and manufactured in order to pursue double channel torch gas metal arc welding of unalloyed structural steel S235JR (EN 10025-2 with fourteen passes. Tensile and Charpy V-notch tests were realized and the results were compared with those of conventional gas metal arc welding. In order to evaluate mechanical testing results, microstructural analyses were conducted. It was found that the increase with double channel gas metal arc welding process in yield and tensile strengths as well as in toughness tests, especially in subzero temperatures, compared with conventional gas metal arc welding was due to longer columnar grains and finer tempered zone grain structure between passes and due to solidification and less dendritic structure formation in all-weld metal in double channel gas metal arc welding.

  13. Remote mechanical C line

    International Nuclear Information System (INIS)

    Nuttall, K.R.; Gardner, P.R.

    1991-01-01

    Westinghouse Hanford Company is developing a desk-top simulation based training program on the operation of the Remote Mechanical C (RMC) Line process in the Plutonium Finishing Plant on the Hanford site, Richland, Washington. Simulations display aod contioually update current values of system parameters on computer graphics of RMC line equipment. Students are able to operate a variety of controllers to maintain proper system status. Programmed faults, selectable by the course instructor, can be used to test student responses to off-normal events. Prior to operation of the simulation, students are given computer-based tutorials on the function, processes, operation, and error conditions associated with individual components. By including the capability of operating each individual component - valves, heaters, agitators, etc. - the computer-based training (CBT) lessons become an interactive training manual. From one perspective RMC represents one step in the diffusion of the well-known and well-documented simulator training activities for nuclear reactor operators to other training programs, equally critical, perhaps, but less well scrutinized in the past. Because of the slowly responding nature of the actual process, RMC can retain many of the capabilities of practice and testing in a simulated work environment while avoiding the cost of a full scale simulator and the exposure and waste developed by practice runs of the RMC line. From another perspective RMC suggests training advances even beyond the most faithful simulators. For example, by integrating CBT lessons with the simulation, RMC permits students to focus in on specific processes occurring inside chosen components. In effect, the interactive training manual is available on-line with the simulation itself. Cost are also discussed

  14. Bonding mechanisms in spot welded three layer combinations

    DEFF Research Database (Denmark)

    Moghadam, Marcel; Tiedje, Niels Skat; Seyyedian Choobi, Mahsa

    2016-01-01

    this interface. It has been shown previously that such a joint can reach relatively high strength resulting in plug failure in tensileshear testing. Additional strength due to these bonding mechanisms is also obtained in common spot welds in the so-called corona band around the weld nugget.......The strength of a spot weld generally stems from fusion bonding of the metal layers, but other solid state bonding mechanisms also contribute to the overall strength. Metallographic analyses are presented to identify the phases formed near and across the weld interfaces and to identify...... the occurring bonding mechanisms. When welding a combination of three galvanized steel layers where one outer layer is a thin low-carbon steel it is a common challenge to obtain nugget penetration into the thin low-carbon steel. It therefore happens in real production that no nugget is formed across...

  15. Characterisation of Dynamic Mechanical Properties of Resistance Welding Machines

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    2005-01-01

    characterizing the dynamic mechanical characteristics of resistance welding machines is suggested, and a test set-up is designed determining the basic, independent machine parameters required in the model. The model is verified by performing a series of mechanical tests as well as real projection welds.......The dynamic mechanical properties of a resistance welding machine have significant influence on weld quality, which must be considered when simulating the welding process numerically. However, due to the complexity of the machine structure and the mutual coupling of components of the machine system......, it is very difficult to measure or calculate the basic, independent machine parameters required in a mathematical model of the machine dynamics, and no test method has so far been presented in literature, which can be applied directly in an industrial environment. In this paper, a mathematical model...

  16. Mechanical behaviour of dissimilar metal welds

    International Nuclear Information System (INIS)

    Escaravage, C.

    1990-01-01

    This report addresses the problems of dissimilar metal welds connecting an austenitic stainless steel component to a ferritic steel component. In LMFBRs such welds appear at the junction of the austenitic stainless steel vessel with the ferritic steel roof and in sodium and water or steam pipes. The latter are exposed to high temperatures in the creep range. A wide range of austenitic stainless steels and ferritic steels (carbon steels, low allow steels and alloy steels) are covered; the study encompasses more than 20 different weld metals (austenitic stainless steels and nickel base alloys). The report begins with a presentation of the materials, geometries and welding procedures treated in the study, followed by a review of service experience from examinations of dissimilar metal welds after elevated temperature service, in particular failed welds. Results of laboratory tests performed for reproducing service failures are then discussed. A further section is devoted to a review of test results on fatigue behaviour and impact toughness for dissimilar metal welded joints when creep is not significant. Finally, the problem of residual life assessment is addressed. A set of recommendations concludes the report. They concern the material selection, welding procedure, life prediction and testing of dissimilar metal welds. 84 refs

  17. Predictive Modeling of Mechanical Properties of Welded Joints Based on Dynamic Fuzzy RBF Neural Network

    Directory of Open Access Journals (Sweden)

    ZHANG Yongzhi

    2016-10-01

    Full Text Available A dynamic fuzzy RBF neural network model was built to predict the mechanical properties of welded joints, and the purpose of the model was to overcome the shortcomings of static neural networks including structural identification, dynamic sample training and learning algorithm. The structure and parameters of the model are no longer head of default, dynamic adaptive adjustment in the training, suitable for dynamic sample data for learning, learning algorithm introduces hierarchical learning and fuzzy rule pruning strategy, to accelerate the training speed of model and make the model more compact. Simulation of the model was carried out by using three kinds of thickness and different process TC4 titanium alloy TIG welding test data. The results show that the model has higher prediction accuracy, which is suitable for predicting the mechanical properties of welded joints, and has opened up a new way for the on-line control of the welding process.

  18. Weld Metallurgy and Mechanical Properties of High Manganese Ultra-high Strength Steel Dissimilar Welds

    Science.gov (United States)

    Dahmen, Martin; Lindner, Stefan; Monfort, Damien; Petring, Dirk

    The increasing demand for ultra-high strength steels in vehicle manufacturing leads to the application of new alloys. This poses a challenge on joining especially by fusion welding. A stainless high manganese steel sheet with excellent strength and deformation properties stands in the centre of the development. Similar and dissimilar welds with a metastable austenitic steel and a hot formed martensitic stainless steel were performed. An investigation of the mixing effects on the local microstructure and the hardness delivers the metallurgical features of the welds. Despite of carbon contents above 0.4 wt.% none of the welds have shown cracks. Mechanical properties drawn from tensile tests deliver high breaking forces enabling a high stiffness of the joints. The results show the potential for the application of laser beam welding for joining in assembly of structural parts.

  19. Device for welding a connection line to an electrode of a solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Lorans, D.Y.

    1976-08-05

    A method with associated device for welding connection lines to the electrodes of solar cells is described. To improve the weldability of the contacts usually consisting of silver, a weld-receiving device is vibrated with respect to the welding electrode, whereby disturbing surface layers are destroyed with a certain application pressure of the welding electrode. The method shows better results than, for example, a previous chemical cleaning of the contacts and is also more easy to handle.

  20. Mechanical properties of dissimilar friction welded steel bars in relation to post weld heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Yu Sik; Kim, Seon Jin [Pukyong National University, Busan (Korea, Republic of)

    2006-04-15

    Dissimilar friction welding were produced using 15(mm) diameter solid bar in chrome molybedenum steel(KS SCM440) to carbon steel(KS S45C) to investigate their mechanical properties. The main friction welding parameters were selected to endure good quality welds on the basis of visual examination, tensile tests, Vickers hardness surveys of the bond of area and H.A.Z and microstructure investigations. The specimens were tested as-welded and Post-Weld Heat Treated(PWHT). The tensile strength of the friction welded steel bars was increased up to 100% of the S45C base metal under the condition of all heating time. Optimal welding conditions were n=2,000(rpm), P{sub 1}=60(MPa), P{sub 2}=100(MPa), t{sub 1}=4(s), t{sub 2}=5(s) when the total upset length is 5.4 and 5.7(mm), respectively. The peak of hardness distribution of the friction welded joints can be eliminated by PWHT. Two different kinds of materials are strongly mixed to show a well-combined structure of macro-particles without any molten material and particle growth or any defects.

  1. Robust Control of Welding Robot for Tracking a Rectangular Welding Line

    Directory of Open Access Journals (Sweden)

    Manh Dung Ngo

    2008-11-01

    Full Text Available This paper highlights a welding robot (WR for its end effector to track a rectangular welding line (RWL. The WR includes five actuators which use a DC motor as a power source. Two controllers are proposed to control the WR's end effector: a main controller and a servo controller. Firstly, based on WR's kinematic equations and its feedback errors using backstepping method the main controller is proposed to design the reference-inputs for the WR's actuators in order that the WR's end effector tracks the RWL. Secondly, based on the dynamic equation of WR's actuator, the servo controller is designed using an active disturbance rejection control method. Finally, a control system incorporated with the main controller and the servo controllers make the WR's end effector robustly track a RWL in the presence of the modeling uncertainty and disturbances during the welding process. In experiment, the main controller which has a function as a master of the control system links to the five servo controllers which have a function as a slave via I2C communication. The effectiveness of the proposed control system is proven through the simulation and experimental results.

  2. Robust Control of Welding Robot for Tracking a Rectangular Welding Line

    Directory of Open Access Journals (Sweden)

    Manh Dung Ngo

    2006-09-01

    Full Text Available This paper highlights a welding robot (WR for its end effector to track a rectangular welding line (RWL. The WR includes five actuators which use a DC motor as a power source. Two controllers are proposed to control the WR's end effector: a main controller and a servo controller. Firstly, based on WR's kinematic equations and its feedback errors using backstepping method the main controller is proposed to design the reference-inputs for the WR's actuators in order that the WR's end effector tracks the RWL. Secondly, based on the dynamic equation of WR's actuator, the servo controller is designed using an active disturbance rejection control method. Finally, a control system incorporated with the main controller and the servo controllers make the WR's end effector robustly track a RWL in the presence of the modeling uncertainty and disturbances during the welding process. In experiment, the main controller which has a function as a master of the control system links to the five servo controllers which have a function as a slave via I2C communication. The effectiveness of the proposed control system is proven through the simulation and experimental results.

  3. Dependence of the mechanical properties of joints welded according to the parameters of the metal active gas (MAG welding regime

    Directory of Open Access Journals (Sweden)

    D. Dobrotă

    2015-10-01

    Full Text Available The main objective followed in the realization of welded structures is to obtain superior mechanical characteristics for these structures. The research aimed at setting ranges of values for the welding voltage (Uw, respectively for the welding current (Iw so as to obtain superior mechanical features for welded constructions. The research was carried out using E 36-4 steel as base material and SG2 wire as filler material, whereas the applied welding process was MAG. The optimization was done with the help of a number of 31 test bars considering various welding procedures for each test bar, and the experimental data were processed using the STATISTCA program.

  4. Low temperature heat treatments of AA5754-Ti6Al4V dissimilar laser welds: Microstructure evolution and mechanical properties

    Science.gov (United States)

    Leo, P.; D'Ostuni, S.; Casalino, G.

    2018-03-01

    This paper presents the effects of the post welding heat treatments (PWHT) performed at 350 °C and 450 °C on the microstructure evolution and mechanical properties of AA5754 and Ti6Al4V dissimilar laser welds. The microstructure and tensile properties of the welds before and after low temperature treatment were analyzed. The off-set welding technique was applied to limit the formation of brittle intermetallic compounds during the welding process. The laser beam was directed onto the titanium side at a small distance from the aluminum edge. The keyhole formed and the full penetration was reached in the titanium side of the weld. Thereafter, the aluminum side melted as the heat that formed the keyhole transferred from the titanium fused zone. Two different energy lines (32 J/mm and 76 J/mm) were used. In this manner, a fused and a heat affected zones was revealed on both sides of the weld. Several intermetallic compounds formed in the intermetallic layer between the two metals. The thickness and the composition of the intermetallic layer depended on the welding parameters and the post welding heat treatment. The hardness and tensile properties of the welds before and after the post welding heat treatment were measured and analyzed.

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

    African Journals Online (AJOL)

    EFFECTS OF METAL INERT GAS WELDING PARAMETERS ON SOME MECHANICAL PROPERTIES OF AUSTENITIC STAINLESS STEEL IN ACIDIC ... Design Expert Software, Scanning Electron Microscopy (SEM), Rockwell Hardness Test, Monsanto Tensometer and Izod Impact Test were used to determine the ...

  6. Design of Friction Stir Spot Welding Tools by Using a Novel Thermal-Mechanical Approach.

    Science.gov (United States)

    Su, Zheng-Ming; Qiu, Qi-Hong; Lin, Pai-Chen

    2016-08-09

    A simple thermal-mechanical model for friction stir spot welding (FSSW) was developed to obtain similar weld performance for different weld tools. Use of the thermal-mechanical model and a combined approach enabled the design of weld tools for various sizes but similar qualities. Three weld tools for weld radii of 4, 5, and 6 mm were made to join 6061-T6 aluminum sheets. Performance evaluations of the three weld tools compared fracture behavior, microstructure, micro-hardness distribution, and welding temperature of welds in lap-shear specimens. For welds made by the three weld tools under identical processing conditions, failure loads were approximately proportional to tool size. Failure modes, microstructures, and micro-hardness distributions were similar. Welding temperatures correlated with frictional heat generation rate densities. Because the three weld tools sufficiently met all design objectives, the proposed approach is considered a simple and feasible guideline for preliminary tool design.

  7. Characterization of appendage weld quality by on line monitoring of electrical parameters

    Energy Technology Data Exchange (ETDEWEB)

    Setty, D.S.; Somani, A.K.; Ram, A.M.; Rao, A.R.; Jayaraj, R.N.; Kalidas, R. [Nuclear Fuel Complex, Dept. of Atomic Energy, Hyderabad (India)

    2005-07-01

    Resistance projection welding of zirconium alloy appendages is one of the most critical processes in the PHWR fuel fabrication. Appendages like Spacers and Bearing pads having multi projections are joined to the fuel sheath using capacitor discharge power source. Variations in the projection sizes, weld parameters and cleanliness of the work pieces have significant effect on the weld quality, in addition to material properties like hardness, tensile strength and surface finish. Defects like metal expulsion and weak welds are occasionally observed in appendage welding process, which need to be identified and segregated. Though numerous off-line inspection methods are available for the weld quality evaluation, on-line monitoring of weld quality is essential for identifying defective welds. For this purpose, various monitoring techniques like acoustic emission, analyzing derived electrical parameters and weld upset/deformation measurements are employed. The derived electrical parameters like A{sup 2}-Sec and Ohm-Sec can also be monitored. The present paper highlights development of suitable acceptance criteria for the monitoring technique by employing derived electrical parameters covering a wide range of weld variables like watt-sec and squeeze force. Excellent correlation could be achieved in identifying the weak welds and weld expulsion defects in mass production. (author)

  8. The fracture mechanics of steam turbine electron beam welded rotors

    International Nuclear Information System (INIS)

    Coulon, P.A.

    1987-01-01

    Increased steam turbine unit ratings presupposes that steelmakers are capable of manufacturing larger and larger rotor components. However, there are few steelmakers in the world capable of manufacturing monobloc rotors for high rated turbines, which limits the choice of supplier. Most nuclear turbine rotors have a composite arrangement and are made either by shrinking discs on a shaft or using elements welded together. Those in favour of welding have applied a classical socalled ''submerged'' method using a filler metal. However welding can also be performed by using an Electron Beam in a vacuum room without a filler metal. This technique has many advantages: mechanical characteristics of the joint are identical to those of the base material after tempering without heat affected zones. Moreover, parts are only very slightly deformed during welding. Two steam turbine rotors have been produced in this way. This paper described the destructive tests carried out in the four Electron Beam (EB) welds (two on each rotor)

  9. Mechanism of selective corrosion in electrical resistance seam welded carbon steel pipe

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Fajardo, Pedro; Godinez Salcedo, Jesus; Gonzalez Velasquez, Jorge L. [Instituto Politecnico Nacional, Mexico D.F., (Mexico). Escuela Superior de Ingenieria Quimica e Industrias Extractivas. Dept. de Ingenieria Metalurgica

    2009-07-01

    In this investigation the studies of the mechanism of selective corrosion in electrical resistance welded (ERW) carbon steel pipe was started. Metallographic characterizations and evaluations for inclusions were performed. The susceptibility of ERW pipe to selective corrosion in sea water (NACE 1D182, with O{sub 2} or CO{sub 2} + H{sub 2}S) was studied by the stepped potential Potentiostatic electrochemical test method in samples of 1 cm{sup 3} (ASTM G5) internal surface of the pipe (metal base-weld). The tests were looking for means for predicting the susceptibility of ERW pipe to selective corrosion, prior to placing the pipeline in service. Manganese sulfide inclusions are observed deformed by the welding process and they are close to the weld centerline. A slight decarburization at the weld line is observed, and a distinct out bent fiber pattern remains despite the post-weld seam annealing. The microstructure of the weld region consists of primarily polygonal ferrite grains mixed with small islands of pearlite. It is possible to observe the differences of sizes of grain of the present phases in the different zones. Finally, scanning electron microscopic observation revealed that the corrosion initiates with the dissolution of MnS inclusions and with small crack between the base metal and ZAC. (author)

  10. The Effect of Welding Energy on the Microstructural and Mechanical Properties of Ultrasonic-Welded Copper Joints

    Science.gov (United States)

    Yang, Jingwei; Cao, Biao; Lu, Qinghua

    2017-01-01

    The effects of welding energy on the mechanical and microstructural characteristics of ultrasonic-welded pure copper plates were investigated. Complex dynamic recrystallization and grain growth occurred inside the weld zone during ultrasonic welding. At a low welding energy, a thin band of straight weld interfaces was observed and had an ultra-fine grain structure. With an increase in welding energy, the weld interface progressively changed from flat to sinusoidal, and eventually turned into a convoluted wavy pattern, bearing similarities to shear instabilities, as observed in fluid dynamics. The lap shear load of the joints initially increased and then remained stable as the welding energy increased. The tensile characteristics of the joints significantly depended on the development of plastic deformation at the interface. The influence of the microstructure on the hardness was also discussed. PMID:28772553

  11. Mechanical properties of friction stir welded butt joint of steel/aluminium alloys: effect of tool geometry

    Science.gov (United States)

    Syafiq, W. M.; Afendi, M.; Daud, R.; Mazlee, M. N.; Majid, M. S. Abdul; Lee, Y. S.

    2017-10-01

    This paper described the mechanical properties from hardness testing and tensile testing of Friction Stir Welded (FSW) materials. In this project, two materials of aluminium and steel are welded using conventional milling machine and tool designed with different profile and shoulder size. During welding the temperature along the weld line is collected using thermocouples. Threaded pins was found to produce stronger joints than cylindrical pins. 20 mm diameter shoulder tool welded a slightly stronger joint than 18 mm diameter one, as well as softer nugget zone due to higher heat input. Threaded pins also contributed to higher weld temperature than cylindrical pins due to increase in pin contact surface. Generally, higher temperatures were recorded in aluminium side due to pin offset away from steel.

  12. Mechanical behaviour of cracked welded structures including mismatch effect

    International Nuclear Information System (INIS)

    Hornet, P.

    2002-01-01

    The most important parameters for predicting more precisely the fracture behaviour of welded structures have been identified. In particular, the plasticity development at the crack tip in the ligament appeared as a major parameter to evaluate the yield load of such a complex structure. In this way defect assessments procedures have been developed or modified to take into account the mismatch effect that is to say the mechanical properties of the different material constituting the weld joint. This paper is a synthesis of the work done in the past at Electricite de France on this topic in regards with other work done in France or around the World. The most important parameters which control the plasticity development at the crack tip and so mainly influence the fracture behaviour of welded structures are underlined: the mismatch ratio (weld to base metal yield strength ratio), the mismatch ratio (weld to base metal yield strength ratio), the ligament size and the weld width. Moreover, commonly used fracture toughness testing procedures developed in case of homogeneous specimens cannot be used in a straight forward manner and so has to be modified to take into account the mismatch effect. Number or defect assessment procedures taking into account the mismatch effect by considering the yield load of the welded structure are shortly described. Then, the 'Equivalent Material Method' developed at EDF which allows a good prediction of the applied J-Integral at the crack tip is more detailed. This procedure includes not only both weld and base metal yield strength, the structure geometry, the crack size and the weld dimension using the yield load of the real structures but also includes the effect of both weld and base metal strain hardening exponents. Some validations of this method are proposed. Finally, the ability of finite element modelling to predict the behaviour of such welded structures is demonstrated by modelling real experiments: crack located in the middle of

  13. Influence of joint line remnant on crack paths under static and fatigue loadings in friction stir welded Al-Mg-Sc alloy

    Directory of Open Access Journals (Sweden)

    Y. Besel

    2016-01-01

    Full Text Available The influence of the joint line remnant (JLR on tensile and fatigue fracture behaviour has been investigated in a friction stir welded Al-Mg-Sc alloy. JLR is one of the microstructural features formed in friction stir welds depending on welding conditions and alloy systems. It is attributed to initial oxide layer on butting surfaces to be welded. In this study, two different tool travel speeds were used. JLR was formed in both welds but its spatial distribution was different depending on the tool travel speeds. Under the tensile test, the weld with the higher heat input fractured partially along JLR, since strong microstructural inhomogeneity existed in the vicinity of JLR in this weld and JLR had weak bonding. Resultantly, the mechanical properties of this weld were deteriorated compared with the other weld. Fatigue crack initiation was not affected by the existence of JLR in all welds. But the crack propagated preferentially along JLR in the weld of the higher heat input, when it initiated on the retreating side. Consequently, such crack propagation behaviour along JLR could bring about shorter fatigue lives in larger components in which crack growth phase is dominant.

  14. A Method for Identifying the Mechanical Parameters in Resistance Spot Welding Machines

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    2003-01-01

    Mechanical dynamic responses of resistance welding machine have a significant influence on weld quality and electrode service life, it must be considered when the real welding production is carried out or the welding process is stimulated. The mathematical models for characterizing the mechanical...

  15. Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

    Directory of Open Access Journals (Sweden)

    Chetan Aneja

    2016-07-01

    Full Text Available In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases with decreasing welding speed. Furthermore mechanical properties were also found to improve as the rotary speed increases and the same phenomenon was found to happen while using straight cylindrical threaded pin profile tool. The microstructure of the dissimilar joints revealed that at low welding speeds, the improved material mixing was observed. The similar phenomenon was found to happen at higher rotational speeds using straight cylindrical threaded tool.

  16. On detection and automatic tracking of butt weld line in thin wall pipe welding by a mobile robot with visual sensor

    International Nuclear Information System (INIS)

    Suga, Yasuo; Ishii, Hideaki; Muto, Akifumi

    1992-01-01

    An automatic pipe welding mobile robot system with visual sensor was constructed. The robot can move along a pipe, and detect the weld line to be welded by visual sensor. Moreover, in order to make an automatic welding, the welding torch can track the butt weld line of the pipes at a constant speed by rotating the robot head. Main results obtained are summarized as follows: 1) Using a proper lighting fixed in front of the CCD camera, the butt weld line of thin wall pipes can be recongnized stably. In this case, the root gap should be approximately 0.5 mm. 2) In order to detect the weld line stably during moving along the pipe, a brightness distribution measured by the CCD camera should be subjected to smoothing and differentiating and then the weld line is judged by the maximum and minimum values of the differentials. 3) By means of the basic robot system with a visual sensor controlled by a personal computer, the detection and in-process automatic tracking of a weld line are possible. The average tracking error was approximately 0.2 mm and maximum error 0.5 mm and the welding speed was held at a constant value with error of about 0.1 cm/min. (author)

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Improved simulation method of automotive spot weld failure with an account of the mechanical properties of spot welds

    Science.gov (United States)

    Wu, H.; Meng, X. M.; Fang, R.; Huang, Y. F.; Zhan, S.

    2017-12-01

    In this paper, the microstructure and mechanical properties of spot weld were studied, the hardness of nugget and heat affected zone (HAZ) were also tested by metallographic microscope and microhardness tester. The strength of the spot weld with the different parts' area has been characterized. According to the experiments result, CAE model of spot weld with HAZ structure was established, and simulation results of different lap-shear CAE models were analyzed. The results show that the spot weld model which contained the HAZ has good performance and more suitable for engineering application in spot weld simulation.

  19. A Review on Solidification and Change in Mechanical Properties Under Vibratory Welding Condition

    OpenAIRE

    Jyoti Prakash; Dr. S.P. Tewari; Bipin Kumar Srivastava

    2010-01-01

    Welding has been applied to various industries in particular, automotive, aerospace and microelectronics. Thermal cycle produced near weld line generates residual stress and inhomogeneous plastic deformation in weldments. However there are many methods for welding the workpieces and one of the method among these is vibratory welding. It has the advantages of less investment, more convenient operation, less pollution and shorter manufacturing period. In vibratory welding, workpiece vibrates in...

  20. The Effect of Vibration during Friction Stir Welding on Corrosion Behavior, Mechanical Properties, and Machining Characteristics of Stir Zone

    Directory of Open Access Journals (Sweden)

    Sajad Fouladi

    2017-10-01

    Full Text Available Different methods have been applied to refine various characteristics of the zone (or nugget obtained by friction stir welding (FSW. In the current research, joining components are vibrated normal to the weld line during FSW to refine the zone microstructure. This process is described as friction stir vibration welding (FSVW. The effect of FSVW on mechanical properties, corrosion behavior, and machining characteristics of the zone are investigated. Al5052 alloy specimens are welded using FSW and FSVW processes and their different characteristics are compared and discussed. The results show that the strength and ductility of the welded parts increase when the vibration is applied. The outcomes also show that corrosion resistance of the nugget for FSV-welded specimens is lower than FS welded samples, and machining force of the former specimens is higher than the latter ones. These are related to smaller grain size in the zone of FSV-welded specimens compared to FS welded parts. Smaller grain size leads to a greater volume fraction of grain boundaries and, correspondingly, higher strength and hardness, as well as lower corrosion resistance.

  1. Effectiveness of amorphous silica encapsulation technology on welding fume particles and its impact on mechanical properties of welds

    International Nuclear Information System (INIS)

    Wang, Jun; Wu, Chang-Yu; Franke, Gene

    2014-01-01

    Highlights: • A novel welding shielding gas containing a silica precursor. • Up to 76% of the welding fume particles encapsulated in an amorphous silica layer. • No statistical difference between different types of welds in mechanical tests. • Can potentially reduce the toxicity of welding fume particles. - Abstract: Stainless steel welding generates nano-sized fume particles containing toxic metals which may cause serious health effects upon inhalation. The objective of this study was to investigate the effectiveness of an amorphous silica encapsulation (ASE) technology by evaluating its silica coating efficiency (SCE), particle morphology, and its impact on the weld’s mechanical properties. Tetramethylsilane (TMS) added to the welding shielding gas decomposed at the high-temperature arc zone to enable the silica coating. Collected welding fume particles were digested by two acid mixtures with different degrees of silica solubility, and the measured mass differences in the digests were used to determine the SCE. The SCEs were around 48–64% at the low and medium primary shielding gas flow rates. The highest SCE of 76% occurred at the high shielding gas flow rate (30 Lpm) with a TMS carrier gas flow of 0.64 Lpm. Transmission electron microscopy (TEM) images confirmed the amorphous silica layer on the welding fume particles at most gas flow rates, as well as abundant stand-alone silica particles formed at the high gas flow rate. Metallography showed that welds from the baseline and from the ASE technology were similar except for a tiny crack found in one particular weld made with the ASE technology. Tensile tests showed no statistical difference between the baseline and the ASE welds. All the above test results confirm that welding equipment retrofitted with the ASE technology has the potential to effectively address the toxicity problem of welding fume particles without affecting the mechanical properties of the welds

  2. Structural and mechanical properties of welded joints of reduced activation martensitic steels

    International Nuclear Information System (INIS)

    Filacchioni, G.; Montanari, R.; Tata, M.E.; Pilloni, L.

    2002-01-01

    Gas tungsten arc welding and electron beam welding methods were used to realise welding pools on plates of reduced activation martensitic steels. Structural and mechanical features of these simulated joints have been investigated in as-welded and post-welding heat-treated conditions. The research allowed to assess how each welding technique affects the original mechanical properties of materials and to find suitable post-welding heat treatments. This paper reports results from experimental activities on BATMAN II and F82H mod. steels carried out in the frame of the European Blanket Project - Structural Materials Program

  3. Bench for mechanical cleaning of circular welded joints

    International Nuclear Information System (INIS)

    Sklifasovskij, V.M.

    1986-01-01

    A special bench for weld reinforcement removal and mechanical cleaning of the heat affected zones was designed to provide for a possibility of an ultrasonic testing of welded joints in the course of steam generator section fabrication. The bench comprises a mechanized roller support for fixing and rotating the workpiece; a lap-cutting device for external machining; milling/grinding tractor for internal machining and a delivery table for tractor approach and departure. The bench performance and overall view are presented. The operation succession is described

  4. Microstructures and mechanical properties of friction stir welded dissimilar steel-copper joints

    Energy Technology Data Exchange (ETDEWEB)

    Jafari, M.; Abbasi, M.; Poursina, D.; Gheysarian, A. [University of Kashan, Kashan (Iran, Islamic Republic of); Bagheri, B. [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2017-03-15

    Welding dissimilar metals by fusion welding is challenging. It results in welding defects. Friction stir welding (FSW) as a solid-state joining method can overcome these problems. In this study, 304L stainless steel was joined to copper by FSW. The optimal values of the welding parameters traverse speed, rotational speed, and tilt angle were obtained through Response surface methodology (RSM). Under optimal welding conditions, the effects of welding pass number on the microstructures and mechanical properties of the welded joints were investigated. Results indicated that appropriate values of FSW parameters could be obtained by RSM and grain size refinement during FSW mainly affected the hardness in the weld regions. Furthermore, the heat from the FSW tool increased the grain size in the Heat-affected zones (HAZs), especially on the copper side. Therefore, the strength and ductility decreased as the welding pass number increased because of grain size enhancement in the HAZs as the welding pass number increased.

  5. Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing.

    Science.gov (United States)

    Villegas, Irene F; Palardy, Genevieve

    2016-02-11

    This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.

  6. Mechanical behavior of multipass welded joint during stress relief annealing

    International Nuclear Information System (INIS)

    Ueda, Yukio; Fukuda, Keiji; Nakacho, Keiji; Takahashi, Eiji; Sakamoto, Koichi.

    1978-01-01

    An investigation into mechanical behavior of a multipass welded joint of a pressure vessel during stress relief annealing was conducted. The study was performed theoretically and experimentally on idealized research models. In the theoretical analysis, the thermal elastic-plastic creep theory developed by the authors was applied. The behavior of multipass welded joints during the entire thermal cycle, from welding to stress relief annealing, was consistently analyzed by this theory. The results of the analysis show a good, fundamentally coincidence with the experimental findings. The outline of the results and conclusions is as follows. (1) In the case of the material (2 1/4Cr-1Mo steel) furnished in this study, the creep strain rate during stress relief annealing below 575 0 C obeys the strain-hardening creep law using the transient creep and the one above 575 0 C obeys the power creep law using the stational creep. (2) In the transverse residual stress (σsub(x)) distribution after annealing, the location of the largest tensile stress on the top surface is about 15 mm away from the toe of weld, and the largest at the cross section is just below the finishing bead. These features are similar to those of welding residual stresses. But the stress distribution after annealing is smoother than one from welding. (3) The effectiveness of stress relief annealing depends greatly on the annealing temperature. For example, most of residual stresses are relieved at the heating stage with a heating rate of 30 0 C/hr. to 100 0 C/hr. if the annealing temperature is 650 0 C, but if the annealing temperature is 550 0 C, the annealing is not effective even with a longer holding time. (4) In the case of multipass welding residual stresses studied in this paper, the behaviors of high stresses during annealing are approximated by ones during anisothermal relaxation. (auth.)

  7. Mechanical properties of duplex steel welded joints in large-size constructions

    OpenAIRE

    J. Nowacki

    2012-01-01

    Purpose: On the basis of sources and own experiments, the analysis of mechanical properties, applications as well as material and technological problems of ferritic-austenitic steel welding were carried out. It was shown the area of welding applications, particularly welding of large-size structures, on the basis of example of the FCAW method of welding of the UNS S3 1803 duplex steel in construction of chemical cargo ships.Design/methodology/approach: Welding tests were carried out for duple...

  8. 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

    Friction welding, a solid-state joining method, is presented as a novel alternative process step for lining mild steel pipe and forged components internally with a corrosion resistant (CR) metal alloy for petrochemical applications. Currently, fusion welding is commonly used for stainless steel overlay cladding, but this method is costly, time-consuming, and can lead to disbonding in service due to a hard martensite layer that forms at the interface due to partial mixing at the interface between the stainless steel CR metal and the mild steel base. Firstly, the process parameter space was explored for inertia friction butt welding using AISI type 304L stainless steel and AISI 1018 steel to determine the microstructure and mechanical properties effects. A conceptual model for heat flux density versus radial location at the faying surface was developed with consideration for non-uniform pressure distribution due to frictional forces. An existing 1 D analytical model for longitudinal transient temperature distribution was modified for the dissimilar metals case and to account for material lost to the flash. Microstructural results from the experimental dissimilar friction welds of 304L stainless steel to 1018 steel were used to discuss model validity. Secondly, the microstructure and mechanical property implications were considered for replacing the current fusion weld cladding processes with friction welding. The nominal friction weld exhibited a smaller heat softened zone in the 1018 steel than the fusion cladding. As determined by longitudinal tensile tests across the bond line, the nominal friction weld had higher strength, but lower apparent ductility, than the fusion welds due to the geometric requirements for neck formation adjacent to a rigid interface. Martensite was identified at the dissimilar friction weld interface, but the thickness was smaller than that of the fusion welds, and the morphology was discontinuous due to formation by a mechanism of solid

  9. 78 FR 60897 - Certain Welded Large Diameter Line Pipe From Japan

    Science.gov (United States)

    2013-10-02

    ... Diameter Line Pipe From Japan Determination On the basis of the record \\1\\ developed in the subject five... order on certain welded large diameter line pipe from Japan would likely to lead to continuation or... Line Pipe from Japan: Investigation No. 731-TA-919 (Second Review). By order of the Commission. Issued...

  10. Weld Growth Mechanisms and Failure Behavior of Three-Sheet Resistance Spot Welds Made of 5052 Aluminum Alloy

    Science.gov (United States)

    Li, Yang; Yan, Fuyu; Luo, Zhen; Chao, Y. J.; Ao, Sansan; Cui, Xuetuan

    2015-06-01

    This paper investigates the weld nugget formation in three-sheet aluminum alloy resistance spot welding. The nugget formation process in three equal thickness sheets and three unequal thickness sheets of 5052 aluminum alloy were studied. The results showed that the nugget was initially formed at the workpiece/workpiece interfaces (i.e., both upper interface and lower interface). The two small nuggets then grew along the radial direction and axial direction (welding direction) as the welding time increased. Eventually, the two nuggets fused into one large nugget. During the welding process, the Peltier effect between the Cu-Al caused the shift of the nugget in the welding direction. In addition, the mechanical strength and fracture mode of the weld nuggets at the upper and lower interfaces were also studied using tensile shear specimen configuration. Three failure modes were identified, namely interfacial, mixed, and pullout. The critical welding time and critical nugget diameter corresponding to the transitions of these modes were investigated. Finally, an empirical failure load formula for three-sheet weld similar to two-sheet spot weld was developed.

  11. Effect of Welding Process on Microstructure, Mechanical and Pitting Corrosion Behaviour of 2205 Duplex Stainless Steel Welds

    Science.gov (United States)

    Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    An attempt has been made to weld 2205 Duplex stainless steel of 6mm thick plate using conventional gas tungsten arc welding (GTAW) and activated gas tungsten arc welding (A- GTAW) process using silica powder as activated flux. Present work is aimed at studying the effect of welding process on depth of penetration, width of weld zone of 2205 duplex stainless steel. It also aims to observe the microstructural changes and its effect on mechanical properties and pitting corrosion resistance of 2205 duplex stainless steel welds. Metallography is done to observe the microstructural changes of the welds using image analyzer attached to the optical microscopy. Hardness studies, tensile and ductility bend tests were evaluated for mechanical properties. Potentio-dynamic polarization studies were carried out using a basic GillAC electro-chemical system in 3.5% NaCl solution to observe the pitting corrosion behaviour. Results of the present investigation established that increased depth of penetration and reduction of weld width in a single pass by activated GTAW with the application of SiO2 flux was observed when compared with conventional GTAW process. It may be attributed to the arc constriction effect. Microstructure of the weld zones for both the welds is observed to be having combination of austenite and delta ferrite. Grain boundary austenite (GBA) with Widmanstatten-type austenite (WA) of plate-like feature was nucleated from the grain boundaries in the weld zone of A-GTAW process. Mechanical properties are relatively low in activated GTAW process and are attributed to changes in microstructural morphology of austenite. Improved pitting corrosion resistance was observed for the welds made with A-GTAW process.

  12. 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.

  13. Characterization of the mechanical properties and structural integrity of T-welded connections repaired by grinding and wet welding

    Energy Technology Data Exchange (ETDEWEB)

    Terán, G., E-mail: gteran@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Cuamatzi-Meléndez, R., E-mail: rcuamatzi@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Albiter, A., E-mail: aalbiter@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Maldonado, C., E-mail: cmzepeda@umich.mx [Instituto de Investigaciones Metalúrgicas, UMSNH, PO Box 52-B, 58000, México (Mexico); Bracarense, A.Q., E-mail: bracarense@ufmg.br [UFMG Departamento de Engeharia Mecánica Belo Horizonte, MG (Brazil)

    2014-04-01

    This paper presents an experimental methodology to characterize the structural integrity and mechanical properties of repaired T-welded connections using in fixed offshore structures. Grinding is employed to remove localized damage like cracking and corrosion and subsequent wet welding can be used to fill the grinded material. But it is important to define the grinding depth and profile in order to maintain structural integrity during the repair. Therefore, in this work different grinding depths were performed, for damage material removal, at the weld toe of the T-welded connections. The grinding was filled by wet welding in a hyperbaric chamber, simulating three different water depths: 50 m, 70 m and 100 m. The electrodes were coated with vinilic varnish, which is cheap and easy to apply. The characterization of the mechanical properties of the T-welded connections was done with standard tensile, hardness and Charpy tests; microstructure and porosity analysis were also performed. The samples were obtained from the welded connections in regions of the wet weld beads. The test results were compared with the mechanical properties of the T-welded connections welded in air conditions performed by other authors. The results showed that the wet welding technique performed in this work produced good mechanical properties of the repaired T-welded connection. The mechanical properties, measured in wet conditions, for 6 mm grinding depth, were similar for the 3 different water depths measured in air conditions. But for 10 mm grinding depth, the values of the mechanical properties measured in wet conditions were quite lower than that for air conditions for the 3 water depths. However a porosity analysis, performed with a Scanning Electronic Microscopy (SEM), showed that the level of porosity in the resulted wet weld beads is in the range of that published in the literature and some samples revealed lower level of porosity. The main resulting microstructure was polygonal

  14. Studies on Fusion Welding of High Nitrogen Stainless Steel: Microstructure, Mechanical and corrosion Behaviour

    Science.gov (United States)

    Mohammed, Raffi; Srinivasa Rao, K.; Madhusudhan Reddy, G.

    2018-03-01

    An attempt has been made in the present investigation to weld high nitrogen steel of 5mm thick plates using various process i.e., shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW) and autogenous electron beam welding (EBW) process. Present work is aimed at studying the microstructural changes and its effects on mechanical properties and corrosion resistance. Microstructure is characterized by optical, scanning electron microscopy and electron back scattered diffraction technique. Vickers hardness, tensile properties, impact toughness and face bend ductility testing of the welds was carried out. Pitting corrosion resistance of welds was determined using potentio-dynamic polarization testing in 3.5%NaCl solution. Results of the present investigation established that SMA welds made using Cr-Mn-N electrode were observed to have a austenite dendritic grain structure in the weld metal and is having poor mechanical properties but good corrosion resistance. GTA welds made using 18Ni (MDN 250) filler wire were observed to have a reverted austenite in martensite matrix of the weld metal and formation of unmixed zone at the fusion boundary which resulted in better mechanical properties and poor corrosion resistance. Fine grains and uniform distribution of delta ferrite in the austenite matrix and narrow width of weld zone are observed in autogeneous electron beam welds. A good combination of mechanical properties and corrosion resistance was achieved for electron beam welds of high nitrogen steel when compared to SMA and GTA welds.

  15. Optimization of pulsed TIG welding process parameters on mechanical properties of AA 5456 Aluminum alloy weldments

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A. [Department of Mechanical Engineering, National Institute of Technology, Warangal 506 004 (India)], E-mail: adepu_kumar7@yahoo.co.in; Sundarrajan, S. [Scientist ' G' , Defence Research and Development Laboratory, Hyderabad 500 028 (India)

    2009-04-15

    The present work pertains to the improvement of mechanical properties of AA 5456 Aluminum alloy welds through pulsed tungsten inert gas (TIG) welding process. Taguchi method was employed to optimize the pulsed TIG welding process parameters of AA 5456 Aluminum alloy welds for increasing the mechanical properties. Regression models were developed. Analysis of variance was employed to check the adequacy of the developed models. The effect of planishing on mechanical properties was also studied and observed that there was improvement in mechanical properties. Microstructures of all the welds were studied and correlated with the mechanical properties.

  16. Optimization of pulsed TIG welding process parameters on mechanical properties of AA 5456 Aluminum alloy weldments

    International Nuclear Information System (INIS)

    Kumar, A.; Sundarrajan, S.

    2009-01-01

    The present work pertains to the improvement of mechanical properties of AA 5456 Aluminum alloy welds through pulsed tungsten inert gas (TIG) welding process. Taguchi method was employed to optimize the pulsed TIG welding process parameters of AA 5456 Aluminum alloy welds for increasing the mechanical properties. Regression models were developed. Analysis of variance was employed to check the adequacy of the developed models. The effect of planishing on mechanical properties was also studied and observed that there was improvement in mechanical properties. Microstructures of all the welds were studied and correlated with the mechanical properties

  17. Effect of post-weld aging treatment on mechanical properties of Tungsten Inert Gas welded low thickness 7075 aluminium alloy joints

    International Nuclear Information System (INIS)

    Temmar, M.; Hadji, M.; Sahraoui, T.

    2011-01-01

    Highlights: → The effects of post-weld aging treatment on the properties of joints is studied. → The post-weld aging treatment increases the tensile strength of TIG welded joints. → The strengthening is due to a balance of dissolution, reversion and precipitation. → Simple post-weld aging at 140 o C enhances the properties of the welded joints. -- Abstract: This paper reports the influence of post-weld aging treatment on the microstructure, tensile strength, hardness and Charpy impact energy of weld joints low thickness 7075 T6 aluminium alloy welded by Tungsten Inert Gas (TIG). Hot cracking occurs in aluminium welds when high levels of thermal stress and solidification shrinkage are present while the weld is undergoing various degrees of solidification. Weld fusion zones typically exhibit microstructure modifications because of the thermal conditions during weld metal solidification. This often results in low weld mechanical properties and low resistance to hot cracking. It has been observed that the mechanical properties are very sensitive to microstructure of weld metal. Simple post-weld aging treatment at 140 o C applied to the joints is found to be beneficial to enhance the mechanical properties of the welded joints. Correlations between microstructures and mechanical properties were discussed.

  18. Comparative Studies on Microstructure, Mechanical and Pitting Corrosion of Post Weld Heat Treated IN718 Superalloy GTA and EB Welds

    Science.gov (United States)

    Dilkush; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    In the present study, an attempt has been made to weld Inconel 718 nickel-base superalloy (IN718 alloy) using gas tungsten arc welding (GTAW) and electron beam welding (EBW) processes. Both the weldments were subjected to post-weld heat treatment condition as follows -980°C / 20 min followed by direct aging condition (DA) as 720°C/8 h/FC followed by 620°C/8 h/AC. The GTA and EB welds of IN718 alloy were compared in two conditions as-received and 980STA conditions. Welds were characterized to observe mechanical properties, pitting corrosion resistance by correlating with observed microstructures. The rate of higher cooling ranges, the fusion zone of EBW exhibited discrete and relative finer lave phases whereas the higher niobium existed laves with coarser structure were observed in GTAW. The significant dissolution of laves were observed at 980STA of EBW. Due to these effects, the EBW of IN718 alloy showed the higher mechanical properties than GTAW. The electrochemical potentiostatic etch test was carried out in 3.5wt% sodium chloride (NaCl) solution to study the pitting corrosion behaviour of the welds. Results of the present investigation established that mechanical properties and pitting corrosion behaviour are significantly better in post weld heat treated condition. The comparative studies showed that the better combination of mechanical properties and pitting corrosion resistance were obtained in 980STA condition of EBW than GTAW.

  19. Characterization of bond line discontinuities in a high-Mn TWIP steel pipe welded by HF-ERW

    Energy Technology Data Exchange (ETDEWEB)

    Park, Gitae; Kim, Bongyoon; Kang, Yongjoon [Division of Materials Science and Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763 (Korea, Republic of); Kang, Heewoong [RD Team, Husteel, 131 Bugokgongdan-ro, Songak-eup, Dangjin-si, Chungnam 31721 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763 (Korea, Republic of)

    2016-08-15

    In this work, the microstructure and defects in a high-frequency electrical resistance welded (HF-ERW) pipe of high-Mn twinning-induced plasticity (TWIP) steel were characterized. The microstructure of the base metal and the bond line were examined using both optical microscopy and scanning electron microscopy. The features of the bond line were similar to those of conventional steel. Simultaneously, the circumferential ductility was evaluated via a flaring test. It was concluded that the deterioration of the circumferential ductility in a high-Mn TWIP steel pipe was caused by irregular shaped oxide defects and a penetrator that had been formed during welding. Specifically, the penetrator, which is composed of MnO and Mn{sub 2}SiO{sub 4}, was found to be the most influential on the circumferential ductility of the welded pipe. The penetrator was analyzed using both an electron probe micro analyzer and transmission electron microscopy, and the formation sequence of the penetrator was evaluated. - Highlights: •This study focused on applying the HF-ERW process to the seam welding of expandable pipe using TWIP steels. •For improvement of the circumferential ductility, deterioration factors were characterized. •Penetrator which would mainly deteriorate the circumferential ductility consisted of round MnO and Mn{sub 2}SiO{sub 4}. •Metallurgical evidence of existing theory regarding the mechanism of defect formation during the HF-ERW was characterized.

  20. Numerical analysis of laser welding with consideration analytical methods of determining phase transformations and mechanical properties of welded joint

    Directory of Open Access Journals (Sweden)

    Piekarska Wiesława

    2018-01-01

    Full Text Available The numerical analysis of laser welding process with consideration analytical methods determining phase transformations and mechanical properties of welded joints are presents in this paper. The analytical CCT diagram and final structural composition of S355 steel are presented. The empirical relations presents in paper are determined by chemical compositions investigated steel and cooling rate between temperatures 800-500°C (t8/5. Phase composition and mechanical properties each of structures of steel in weld and heat affected zone (HAZ are determined on the basis of analytical methods. Laser welded flat is used in numerical simulations in ABAQUS. Mathematical modes of volumetric welding source are used in the calculations. Temperature fields, shape and size of melting zone for selected points in the cross-section of the joint are determined on the basis of thermal cycles obtained numerical.

  1. Mechanical Properties and Microstructure of Dissimilar Material Welded Joints

    Directory of Open Access Journals (Sweden)

    Ziewiec A.

    2014-10-01

    Full Text Available The paper presents results of the mechanical testing and the microstructure analysis of dissimilar welded joint of the R350HT steel and the high-manganese (Hadfield cast steel using Cr-Ni cast steel spacer. The simulation tests of the welded joint surface deformation were carried out. The macroscopic and microscopic investigation were made using light microscopy (LM and scanning electron microscopy (SEM. Content of the magnetic phase was measured using magnetoscope. The quantitative metallographic investigation was used for assessment of ferrite and martensite contents and X-ray diffraction phase analysis was carried out. The results showed that during cooling of the spacer after welding, the transformation of metastable austenite into martensite proceeded. In addition to work hardening, the phase transformation of austenite into martensite occurs during the process of the superficial deformation of the spacer while simulated exploitation. This leads to a substantial increase of hardness, and at the same time, causes the increase of wear resistance of the welded joints of crossovers.

  2. Tailored Welding Technique for High Strength Al-Cu Alloy for Higher Mechanical Properties

    Science.gov (United States)

    Biradar, N. S.; Raman, R.

    AA2014 aluminum alloy, with 4.5% Cu as major alloying element, offers highest strength and hardness values in T6 temper and finds extensive use in aircraft primary structures. However, this alloy is difficult to weld by fusion welding because the dendritic structure formed can affect weld properties seriously. Among the welding processes, AC-TIG technique is largely used for welding. As welded yield strength was in the range of 190-195 MPa, using conventional TIG technique. Welding metallurgy of AA2014 was critically reviewed and factors responsible for lower properties were identified. Square-wave AC TIG with Transverse mechanical arc oscillation (TMAO) was postulated to improve the weld strength. A systematic experimentation using 4 mm thick plates produced YS in the range of 230-240 MPa, has been achieved. Through characterization including optical and SEM/EDX was conducted to validate the metallurgical phenomena attributable to improvement in weld properties.

  3. Mechanisms of joint and microstructure formation in high power ultrasonic spot welding 6111 aluminium automotive sheet

    International Nuclear Information System (INIS)

    Bakavos, D.; Prangnell, P.B.

    2010-01-01

    Resistance spot welding (RSW) is difficult to apply to aluminium automotive alloys. High power ultrasonic spot welding (HP-USW) is a new alternative method which is extremely efficient, using ∼2% of the energy of RSW. However, to date there have been few studies of the mechanisms of bond formation and the material interactions that take place with this process. Here, we report on a detailed investigation where we have used X-ray tomography, high resolution SEM, and EBSD, and dissimilar alloy welds, to track the interface position and characterise the stages of weld formation, and microstructure evolution, as a function of welding energy. Under optimum conditions high quality welds are produced, showing few defects. Welding proceeds by the development and spread of microwelds, until extensive plastic deformation occurs within the weld zone, where the temperature reaches ∼380 deg. C. The origin of the weld interface 'flow features' characteristic of HP-USW are discussed.

  4. Effect of Welding Processes on the Microstructure, Mechanical Properties and Residual Stresses of Plain 9Cr-1Mo Steel Weld Joints

    Science.gov (United States)

    Nagaraju, S.; Vasantharaja, P.; Brahadees, G.; Vasudevan, M.; Mahadevan, S.

    2017-12-01

    9Cr-1Mo steel designated as P9 is widely used in the construction of power plants and high-temperature applications. It is chosen for fabricating hexcan fuel subassembly wrapper components of fast breeder reactors. Arc welding processes are generally used for fabricating 9Cr-1Mo steel weld joints. A-TIG welding process is increasingly being adopted by the industries. In the present study, shielded metal arc (SMA), tungsten inert gas (TIG) and A-TIG welding processes are used for fabricating the 9Cr-1Mo steel weld joints of 10 mm thickness. Effect of the above welding processes on the microstructure evolution, mechanical properties and residual stresses of the weld joints has been studied in detail. All the three weld joints exhibited comparable strength and ductility values. 9Cr-1Mo steel weld joint fabricated by SMAW process exhibited lower impact toughness values caused by coarser grain size and inclusions. 9Cr-1Mo steel weld joint fabricated by TIG welding exhibited higher toughness due to finer grain size, while the weld joint fabricated by A-TIG welding process exhibited adequate toughness values. SMA steel weld joint exhibited compressive residual stresses in the weld metal and HAZ, while TIG and A-TIG weld joint exhibited tensile residual stresses in the weld metal and HAZ.

  5. Weld line optimization on thermoplastic elastomer micro injection moulded components using 3D focus variation optical microscopy

    DEFF Research Database (Denmark)

    Hasnaes, F.B.; Elsborg, R.; Tosello, G.

    2015-01-01

    The presented study investigates weld line depth development across a micro suspension ring. A focus variation microscope was used to obtain 3D images of the weld line area. Suspension rings produced with different micro injection moulding process parameters were examined to identify the correlat......The presented study investigates weld line depth development across a micro suspension ring. A focus variation microscope was used to obtain 3D images of the weld line area. Suspension rings produced with different micro injection moulding process parameters were examined to identify...

  6. Effect of Mg and Cu on mechanical properties of high-strength welded joints of aluminum alloys obtained by laser welding

    Science.gov (United States)

    Annin, B. D.; Fomin, V. M.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.

    2017-09-01

    Results of experimental investigations of welded joints of high-strength aluminum-lithium alloys of the Al-Cu-Li and Al-Mg-Li systems are reported. The welded joints are obtained by means of laser welding and are subjected to various types of processing for obtaining high-strength welded joints. A microstructural analysis is performed. The phase composition and mechanical properties of the welded joints before and after heat treatment are studied. It is found that combined heat treatment of the welded joint (annealing, quenching, and artificial ageing) increases the joint strength, but appreciably decreases the alloy strength outside the region thermally affected by the welding process.

  7. Microstructure and mechanical properties of electron beam welded dissimilar steel to Fe–Al alloy joints

    Energy Technology Data Exchange (ETDEWEB)

    Dinda, Soumitra Kumar; Basiruddin Sk, Md.; Roy, Gour Gopal [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur (India); Srirangam, Prakash, E-mail: p.srirangam@warwick.ac.uk [Warwick Manufacturing Group (WMG), University of Warwick, Coventry CV4 7AL (United Kingdom)

    2016-11-20

    Electron beam welding (EBW) technique was used to perform dissimilar joining of plain carbon steel to Fe–7%Al alloy under three different weld conditions such as with beam oscillation, without beam oscillation and at higher welding speed. The effect of weld parameters on the microstructure and mechanical properties of dissimilar joints was studied using optical microscopy, SEM, EBSD, hardness, tensile and erichsen cup tests. Microstructure results show that the application of beam oscillation resulted in uniform and homogeneous microstructure compared to without beam oscillations and higher welding speed. Further, it was observed that weld microstructure changes from equiaxed to columnar grains depending on the weld speed. High weld speed results in columnar grain structure in the weld joint. Erichsen cup test results show that the application of beam oscillation results in excellent formability as compared to high weld speed. Tensile test results show no significant difference in strength properties in all three weld conditions, but the ductility was found to be highest for joints obtained with the application of weld beam oscillation as compared to without beam oscillation and high weld speed. This study shows that the application of beam oscillations plays an important role in improving the weld quality and performance of EBW dissimilar steel to Fe–Al joints.

  8. Counterrotating-Shoulder Mechanism for Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2007-01-01

    A counterrotating-shoulder mechanism has been proposed as an alternative to the mechanism and fixtures used in conventional friction stir welding. The mechanism would internally react most or all of the forces and torques exerted on the workpiece, making it unnecessary to react the forces and torques through massive external fixtures. In conventional friction stir welding, a rotating pin tool is inserted into, and moved along, a weld seam. As the pin tool moves, it stirs together material from the opposite sides of the seam to form the weld. A large axial plunge force must be exerted upon the workpiece through and by the pin tool and a shoulder attached above the pin tool in order to maintain the pressure necessary for the process. The workpiece is secured on top of an anvil, which supports the workpiece against the axial plunge force and against the torque exerted by the pin tool and shoulder. The anvil and associated fixtures must be made heavy (and, therefore, are expensive) to keep the workpiece stationary. In addition, workpiece geometries must be limited to those that can be accommodated by the fixtures. The predecessor of the proposed counterrotating-shoulder mechanism is a second-generation, self-reacting tool, resembling a bobbin, that makes it possible to dispense with the heavy anvil. This tool consists essentially of a rotating pin tool with opposing shoulders. Although the opposing shoulders maintain the necessary pressure without need to externally apply or react a large plunge force, the torque exerted on the workpiece remains unreacted in the absence of a substantial external fixture. Depending on the RPM and the thickness of the workpiece, the torque can be large. The proposed mechanism (see figure) would include a spindle attached to a pin tool with a lower shoulder. The spindle would be coupled via splines to the upper one of three bevel gears in a differential drive. The middle bevel gear would be the power-input gear and would be coupled to the

  9. Effect of yield stress matching on ductile fracture behavior of girth welds for X line pipe

    Energy Technology Data Exchange (ETDEWEB)

    Motohashi, Hiroyuki; Hagiwara, Naoto [Tokyo Gas Co., Ltd. (Japan)

    2005-07-01

    This paper describes the effects of yield stress matching on the ductile fracture behavior of girth welded joints for X linepipes. Three welded joints were made on an X line pipe using several consumables to obtain about a 20% overmatched, even matched and about a 20% under matched weld metal. For these three welded joints, curved wide plate tensile tests were then conducted with a surface notch in the weld metal. To determine the ductile crack initiation from the surface notch, these tests employed a direct-current electric potential (d-c E P) method. Crack opening displacement, gauge length strain and local strain adjacent to the surface notch were also measured. The ductile crack initiation was successfully detected using the d-c E P method. The yield stress matching significantly affected the ductile crack initiation and fracture behavior, that is, the overmatched welded joint had a higher resistance to ductile fracture than that of the under matched welded joint. The allowable strength matching level was determined from the relationship between the strength matching and the gauge length strain at the ductile crack initiation detected using the d-c E P method. (author)

  10. Mechanical Properties of Steel P92 Welded Joints Obtained By TIG Technology

    Science.gov (United States)

    Mohyla, P.; Havelka, L.; Schmidová, E.; Vontorová, J.

    2017-11-01

    Mechanical properties of P92 steel welded joints obtained using the TIG (141) technology have been studied upon post-welding heat treatment (PWHT). The microhardness, tensile strength, and impact toughness of metal in the weld and heat-affected zone are determined. The PWHT is shown to be obligatory.

  11. Analysis of the Mechanism of Longitudinal Bending Deformation Due to Welding in a Steel Plate by Using a Numerical Model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Rae; Yan, Jieshen; Kim, Jae-Woong [Yeungnam Univ., Gyeongsan (Korea, Republic of); Song, Gyu Yeong [Gyeongbuk Hybrid Technology Institute, Yeongcheon (Korea, Republic of)

    2017-01-15

    Welding deformation is a permanent deformation that is caused in structures by welding heat. Welding distortion is the primary cause of reduced productivity, due to welded structural strength degradation, low dimensional accuracy, and appearance. As a result, research and numerous experiments are being carried out to control welding deformation. The aim of this study is to analyze the mechanism of longitudinal bending deformation due to welding. Welding experiments and numerical analyses were performed for this study. The welding experiments were performed on 4 mm and 8.5 mm thickness steel plates, and the numerical analysis was conducted on the welding deformation using the FE software MSC.marc.

  12. Mechanical properties of TIG and EB weld joints of F82H

    Energy Technology Data Exchange (ETDEWEB)

    Hirose, Takanori, E-mail: hirose.takanori@jaea.go.jp; Sakasegawa, Hideo; Nakajima, Motoki; Tanigawa, Hiroyasu

    2015-10-15

    Highlights: • Narrow groove TIG minimized volume of F82H weld. • Mechanical properties of TIG and EB welds of F82H have been characterized. • Post weld heat treatment successfully moderate the toughness of weld metal without softening the base metal. - Abstract: This work investigates mechanical properties of weld joints of a reduced activation ferritic/martensitic steel, F82H and effects of post weld heat treatment on the welds. Vickers hardness, tensile and Charpy impact tests were conducted on F82H weld joints prepared using tungsten-inert-gas and electron beam after various heat treatments. Although narrow groove tungsten-inert-gas welding reduced volume of weld bead, significant embrittlement was observed in a heat affected zone transformed due to heat input. Post weld heat treatment above 993 K successfully moderated the brittle transformed region. The hardness of the brittle region strongly depends on the heat treatment temperature. Meanwhile, strength of base metal was slightly reduced by the treatment at temperature ranging from 993 to 1053 K. Moreover, softening due to double welding was observed only in the weld metal, but negligible in base metal.

  13. Microstructure and mechanical properties of the TIG welded joints of fusion CLAM steel

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Zhizhong, E-mail: zhizhongjiang2006@yahoo.com.c [School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road, Beijing 100083 (China); Ren Litian; Huang Jihua; Ju Xin; Wu Huibin [School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road, Beijing 100083 (China); Huang Qunying; Wu Yican [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2010-12-15

    The CLAM steel plates were butt-welded through manual tungsten inert gas welding (TIG) process, and the following post-welding heat treatment (PWHT) at 740 {sup o}C for 1 h. The microstructure and mechanical properties of the welded joints were measured. The results show that both hardening and softening occur in the weld joints before PWHT, but the hardening is not removed completely in the weld metal and the fusion zone after PWHT. In as-welded condition, the microstructure of the weld metal is coarse lath martensite, and softened zone in heat-affected zone (HAZ) consists of a mixture of tempered martensite and ferrite. After PWHT, a lot of carbides precipitate at all zones in weld joints. The microstructure of softened zone transforms to tempered sorbite. Tensile strength of the weld metal is higher than that of HAZ and base metal regardless of PWHT. However, the weld metal has poor toughness without PWHT. The impact energy of the weld metal after PWHT reaches almost the same level as the base metal. So it is concluded that microstructure and mechanical properties of the CLAM steel welded joints can be improved by a reasonable PWHT.

  14. A development of an automated ultrasonic TOFD inspection system using an welding line tracing robot

    International Nuclear Information System (INIS)

    Cho, Hyun; Song, Sung Jin; Lee, Kang Won; Kim, Young Jin; Woo, Jong Sik

    2006-01-01

    Large scaled ships, manufactured inside of the country, should be passed welding inspection and painting film inspection. Normally, these kind of inspections are conducted by human inspectors manually, although it cause industrial disasters such as falling accidents and diving accidents frequently. In addition, Ship makers are not to give a full trust to shipowners because manual inspections cannot be conducted all over the welding parts. So, in this study we developed an automated ultrasonic TOFD inspection system using an welding line tracing robot. This system, controlled by an inspector at a remote field, can inspect welding parts of ship outer panel both under water and in air. In this paper we present the developed robot and ultrasonic TOFD inspection system and the inspection result.

  15. A development of an automated ultrasonic TOFD inspection system using an welding line tracing robot

    International Nuclear Information System (INIS)

    Cho, Hyun; Song, Sung Jin; Lee, Kang Won; Kim, Young Jin; Woo, Jong Sik

    2006-01-01

    Large scaled ships, manufactured inside of the country, should be passed welding inspection and painting film inspection. Normally, these kind of inspections are conducted by human inspectors manually, although it cause industrial disasters such as falling accidents and diving accidents frequently. In addition, Ship makers are not to give a full trust to ship owners because manual inspections cannot be conducted all over the welding parts. So, in this study we developed an automated ultrasonic TOFD inspection system using an welding line tracing robot. This system, controlled by an inspector at a remote field, can inspect welding parts of ship outer panel both under water and in air. In this paper we present the developed robot and ultrasonic TOFD inspection system and the inspection result.

  16. Thermo-mechanical process for treatment of welds

    International Nuclear Information System (INIS)

    Malik, R.K.

    1980-03-01

    Benefits from thermo-mechanical processing (TMP) of austenitic stainless steel weldments, analogous to hot isostatic pressing (HIP) of castings, most likely result from compressive plastic deformation, enhanced diffusion, and/or increased dislocation density. TMP improves ultrasonic inspectability of austenitic stainless steel welds owing to: conversion of cast dendrites into equiaxed austenitic grains, reduction in size and number of stringers and inclusions, and reduction of delta ferrite content. TMP induces structural homogenization and healing of void-type defects and thus contributes to an increase in elongation, impact strength, and fracture toughness as well as a significant reduction in data scatter for these properties. An optimum temperature for TMP or HIP of welds is one which causes negligible grain growth and an acceptable reduction in yield strength, and permits healing of porosity

  17. 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.

  18. The effect of welding line heat-affected-zone on the formability of tube hydroforming process

    Science.gov (United States)

    ChiuHuang, Cheng-Kai; Hsu, Cheng-En; Lee, Ping-Kun

    2016-08-01

    Tube hydroforming has been used as a lightweight design approach to reduce CO2 emission for the automotive industry. For the high strength steel tube, the strength and quality of the welding line is very important for a successful tube hydroforming process. This paper aims to investigate the effect of the welding line's strength and the width of the heat-affected zone on the tube thinning during the hydroforming process. The simulation results show that both factors play an important role on the thickness distribution during the tube expansion.

  19. The effect of welding line heat-affected-zone on the formability of tube hydroforming process

    International Nuclear Information System (INIS)

    ChiuHuang, Cheng-Kai; Hsu, Cheng-En; Lee, Ping-Kun

    2016-01-01

    Tube hydroforming has been used as a lightweight design approach to reduce CO_2 emission for the automotive industry. For the high strength steel tube, the strength and quality of the welding line is very important for a successful tube hydroforming process. This paper aims to investigate the effect of the welding line's strength and the width of the heat-affected zone on the tube thinning during the hydroforming process. The simulation results show that both factors play an important role on the thickness distribution during the tube expansion. (paper)

  20. Computational simulation of weld microstructure and distortion by considering process mechanics

    Science.gov (United States)

    Mochizuki, M.; Mikami, Y.; Okano, S.; Itoh, S.

    2009-05-01

    Highly precise fabrication of welded materials is in great demand, and so microstructure and distortion controls are essential. Furthermore, consideration of process mechanics is important for intelligent fabrication. In this study, the microstructure and hardness distribution in multi-pass weld metal are evaluated by computational simulations under the conditions of multiple heat cycles and phase transformation. Because conventional CCT diagrams of weld metal are not available even for single-pass weld metal, new diagrams for multi-pass weld metals are created. The weld microstructure and hardness distribution are precisely predicted when using the created CCT diagram for multi-pass weld metal and calculating the weld thermal cycle. Weld distortion is also investigated by using numerical simulation with a thermal elastic-plastic analysis. In conventional evaluations of weld distortion, the average heat input has been used as the dominant parameter; however, it is difficult to consider the effect of molten pool configurations on weld distortion based only on the heat input. Thus, the effect of welding process conditions on weld distortion is studied by considering molten pool configurations, determined by temperature distribution and history.

  1. Dynamic modelling, identification and simulation of industrial robots – for off-line programming of robotised laser welding

    NARCIS (Netherlands)

    Waiboer, R.R.

    2007-01-01

    Robotised laser welding is an innovative joining technique which is increasingly finding applications, especially in the automotive industry. In order to reduce the time needed to prepare and programthe laser welding robot, off-line programming systems are used. The off-line programming systems

  2. Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

    Science.gov (United States)

    2013-01-01

    REPORT Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions 14. ABSTRACT 16. SECURITY...properties and of the attendant ballistic-impact failure mechanisms in prototypical friction stir welding (FSW) joints found in armor structures made of high...mechanisms, friction stir welding M. Grujicic, B. Pandurangan, A. Arakere, C-F. Yen, B. A. Cheeseman Clemson University Office of Sponsored Programs 300

  3. Application of laser ultrasonic method for on-line monitoring of friction stir spot welding process.

    Science.gov (United States)

    Zhang, Kuanshuang; Zhou, Zhenggan; Zhou, Jianghua

    2015-09-01

    Application of a laser ultrasonic method is developed for on-line monitoring of the friction stir spot welding (FSSW) process. Based on the technology of FSSW, laser-generated ultrasonic waves in a good weld and nonweld area are simulated by a finite element method. The reflected and transmitted waves are analyzed to disclose the properties of the welded interface. The noncontact-laser ultrasonic-inspection system was established to verify the numerical results. The reflected waves in the good-weld and nonweld area can be distinguished by time-of-flight. The transmitted waves evidently attenuate in the nonweld area in contrast to signal amplitude in the good weld area because of interfacial impedance difference. Laser ultrasonic C-scan images can sufficiently evaluate the intrinsic character of the weld area in comparison with traditional water-immersion ultrasonic testing results. The research results confirm that laser ultrasonics would be an effective method to realize the characterization of FSSW defects.

  4. Mechanical properties and corrosion behaviour of MIG welded 5083 aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Durmus, Huelya [Celal Bayar Univ., Turgutlu-Manisa (Turkey)

    2011-07-01

    For this study 5083 Aluminium alloy plates, as used in automobiles and watercraft, were experimentally MIG welded. The plates were joined with different wires and at various currents. The effects of welding with different parameters on the mechanical and corrosion properties were investigated. The corrosion behaviour of the MIG welded 5083 Aluminium base material was also investigated. The effects of the chemical composition of the filler material on the mechanical properties were examined by metallographic inspection and tensile testing. By EDS and XRD analyses of specimens it turned out that different structures in the weld metal (Cu3Si) affect its mechanical properties. The mechanical properties of the specimens welded with 5356 filler metal were found as quite well improved as compared to those specimens welded with 4043 and 5183 filler material. The results of the metallographic analysis, and mechanical and corrosion tests exhibited that the 5356 filler material was most suitable for the 5083 Al alloy base material. (orig.)

  5. Microstructure and mechanical properties of friction stir welded and laser welded high entropy alloy CrMnFeCoNi

    Science.gov (United States)

    Jo, Min-Gu; Kim, Han-Jin; Kang, Minjung; Madakashira, Phaniraj P.; Park, Eun Soo; Suh, Jin-Yoo; Kim, Dong-Ik; Hong, Sung-Tae; Han, Heung Nam

    2018-01-01

    The high entropy alloy CrMnFeCoNi has been shown to have promising structural properties. For a new alloy to be used in a structural application it should be weldable. In the present study, friction stir welding (FSW) and laser welding (LW) techniques were used to butt weld thin plates of CrMnFeCoNi. The microstructure, chemical homogeneity and mechanical behavior of the welds were characterized and compared with the base metal. The tensile stress-strain behavior of the welded specimens were reasonable when compared with that of the base metal. FSW refined the grain size in the weld region by a factor of ˜14 when compared with the base metal. High-angle annular dark field transmission electron microscopy in combination with energy dispersive X-ray spectroscopy showed chemical inhomogeneity between dendritic and interdendritic regions in the fusion zone of LW. Large fluctuations in composition (up to 15 at%) did not change the crystal structure in the fusion zone. Hardness measurements were carried out in the weld cross section and discussed in view of the grain size, low angle grain boundaries and twin boundaries in FSW specimens and the dendritic microstructure in LW specimens.

  6. Microstructure, mechanical properties and microtexture of friction stir welded S690QL high yield steel

    Energy Technology Data Exchange (ETDEWEB)

    Paillard, Pascal [Institut des Matériaux Jean Rouxel, UMR 6205, Polytech Nantes, Site de la Chantrerie, BP 50609, 44306 Nantes cedex 3 (France); Bertrand, Emmanuel, E-mail: emmanuel.bertrand@univ-nantes.fr [Institut des Matériaux Jean Rouxel, UMR 6205, Polytech Nantes, Site de la Chantrerie, BP 50609, 44306 Nantes cedex 3 (France); Allart, Marion; Benoit, Alexandre [Institut de Recherche Technologique Jules Verne, Chemin du Chaffault, 44340 Bouguenais (France); Ruckert, Guillaume [DCNS Research, Technocampus Ocean, 5 rue de l' Halbrane, 44340 Bouguenais (France)

    2016-12-15

    Two try-out campaigns of friction stir welding (FSW) were performed with different friction parameters to join S690QL high yield strength steel. The welds were investigated at macroscopic and microscopic scales using optical and electronic microscopy and microhardness mapping. Welds of the second campaign exhibit microstructures and mechanical properties in accordance with requirements for service use. Microtexture measurements were carried out in different zones of welds by electron backscattered diffraction (EBSD). It is shown that that texture of the bottom of the weld is similar to that of the base metal, suggesting a diffusion bonding mechanism. Finally, the mechanical properties (tensile strength, resilience, bending) were established on the most promising welds. It is shown that it is possible to weld this high yield strength steel using FSW process with satisfactory geometric, microstructural and mechanical properties. - Highlights: •1000 mm ∗ 400 mm ∗ 8 mm S690QL steel plates are joined by friction stir welding (FSW). •Maximum hardness is reduced by optimization of process parameters. •Various microstructures are formed but no martensite after process optimization. •Texture is modified in mechanically affected zones of the weld. •Texture in the bottom of the weld is preserved, suggesting diffusion bonding.

  7. Gamma-radiography techniques applied to quality control of welds in water pipe lines

    International Nuclear Information System (INIS)

    Sanchez, W.; Oki, H.

    1974-01-01

    Non-destructive testing of welds may be done by the gamma-radiography technique, in order to detect the presence or absence of discontinuities and defects in the bulk of deposited metal and near the base metal. Gamma-radiography allows the documentation of the test with a complete inspection record, which is a fact not common in other non-destructive testing methods. In the quality control of longitudinal or transversal welds in water pipe lines, two exposition techniques are used: double wall and panoramic exposition. Three different water pipe lines systems have analysed for weld defects, giving a total of 16,000 gamma-radiographies. The tests were made according to the criteria established by the ASME standard. The principal metallic discontinuites found in the weld were: porosity (32%), lack of penetration (29%), lack of fusion (20%), and slag inclusion (19%). The percentage of gamma-radiographies showing welds without defects was 39% (6168 gamma-radiographies). On the other hand, 53% (8502 gamma-radiographies) showed the presence of acceptable discontinuities and 8% (1330 gamma-radiographies) were rejected according to the ASME standards [pt

  8. Evaluation of the sheet mechanical response to laser welding processes

    International Nuclear Information System (INIS)

    Carmignani, B.; Daneri, A.; Toselli, G.; Bellei, M.

    1995-07-01

    The simulation of the mechanical response of steel sheets, due to the heating during welding processes by a laser source beam, obtained by Abaqus standard code, is discussed. Different hypotheses for the material behaviour at temperatures greater than the fusion one have been tested and compared; in particular, some tests have been made taking the annealing effect into account by means of an user routine UMAT developed ad hoc. This work was presented at the 8th international Abaqus Users' conference at Paris, 31 May - 2 June 1995

  9. Mechanical Properties of Welded Deformed Reinforcing Steel Bars

    Directory of Open Access Journals (Sweden)

    Ghafur H. Ahmed

    2015-05-01

    Full Text Available Reinforcement strength, ductility and bendability properties are important components in design of reinforced concrete members, as the strength of any member comes mainly from reinforcement. Strain compatibility and plastic behaviors are mainly depending on reinforcement ductility. In construction practice, often welding of the bars is required. Welding of reinforcement is an instant solution in many cases, whereas welding is not a routine connection process. Welding will cause deficiencies in reinforcement bars, metallurgical changes and re-crystallization of microstructure of particles. Weld metal toughness is extremely sensitive to the welding heat input that decreases both of its strength and ductility. For determining the effects of welding in reinforcement properties, 48 specimens were tested with 5 different bar diameters, divided into six groups. Investigated parameters were: properties of un-welded bars; strength, ductility and density of weld metal; strength and ductility reduction due to heat input for bundled bars and transverse bars; welding effect on bars’ bending properties; behavior of different joint types; properties of three weld groove shapes also the locations and types of failures sections. Results show that, strength and elongation of the welded bars decreased by (10-40% and (30-60% respectively. Cold bending of welded bars and groove welds shall be prevented.

  10. Microstructure and Mechanical Properties of Three-Layer TIG-Welded 2219 Aluminum Alloys with Dissimilar Heat Treatments

    Science.gov (United States)

    Zhang, Dengkui; Li, Quan; Zhao, Yue; Liu, Xianli; Song, Jianling; Wang, Guoqing; Wu, Aiping

    2018-05-01

    2219-C10S and 2219-CYS aluminum alloys are 2219 aluminum alloys with different heat treatment processes, and they have been widely used in the aerospace industry. In the present study, 2219-C10S and 2219-CYS aluminum alloys were butt-welded by three-layer tungsten inert gas arc welding (with the welding center of the third layer shifted toward the CYS side), and the microstructure characteristics and mechanical properties of the welded joint were investigated. The lamellar θ' phases, the bulk or rod θ phases, and the coarse rod-shaped or pancake-shaped Al-Cu-Fe-Mn phases coexisted in the two aluminum alloys. The Cu content of the α-Al matrix and the distribution of eutectic structures of different welding layers in the weld zone (WZ) were varied, implying that the segregation degrees of the Cu element were different due to the different welding thermal cycles in different welding layers. The microhardness values of the CYS side were much higher than those of the C10S side in each region on both sides of the joint. The tensile test deformation was concentrated mainly in the regions of WZ and the over aged zone (OAZ), where the microhardness values were relatively low. The main deformation concentrated region was transferred from the CYS side to the C10S side with the increase in the tensile load during the tensile test. The fracture behavior of the tensile test showed that the macroscopic crack initiated near the front weld toe had gone through the crack blunt region, the shear fracture region of the partially melted zone (PMZ), and the shear fracture region of OAZ. Meanwhile, the fracture characteristics gradually evolved from brittle to ductile. The concentrated stress and the dense eutectic structure in the region near the front weld toe of the C10S side contributed to the fracture of the joint. The shift of the welding center of the third layer to the CYS side resulted in two effects: (i) the microhardness values from the middle layer to the top layer in the

  11. Numerical Simulation of Mechanical Property of Post Friction Stir Weld Artificial Ageing of Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    WAN Zhenyu

    2017-08-01

    Full Text Available KWN model was used to establish the precipitation evolution model of friction stir welding of Al-Mg-Si alloy. The yield strength was divided into three parts:the contribution from grain size, the contribution from solid solution and the contribution from the precipitations. Based on this model, the yield strength and hardness of friction stir weld was predicted. The effect of post weld artificial ageing on mechanical properties of friction stir weld was further investigated. The results indicate that longer holding time can be beneficial to the recovery of mechanical properties in the stirring zone. Higher temperature can lead to quick recovery of mechanical properties in the stirring zone, but when the holding temperature is higher than 200℃, longer holding time can lead the base metal softened, which is harmful to the service of friction stir welds. The mechanical property in the heat affected zone cannot be improved by post weld artificial ageing.

  12. Effect of nickel content on mechanical properties and fracture toughness of weld metal of WWER-1000 reactor vessel welded joints

    Energy Technology Data Exchange (ETDEWEB)

    Zubchenko, A.S.; Vasilchenko, G.S.; Starchenko, E.G.; Nosov, S.I

    2004-08-01

    Welding of WWER-1000 reactor vessel of steel 15X2HMPHIA is performed using the C{sub B}-12X2H2MAA wire and PHI-16 or PHI-16A flux. Nickel content in the weld metal usually lays within the limits 1.2-1.9%. The experimental data is shown on the weld metal with the nickel contents 1.28-2.45% after irradiation with fluence up to 260.10{sup 22}n/m{sup 2} at energy more than 0.5 MEV. The embrittlement was measured by shift of critical brittleness temperature. Has appeared, that the weld metal with the low nickel content is the least responsive to irradiation embrittlement. The mechanical properties and fracture toughness of the weld metal with the contents of a nickel less than 1.3% are studied. Specimens CT-1T are tested, the 'master-curve', and its confidence bounds with probability of destruction 5 and 95% is built. 'Master-curve' in the specified confidence interval is affirmed by CT-4T specimens test data. Is shown, that the mechanical properties and fracture toughness of the weld metal with the contents of nickel less than 1.3% satisfy the normative requirements.

  13. Effect of nickel content on mechanical properties and fracture toughness of weld metal of WWER-1000 reactor vessel welded joints

    International Nuclear Information System (INIS)

    Zubchenko, A.S.; Vasilchenko, G.S.; Starchenko, E.G.; Nosov, S.I.

    2004-01-01

    Welding of WWER-1000 reactor vessel of steel 15X2HMPHIA is performed using the C B -12X2H2MAA wire and PHI-16 or PHI-16A flux. Nickel content in the weld metal usually lays within the limits 1.2-1.9%. The experimental data is shown on the weld metal with the nickel contents 1.28-2.45% after irradiation with fluence up to 260.10 22 n/m 2 at energy more than 0.5 MEV. The embrittlement was measured by shift of critical brittleness temperature. Has appeared, that the weld metal with the low nickel content is the least responsive to irradiation embrittlement. The mechanical properties and fracture toughness of the weld metal with the contents of a nickel less than 1.3% are studied. Specimens CT-1T are tested, the 'master-curve', and its confidence bounds with probability of destruction 5 and 95% is built. 'Master-curve' in the specified confidence interval is affirmed by CT-4T specimens test data. Is shown, that the mechanical properties and fracture toughness of the weld metal with the contents of nickel less than 1.3% satisfy the normative requirements

  14. Microstructure, mechanical and corrosion behavior of high strength AA7075 aluminium alloy friction stir welds – Effect of post weld heat treatment

    Directory of Open Access Journals (Sweden)

    P. Vijaya Kumar

    2015-12-01

    It was observed that the hardness and strength of weld were observed to be comparatively high in peak aged (T6 condition but the welds showed poor corrosion resistance. The resistance to pitting corrosion was improved and the mechanical properties were maintained by RRA treatment. The resistance to pitting corrosion was improved in RRA condition with the minimum loss of weld strength.

  15. Model development for mechanical properties and weld quality class of friction stir welding using multi-objective Taguchi method and response surface methodology

    International Nuclear Information System (INIS)

    Mohamed, Mohamed Ackiel; Manurung, Yupiter HP; Berhan, Mohamed Nor

    2015-01-01

    This study presents the effect of the governing parameters in friction stir welding (FSW) on the mechanical properties and weld quality of a 6mm thick 6061 T651 Aluminum alloy butt joint. The main FSW parameters, the rotational and traverse speed were optimized based on multiple mechanical properties and quality features, which focus on the tensile strength, hardness and the weld quality class using the multi-objective Taguchi method (MTM). Multi signal to noise ratio (MSNR) was employed to determine the optimum welding parameters for MTM while further analysis concerning the significant level determination was accomplished via the well-established analysis of variance (ANOVA). Furthermore, the first order model for predicting the mechanical properties and weld quality class is derived by applying response surface methodology (RSM). Based on the experimental confirmation test, the proposed method can effectively estimate the mechanical properties and weld quality class which can be used to enhance the welding performance in FSW or other applications.

  16. Model development for mechanical properties and weld quality class of friction stir welding using multi-objective Taguchi method and response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Mohamed Ackiel [University Kuala Lumpur Malaysia France Institute, Bandar Baru Bangi (Malaysia); Manurung, Yupiter HP; Berhan, Mohamed Nor [Universiti Teknologi MARA, Shah Alam (Malaysia)

    2015-06-15

    This study presents the effect of the governing parameters in friction stir welding (FSW) on the mechanical properties and weld quality of a 6mm thick 6061 T651 Aluminum alloy butt joint. The main FSW parameters, the rotational and traverse speed were optimized based on multiple mechanical properties and quality features, which focus on the tensile strength, hardness and the weld quality class using the multi-objective Taguchi method (MTM). Multi signal to noise ratio (MSNR) was employed to determine the optimum welding parameters for MTM while further analysis concerning the significant level determination was accomplished via the well-established analysis of variance (ANOVA). Furthermore, the first order model for predicting the mechanical properties and weld quality class is derived by applying response surface methodology (RSM). Based on the experimental confirmation test, the proposed method can effectively estimate the mechanical properties and weld quality class which can be used to enhance the welding performance in FSW or other applications.

  17. Mechanical properties of CO2/MIG welded structural rolled steel and stainless steel

    International Nuclear Information System (INIS)

    Lim, Jong Young; Yoon, Myong Jin; Kim, Sang Youn; Kim, Tae Gyu; Shin, Hyeon Seung

    2015-01-01

    To accomplish long-term use of specific parts of steel, welding technology is widely applied. In this study, to compare the efficiency in improving mechanical properties, rolled steel (SS400) was welded with stainless steel (STS304) by both CO 2 welding method and MIG (metal inert gas) welding method, respectively. Multi-tests were conducted on the welded specimen, such as X-ray irradiation, Vickers' Hardness, tensile test, fatigue test and fatigue crack growth test. Based on the fatigue crack growth test performed by two different methods, the relationship of da/dN was analyzed. Although the hardness by the two methods was similar, tensile test and fatigue properties of MIG welded specimen are superior to CO 2 welded one.

  18. Fully mechanized welding of pipelines in the chemical industry and reactor construction

    International Nuclear Information System (INIS)

    Born, K.

    1984-01-01

    Pipes are increasingly being used as a construction element involving a growing demand for modern welding technology. The pulsed-arc welding procedures occupy an important position in mechanized pipe welding especially where flanged joints are to be made on turning pipes with a burner fixed in place. When the construction prohibits the turning of pipes, the orbital welding technique may be used. The paper discusses the question how the economic efficiency of TIG in inert-gas welding, which is the commonly used welding technique, could be enhanced and in how far other pulsed-arc welding methods, e.g. plasma keyhole or MIG/MAG pulsed-arc could be used in future. This could be done using the new possibilities offered by modern power sources and process technology. (orig.) [de

  19. Grain structure, texture and mechanical property evolution of automotive aluminium sheet during high power ultrasonic welding

    International Nuclear Information System (INIS)

    Haddadi, Farid; Tsivoulas, Dimitrios

    2016-01-01

    High power ultrasonic spot welding (HPUSW) is a joining technique which is performed within less than a second and provides a more energy-efficient alternative to friction stir spot welding (FSSW), which is considered a longer cycle manufacturing process for joining automotive alloys. To date, only a few reports exist on the deformation mechanisms that take place during high power ultrasonic spot welding. In this work, dynamic recrystallization and grain growth were examined using electron backscatter diffraction (EBSD). HPUSW causes extensive deformation within the weld zone where the temperature increases to 440 °C. An ultra-fine grain structure was observed in a thin band of flat weld interface within a short welding time of 0.10 s. With increasing welding time the interface was displaced and ‘folds’ or ‘crests’ appeared together with shear bands. The weld interface progressively changed from flat to sinusoidal and eventually to a convoluted wave-like pattern when the tool fully penetrated the workpiece, having a wavelength of ~ 1 mm after 0.40 s. Finally, the microstructure and texture varied significantly depending on the location within the weld. Although the texture near the weld interface was relatively weak, a shift was observed with increasing welding time from an initially Cube-dominated texture to one where the typical β-fibre Brass component prevailed. - Highlights: •Lap shear strength of ~2.9 kN was achieved in 0.30 sec welding time. •Temperature approached 440 °C along the weld centreline for the highest welding time. •The texture near the teeth was dominated by Brass, P and S components at optimum condition. •The weld interface showed typical β-fibre deformation texture at optimum condition.

  20. Grain structure, texture and mechanical property evolution of automotive aluminium sheet during high power ultrasonic welding

    Energy Technology Data Exchange (ETDEWEB)

    Haddadi, Farid, E-mail: farid.haddadi@gmail.com [Clemson University–International Center for Automotive Research (CU-ICAR), #347, 4 Research Drive, Greenville, SC 29607 (United States); School of Materials, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Tsivoulas, Dimitrios, E-mail: dim.tsivoulas@gmail.com [School of Materials, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Clean Energy/Nuclear Services, Amec Foster Wheeler, 601 Faraday Street, Birchwood Park, Warrington WA3 6GN (United Kingdom)

    2016-08-15

    High power ultrasonic spot welding (HPUSW) is a joining technique which is performed within less than a second and provides a more energy-efficient alternative to friction stir spot welding (FSSW), which is considered a longer cycle manufacturing process for joining automotive alloys. To date, only a few reports exist on the deformation mechanisms that take place during high power ultrasonic spot welding. In this work, dynamic recrystallization and grain growth were examined using electron backscatter diffraction (EBSD). HPUSW causes extensive deformation within the weld zone where the temperature increases to 440 °C. An ultra-fine grain structure was observed in a thin band of flat weld interface within a short welding time of 0.10 s. With increasing welding time the interface was displaced and ‘folds’ or ‘crests’ appeared together with shear bands. The weld interface progressively changed from flat to sinusoidal and eventually to a convoluted wave-like pattern when the tool fully penetrated the workpiece, having a wavelength of ~ 1 mm after 0.40 s. Finally, the microstructure and texture varied significantly depending on the location within the weld. Although the texture near the weld interface was relatively weak, a shift was observed with increasing welding time from an initially Cube-dominated texture to one where the typical β-fibre Brass component prevailed. - Highlights: •Lap shear strength of ~2.9 kN was achieved in 0.30 sec welding time. •Temperature approached 440 °C along the weld centreline for the highest welding time. •The texture near the teeth was dominated by Brass, P and S components at optimum condition. •The weld interface showed typical β-fibre deformation texture at optimum condition.

  1. A comparative study of the microstructure and mechanical properties of HTLA steel welds obtained by the tungsten arc welding and resistance spot welding

    Energy Technology Data Exchange (ETDEWEB)

    Ghazanfari, H., E-mail: ghazanfari@aut.ac.ir [AmirKabir University of Technology, Department of Mining and Metallurgy, 424 Hafez Ave, Tehran (Iran, Islamic Republic of); Naderi, M., E-mail: mnaderi@aut.ac.ir [AmirKabir University of Technology, Department of Mining and Metallurgy, 424 Hafez Ave, Tehran (Iran, Islamic Republic of); Iranmanesh, M., E-mail: imehdi@aut.ac.ir [AmirKabir University of Technology, Department of Maritime Engineering, 424 Hafez Ave, Tehran (Iran, Islamic Republic of); Seydi, M., E-mail: afsan_sy@yahoo.com [Zarin Joosh Aria Co., Tehran (Iran, Islamic Republic of); Poshteban, A., E-mail: ali_poshtiban@yahoo.com [Hamyar Sanat Eghbal Co., Tehran (Iran, Islamic Republic of)

    2012-02-01

    Highlights: Black-Right-Pointing-Pointer Hardness mapping is a novel method to identify different phases. Black-Right-Pointing-Pointer Surface hardness mapping, tabulates the hardness of a large area of weld. Black-Right-Pointing-Pointer Hardness maps can be used to depict the strength map through the specimen. Black-Right-Pointing-Pointer Hardness mapping is an easy way to identify the phase fractions within the specimen. - Abstract: Hardness tests are routinely employed as simple and efficient methods to investigate the microstructure and mechanical properties of steels. Each microstructural phase in steel has its own hardness level. Therefore, using surface hardness mapping data over a large area of weld zone would be a reasonable method to identify the present phases in steel. The microstructure distribution and mechanical properties variation through welded structures is inhomogeneous and not suitable for certain applications. So, studying the microstructure of weld zone has a significant importance. 4130 steel is classified in HTLA steels and it is widely used in marine industry due to its superior hardenability, good corrosion resistance and high strength. Gas tungsten arc and resistance spot welding are the most usable processes in joining of 4130 sheets. In this work a series of welds have been fabricated in 4130 steel tube by gas tungsten arc and resistance spot welding. The tube was subjected to quench-tempered heat treatment. Slices from the welds before and after heat treatment were polished and etched and the macrostructure and microstructure were observed. Hardness maps were then determined over the large area of weld zone, including the heat affected zone and base plate. Results show good relations between the various microstructures, strength and hardness values. It is also proved that this method is precise and applicable to estimate phase fraction of each phase in various regions of weld. In the current study some equations were proposed to

  2. A comparative study of the microstructure and mechanical properties of HTLA steel welds obtained by the tungsten arc welding and resistance spot welding

    International Nuclear Information System (INIS)

    Ghazanfari, H.; Naderi, M.; Iranmanesh, M.; Seydi, M.; Poshteban, A.

    2012-01-01

    Highlights: ► Hardness mapping is a novel method to identify different phases. ► Surface hardness mapping, tabulates the hardness of a large area of weld. ► Hardness maps can be used to depict the strength map through the specimen. ► Hardness mapping is an easy way to identify the phase fractions within the specimen. - Abstract: Hardness tests are routinely employed as simple and efficient methods to investigate the microstructure and mechanical properties of steels. Each microstructural phase in steel has its own hardness level. Therefore, using surface hardness mapping data over a large area of weld zone would be a reasonable method to identify the present phases in steel. The microstructure distribution and mechanical properties variation through welded structures is inhomogeneous and not suitable for certain applications. So, studying the microstructure of weld zone has a significant importance. 4130 steel is classified in HTLA steels and it is widely used in marine industry due to its superior hardenability, good corrosion resistance and high strength. Gas tungsten arc and resistance spot welding are the most usable processes in joining of 4130 sheets. In this work a series of welds have been fabricated in 4130 steel tube by gas tungsten arc and resistance spot welding. The tube was subjected to quench-tempered heat treatment. Slices from the welds before and after heat treatment were polished and etched and the macrostructure and microstructure were observed. Hardness maps were then determined over the large area of weld zone, including the heat affected zone and base plate. Results show good relations between the various microstructures, strength and hardness values. It is also proved that this method is precise and applicable to estimate phase fraction of each phase in various regions of weld. In the current study some equations were proposed to calculate the ultimate tensile stress and yield stress from the weld. The calculated data were compared

  3. Experimental study of mechanical properties of friction welded AISI ...

    Indian Academy of Sciences (India)

    to their wide application in the manufacturing industry. For the first set of ... the friction welded joint; destructive testing and non-destructive testing. ..... hardness was found at the weld interfaces for almost every case, this might be attributed to.

  4. Process parameters-weld bead geometry interactions and their influence on mechanical properties: A case of dissimilar aluminium alloy electron beam welds

    Directory of Open Access Journals (Sweden)

    P. Mastanaiah

    2018-04-01

    Full Text Available Prediction of weld bead geometry is always an interesting and challenging research topic as it involves understanding of complex multi input and multi output system. The weld bead geometry has a profound impact on the load bearing capability of a weld joint, which in-turn decides the performance in real time service conditions. The present study introduces a novel approach of detecting a relationship between weld bead geometry and mechanical properties (e.g. tensile load for the purpose of catering the best the process could offer. The significance of the proposed approach is demonstrated by a case of dissimilar aluminium alloy (AA2219 and AA5083 electron beam welds. A mathematical model of tensile braking load as a function of geometrical attributes of weld bead geometry is presented. The results of investigation suggests the effective thickness of weld – a geometric parameter of weld bead has the most significant influence on tensile breaking load of dissimilar weld joint. The observations on bead geometry and the mechanical properties (microhardness, ultimate tensile load and face bend angle are correlated with detailed metallurgical analysis. The fusion zone of dissimilar electron beam weld has finer grain size with a moderate evaporation and segregation of alloying elements magnesium and copper respectively. The mechanical properties of weld joint are controlled by optimum bead geometry and HAZ softening in weaker AA5083 Al alloy. Keywords: Electron beam welding, AA2219, AA5083, Bead geometry, Tensile breaking load

  5. The Simulation of Precipitation Evolutions and Mechanical Properties in Friction Stir Welding with Post-Weld Heat Treatments

    Science.gov (United States)

    Zhang, Z.; Wan, Z. Y.; Lindgren, L.-E.; Tan, Z. J.; Zhou, X.

    2017-12-01

    A finite element model of friction stir welding capable of re-meshing is used to simulate the temperature variations. Re-meshing of the finite element model is used to maintain a fine mesh resolving the gradients of the solution. The Kampmann-Wagner numerical model for precipitation is then used to study the relation between friction stir welds with post-weld heat treatment (PWHT) and the changes in mechanical properties. Results indicate that the PWHT holding time and PWHT holding temperature need to be optimally designed to obtain FSW with better mechanical properties. Higher precipitate number with lower precipitate sizes gives higher strength in the stirring zone after PWHT. The coarsening of precipitates in HAZ are the main reason to hinder the improvement of mechanical property when PWHT is used.

  6. Constitutive model of friction stir weld with consideration of its inhomogeneous mechanical properties

    Science.gov (United States)

    Zhang, Ling; Min, Junying; Wang, Bin; Lin, Jianping; Li, Fangfang; Liu, Jing

    2016-03-01

    In practical engineering, finite element(FE) modeling for weld seam is commonly simplified by neglecting its inhomogeneous mechanical properties. This will cause a significant loss in accuracy of FE forming analysis, in particular, for friction stir welded(FSW) blanks due to the large width and good formability of its weld seam. The inhomogeneous mechanical properties across weld seam need to be well characterized for an accurate FE analysis. Based on a similar AA5182 FSW blank, the metallographic observation and micro-Vickers hardness analysis upon the weld cross-section are performed to identify the interfaces of different sub-zones, i.e., heat affected zone(HAZ), thermal-mechanically affected zone(TMAZ) and weld nugget(WN). Based on the rule of mixture and hardness distribution, a constitutive model is established for each sub-zone to characterize the inhomogeneous mechanical properties across the weld seam. Uniaxial tensile tests of the AA5182 FSW blank are performed with the aid of digital image correlation(DIC) techniques. Experimental local stress-strain curves are obtained for different weld sub-zones. The experimental results show good agreement with those derived from the constitutive models, which demonstrates the feasibility and accuracy of these models. The proposed research gives an accurate characterization of inhomogeneous mechanical properties across the weld seam produced by FSW, which provides solutions for improving the FE simulation accuracy of FSW sheet forming.

  7. Analysis of microstructure and mechanical properties of aluminium-copper joints welded by FSW process

    Science.gov (United States)

    Iordache, M.; Sicoe, G.; Iacomi, D.; Niţu, E.; Ducu, C.

    2017-08-01

    The research conducted in this article aimed to check the quality of joining some dissimilar materials Al-Cu by determining the mechanical properties and microstructure analysis. For the experimental measurements there were used tin alloy Al - EN-AW-1050A with a thickness of 2 mm and Cu99 sheet with a thickness of 2 mm, joined by FSW weld overlay. The main welding parameters were: rotating speed of the rotating element 1400 rev/min, speed of the rotating element 50 mm/min. The experimental results were determined on samples specially prepared for metallographic analysis. In order to prepare samples for their characterization, there was designed and built a device that allowed simultaneous positioning and fixing for grinding. The characteristics analyzed in the joint welded samples were mictrostructure, microhardness and residual stresses. The techniques used to determine these characteristics were optical microscopy, electron microscopy with fluorescence radioactive elemental analysis (EDS), Vickers microhardness line - HV0.3 and X-ray diffractometry.

  8. Microstructure and Mechanical Characterization of Friction-Stir-Welded Dual-Phase Brass

    Science.gov (United States)

    Ramesh, R.; Dinaharan, I.; Akinlabi, E. T.; Murugan, N.

    2018-03-01

    Friction stir welding (FSW) is an ideal process to join brass to avoid the evaporation of zinc. In the present investigation, 6-mm-thick dual-phase brass plates were joined efficiently using FSW at various tool rotational speeds. The microstructures were studied using optical microscopy, electron backscattered diffraction and transmission electron microscopy. The optical micrographs revealed the evolution of various zones across the joint line. The microstructure of the heat-affected zone was similar to that of base metal. The weld zone exhibited finer grains due to dynamic recrystallization. The recrystallization was inhomogeneous and the inhomogeneity reduced with increased tool rotational speed. The dual phase was preserved in the weld zone due to the retention of zinc. The severe plastic deformation created a lot of dislocations in the weld zone. The weld zone was strengthened after welding. The role of tool rotational speed on the joint strength is further reported.

  9. Fundamental studies on electron-beam welding of heat-resistant superalloys for nuclear plants: Report 4. Mechanical properties of welded joints

    International Nuclear Information System (INIS)

    Susei, S.; Shimizu, S.; Aota, T.

    1982-04-01

    In this report, electron-beam (EB) welded joints and TIG welded joints of various superalloys to be used for nuclear plants, such as Hastelloy-type, Inconel-type and Incoloy-type, are systematically evaluated in terms of tensile properties, low-cycle fatigue properties at elevated temperatures, creep and creep-rupture properties. It was fully confirmed as conclusion that the EB welded joints are superior to the TIG welded ones in mechanical properties, especially at high temperature. In the evaluation of creep properties, ductility is one of the most important criteria to represent the resistance against fracture due to creep deformation, and this criterion is very useful in evaluating the properties of welded joints. Therefore, the more comparable to the base metal the electron beam welded joint becomes in terms of ductility, the more resistant is it against fracture. From this point of view, the electron beam welded joint is considerably superior to the TIG welded joint [fr

  10. Prediction of mechanical properties in friction stir welds of pure copper

    International Nuclear Information System (INIS)

    Heidarzadeh, A.; Saeid, T.

    2013-01-01

    Highlights: • Range of parameters for defect-free friction stir welded pure copper was reached. • Models were developed for predicting UTS, TE and hardness of pure copper joints. • Analysis of variance was used to validate the developed models. • Effect of welding parameters on mechanical behavior of welded joints was explored. • The microstructure and fracture surface of welded joints were investigated. - Abstract: This research was carried out to predict the mechanical properties of friction stir welded pure copper joints. Response surface methodology based on a central composite rotatable design with three parameters, five levels, and 20 runs, was used to conduct the experiments and to develop the mathematical regression model by using of Design-Expert software. The three welding parameters considered were rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted models. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on mechanical properties of friction stir welded joints were analyzed in detail. The results showed that the developed models were reasonably accurate. The increase in welding parameters resulted in increasing of tensile strength of the joints up to a maximum value. Elongation percent of the joints increased with increase of rotational speed and axial force, but decreased by increasing of welding speed, continuously. In addition, hardness of the joints decreased with increase of rotational speed and axial force, but increased by increasing of welding speed. The joints welded at higher heat input conditions revealed more ductility fracture mode

  11. Microstructural and mechanical properties of pure aluminum, 5083 and 7075 alloys joined by friction stir welding

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Selim Sarper [Celal Bayar Univ., Manisa, Muradiye (Turkey)

    2012-07-01

    In this study, microstructural and mechanical properties of pure aluminum, 5083 and 7075 alloys joined by friction stir welding were investigated. Hardness, tensile, bending and impact tests were applied to the welded samples. In addition, optical and SEM tests were carried out. The effects of welding speed on microstructure and mechanical properties were investigated in these materials. Then, the optimal conditions for friction stir welding were determined for pure aluminum, 5083 and 7075 alloys. The maximum hardness was observed for 7075 while the minimum hardness was observed for pure aluminum. (orig.)

  12. ADVANCED INTEGRATION OF MULTI-SCALE MECHANICS AND WELDING PROCESS SIMULATION IN WELD INTEGRITY ASSESSMENT

    Energy Technology Data Exchange (ETDEWEB)

    Wilkowski, Gery M.; Rudland, David L.; Shim, Do-Jun; Brust, Frederick W.; Babu, Sundarsanam

    2008-06-30

    The potential to save trillions of BTU’s in energy usage and billions of dollars in cost on an annual basis based on use of higher strength steel in major oil and gas transmission pipeline construction is a compelling opportunity recognized by both the US Department of Energy (DOE). The use of high-strength steels (X100) is expected to result in energy savings across the spectrum, from manufacturing the pipe to transportation and fabrication, including welding of line pipe. Elementary examples of energy savings include more the 25 trillion BTUs saved annually based on lower energy costs to produce the thinner-walled high-strength steel pipe, with the potential for the US part of the Alaskan pipeline alone saving more than 7 trillion BTU in production and much more in transportation and assembling. Annual production, maintenance and installation of just US domestic transmission pipeline is likely to save 5 to 10 times this amount based on current planned and anticipated expansions of oil and gas lines in North America. Among the most important conclusions from these studies were: • While computational weld models to predict residual stress and distortions are well-established and accurate, related microstructure models need improvement. • Fracture Initiation Transition Temperature (FITT) Master Curve properly predicts surface-cracked pipe brittle-to-ductile initiation temperature. It has value in developing Codes and Standards to better correlate full-scale behavior from either CTOD or Charpy test results with the proper temperature shifts from the FITT master curve method. • For stress-based flaw evaluation criteria, the new circumferentially cracked pipe limit-load solution in the 2007 API 1104 Appendix A approach is overly conservative by a factor of 4/π, which has additional implications. . • For strain-based design of girth weld defects, the hoop stress effect is the most significant parameter impacting CTOD-driving force and can increase the crack

  13. Joining technologies for the 1990s: Welding, brazing, soldering, mechanical, explosive, solid-state, adhesive

    Science.gov (United States)

    Buckley, John D. (Editor); Stein, Bland A. (Editor)

    1986-01-01

    A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Society, and Society of Manufacturing Engineers Conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

  14. Strengthening mechanisms in an inertia friction welded nickel-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Tiley, J.S., E-mail: Jaimie.Tiley@us.af.mil [Air Force Research Laboratory, Wright Patterson Air Force Base, OH 45433 (United States); Mahaffey, D.W. [Air Force Research Laboratory, Wright Patterson Air Force Base, OH 45433 (United States); Alam, T.; Rojhirunsakool, T. [Department of Materials Engineering, University of North Texas, Denton, TX 76203 (United States); Senkov, O.; Parthasarthy, T. [Air Force Research Laboratory, Wright Patterson Air Force Base, OH 45433 (United States); UES, Inc., Dayton, OH 45433 (United States); Banerjee, R. [Department of Materials Engineering, University of North Texas, Denton, TX 76203 (United States)

    2016-04-26

    This research investigated the strengthening mechanisms associated with the as-welded microstructure developed during inertia friction welding of dissimilar superalloys LHSR and Mar-M247. The weld interface and heat affected regions of the sample were analyzed using hardness indentation techniques and subsequently characterized using SEM, TEM and advanced atom probe tomography. The yield strength of the welded joint was modeled to determine the impact of the gradients in the as-welded microstructure on strengthening mechanisms within the LSHR material. Characterization centered on formation of γ′, γ grain size and chemical segregation within the heat affected regions. Results indicate an increased hardness in the vicinity of the weld interface, resulting from the refined dispersion of γ′ and γ grains.

  15. The Design of Intelligent Repair Welding Mechanism and Relative Control System of Big Gear

    Directory of Open Access Journals (Sweden)

    Hong-Yu LIU

    2014-10-01

    Full Text Available Effective repair of worn big gear has large influence on ensuring safety production and enhancing economic benefits. A kind of intelligent repair welding method was put forward mainly aimed at the big gear restriction conditions of high production cost, long production cycle and high- intensity artificial repair welding work. Big gear repair welding mechanism was designed in this paper. The work principle and part selection of big gear repair welding mechanism was introduced. The three dimensional mode of big gear repair welding mechanism was constructed by Pro/E three dimensional design software. Three dimensional motions can be realized by motor controlling ball screw. According to involute gear feature, the complicated curve motion on curved gear surface can be transformed to linear motion by orientation. By this way, the repair welding on worn gear area can be realized. In the design of big gear repair welding mechanism control system, Siemens S7-200 series hardware was chosen. Siemens STEP7 programming software was chosen as system design tool. The entire repair welding process was simulated by experiment simulation. It provides a kind of practical and feasible method for the intelligent repair welding of big worn gear.

  16. Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe.

    Science.gov (United States)

    Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

    2015-01-01

    On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.

  17. Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe

    Science.gov (United States)

    Chen, Zejun; Han, Huiquan; Ren, Wei; Huang, Guangjie

    2015-01-01

    On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes. PMID:26201073

  18. The microstructure and mechanical properties of a welded molybdenum alloy

    International Nuclear Information System (INIS)

    Wadsworth, J.; Morse, G.R.; Chewey, P.M.

    1983-01-01

    Wrought Ti-Zr-Mo (TZM) alloy has been welded using electron beam, laser and tungsten-inert gas welding techniques. The microstructure, tensile properties and fracture surfaces of these welded samples have been examined. Although the welds have been found to be defect free, a disparity in grain size leading to large strength differences exists between the weld and parent metal. Tensile tests have revealed that fusion zone strengths are typical of those expected for the grain size in the weld metal. However, brittle behavior is also always observed, with fracture initiating at grain boundaries and propagating by intergranular and cleavage modes. Auger electron spectroscopy analysis has eliminated oxygen or other interstitial elements as sources of grain boundary embrittlement. It is proposed that brittle behavior is a result of local high strain rates in the weld zone. These local high strain rates arise from the strength difference between the wrought parent metal and the weld metal as a result of the strong grain size dependence of TZM. It is shown that, either by reducing the strain rate of testing or by removing the grain size difference between the parent and weld metals by heat treatment, significant ductility can in fact be achieved in tensile-tested butt-welded TZM. Thus, it is proposed that TZM welds are not inherently brittle as had commonly been believed. (Auth.)

  19. Lamb Wave Line Sensing for Crack Detection in a Welded Stiffener

    Directory of Open Access Journals (Sweden)

    Yun-Kyu An

    2014-07-01

    Full Text Available This paper proposes a novel Lamb wave line sensing technique for crack detection in a welded stiffener. The proposed technique overcomes one of the biggest technical challenges of Lamb wave crack detection for real structure applications: crack-induced Lamb waves are often mixed with multiple reflections from complex waveguides. In particular, crack detection in a welded joint, one of the structural hot spots due to stress concentration, is accompanied by reflections from the welded joint as well as a crack. Extracting and highlighting crack-induced Lamb wave modes from Lamb wave responses measured at multi-spatial points along a single line can be accomplished through a frequency-wavenumber domain analysis. The advantages of the proposed technique enable us not only to enhance the crack detectability in the welded joint but also to minimize false alarms caused by environmental and operational variations by avoiding the direct comparison with the baseline data previously accumulated from the pristine condition of a target structure. The proposed technique is experimentally and numerically validated in vertically stiffened metallic structures, revealing that it successfully identifies and localizes subsurface cracks, regardless of the coexistence with the vertical stiffener.

  20. Use of automation and mechanization elements in welding and surfacing nuclear reactor pressure vessels

    International Nuclear Information System (INIS)

    Bartak, J.; Elckner, J.

    1986-01-01

    The problems are discussed of automation and mechanization of individual operations in the production cycle of pressure vessels whose manufacture cannot for its great exactingness be automated as a whole. Examples are given of workplaces and single-purpose welding facilities with a high level of automation. The present state of the development and implementation of automation of arc welding is described and further development is indicated of the automation of welding processes in the manufacture of nuclear facilities. (J.C.)

  1. TIG AISI-316 welds using an inert gas welding chamber and different filler metals: Changes in mechanical properties and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Pascual, M.; Salas, F.; Carcel, F.J.; Perales, M.; Sanchez, A.

    2010-07-01

    This report analyses the influence of the use of an inert gas welding chamber with a totally inert atmosphere on the microstructure and mechanical properties of austenitic AISI 316L stainless steel TIG welds, using AISI ER316L, AISI 308L and Inconel 625 as filler metals. When compared with the typical TIG process, the use of the inert gas chamber induced changes in the microstructure, mainly an increase in the presence of vermicular ferrite and ferrite stringers, what resulted in higher yield strengths and lower values of hardness. Its effect on other characteristics of the joins, such as tensile strength, depended on the filler metal. The best combination of mechanical characteristics was obtained when welding in the inert gas chamber using Inconel 625 as filler metal. (Author). 12 refs.

  2. Welding.

    Science.gov (United States)

    Cowan, Earl; And Others

    The curriculum guide for welding instruction contains 16 units presented in six sections. Each unit is divided into the following areas, each of which is color coded: terminal objectives, specific objectives, suggested activities, and instructional materials; information sheet; transparency masters; assignment sheet; test; and test answers. The…

  3. The effects of welded joint characteristics on its properties in HDPE thermal fusion welding

    Science.gov (United States)

    Dai, Hongbin; Peng, Jun

    2017-05-01

    In this paper, PE100 pipes with the diameter of 200 mm and the thickness of 11.9 mm were used as material. The welded joints were obtained in different welding pressures with the optimal welding temperature of 220∘C. Reheating process on the welded joints with the temperature of 130∘C was carried out. The joints exhibited X-type, and the cause of X-type joints was discussed. The temperature field in the forming process of welded joints was measured, and tensile and bending tests on welded joints were carried out. The fracture surface of welded joints was observed by scanning electron microscopy (SEM), and crystallinity calculation was taken by X-ray diffraction (XRD). The mechanism of X-type weld profile effects on welded joints properties was analyzed. It was concluded that the mechanical properties of welded joints decrease with the reduced X distance between lines.

  4. Correlation of Weld Appearance with Microstructure and Mechanical Properties of 2024-T4 Aluminum Alloy Welded by Fiber Laser with Filler Wire

    Directory of Open Access Journals (Sweden)

    XU Fei

    2017-11-01

    Full Text Available Two typical cross-section of welds, including nail shape and near X shape, are obtained in the process of fiber laser welding 2024-T4 Al alloy with filler wire. The correlations of the two weld appearances and other elements (such as microstructure, microhardness, and joint's tensile properties were analyzed. The results show that the weld with near X shape cross-section during the welding process is more stable than that with nail shape cross-section, and the welding spatter of the former is smaller than that of the latter. The microstructure of the weld zone is columnar grains and equiaxed grains, the columnar grains are formed near the fusion line and growing along the vertical direction of the fusion line, the equiaxed grains are distributed in the center of the weld zone. The secondary dendrite of the grains in the center of the weld with nail shape cross-section grows better, and gradually forms to equiaxed dendrite, while the grains size of the weld with near X shape cross-section is relatively finer, exhibiting equiaxed cellular grain. Compared with the joint with nail shape cross-section of the weld, the joint with near X shape cross-section of the weld have some different characteristics, the precipitation strengthening phase θ(Al2Cu content in weld zone of the latter is more than that of the former, the average microhardness value of the weld zone of the latter is higher than that of the former, the softening phenomenon of heat affect zone (HAZ of the latter is weaker than that of the former, and the joint's tensile strength and plasticity of the latter are lower than that of the former slightly.

  5. Parametric Investigation on Microstructure and Mechanical Properties of Ultrasonic spot welded Aluminium to Copper sheets

    Science.gov (United States)

    Prasad Satpathy, Mantra; Das Mohapatra, Kasinath; Sahoo, Ananda Kumar; Sahoo, Susanta Kumar

    2018-03-01

    Ultrasonic welding is one of the promising solid state welding methods which have been widely used to join highly conductive materials like aluminum and copper. Despite these applications in the automotive field, other industries also have a strong interest to adopt this process for joining of various advanced alloys. In some of its applications, poor weld strength and sticking of the workpiece to the tool are issues. Thus, an attempt has been taken in the present study to overcome these issues by performing experiments with a suitable range of weld parameters. The major objectives of this study are to obtain a good joint strength with a reduced sticking phenomenon and microstructure of Al-Cu weld coupons. The results uncovered the mechanical strength of the joint increased up to 0.34 sec of weld time and afterward, it gradually decreased. Meantime, the plastic deformation in the weld zone enhanced the formation of an intermetallic layer of 1.5 μm thick, and it is composed of mainly Al2Cu compound. The temperature evolved during the welding process is also measured by thermocouples to show its relationship with the plastic deformation. The present work exemplifies a finer understanding of the failure behavior of joints and provides an insight of ultrasonic welding towards the improvement in the quality of weld.

  6. Microstructure and Mechanical Properties of ASTM A743 CA6NM Steel Welded by FCAW Process

    OpenAIRE

    Silva, Rafael de Paula; Faria, Maria Ismenia Sodero Toledo; Almeida, Luiz Fernando Cursino Briet de; Nunes, Carlos Angelo; Vieira, Décio; Borges Júnior, Wanderlei

    2017-01-01

    CA6NM steel is widely used in the manufacture of hydraulic turbines metallic parts, due to its resistance to corrosion and cavitation damage, combined with good weldability and fatigue properties. However, welding of this type of steel is complex and to ensure a minimum residual stress after welding it is necessary perform a post welding heat treatment (PWHT) of the part. This study aims to analyze the effect of a PWHT on the microstructure and mechanical properties of CA6NM steel weld joint ...

  7. Mechanisms of the porosity formation during the fiber laser lap welding of aluminium alloy

    Directory of Open Access Journals (Sweden)

    J. Wang

    2015-10-01

    Full Text Available When joining the aluminum alloys, one of the biggest challenges is the formation of porosity, which deteriorates mechanical properties of welds. In this study, the lap welding was conducted on an aluminum alloy 5754 metal sheets with a thickness of 2 mm. The effects of various laser welding parameters on the weld quality were investigated. The porosity content was measured by X-ray inspections. The key is to control the solidification duration of molten pool. When the solidification duration of molten pool is large enough, more bubbles can escape from the molten pool and less remain as porosity.

  8. Mechanical properties of friction stir welded 11Cr-ferritic/martensitic steel

    International Nuclear Information System (INIS)

    Yano, Y.; Sato, Y.S.; Sekio, Y.; Ohtsuka, S.; Kaito, T.; Ogawa, R.; Kokawa, H.

    2013-01-01

    Friction stir welding was applied to the wrapper tube materials, 11Cr-ferritic/martensitic steel, designed for fast reactors and defect-free welds were successfully produced. The mechanical and microstructural properties of the friction stir welded steel were subsequently investigated. The hardness values of the stir zone were approximately 550 Hv (5.4 GPa) with minimal dependence on the rotational speed, even though they were much higher than those of the base material. However, tensile strengths and elongations of the stir zones were high at 298 K, compared to those of the base material. The excellent tensile properties are attributable to the fine grain formation during friction stir welding

  9. Resistance spot welding of AISI 430 ferritic stainless steel: Phase transformations and mechanical properties

    International Nuclear Information System (INIS)

    Alizadeh-Sh, M.; Marashi, S.P.H.; Pouranvari, M.

    2014-01-01

    Highlights: • Phase transformations during RSW of AISI430 are detailed. • Grain growth, martensite formation and carbide precipitation are dominant phase transformations. • Failure mode of AISI430 resistance spot welded joints are analyzed. • Larger FZ size provided improved load bearing capacity and energy absorption capability. - Abstract: The paper aims at investigating the process–microstructure–performance relationship in resistance spot welding of AISI 430 ferritic stainless steel. The phase transformations which occur during weld thermal cycle were analyzed in details, based on the physical metallurgy of welding of the ferritic stainless steels. It was found that the microstructure of the fusion zone and the heat affected zone is influenced by different phenomena including grain growth, martensite formation and carbide precipitation. The effects of welding cycle on the mechanical properties of the spot welds in terms of peak load, energy absorption and failure mode are discussed

  10. Post-irradiation mechanical tests on F82H EB and TIG welds

    International Nuclear Information System (INIS)

    Rensman, J.; Osch, E.V. van; Horsten, M.G.; D'Hulst, D.S.

    2000-01-01

    The irradiation behaviour of electron beam (EB) and tungsten inert gas (TIG) welded joints of the reduced-activation martensitic steel IEA heat F82H-mod. was investigated by neutron irradiation experiments in the high flux reactor (HFR) in Petten. Mechanical test specimens, such as tensile specimens and KLST-type Charpy impact specimens, were neutron irradiated up to a dose level of 2-3 dpa at a temperature of 300 deg. C in the HFR reactor in Petten. The tensile results for TIG and EB welds are as expected with practically no strain hardening capacity left. Considering impact properties, there is a large variation in impact properties for the TIG weld. The irradiation tends to shift the DBTT of particularly the EB welds to very high values, some cases even above +250 deg. C. PWHT of EB-welded material gives a significant improvement of the DBTT and USE compared to the as-welded condition

  11. Microstructure and mechanical properties of friction stir welded SAF 2507 super duplex stainless steel

    International Nuclear Information System (INIS)

    Sato, Y.S.; Nelson, T.W.; Sterling, C.J.; Steel, R.J.; Pettersson, C.-O.

    2005-01-01

    The microstructure and mechanical properties of friction stir (FS) welded SAF 2507 super duplex stainless steel were examined. High-quality, full-penetration welds were successfully produced in the super duplex stainless steel by friction stir welding (FSW) using polycrystalline cubic boron nitride (PCBN) tool. The base material had a microstructure consisting of the ferrite matrix with austenite islands, but FSW refined grains of the ferrite and austenite phases in the stir zone through dynamic recrystallisation. Ferrite content was held between 50 and 60% throughout the weld. The smaller grain sizes of the ferrite and austenite phases caused increase in hardness and strength within the stir zone. Welded transverse tensile specimen failed near the border between the stir zone and TMAZ at the retreating side as the weld had roughly the same strengths as the base material

  12. Microstructure and mechanical properties in TIG welding of CLAM steel

    International Nuclear Information System (INIS)

    Zhu Qiang; Lei Yucheng; Chen Xizhang; Ren Wenjie; Ju Xin; Ye Yimin

    2011-01-01

    Tungsten insert gas (TIG) welding on China low activation martensitic (CLAM) steel under identical conditions was performed. Microhardness test, tensile test, Charpy impact test and microstructure measurements were carried out on TIG welded joints after post weld heat-treatment. Hardening at WM and softening in HAZ is detected in the TIG weld joint. Microhardness in WM decreased when the temperature of PWHT increased. The ultimate tensile stress of weld metal is higher than that of HAZ and BM. Absorbed energy increased with PWHT temperature rising, until PWHT was done at 760 deg. C/30 min, the specimen ductile fractured in local area. The microstructure of the weld metal for every specimen was found to be tempered martensite with a little of delta ferrite. M 23 C 6 particles are the predominant type of carbides. Oxide precipitate phases appeared in WM, which are the primary crack initiation sites and it is critically important minimize their formation.

  13. Effect of Multipass TIG and Activated TIG Welding Process on the Thermo-Mechanical Behavior of 316LN Stainless Steel Weld Joints

    Science.gov (United States)

    Ganesh, K. C.; Balasubramanian, K. R.; Vasudevan, M.; Vasantharaja, P.; Chandrasekhar, N.

    2016-04-01

    The primary objective of this work was to develop a finite element model to predict the thermo-mechanical behavior of an activated tungsten inert gas (ATIG)-welded joint. The ATIG-welded joint was fabricated using 10 mm thickness of 316LN stainless steel plates in a single pass. To distinguish the merits of ATIG welding process, it was compared with manual multipass tungsten inert gas (MPTIG)-welded joint. The ATIG-welded joint was fabricated with square butt edge configuration using an activating flux developed in-house. The MPTIG-welded joint was fabricated in thirteen passes with V-groove edge configuration. The finite element model was developed to predict the transient temperature, residual stress, and distortion of the welded joints. Also, microhardness, impact toughness, tensile strength, ferrite measurement, and microstructure were characterized. Since most of the recent publications of ATIG-welded joint was focused on the molten weld pool dynamics, this research work gives an insight on the thermo-mechanical behavior of ATIG-welded joint over MPTIG-welded joint.

  14. Influence of tool geometry and processing parameters on welding defects and mechanical properties for friction stir welding of 6061 Aluminium alloy

    Science.gov (United States)

    Daneji, A.; Ali, M.; Pervaiz, S.

    2018-04-01

    Friction stir welding (FSW) is a form of solid state welding process for joining metals, alloys, and selective composites. Over the years, FSW development has provided an improved way of producing welding joints, and consequently got accepted in numerous industries such as aerospace, automotive, rail and marine etc. In FSW, the base metal properties control the material’s plastic flow under the influence of a rotating tool whereas, the process and tool parameters play a vital role in the quality of weld. In the current investigation, an array of square butt joints of 6061 Aluminum alloy was to be welded under varying FSW process and tool geometry related parameters, after which the resulting weld was evaluated for the corresponding mechanical properties and welding defects. The study incorporates FSW process and tool parameters such as welding speed, pin height and pin thread pitch as input parameters. However, the weld quality related defects and mechanical properties were treated as output parameters. The experimentation paves way to investigate the correlation between the inputs and the outputs. The correlation between inputs and outputs were used as tool to predict the optimized FSW process and tool parameters for a desired weld output of the base metals under investigation. The study also provides reflection on the effect of said parameters on a welding defect such as wormhole.

  15. Comparative Studies on microstructure, mechanical and corrosion behaviour of DMR 249A Steel and its welds

    Science.gov (United States)

    Mohammed, Raffi; Dilkush; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    DMR249A Medium strength (low carbon) Low-alloy steels are used as structural components in naval applications due to its low cost and high availability. An attempt has been made to weld the DMR 249A steel plates of 8mm thickness using shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). Welds were characterized for metallography to carry out the microstructural changes, mechanical properties were evaluated using vickers hardness tester and universal testing machine. Potentio-dynamic polarization tests were carried out to determine the pitting corrosion behaviour. Constant load type Stress corrosion cracking (SCC) testing was done to observe the cracking tendency of the joints in a 3.5%NaCl solution. Results of the present study established that SMA welds resulted in formation of relatively higher amount of martensite in ferrite matrix when compared to gas tungsten arc welding (GTAW). It is attributed to faster cooling rates achieved due to high thermal efficiency. Improved mechanical properties were observed for the SMA welds and are due to higher amount of martensite. Pitting corrosion and stress corrosion cracking resistance of SMA welds were poor when compared to GTA welds.

  16. Mechanical properties of friction stir welded aluminum alloys 5083 and 5383

    Directory of Open Access Journals (Sweden)

    Jeom Kee Paik

    2009-09-01

    Full Text Available The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW, laser welding and friction stir welding (FSW, FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009, jointly funded by its member agencies.

  17. Mechanism and Microstructure of Oxide Fluxes for Gas Tungsten Arc Welding of Magnesium Alloy

    Science.gov (United States)

    Liu, L. M.; Zhang, Z. D.; Song, G.; Wang, L.

    2007-03-01

    Five single oxide fluxes—MgO, CaO, TiO2, MnO2, and Cr2O3—were used to investigate the effect of active flux on the depth/width ratio in AZ31B magnesium alloy. The microstructure and mechanical property of the tungsten inert gas (TIG) welding seam were studied. The oxygen content in the weld seam and the arc images during the TIG welding process were analyzed. A series of emission spectroscopy of weld arc for TIG welding for magnesium with and without flux were developed. The results showed that for the five single oxide fluxes, all can increase the weld penetration effectively and grain size in the weld seam of alternating current tungsten inert gas (ACTIG) welding of the Mg alloy. The oxygen content of the welds made without flux is not very different from those produced with oxide fluxes not considering trapped oxide. However, welds that have the best penetration have a relatively higher oxygen content among those produced with flux. It was found that the arc images with the oxide fluxes were only the enlarged form of the arc images without flux; the arc constriction was not observed. The detection of arc spectroscopy showed that the metal elements in the oxides exist as the neutral atom or the first cation in the weld arc. This finding would influence the arc properties. When TIG simulation was carried out on a plate with flux applied only on one side, the arc image video showed an asymmetric arc, which deviated toward the flux free side. The thermal stability, the dissociation energy, and the electrical conductivity of oxide should be considered when studying the mechanism for increased TIG flux weld penetration.

  18. Mechanical properties of weldings by electron beams on alloy 8090 (CP 271)

    International Nuclear Information System (INIS)

    Le Poac, P.; Nomine, A.M.; Miannay, D.

    1987-06-01

    Weldings by electron beams got on rings in alloy 8090 in the T4 and T6 state are mechanically tested in traction in the original state of welding or after a thermal processing of 12 hours at 210 0 C [fr

  19. Ultrasonic test results for the reactor pressure vessel of the HTTR. Longitudinal welding line of bottom dome

    International Nuclear Information System (INIS)

    Nojiri, Naoki; Ohwada, Hiroyuki; Kato, Yasushi

    2008-06-01

    This paper describes the inspection method, the measured area, etc. of the ultrasonic test of the in-service inspection (ISI) for welding lines of the reactor pressure vessel of the HTTR and the inspection results of the longitudinal welding line of the bottom dome. The pre-service inspection (PSI) results for estimation of occurrence and progression of defects to compare the ISI results is described also. (author)

  20. Studies on microstructure, mechanical and pitting corrosion behaviour of similar and dissimilar stainless steel gas tungsten arc welds

    Science.gov (United States)

    Mohammed, Raffi; Dilkush; Srinivasa Rao, K.; Madhusudhan Reddy, G.

    2018-03-01

    In the present study, an attempt has been made to weld dissimilar alloys of 5mm thick plates i.e., austenitic stainless steel (316L) and duplex stainless steel (2205) and compared with that of similar welds. Welds are made with conventional gas tungsten arc welding (GTAW) process with two different filler wires namely i.e., 309L and 2209. Welds were characterized using optical microscopy to observe the microstructural changes and correlate with mechanical properties using hardness, tensile and impact testing. Potentio-dynamic polarization studies were carried out to observe the pitting corrosion behaviour in different regions of the welds. Results of the present study established that change in filler wire composition resulted in microstructural variation in all the welds with different morphology of ferrite and austenite. Welds made with 2209 filler showed plate like widmanstatten austenite (WA) nucleated at grain boundaries. Compared to similar stainless steel welds inferior mechanical properties was observed in dissimilar stainless steel welds. Pitting corrosion resistance is observed to be low for dissimilar stainless steel welds when compared to similar stainless steel welds. Overall study showed that similar duplex stainless steel welds having favorable microstructure and resulted in better mechanical properties and corrosion resistance. Relatively dissimilar stainless steel welds made with 309L filler obtained optimum combination of mechanical properties and pitting corrosion resistance when compared to 2209 filler and is recommended for industrial practice.

  1. Contribution to the study of an on line inspection system for pulsed Nd:YAG laser welding operations

    International Nuclear Information System (INIS)

    Charton, Stephane

    1999-01-01

    This thesis deals with the study of a on line inspection system for pulsed Nd 3+ :YAG laser welding operations. During a welding operation, laser-material interaction results in the emission of signals (optical, acoustical, electrical, thermal), characteristic of its behavior. On line inspection is based on the hypothesis that the signals evolutions, measured by sensors such as photodiodes, microphones.., may be correlated with the welding defects. Laser weld quality inspection can be done by the machine qualification (before and during welding), and by on line monitoring of the welding operation. The similarity of the signals produced by pulsed lasers (machine or interaction) has led us to develop a specific data acquisition and processing software. Signal processing tools utilization (Fourier and wavelets transforms) in conjunction with classification techniques (stress polytopes), introduces an innovating on line inspection approach. Discriminant parameters determination (signals/defect correlation) becomes thus automatic and non subjective. The developed prototype is not dedicated to the detection of a particular defect because the classification operator is a supervised one and needs a learning phase. lt has been validated on welding defects which are easy to deal with, and then applied to a precise production control at the Nuclear Fabrications and Technology Division of the Valduc Center of the French Atomic Energy Agency. (author) [fr

  2. Aluminum alloy weldability. Identification of weld solidification cracking mechanisms through novel experimental technique and model development

    Energy Technology Data Exchange (ETDEWEB)

    Coniglio, Nicolas

    2008-07-01

    The objective of the present thesis is to make advancements in understanding solidification crack formation in aluminum welds, by investigating in particular the aluminum 6060/4043 system. Alloy 6060 is typical of a family of Al-Mg-Si extrusion alloys, which are considered weldable only when using an appropriate filler alloy such as 4043 (Al-5Si). The effect of 4043 filler dilution (i.e. weld metal silicon content) on cracking sensitivity and solidification path of Alloy 6060 welds are investigated. Afterwards, cracking models are developed to propose mechanisms for solidification crack initiation and growth. Cracking Sensitivity. Building upon the concept that silicon improves weldability and that weldability can be defined by a critical strain rate, strain rate-composition combinations required for solidification crack formation in the Al- 6060/4043 system were determined using the newly developed Controlled Tensile Weldability (CTW) test utilizing local strain extensometer measurements. Results, presented in a critical strain rate - dilution map, show a crack - no crack boundary which reveals that higher local strain rates require higher 4043 filler dilution to avoid solidification cracking when arc welding Alloy 6060. Using the established crack - no crack boundary as a line of reference, additional parameters were examined and their influence on cracking characterized. These parameter influences have included studies of weld travel speed, weld pool contaminants (Fe, O, and H), and grain refiner additions (TiAl{sub 3} + Boron). Each parameter has been independently varied and its effect on cracking susceptibility quantified in terms of strain rate - composition combinations. Solidification Path. Solidification path of the Al-6060/4043 system was characterized using thermal analysis and phase identification. Increasing 4043 filler dilution from 0 to 16% in Alloy 6060 arc welds resulted in little effect on thermal arrests and microstructure, no effect on

  3. Mechanical behaviour of Nd:YAG laser welded superelastic NiTi

    International Nuclear Information System (INIS)

    Vieira, L. Alberty; Fernandes, F.M. Braz; Miranda, R.M.; Silva, R.J.C.; Quintino, L.; Cuesta, A.; Ocana, J.L.

    2011-01-01

    Highlights: → The main innovations claimed are: understand rolling direction effect on mechanical cycling of laser welded NiTi. → Functionality confirmed by stabilization of hysteretic response up to 8% strain. → Welds tensile cycled exhibited superior functional mechanical behaviour. → For applied stresses of 50 MPa below UTS the joints showed superelastic behaviour. - Abstract: Joining techniques for shape memory alloys (SMA) has become of great interest, as their functional properties, namely shape memory effect (SME) and superelasticity (SE), present unique solutions for state-of-the-art applications, although limited results concerning mechanical properties are reported. This paper reports experimental work performed with Nd:YAG continuous wave laser welding of superelastic cold-rolled plates of NiTi 1 mm thick. The mechanical behaviour was evaluated by means of tensile tests performed both to failure and to cycling. The superelastic behaviour of the welded joints was observed for applied stresses close to about 50 MPa below the ultimate tensile strength of the welds. The functionality was confirmed by analyzing the stabilization of the mechanical hysteretic response to strain levels up to 8%. For tensile cycling involving strain levels larger than 6%, welded specimens were found to exhibit superior functional mechanical behaviour presenting larger recoverable strain levels. The fracture surfaces were observed by scanning electron microscopy (SEM) and the effect of the rolling direction on mechanical properties was evaluated and discussed, reinforcing the importance of joint design when laser welding these alloys.

  4. Effect of friction stir welding parameters on microstructure and mechanical properties of DSS–Cu joints

    Energy Technology Data Exchange (ETDEWEB)

    Shokri, V., E-mail: v.shokri@modares.ac.ir [Department of Mechanical Engineering, Tarbiat Modarres University, Tehran (Iran, Islamic Republic of); Sadeghi, A. [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Sadeghi, M.H. [Department of Mechanical Engineering, Tarbiat Modarres University, Tehran (Iran, Islamic Republic of)

    2017-05-02

    Dissimilar joining of copper to duplex stainless steel (DSS) is challenging at high temperatures of fusion welding owing to the large difference in physical properties of the base metals. To reduce negative effects of welding at high temperatures, solid state welding at lower temperatures has been proposed. To study different effects of welding parameters (rotation speed, travel speed and tool offset) on weld zone microstructure and mechanical properties butt joints of a copper alloy and duplex stainless steel (DSS) were produced by friction stir welding (FSW). It has been found that heat input generated by the interaction of different welding conditions has a significant effect on the formation of a brittle intermetallic at the interface and eventually the final mechanical properties. At low heat inputs, mixing of the two sides is insufficient and metallurgical bonding is weak; while at high heat inputs, the thickness of the formed intermetallic is too thick which causes stress concentration at the interface and premature failure. An optimum welding condition was found (rotation speed of 1200 rpm, travel speed of 30 mm/min and tool offset of 0.5 mm) which almost reached the mechanical properties of the Cu-alloy monolayer.

  5. Evaluation the Mechanical Properties of Shot Peened TIG Welded Aluminum Sheets

    Directory of Open Access Journals (Sweden)

    Ahmed Ameed Zain Al-Abideen

    2017-04-01

    Full Text Available A tungsten inert gas (TIG welding is one of the most popular kinds of welding used to join metals mainly for aluminum alloys. However, many challenges may be met with this kind of joining process; these challenges arise from decay of mechanical properties of welded materials. In the present study, an attempt was made to enhancing the mechanical properties of TIG weld joint of 6061-T6 aluminum alloy by hardening the surfaces using shoot peening technique. To optimize the shoot peening process three times of exposure (5, 10, and 15 min. was used. All peened and unpeened, and welded and unwelded samples were characterized by metallographic test to indicate the phase transformation and modification in microstructure occurring during welding process. Tensile test and Vickers micro-hardness measurements were performed for all samples to investigate the effect of shoot peening on mechanical properties of welded aluminum. The results indicated a significant improvement in properties for peened welded and unwelded samples compared with those unpeened one. Also, the results showed that the tensile and microhardness properties were increased with increasing the time of exposure to 15 min. due to generation of compressive residual stresses at surface.

  6. Soldadura (Welding). Spanish Translations for Welding.

    Science.gov (United States)

    Hohhertz, Durwin

    Thirty transparency masters with Spanish subtitles for key words are provided for a welding/general mechanical repair course. The transparency masters are on such topics as oxyacetylene welding; oxyacetylene welding equipment; welding safety; different types of welds; braze welding; cutting torches; cutting with a torch; protective equipment; arc…

  7. Metallurgical and mechanical characterization of a submerged arc welded joint in a 316 type stainless steel

    International Nuclear Information System (INIS)

    Piatti, G.; Vedani, M.

    1990-01-01

    The tensile (deformation and fracture) behaviour of a multipass submerged arc welded joint Type 316 stainless steel is investigated by tests at room temperature and at 400 0 C on all-weld metal and transverse to weld (composite) specimens as well as by microstructural and compositional analyses (optical, scanning electron and transmission electron microscopy). The as-deposited metal is characterised by a systematic variation in the tensile properties across the thickness with the higher strength and the lower ductility in the weld centre. These variations are related to material variability (mainly in dislocation density) because of local dissimilarities in thermal and mechanical histories occurring during the welding process. However, the material variability in the fusion zone, although important is not so large in the present weld and it does not influence the tensile properties of the weld as a whole. Moreover, the tensile behaviour concerning the transverse to weld specimens is characterized by a supporting effect from the higher yield strength material zone (fusion zone) to the lower yield strength material zone (parent metal) justified by the different contribution of the parent metal and of the weld-deposit metal to the integral plastic strain of the specimens. (author)

  8. 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.

  9. Microstructure and mechanical characteristics of a laser welded joint in SA508 nuclear pressure vessel steel

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wei, E-mail: wei.guo-2@manchester.ac.uk [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom); Dong, Shiyun [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom); Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Guo, Wei; Francis, John A.; Li, Lin [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester, M13 9 PL (United Kingdom)

    2015-02-11

    SA508 steels are typically used in civil nuclear reactors for critical components such as the reactor pressure vessel. Nuclear components are commonly joined using arc welding processes, but with design lives for prospective new build projects exceeding 60 years, new welding technologies are being sought. In this exploratory study, for the first time, autogenous laser welding was carried out on 6 mm thick SA508 Cl.3 steel sheets using a 16 kW fiber laser system operating at a power of 4 kW. The microstructure and mechanical properties (including microhardness, tensile strength, elongation, and Charpy impact toughness) were characterized and the microstructures were compared with those produced through arc welding. A three-dimensional transient model based on a moving volumetric heat source model was also developed to simulate the laser welding thermal cycles in order to estimate the cooling rates included by the process. Preliminary results suggest that the laser welding process can produce welds that are free of macroscopic defects, while the strength and toughness of the laser welded joint in this study matched the values that were obtained for the parent material in the as-welded condition.

  10. Development of Mechanical Sealing and Laser Welding Technology to Instrument Thermocouple for Nuclear Fuel Test Rod

    International Nuclear Information System (INIS)

    Joung, Chang-Young; Ahn, Sung-Ho; Hong, Jin-Tae; Kim, Ka-Hye; Huh, Sung-Ho

    2015-01-01

    Zircaloy-4 of the nuclear fuel test rod, AISI 316L of the mechanical sealing parts, and the MI (mineral insulated) cable at a thermocouple instrumentation are hetero-metals, and are difficult to weld to dissimilar materials. Therefore, a mechanical sealing method to instrument the thermocouple should be conducted using two kinds of sealing process as follows: One is a mechanical sealing process using Swagelok, which is composed of sealing components that consists of an end-cap, a seal tube, a compression ring and a Swagelok nut. The other is a laser welding process used to join a seal tube, and an MI cable, which are made of the same material. The mechanical sealing process should be sealed up with the mechanical contact compressed by the strength forced between a seal tube and an end-cap, and the laser welding process should be conducted to have no defects on the sealing area between a seal tube and an MI cable. Therefore, the mechanical sealing and laser welding techniques need to be developed to accurately measure the centerline temperature of the nuclear fuel test rod in an experimental reactor. The mechanical sealing and laser welding tests were conducted to develop the thermocouple instrumentation techniques for the nuclear fuel test rod. The optimum torque value of a Swagelok nut to seal the mechanical sealing part between the end-cap and seal tube was established through various torque tests using a torque wrench. The optimum laser welding conditions to seal the welding part between a seal tube and an MI cable were obtained through various welding tests using a laser welding system

  11. Development of Mechanical Sealing and Laser Welding Technology to Instrument Thermocouple for Nuclear Fuel Test Rod

    Energy Technology Data Exchange (ETDEWEB)

    Joung, Chang-Young; Ahn, Sung-Ho; Hong, Jin-Tae; Kim, Ka-Hye; Huh, Sung-Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Zircaloy-4 of the nuclear fuel test rod, AISI 316L of the mechanical sealing parts, and the MI (mineral insulated) cable at a thermocouple instrumentation are hetero-metals, and are difficult to weld to dissimilar materials. Therefore, a mechanical sealing method to instrument the thermocouple should be conducted using two kinds of sealing process as follows: One is a mechanical sealing process using Swagelok, which is composed of sealing components that consists of an end-cap, a seal tube, a compression ring and a Swagelok nut. The other is a laser welding process used to join a seal tube, and an MI cable, which are made of the same material. The mechanical sealing process should be sealed up with the mechanical contact compressed by the strength forced between a seal tube and an end-cap, and the laser welding process should be conducted to have no defects on the sealing area between a seal tube and an MI cable. Therefore, the mechanical sealing and laser welding techniques need to be developed to accurately measure the centerline temperature of the nuclear fuel test rod in an experimental reactor. The mechanical sealing and laser welding tests were conducted to develop the thermocouple instrumentation techniques for the nuclear fuel test rod. The optimum torque value of a Swagelok nut to seal the mechanical sealing part between the end-cap and seal tube was established through various torque tests using a torque wrench. The optimum laser welding conditions to seal the welding part between a seal tube and an MI cable were obtained through various welding tests using a laser welding system.

  12. Mechanical evaluation of linear friction welds in titanium alloys through indentation experiments

    International Nuclear Information System (INIS)

    Corzo, M.; Casals, O.; Alcala, J.; Mateo, A.; Anglada, M.

    2005-01-01

    This article shows the results of a project that focuses on the characterization of the weld interface region of dissimilar joints between titanium alloys for aeronautical applications, specifically Ti-6Al-2Sn-4Zr-6Mo with Ti-6Al-4V, and Ti-6Al-2Sn-4Zr-6Mo with Ti-6Al-2Sn-4Zr-2Mo. The uniaxial flow stress and hardening response of the material containing the weld were analyzed following the finite elements simulations and mathematical formulations to correlate hardness and the amount of pile-up and sinking-in phenomena around sharp indenters with uniaxial mechanical properties. This allows to accurately stablishing the influence that welding process has on the mechanical response of the parts. Tests performed on these friction-welded specimens showed that the fine grained microstructures in the welds exhibited better properties than the base materials. (Author) 12 refs

  13. Microstructural Characterization and Mechanical Properties of Electron Beam Welded Joint of High Strength Steel Grade S690QL

    Directory of Open Access Journals (Sweden)

    Błacha S.

    2016-06-01

    Full Text Available In the paper the results of metallographic examination and mechanical properties of electron beam welded joint of quenched and tempered steel grade S690QL are presented. Metallographic examination revealed that the concentrated electron beam significantly affect the changes of microstructure in the steel. Parent material as a delivered condition (quenched and tempered had a bainitic-martensitic microstructure at hardness about 290 HV0.5. After welding, the microstructure of heat affected zone is composed mainly of martensite (in the vicinity of the fusion line of hardness 420 HV0.5. It should be noted, however, that the microstructure of steel in the heat affected zone varies with the distance from the fusion line. The observed microstructural changes were in accordance with the CCT-S transformation diagram for the examined steel.

  14. Microstructural variation through weld thickness and mechanical properties of peened friction stir welded 6061 aluminum alloy joints

    Energy Technology Data Exchange (ETDEWEB)

    Abdulstaar, Mustafa A., E-mail: mustafa.abdulstaar@gmail.com [Institute of Material Science and Engineering, Clausthal University of Technology, Agricolastr. 6, 38678 Clausthal-Zellerfeld (Germany); Al-Fadhalah, Khaled J. [Department of Mechanical Engineering, College of Engineering & Petroleum, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait); Wagner, Lothar [Institute of Material Science and Engineering, Clausthal University of Technology, Agricolastr. 6, 38678 Clausthal-Zellerfeld (Germany)

    2017-04-15

    The current study examined the effect of microstructure variation on the development of mechanical properties in friction stir welded joints of 6061-T6 aluminum alloy, which were subsequently processed by shot peening (SP). Following to FSW, fatigue specimens were extracted perpendicularly to the welding direction. Surface Skimming to 0.5 mm from crown and root sides of the joint was made and SP was later applied on the two sides using ceramic shots of two different Almen intensities of 0.18 mmA and 0.24 mmA. Microstructural examination by electron back scattered diffraction (EBSD) indicated variation in the grain refinement of the weld zone, with coarsest grains (5 μm) at the crown side and finest grains (2 μm) at the root side. Reduction of microhardness to 60 HV occurred in the weld zone for samples in FSW condition. Application of SP promoted significant strain hardening at the crown side, with Almen intensities of 0.24 mmA providing maximum increase in microhardness to 120 HV. On the contrary, only a maximum microhardness of 75 HV was obtained at the root side. The difference in strain hardening capability at the two sides was strongly dependent on grain size. The two Almen intensities produced similar distribution of compressive residual stresses in the subsurface regions that led to enhance the fatigue strength to the level of base metal for N ≥ 10{sup 5} cycles. Yet, the increase in fatigue strength was more pronounced with increasing Almen intensity to 0.24 mmA, demonstrating further enhancement by strain hardening. - Highlights: • Grain refinement was observed after friction stir welding of AA 6061-T6. • Reduction in microhardness and fatigue strength were obtained after welding. • Variation in grain refinement led to different hardening behavior after peening. • Shot peening induced beneficial compressive residual stresses. • Shot peening and surface skimming markedly improved the fatigue performance.

  15. Mismatch effect on CT specimen mechanical effect and consequences on the weld toughness characterization

    International Nuclear Information System (INIS)

    Marie, S.; Nedelec, M.

    2012-01-01

    The welded joints are particularly sensitive areas in the structures in terms of harmfulness of defects. Given the complexity of the problem (geometry poorly controlled, multi-material aspect, the potential influence of residual stresses), the tests are conducted based on pessimistic assumptions that can wrap all the uncertainties of the problem. In the case of a defect assessment, the considered toughness is deduced from conventional characterization tests with a crack in the welding, considering the current standards, ISO 12135 or ASTM E-1820 which are valid only for an homogeneous specimen. In 2010, a new standard ISO 16563 was published to address the specificity of welded joints. If it covers some of the difficulties, it remains incomplete. In nuclear piping, welds have a mismatch M, i.e. the ratio between the yield strength of the weld metal and the base metal, usually greater than 1: this avoids any problem of strain localization at the junction and ensure that the stresses in the base metal are also easily supported by the welded joint. In this configuration, it turns out that for a given mechanical loading, a crack in the weld located generally has a solicitation, quantified by the parameter J, less (depending on the size of the junction) to those that would see the same crack located in the base metal. Unfortunately, this phenomenon exists also potentially for a characterization test, which would overestimate the true toughness of the welded joint. Plasticity that develops from the crack tip can quickly reach this interface and be affected. To evaluate this phenomenon, we considered two types of representative welded joint (PWR secondary loop ferritic weld and a 316 stainless steel weld) and performed a F.E. analysis of the multi-material CT specimen mechanical answer and on the η coefficient conventionally used to derive the plastic component of J from the area under the curve force-opening displacement. (authors)

  16. A Study on Tooling and Its Effect on Heat Generation and Mechanical Properties of Welded Joints in Friction Stir Welding

    Science.gov (United States)

    Tikader, Sujoy; Biswas, Pankaj; Puri, Asit Baran

    2018-04-01

    Friction stir welding (FSW) has been the most attracting solid state welding process as it serves numerous advantages like good mechanical, metallurgical properties etc. Non weldable aluminium alloys like 5XXX, 7XXX series can be simply joined by this process. In this present study a mathematical model has been developed and experiments were successfully performed to evaluate mechanical properties of FSW on similar aluminium alloys i.e. AA1100 for different process parameters and mainly two kind of tool geometry (straight cylindrical and conical or cylindrical tapered shaped pin with flat shoulder). Tensile strength and micro hardness for different process parameters are reported of the welded plate sample. It was noticed that in FSW of similar alloy with tool made of SS-310 tool steel, friction is the major contributor for the heat generation. It was seen that tool geometry, tool rotational speed, plunging force by the tool and traverse speed have significant effect on tensile strength and hardness of friction stir welded joints.

  17. Microstructures and mechanical properties of magnesium alloy and stainless steel weld-joint made by friction stir lap welding

    International Nuclear Information System (INIS)

    Wei, Yanni; Li, Jinglong; Xiong, Jiangtao; Huang, Fu; Zhang, Fusheng

    2012-01-01

    Highlights: → Friction stir lap welding technology with cutting pin was successfully employed to form lap joint of magnesium and steel. → The cutting pin made the lower steel participate in deformation and the interface was no longer flat. → A saw-toothed structure formed due to a mechanical mixing of the magnesium and steel was found at the interface. → A high-strength joint was produced which fractured in the magnesium side. -- Abstract: Friction stir lap welding was conducted on soft/hard metals. A welding tool was designed with a cutting pin of rotary burr made of tungsten carbide, which makes the stirring pin possible to penetrate and cut the surface layer of the hard metal. Magnesium alloy AZ31 and stainless steel SUS302 were chosen as soft/hard base metals. The structures of the joining interface were analyzed by scanning electron microscopy (SEM). The joining strength was evaluated by tensile shear test. The results showed that flower-like interfacial morphologies were presented with steel flashes and scraps, which formed bonding mechanisms of nail effect by long steel flashes, zipper effect by saw-tooth structure and metallurgical bonding. The shear strength of the lap joint falls around the shear strength of butt joint of friction stir welded magnesium alloy.

  18. 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.

  19. Microstructure and Mechanical Performance of Friction Stir Spot-Welded Aluminum-5754 Sheets

    Science.gov (United States)

    Pathak, N.; Bandyopadhyay, K.; Sarangi, M.; Panda, Sushanta Kumar

    2013-01-01

    Friction stir spot welding (FSSW) is a recent trend of joining light-weight sheet metals while fabricating automotive and aerospace body components. For the successful application of this solid-state welding process, it is imperative to have a thorough understanding of the weld microstructure, mechanical performance, and failure mechanism. In the present study, FSSW of aluminum-5754 sheet metal was tried using tools with circular and tapered pin considering different tool rotational speeds, plunge depths, and dwell times. The effects of tool design and process parameters on temperature distribution near the sheet-tool interface, weld microstructure, weld strength, and failure modes were studied. It was found that the peak temperature was higher while welding with a tool having circular pin compared to tapered pin, leading to a bigger dynamic recrystallized stir zone (SZ) with a hook tip bending towards the upper sheet and away from the keyhole. Hence, higher lap shear separation load was observed in the welds made from circular pin compared to those made from tapered pin. Due to influence of size and hardness of SZ on crack propagation, three different failure modes of weld nugget were observed through optical cross-sectional micrograph and SEM fractographs.

  20. Microstructure and mechanical properties of GTAW welded joints of AA6105 aluminum alloy

    Directory of Open Access Journals (Sweden)

    Minerva Dorta-Almenara

    2016-09-01

    Full Text Available Gas Tungsten Arc Welding (GTAW is one of the most used methods to weld aluminum. This work investigates the influence of welding parameters on the microstructure and mechanical properties of GTAW welded AA6105 aluminum alloy joints. AA6105 alloy plates with different percent values of cold work were joined by GTAW, using various combinations of welding current and speed. The fusion zone, in which the effects of cold work have disappeared, and the heat affected zone of the welded samples were examined under optical and scanning electron microscopes, additionally, mechanical tests and measures of Vickers microhardness were performed. Results showed dendritic morphology with solute micro- and macrosegregation in the fusion zone, which is favored by the constitutional supercooling when heat input increases. When heat input increased and welding speed increased or remained constant, greater segregation was obtained, whereas welding speed decrease produced a coarser microstructure. In the heat affected zone recrystallization, dissolution, and coarsening of precipitates occurred, which led to variations in hardness and strength.

  1. Mechanical strength and analysis of fracture of titanium joining submitted to laser and tig welding

    Directory of Open Access Journals (Sweden)

    Ana Cláudia Gabrielli Piveta

    2012-12-01

    Full Text Available This study compared the tensile strength and fracture mechanism of tungsten inert gas (TIG welds in cylindrical rods of commercially pure titanium (cp Ti with those of laser welds and intact samples. Thirty dumbbell-shaped samples were developed by using brass rods as patterns. The samples were invested in casings, subjected to thermal cycles, and positioned in a plasma arc welding machine under argon atmosphere and vacuum, and titanium was injected under vacuum/pressure. The samples were X-rayed to detect possible welding flaws and randomly assigned to three groups to test the tensile strength and the fracture mechanism: intact, laser welding, and TIG welding. The tensile test results were investigated using ANOVA, which indicated that the samples were statistically similar. The fracture analysis showed that the cpTi samples subjected to laser welding exhibited brittle fracture and those subjected to TIG welding exhibited mixed brittle/ductile fracture with a predominance of ductile fracture with the presence of microcavities and cleavage areas. Intact samples presented the characteristic straightening in the fracture areas, indicating the ductility of the material.

  2. Literature Review: Theory and Application of In-Line Inspection Technologies for Oil and Gas Pipeline Girth Weld Defection

    Science.gov (United States)

    Feng, Qingshan; Li, Rui; Nie, Baohua; Liu, Shucong; Zhao, Lianyu; Zhang, Hong

    2016-01-01

    Girth weld cracking is one of the main failure modes in oil and gas pipelines; girth weld cracking inspection has great economic and social significance for the intrinsic safety of pipelines. This paper introduces the typical girth weld defects of oil and gas pipelines and the common nondestructive testing methods, and systematically generalizes the progress in the studies on technical principles, signal analysis, defect sizing method and inspection reliability, etc., of magnetic flux leakage (MFL) inspection, liquid ultrasonic inspection, electromagnetic acoustic transducer (EMAT) inspection and remote field eddy current (RFDC) inspection for oil and gas pipeline girth weld defects. Additionally, it introduces the new technologies for composite ultrasonic, laser ultrasonic, and magnetostriction inspection, and provides reference for development and application of oil and gas pipeline girth weld defect in-line inspection technology. PMID:28036016

  3. Microstructure and mechanical properties of resistance upset butt welded 304 austenitic stainless steel joints

    International Nuclear Information System (INIS)

    Sharifitabar, M.; Halvaee, A.; Khorshahian, S.

    2011-01-01

    Graphical abstract: Three different microstructural zones formed at different distances from the joint interface in resistance upset butt welding of 304 austenitic stainless steel. Highlights: → Evaluation of microstructure in resistance upset welding of 304 stainless steel. → Evaluation of welding parameters effects on mechanical properties of the joint. → Introducing the optimum welding condition for joining stainless steel bars. -- Abstract: Resistance upset welding (UW) is a widely used process for joining metal parts. In this process, current, time and upset pressure are three parameters that affect the quality of welded products. In the present research, resistance upset butt welding of 304 austenitic stainless steel and effect of welding power and upset pressure on microstructure, tensile strength and fatigue life of the joint were investigated. Microstructure of welds were studied using scanning electron microscopy (SEM). X-ray diffraction (XRD) analysis was used to distinguish the phase(s) that formed at the joint interface and in heat affected zone (HAZ). Energy dispersive spectroscopy (EDS) linked to the SEM was used to determine chemical composition of phases formed at the joint interface. Fatigue tests were performed using a pull-push fatigue test machine and the fatigue properties were analyzed drawing stress-number of cycles to failure (S-N) curves. Also tensile strength tests were performed. Finally tensile and fatigue fracture surfaces were studied by SEM. Results showed that there were three different microstructural zones at different distances from the joint interface and delta ferrite phase has formed in these regions. There was no precipitation of chromium carbide at the joint interface and in the HAZ. Tensile and fatigue strengths of the joint decreased with welding power. Increasing of upset pressure has also considerable influence on tensile strength of the joint. Fractography of fractured samples showed that formation of hot spots at

  4. Effect of process parameters on mechanical properties of friction stir spot welded magnesium to aluminum alloys

    International Nuclear Information System (INIS)

    Rao, H.M.; Yuan, W.; Badarinarayan, H.

    2015-01-01

    Highlights: • Lap-shear failure load of ∼2.5 kN was achieved in dissimilar Mg to Al spot welds. • Failure load depends on both welding geometrical features and IMCs formation. • Thin and discontinuous IMCs formed in stir zone are beneficial for weld strength. • Low heat input and good material mixing/interlocking is essential for high strength. - Abstract: Friction stir spot welding was applied to dissimilar cast magnesium (Mg) alloy AM60B and wrought aluminum (Al) alloy 6022-T4 under various welding conditions. The influence of tool rotation rate and shoulder plunge depth on lap-shear failure load was examined. Welds were made at four different tool rotation rates of 1000, 1500, 2000 and 2500 revolution per minute (rpm) and various tool shoulder plunge depths from 0 mm to 0.9 mm. The cross section of each weld exhibited the formation of intermetallic compounds (IMCs) in the stir zone. An increase in tool rotation rate decreased the width of the stir zone and resulted in lower lap-shear failure loads. The stir zone width increased and interlocking of IMCs was observed with an increase in tool shoulder plunge depth at 1000 rpm. High lap-shear failure loads were achieved in welds having a large stir zone width with formation of discontinuous IMCs at the tip of the interfacial hook. An average lap-shear failure load of 2.5 kN was achieved for welds made at 1000 rpm and 0.9 mm shoulder plunge. The present study suggests that the mechanical properties of friction stir spot welded dissimilar alloys are greatly influenced by the stir zone width, interfacial hooks and IMCs which are all weld process dependent

  5. Effects of off-specification procedures on the mechanical properties of half-bead weld repairs

    International Nuclear Information System (INIS)

    Hobson, D.O.; Nanstad, R.K.

    1983-07-01

    We examined the effects of off-specification procedures on the mechanical properties of half-bead weld repairs. The name half-bead is derived from the specification that half the thickness of the initial weld layer be ground off before the second layer is deposited. In this study the heat-affected zones of a weldment made with both all and none of the first layer removed were tested for toughness, hardness, and microstructural differences, and the results were compared with the properties of a protypical half-bead repair made under ASME Boiler and Pressure Vessel Code, Sect. XI, guidelines. The results of this limited study showed no apparent justification for the requirement to grind off half the first layer in this type of weld repair. The graded electrode sizes used to make the welds probably had more to do with the weld properties than did the range of first-layer thicknesses used in this study

  6. Fatigue behaviour of 304L steel welded structures: influence of residual stresses and surface mechanical finishing

    International Nuclear Information System (INIS)

    Magnier-Monin, L.

    2007-12-01

    This study focuses on the influence of residual stresses and surface mechanical finishing on lifetime of stainless steel 304L welded structures. Residual stresses are determined on specific specimens of three types: base-metal, as-welded and ground-welded specimens. Each type is submitted to fatigue tests in order to assess the influence of these parameters on the lifetime, and to determine their evolution. The experiments show that an important surface stress concentration is located in the weld root of as-welded structures, which has a negative effect on the fatigue life. The grinding operation generates high-level surface residual stresses but the lifetime is higher thanks to the reduction of the notch effect. The fatigue test results are compared to the nuclear industry best-fit S-N curves. This enables the determination of correction factors related to fatigue test results of polished specimens, and to assess the lifetime of structures. (author)

  7. Microstructural Characteristics and Mechanical Properties of 2205/AZ31B Laminates Fabricated by Explosive Welding

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-04-01

    Full Text Available A bimetal composite of 2205 duplex stainless steel and AZ31B magnesium alloy was cladded successfully through the method of explosive welding. The microstructural characteristics and mechanical properties of 2205/AZ31B bimetal composite are discussed. The interface of 2205/AZ31B bimetallic composite was a less regular wavy morphology with locally melted pockets. Adiabatic shear bands occurred only in the AZ31B side near explosive welding interface. The microstructure observed with EBSD showed a strong refinement near the interface zones. Line scan confirmed that the interface had a short element diffusion zone which would contribute to the metallurgical bonding between 2205 duplex stainless steel and AZ31B magnesium alloy. The value of micro-hardness near the bonding interface of composite plate increased because of work hardening and grain refinement. The tensile shear strength of bonding interface of 2205/AZ31B composite was 105.63 MPa. Tensile strength of 2205/AZ31B composite material was higher than the base AZ31B. There were two abrupt drops in stress in the stress–strain curves of the 2205/AZ31B composite materials.

  8. Improving the particle distribution and mechanical properties of friction-stir-welded composites by using a smooth pin tool

    Science.gov (United States)

    Liu, Huijie; Hu, Yanying; Zhao, Yunqiang; Fujii, Hidetoshi

    2017-09-01

    Friction stir welding (FSW) is a very promising technique for joining particle-reinforced aluminum-matrix composites (PRAMCs), but with increase in the volume fraction of reinforcing particles, their distribution in welds becomes inhomogeneous. This leads to an inconsistent deformation of welds and their destruction at low stresses. In order to improve the weld microstructure, a smooth pin tool was used for the friction stir welding of AC4A + 30 vol.% SiC particle-reinforced aluminum-matrix composites. The present work describes the effect of welding parameters on the characteristics of particle distribution and the mechanical properties of welds. The ultimate strength of weld reached, 309 MPa, was almost 190% of that of the basic material. The mechanism of SiC particle conglomeration is clearly illustrated by means of schematic illustrations.

  9. IMPROVEMENT OF WELDED CONNECTIONS WITH SIDE LAP WELDS BY REDISTRIBUTION OF ALL-WELD METAL ALONG LENGTHS AND CROSS-SECTIONS THEREOF USING MECHANIZED AND ROBOTIC WELDING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Pavlov Evgeniy Igorevich

    2017-05-01

    Full Text Available Experimental study of bearing capacity of samples of two series performed by semiautomatic welding in CO2 on the axis, and by robotic welding machine in mixture (CO2 + Ar, is presented. Welds of constant cross section, welds with extended leg on end sections, and welds in the form of two dowels on end sections were performed. Efficiency of pilot samples of the first series (with extended leg on end sections by way of a smooth transition defined by the ratio of weld metal volume to a crushing load reaches 28 % relative to samples with a leg constant as per length. Samples of the first series with an extended leg on end sections also showed efficiency increased to 17 %. According to the second series samples test results, the exceeding of bearing capacity of the samples performed with an extended leg on end sections by 24 % in comparison with the samples with a leg of constant cross section was determined. Samples of the second series performed in the form of two dowels on end sections demonstrated the exceeding of the relative bearing capacity by 42 % in comparison with the samples with a continuous leg of constant cross-section.

  10. Fast algorithm for spectral processing with application to on-line welding quality assurance

    Science.gov (United States)

    Mirapeix, J.; Cobo, A.; Jaúregui, C.; López-Higuera, J. M.

    2006-10-01

    A new technique is presented in this paper for the analysis of welding process emission spectra to accurately estimate in real-time the plasma electronic temperature. The estimation of the electronic temperature of the plasma, through the analysis of the emission lines from multiple atomic species, may be used to monitor possible perturbations during the welding process. Unlike traditional techniques, which usually involve peak fitting to Voigt functions using the Levenberg-Marquardt recursive method, sub-pixel algorithms are used to more accurately estimate the central wavelength of the peaks. Three different sub-pixel algorithms will be analysed and compared, and it will be shown that the LPO (linear phase operator) sub-pixel algorithm is a better solution within the proposed system. Experimental tests during TIG-welding using a fibre optic to capture the arc light, together with a low cost CCD-based spectrometer, show that some typical defects associated with perturbations in the electron temperature can be easily detected and identified with this technique. A typical processing time for multiple peak analysis is less than 20 ms running on a conventional PC.

  11. The First Assembly Line of Large-longitudinally-welded Steel Pipe in China Went into Operation

    Institute of Scientific and Technical Information of China (English)

    Li Bing

    2002-01-01

    @@ On July 27, the first assembly line to produce JCOE large diameter Longitudinally-submerged-arc-welded steel pipe in China, Which is the key homemade equipment project of "West-East Gas Transmission"project, was put into production. Chen Gen, vice general manager of CNPC; Xie Zhiqiang and Liu Haisheng, assistant chief manager of CNPC; Shi Xingquan, vice president of PetroChina; and the president of Itochu-Marubeni Steel & iron Co., Ltd.of Japan; attended the opening ceremony and cut the ribbon.

  12. Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, H., E-mail: huwdawson@gmail.com [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Serrano, M.; Hernandez, R. [Structural Materials Division, Technology Department, CIEMAT, Avda de la Complutense 40, 28040 Madrid (Spain); Cater, S. [Friction and Forge Processes Department, Joining Technologies Group, TWI Technology Centre (Yorkshire), Advanced Manufacturing Park, Wallis Way, Catcliffe, Rotherham S60 5TZ (United Kingdom); Jimenez-Melero, E. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom)

    2017-05-02

    We have assessed the microstructure and the temperature-dependent mechanical behaviour of five bead-on-plate friction stir welds of Oxide Dispersion Strengthened (ODS) steel, produced using systematic changes to the tool rotation and traverse speed. Friction stir welding can potentially retain the fine dispersion of nanoparticles, and therefore also the high-temperature strength and radiation damage resistance of these materials. Tensile testing was carried out on the MA956 base material at a range of temperatures, from room temperature up to 750 °C. The mechanical properties of the welds were investigated via tensile testing at room temperature and at 500 °C, together with micro-hardness testing. The welds exhibited similar strength and ductility to the base material at both testing temperatures as welding caused a partial loss of particle strengthening, alongside an increase in grain boundary strengthening due to a greatly refined grain size in the stir zones. The micro-hardness data revealed a trend of increasing hardness with increasing tool traverse speed or decreasing rotation speed. This was attributed to the smaller grain size and lower nanoparticle number density in the welds created with these parameters. At 500 °C, the yield stress and ultimate tensile stress of the base material and the welds decreased, due to a progressive reduction in both the Orowan-type particle strengthening and the grain boundary strengthening.

  13. Characterization of Mechanical Properties and Residual Stress in API 5L X80 Steel Welded Joints

    Science.gov (United States)

    de Sousa Lins, Amilton; de Souza, Luís Felipe Guimarães; Fonseca, Maria Cindra

    2018-01-01

    The use of high-strength and low-alloy steels, high design factors and increasingly stringent safety requirements have increased the operating pressure levels and, consequently, the need for further studies to avoid and prevent premature pipe failure. To evaluate the possibility of improving productivity in manual arc welding of this type of steel, this work characterizes the mechanical properties and residual stresses in API 5L X80 steel welded joints using the SMAW and FCAW processes. The residual stresses were analyzed using x-ray diffraction with the sin2 ψ method at the top and root of the welded joints in the longitudinal and transverse directions of the weld bead. The mechanical properties of the welded joints by both processes were characterized in terms of tensile strength, impact toughness and Vickers microhardness in the welded and shot peening conditions. A predominantly compressive residual stress was found, and shot peening increased the tensile strength and impact toughness in both welded joints.

  14. Improving Mechanical Properties of PVPPA Welded Joints of 7075 Aluminum Alloy by PWHT

    Directory of Open Access Journals (Sweden)

    Guowei Li

    2018-03-01

    Full Text Available In this study, 7075 aluminum alloy with a thickness of 10 mm was successfully welded with no obvious defects by pulsed variable polarity plasma arc (PVPPA welding. The mechanical properties of PVPPA welded joints have been researched by post weld heat treatment (PWHT. The results indicate that the heat treatment strongly affects the mechanical properties of the welded joints. The tensile strength and the microhardness of the welded joints gradually improved with the increase of the solution temperature. With the increase of the solution time, the tensile strength, and microhardness first dramatically increased and then decreased slightly. The best tensile strength of 537.5 MPa and the microhardness of 143.7 HV were obtained after 490 °C × 80 min + 120 °C × 24 h, and the strength was nearly 91.2% of that of the parent metal, and increased about 35% compared with as-welded. The improvement of strength and microhardness was mainly due to the precipitation of η′ phase.

  15. Mechanized and robotized welding in shipbuilding; Zosen ni okeru yosetsu no jidoka robot ka

    Energy Technology Data Exchange (ETDEWEB)

    Kanda, Y. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1997-12-01

    Large-scale ships such as VLCC are built at the Kure No.1 Works of IHI (Ishikawajima-Harima Heavy Industry). This paper introduces current status of mechanized and robotized welding at the works. For the sub-assembly with short weld length and horizontal fillet, simplified automatic welders are used in which mag-welding method using CO2 is adopted. The frequent wound welding of member ends can be automatically conducted using welders developed by IHI. In the large-scale assembly processes, remarkable rationalization and highly accurate assembly of flat plate welding have been promoted. Tankers, container ships, and bulk carriers can be treated at the same time. Teaching times of welding robots can be greatly reduced by a technique called parametric treatment. In the future, it is essential to enhance the accuracy of members by introducing the laser cutting during machining processes. Completely self-type mechanization is required as well as large-output laser welding and sensor technology. 3 refs., 12 figs., 2 tabs.

  16. Structure and Mechanical Properties of Friction Stir Weld Joints of Magnesium Alloy AZ31

    Science.gov (United States)

    Nagasawa, T.; Otsuka, M.; Yokota, T.; Ueki, T.

    The applicability of friction stir welding to hot rolled sheet of commercial magnesium alloy AZ31 plates has been investigated. Friction stir weld joint showed mechanical strength comparable to that of base material, though the ductility remained at one half of that of the latter. The results are consistent with the microstructure which is characterized by a fine grained bond layer bounded by-intermediate grained base metals. It is found that both anodizing treatment and insertion of aluminum foil between batting faces do not degrade the joint properties at all. The results suggest that friction stir welding can be potentially applied to magnesium alloy.

  17. Study on mechanical and microstructure behavior of submerged arc welding flux using red mud

    Science.gov (United States)

    Dewangan, Rishi; Pandey, Pankaj K.; Upadhyay, Renu

    2018-05-01

    This paper emphasis on utilization of Red Mud for preparing submerged arc welding flux and study its mechanical and microstructure behavior. Among the six fluxes prepared in the laboratory, Flux no. 1 (basicity 1.106) found to be best due to its running performance, micro hardness and Brinell hardness. The hardness value (HV) of the fluxes was varying from 165.70 to 217.15 at a load of 1000gm respectively. From the micrograph of welded metal, acicular ferrite found to be optimum which helps in increasing the ductility and hardness of the welded material.

  18. Damage mechanism of piping welded joints made from austenitic Steel for the type RBMK reactor

    International Nuclear Information System (INIS)

    Karzov, G.; Timofeev, B.; Gorbakony, A.; Petrov, V.; Chernaenko, T.

    1999-01-01

    In the process of operation of RBMK reactors the damages were taking place on welded piping, produced from austenitic stainless steel of the type 08X18H10T. The inspection of damaged sections in piping has shown that in most cases crack-like defects are of corrosion and mechanical character. The paper considers in details the reasons of damages appearance and their development for this type of welded joints of downcomers 325xl6 mm, which were fabricated from austenitic stainless steel using TlG and MAW welding methods. (author)

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Evolution of microstructure and mechanical properties in naturally aged 7050 and 7075 Al friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, Christian B., E-mail: christian.fuller@yahoo.com [Rockwell Scientific, 1049 Camino Dos Rios, Thousand Oaks, CA 93021 (United States); Mahoney, Murray W., E-mail: murraymahoney@comcast.net [Rockwell Scientific, 1049 Camino Dos Rios, Thousand Oaks, CA 93021 (United States); Calabrese, Mike [Rockwell Scientific, 1049 Camino Dos Rios, Thousand Oaks, CA 93021 (United States); Micona, Leanna [The Boeing Company, P.O. Box 3707 MC 19-HP, Seattle, WA 98124 (United States)

    2010-04-15

    The microstructural and mechanical property evolution of friction stir welded 7050-T7651 and 7075-T651 Al alloys were examined as a function of room temperature (natural) aging for up to 67,920 h. During the range of aging times studied, transverse tensile strengths continuously increased, and are still increasing, with improvements of 24% and 29% measured for the 7050-T7651 and 7075-T651 Al alloy friction stir welds, respectively. Microstructural evolution within the weld nugget and heat-affected zone was evaluated with both transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Formation of a high volume fraction of GP(II) zones produced a majority of the strength improvement within the weld nugget and HAZ regions. The rational for the microstructural changes are discussed in light of the mechanical properties.

  1. Mechanical testing of austenitic steel welded joints. Joint final report - Vol. 2

    International Nuclear Information System (INIS)

    Boerman, D.J.; Krischer, W.

    1990-01-01

    In the field of material properties and structural behaviour of LMFBR reactor components under normal operation and accident conditions, the Commission of the European Communities has promoted an experimental study on the mechanical properties of welded austenitic steel type AISI 316L. The study was launched in the frame of the Shared Cost Action (SCA) programme 1985-1987 on reactor safety. The research was performed in four European laboratories and coordinated by JRC-Ispra. Five different welding methods have been examined. The manufacture and characterization of the welds has been described in a separate report. The present report gives the results of four different mechanical tests carried out on the weld material. The comparison of results proved that, at the present state of development, the vacuum electron beam method seems to have clear advantages as compared with the other methods investigated

  2. Application of the weld in maintenance mechanics at the Nuclear Power Station Atucha I

    International Nuclear Information System (INIS)

    Cosentino, R.E.

    1988-01-01

    The application of the 'weld procedures', in the field of activity of nuclear power is an special chapter of weld. The so called 'Nuclear Installations' are actually under control from their contruction up to their life extension operation to special control programs and quality assurance. This situation obliges the implementation of procedures to assure the fulfilment of the programs for the need to make the reparations or mechanics construction. This paper describes the considerations that has been taken into account to repare some components of the plant. The works carried out constitute applications to the TIG weld procedure. The 'lip weld' is a mechanic component required in pressurized systems subject to air pressure. (Author)

  3. Effect of Post Weld Heat Treatment on Microstructure and Mechanical Properties of Submerged Friction Stir Welded 7A04 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    HAO Ya-xin

    2016-06-01

    Full Text Available 7A04 aluminum alloy plate was jointed by submerged friction stir welding(SFSW, and welded joints were treated (Post Weld Heat Treatment, PWHT, and the effect of post weld heat treatment on the microstructure and mechanical properties in SFSW was investigated. The results show that PWHT joints exhibit dispersively distributed fine precipitates phase morphology, are significantly superior than the feature of the small amount of precipitates with dispersed distribution in SFSW joints. Compared with SFSW joints, the mechanical properties of joints are improved significantly by PWHT. The average hardness of the weld joints nugget zone is increased by 39.7HV, and the tensile strength is increased by 67MPa, reaches 96.1% of the base material, strain hardening capacity of the joints is also enhanced, the tensile fracture exhibits mixed fracture feature of microporous polymerization and cleavage.

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

    OpenAIRE

    Raffi Mohammed; G. Madhusudhan Reddy; K. Srinivasa Rao

    2017-01-01

    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 poo...

  5. Influence of laser hardening with weld penetration onto mechanical and fatigue properties of 40H steel

    International Nuclear Information System (INIS)

    Napadlek, W.; Przetakiewicz, W.

    2003-01-01

    In the article were described investigations results of mechanical properties (hardness, R 0.2 , R m , A 5 , Z) and fatigue properties (rotary bending) of the 40H steel samples, being quenched and tempered, induction and laser hardened. In the laser hardened samples with weld penetration of top layer cracking process in fatigue strength is started mainly in weld penetration area as structural notch. (author)

  6. Analysis of mechanical tensile properties of irradiated and annealed RPV weld overlay cladding

    Energy Technology Data Exchange (ETDEWEB)

    Novak, J [Czech Nuclear Society, Prague (Czech Republic)

    1994-12-31

    Mechanical tensile properties of irradiated and annealed outer layer of reactor pressure vessel weld overlay cladding, composed of Cr19Ni10Nb alloy, have been experimentally determined by conventional tensile testing and indentation testing. The constitutive properties of weld overlay cladding are then modelled with two homogenization models of the constitutive properties of elastic-plastic matrix-inclusion composites; numerical and experimental results are then compared. 10 refs., 4 figs., 4 tabs.

  7. Strength analysis and optimization of welding robot mechanism in emergency stop state

    OpenAIRE

    Zdeněk Poruba; Jiří Podešva; Ondřej František; Martin Fusek; Robert Brázda; Marek Sadílek

    2016-01-01

    The contribution deals with the strength analysis and optimization of the welding robot mechanism in emergency stop state. The common operational positioning of the welding robot is characterized by smooth course of speeds in the time. The resulting load does not differ significantly from the static loading. However the safety requirements given by the norm require the ability of emergency stop function. Since the course of speed in time is rather steep the higher values of acceleration and t...

  8. Prediction of retained residual stresses in laboratory fracture mechanics specimens extracted from welded components

    International Nuclear Information System (INIS)

    Hurlston, R.G.; Sherry, A.H.; James, P.; Sharples, J.K.

    2015-01-01

    The measurement of weld material fracture toughness properties is important for the structural integrity assessment of engineering components. However, welds can contain high levels of residual stress and these can be retained in fracture mechanics specimens, particularly when machined from non-stress relieved welds. Retained residual stresses can make the measurement of valid fracture toughness properties difficult. This paper describes the results of analytical work undertaken to investigate factors that can influence the magnitude and distribution of residual stresses retained in fracture mechanics specimen blanks extracted from as-welded ferritic and austenitic stainless steel plates. The results indicate that significant levels of residual stress can be retained in specimen blanks prior to notching, and that the magnitude and distribution of stress is dependent upon material properties, specimen geometry and size, and extraction location through the thickness of the weld. Finite element modelling is shown to provide a useful approach for estimating the level and distributions of retained residual stresses. A new stress partitioning approach has been developed to estimate retained stress levels and results compare favourably with FE analysis and available experimental data. The approach can help guide the selection of specimen geometry and machining strategies to minimise the level of residual stresses retained in fracture mechanics specimen blanks extracted from non stress-relieved welds and thus improve the measurement of weld fracture toughness properties. - Highlights: • A simplified method for generating realistic weld residual stresses has been developed. • It has been shown that significant levels of residual stress can be retained within laboratory fracture mechanics specimens. • The level and distribution is dependant upon material, specimen type, specimen size and extraction location. • A method has been developed to allow estimates of the

  9. Analysis of mechanical tensile properties of irradiated and annealed RPV weld overlay cladding

    International Nuclear Information System (INIS)

    Novak, J.

    1993-01-01

    Mechanical tensile properties of irradiated and annealed outer layer of reactor pressure vessel weld overlay cladding, composed of Cr19Ni10Nb alloy, have been experimentally determined by conventional tensile testing and indentation testing. The constitutive properties of weld overlay cladding are then modelled with two homogenization models of the constitutive properties of elastic-plastic matrix-inclusion composites; numerical and experimental results are then compared. 10 refs., 4 figs., 4 tabs

  10. Microstructural Characteristics and Mechanical Properties of an Electron Beam-Welded Ti/Cu/Ni Joint

    Science.gov (United States)

    Zhang, Feng; Wang, Ting; Jiang, Siyuan; Zhang, Binggang; Feng, Jicai

    2018-05-01

    Electron beam welding experiments of TA15 titanium alloy to GH600 nickel superalloy with and without a copper sheet interlayer were carried out. Surface appearance, microstructure and phase constitution of the joint were examined by optical microscopy, scanning electron microscopy and x-ray diffraction analysis. Mechanical properties of Ti/Ni and Ti/Cu/Ni joint were evaluated based on tensile strength and microhardness tests. The results showed that cracking occurred in Ti/Ni electron beam weldment for the formation of brittle Ni-Ti intermetallics, while a crack-free electron beam-welded Ti/Ni joint can be obtained by using a copper sheet as filler metal. The addition of copper into the weld affected the welding metallurgical process of the electron beam-welded Ti/Ni joint significantly and was helpful for restraining the formation of Ti-Ni intermetallics in Ti/Ni joint. The microstructure of the weld was mainly characterized by a copper-based solid solution and Ti-Cu interfacial intermetallic compounds. Ti-Ni intermetallic compounds were almost entirely suppressed. The hardness of the weld zone was significantly lower than that of Ti/Ni joint, and the tensile strength of the joint can be up to 282 MPa.

  11. Microstructure and Mechanical Properties of TIG Weld Joint of ZM5 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    QIN Ren-yao

    2016-06-01

    Full Text Available The ZM5 magnesium alloy plates were welded by TIG welding method. The microstructural characteristics and mechanical properties of ZM5 magnesium alloy joint were studied by optical microscopy, microhardness and tensile testers. The results show that the TIG weld joint of ZM5 magnesium alloy is composed of heat affected zone, partially melted zone and weld metal. The heat affected zone is consisted of primary α-Mg phase and eutectic phase that is composed of eutectic α-Mg and eutectic β-Mg17Al12 phase and mainly precipitated at grain boundaries. In the partially melted zone, the eutectic phase is not only increasingly precipitated at grain boundaries, but also dispersed in grains, and the growth of the β-Mg17Al12 phase is obviously observed. The microstructure in the weld is the typical dendritic morphology. The dendrites are considered as primary α-Mg phase, and the interdendritic regions are α+β eutectic phase. The difference in the microstructure of the heat affected zone, partially melted zone and weld results in their various microhardness values, and leads to the smaller tensile strength and ductility in the ZM5 alloy weld joint than parent metal.

  12. Flatiron-Erie 115kV transmission line project, Larimer, Weld and Boulder Counties, Colorado

    International Nuclear Information System (INIS)

    1993-05-01

    Western Area Power Administration (Western) proposes to uprate its existing 115-kV Flatiron-Erie transmission line. The line is located in Larimer, Weld and Boulder Counties, Colorado, and passes through the City of Longmont. The line connects Flatiron Substation and several of the substations supplying Longmont. It is a single circuit 115-kV line, 31.5 miles long, and was built in 1950-51 on a 75-foot wide right-of-way (ROW) using wood H-frame structures. Western proposes to build 27 new structures along the line, to replace or modify 45 of the existing structures and to remote 11 of them. Many of these additions and changes would involve structures that are approximately 5 to 15 feet taller than the existing ones. The existing conductors and ground wires would remain in place. The purpose of these actions would be to allow the power carrying capability of the line to be increased and to replace deteriorating/structural members. Western would be the sole participant in the proposed project. This report gives an analysis of the study area environment and the development of alternative routes. An assessment is presented of the impacts of the primary alternative routes. The environmental consequences of this project are addressed

  13. Effect of Welding Speed on Microstructure and Mechanical Properties due to The Deposition of Reinforcements on Friction Stir Welded Dissimilar Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Baridula Ravinder Reddy

    2017-01-01

    Full Text Available The strength of the welded joint obtained by solid state stir welding process was found to be improved as compared to fusion welding process. The deposition of reinforcements during friction stir welding process can further enhance the strength of the welded joint by locking the movement of grain boundaries. In the present study, the aluminium alloys AA2024 and AA7075 were welded effectively by depositing the multi-walled carbon nanotubes in to the stir zone. The mechanical properties and microstructures were studied by varying the traverse speed at constant rotational speed. The results show that rotating tool pin stirring action and heat input play an important role in controlling the grain size. The carbon nanotubes were found to be distributed uniformly at a welding speed (traverse speed of 80mm/min. This enhanced the mechanical properties of the welded joint. The microstructure and Electron dispersive X-ray analysis (EDX studies indicate that the deposition of carbon nanotubes in the stir zone was influenced by the traverse speed.

  14. Feasibility evaluations for the integration of laser butt welding of tubes in industrial pipe coil production lines

    Science.gov (United States)

    Penasa, Mauro; Colombo, Enrico; Giolfo, Mauro

    1994-09-01

    Due to the good performance shown by laser welded joints, to the quality and repeatability achievable by this welding technique and to its high process productivity, a feature inherent to the laser technology which, together with its high flexibility, allows different operations to be performed by a single source, consistent savings in a production line may be obtained. Therefore laser welding techniques may be of high relevance for industrial applications, provided that a sufficient attention is paid to avoiding a low utilization time to the operating laser source. The paper describes a feasibility study for the integration of a laser source as an automatic unit for circumferential butt welding of tubes in production lines of pipe coils, just before the cold bending station. Using a 6 kW CO2 source, thickness ranging from 3.5 to 11.2 mm in carbon, low alloyed Cr-Mo and austenitic stainless steels, have been successfully welded. Cr-Mo steels require on line preheating treatment, which however can be achieved by laser defocused passes just before welding. The results of the preliminary qualification performed on laser welded joints of the involved topologies of product (materials, diameters and thicknesses) are described together with technological tests required for approval: laser circumferential butt welding of tubes has proven to be effective, with satisfactory and repeatable results and good joint performances. An exhaustive comparison with current welding techniques (TIG, MIG) is then carried out, along with a detailed analysis of the potential advantages and benefits which may be expected by using the laser welding technique, as well as with a first estimation of the investments and running costs. Since laser productivity is saturated only at a rough 35% during the year, an accurate analysis of other possible applications and of a possible lay out of a laser working cell integrated in the factory production lines is performed. Usually little attention is

  15. Modeling of the mechanical behaviour of welded structures: behaviour laws and rupture criteria

    International Nuclear Information System (INIS)

    Paris, T.; Delaplanche, D.; Saanouni, K.

    2006-01-01

    In the framework of the technological developments carried out in the CEA, the analysis of the mechanical behaviour of the heterogeneous welded bonds Ta/TA6V is a main preoccupation. Indeed, the welding of these two materials which cannot be distinguished by their mechanical and thermal properties induces strong microstructural heterogeneities in the melted zone. In order to characterize the behaviour of the welded joints and to develop a model of mechanical behaviour, a four points bending test on a notched specimen has been developed and implemented. This new test has allowed to obtain a macroscopic response of strength-displacement type but to analyze too more finely, with an optical extensometry and images correlation method, the influence of the heterogeneities on the local deformation of the welded joint. The confrontation of these results to a metallurgical study allows to validate the first conclusions deduced of the mechanical characterization tests and to conclude as for the local mechanisms governing the behaviour and the damage of the melted zone. The mechanical behaviour can be restored by an elasto-viscoplastic model with isotropic and non linear kinematic strain hardening coupled to this damage. The proposed model allows to identify the macroscopic behaviour of the weld bead. (O.M.)

  16. Microstructure, local and global mechanical properties of friction stir welds in aluminium alloy 6005A-T6

    International Nuclear Information System (INIS)

    Simar, A.; Brechet, Y.; Meester, B. de; Denquin, A.; Pardoen, T.

    2008-01-01

    The effect of the welding speed on the microstructure, local and overall mechanical properties of friction stir welded joints has been investigated in the aluminium alloy 6005A-T6. The fine hardening precipitation within the heat-affected zone has been characterized by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Post-welding heat treatments have been applied to obtain indications on the level of solid solution supersaturation in the as welded state. The local mechanical behaviour was determined using thin specimens extracted from various regions of the weld. The overall properties were measured on samples cut perpendicular to the weld. Specific attention was devoted to the relationship between the local microstructure and local hardening properties in the weakest region, which govern the overall strength and ductility of the welds

  17. Metallurgical characteristics and fracture mechanical properties of unirradiated Kori-1 RPV weld: Linde 80, WF-233

    International Nuclear Information System (INIS)

    Hong, Jun Hwa; Lee, B. S.; Oh, Y. J.; Chi, S. H.; Kim, J. H.; Park, D. G.; Yoon, J. H.; Oh, J. M.

    2000-07-01

    The fracture toughness transition properties of the low upper shelf weld, Linde 80 WF-233, of Kori-1 RPV were evaluated by the master curve method, which is designated by ASTM E 1921, 'Standard test method for determination of reference temperature, T o , for ferritic steels in the transition range'. The reference temperature, T o =-83 deg C, was determined by PCVN specimens at -90 deg C. This value is similar to that of other high copper welds. The initial RT NDT was conservatively estimated as -26 deg F from the current fracture toughness results. From the studies on the chemistry and microstructure, the fracture mechanical properties of WF-233 weld is convincingly not worse than WF-70 and 72W welds

  18. Toughness study of an under matched welded joint: application to the mechanical integrity of the electron beam welded joint of 6016-T6 aluminium alloy

    International Nuclear Information System (INIS)

    Rekik, Wissal

    2016-01-01

    For the demonstration of the integrity of the most sensitive nuclear components, conventional defects, as cracks for example, must be considered within the design step as required by the nuclear safety authority. This phase is particularly crucial for dimensioning of welded structures. To ensure a conservative prediction, the position of the initial crack within the welded joint must be the most detrimental in fracture behavior. Commonly used analyzes consider homogeneous structure with the behavior of the base metal of the welded joint, considered as the weakest metallurgical zone in the case of an overmatched weld. In contrast, similar analysis is not conservative in case of under matched weld. The thesis contributes by the development of an experimental and numerical methodology allowing the identification of the detrimental metallurgical zone in fracture behavior of an under matched welded joint. The methodology proposed is applied to an electron beam welded joint on al 6061-T6. To reach this goal, the gradient of the mechanical behavior along the welded joint was first identified. This is particularly interesting to conduct an advanced analysis based on a multi material approach. In a second step, the fracture behavior of the welded joint was studied on CT specimen. The transferability of the J integral at initiation was approved on another geometry: this represents an important foundation for the transferability assumption to structure. Finally, a numerical analysis on full scale tube was developed. Residual welding stresses and structural effects were considered. The results demonstrate that the heat affected zone located at 13 mm from the middle of the welded joint is the most detrimental zone for fracture analysis. This contradicts the conventional methods conducted on fracture analysis which consider a conventional defect within the fusion zone. (author) [fr

  19. Microstructures and Mechanical Properties of Friction Tapered Stud Overlap Welding for X65 Pipeline Steel Under Wet Conditions

    Science.gov (United States)

    Xu, Y. C.; Jing, H. Y.; Han, Y. D.; Xu, L. Y.

    2017-08-01

    This paper exhibits a novel in situ remediation technique named friction tapered stud overlap welding (FTSOW) to repair a through crack in structures and components in extremely harsh environments. Furthermore, this paper presents variations in process data, including rotational speed, stud displacement, welding force, and torque for a typical FTSOW weld. In the present study, the effects of welding parameters on the microstructures and mechanical properties of the welding joints were investigated. Inapposite welding parameters consisted of low rotational speeds and welding forces, and when utilized, they increased the occurrence of a lack of bonding and unfilled defects within the weld. The microstructures with a welding zone and heat-affected zone mainly consisted of upper bainite. The hardness value was highest in the welding zone and lowest in the base material. During the pull-out tests, all the welds failed in the stud. Moreover, the defect-free welds broke at the interface of the lap plate and substrate during the cruciform uniaxial tensile test. The best tensile test results at different depths and shear tests were 721.6 MPa and 581.9 MPa, respectively. The favorable Charpy impact-absorbed energy was 68.64 J at 0 °C. The Charpy impact tests revealed a brittle fracture characteristic with a large area of cleavage.

  20. Mechanical properties of 9Cr–1W reduced activation ferritic martensitic steel weldment prepared by electron beam welding process

    Energy Technology Data Exchange (ETDEWEB)

    Das, C.R., E-mail: chitta@igcar.gov.in [Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Albert, S.K. [Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Sam, Shiju [Institute for Plasma Research, Gandhinagar (India); Mastanaiah, P. [Defense Research and Development Laboratory, Hyderabad (India); Chaitanya, G.M.S.K.; Bhaduri, A.K.; Jayakumar, T. [Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Murthy, C.V.S. [Defense Research and Development Laboratory, Hyderabad (India); Kumar, E. Rajendra [Institute for Plasma Research, Gandhinagar (India)

    2014-11-15

    Highlights: • Width of HAZ is smaller in the 9Cr–1W RAFM weldment prepared by EB process compared to that reported for TIG weldments in literature. • Weld joint is stronger than that of the base metal. • Toughness of weld metal prepared by EB welding process is comparable to that (in PWHT condition) prepared by TIG process. • DBTT of as-welded 9Cr–1W RAFM weldment prepared by EB process is comparable to that reported for TIG weld metal in PWHT condition. - Abstract: Microstructure and mechanical properties of the weldments prepared from 9Cr–1W reduced activation ferritic martensitic (RAFM) steel using electron beam welding (EBW) process were studied. Microstructure consists of tempered lath martensite where precipitates decorating the boundaries in post weld heat treated (PWHT) condition. Lath and precipitate sizes were found to be finer in the weld metal than in base metal. Accordingly, hardness of the weld metal was found to be higher than the base metal. Tensile strength of the cross weldment specimen was 684 MPa, which was comparable with the base metal tensile strength of 670 MPa. On the other hand, DBTT of 9Cr–1W weld metal in as-welded condition is similar to that reported for TIG weld metal in PWHT condition.

  1. Mechanical properties of 9Cr–1W reduced activation ferritic martensitic steel weldment prepared by electron beam welding process

    International Nuclear Information System (INIS)

    Das, C.R.; Albert, S.K.; Sam, Shiju; Mastanaiah, P.; Chaitanya, G.M.S.K.; Bhaduri, A.K.; Jayakumar, T.; Murthy, C.V.S.; Kumar, E. Rajendra

    2014-01-01

    Highlights: • Width of HAZ is smaller in the 9Cr–1W RAFM weldment prepared by EB process compared to that reported for TIG weldments in literature. • Weld joint is stronger than that of the base metal. • Toughness of weld metal prepared by EB welding process is comparable to that (in PWHT condition) prepared by TIG process. • DBTT of as-welded 9Cr–1W RAFM weldment prepared by EB process is comparable to that reported for TIG weld metal in PWHT condition. - Abstract: Microstructure and mechanical properties of the weldments prepared from 9Cr–1W reduced activation ferritic martensitic (RAFM) steel using electron beam welding (EBW) process were studied. Microstructure consists of tempered lath martensite where precipitates decorating the boundaries in post weld heat treated (PWHT) condition. Lath and precipitate sizes were found to be finer in the weld metal than in base metal. Accordingly, hardness of the weld metal was found to be higher than the base metal. Tensile strength of the cross weldment specimen was 684 MPa, which was comparable with the base metal tensile strength of 670 MPa. On the other hand, DBTT of 9Cr–1W weld metal in as-welded condition is similar to that reported for TIG weld metal in PWHT condition

  2. The Welding Effect on Mechanical Strength of Low Level Radioactive Waste Drum Container

    International Nuclear Information System (INIS)

    Aisyah; Herlan Martono

    2007-01-01

    The treatment of compactable low level solid waste was started by compaction of 100 liter drum containing the waste using 600 kN hydraulic press in 200 liters drum. The 200 liter drum of waste container containing of compacted waste then immobilized with cement and stored in interm storage. The 200 liter drum of waste container made of carbon steel material to comply with a good mechanical strength request in order to be able to retain the waste content for long period. Welding is a one step in a waste drum container fabrication process that has an opportunity in decreasing these mechanical strength. The research is carried out by welding the waste drum container material sample by electric arc welding. Mechanical strength test carried out by measuring the tensile strength by using the tensile strength machine, hardness test by using Vickers hardness test and microstructure observation by using the optic microscope. The result shows that the welding cause the microstructure changes, its meaning of forming ferro oxide phase on welding area that leads to the brittle material, so that the mechanical strength has a decreasing slightly. Nevertheless the decreasing of mechanical strength is still in the range of safety limit. (author)

  3. A Comparison Between Mechanical And Electrochemical Tests on Ti6Al4V Welded By LBW

    Science.gov (United States)

    Serroni, G.; Bitondo, C.; Astarita, A.; Scala, A.; Gloria, A.; Prisco, U.; Squillace, A.; Bellucci, F.

    2011-05-01

    Titanium and its alloys are nowadays widely used in many sectors: in the medical field (orthopedic and dental ones), in the architectural field, in the chemical plants field and in aeronautic. In this last field it is more and more used both for its contribution to make lightweight and time durable structures and for its compatibility with new materials, first of all Carbon Fiber Reinforced Plastics (CFRP). To this aim, lots of researches are now focusing on new and emerging technologies capable to make titanium objects and, at the same time, reducing the scrap, since titanium alloys for aeronautic application are very expensive. This paper examines Grade 5 Titanium Alloy (Ti6Al4V) welded by Laser Beam (LBW) in butt-joint configuration. The source was Nd:YAG laser, moreover two inert gases were used, in order to provide a shield both on the top and on the bottom of the weld bead. The joints were studied by varying two process parameters: welding speed and power of the laser beam. It was not possible to realize a full experimental plan, due to technological limits in making titanium laser beam welds. The joints were tested to measure their mechanical properties and the corrosion resistance. The process parameters do not significantly affect the maximum static strength of the joints. Microscopic analysis showed that welds made with high power and low welding speed have a uniform weld bead, and no macroscopic defect occurs. Fatigue test results, instead, show a marked influence of the morphology of the weld bead: the occurrence of some defects, such as the undercut, both on the top and on the bottom of the weld bead, dramatically reduced fatigue resistance of the joints. Corrosion resistance was studied using the electrochemical micro cell technique, which allows to distinguish electrochemical properties of each zone of the weld bead, even when, as in this case, they are very narrow. By a general point of view, it has been demonstrated that the joints showing the best

  4. Formation Mechanisms for Entry and Exit Defects in Bobbin Friction Stir Welding

    Directory of Open Access Journals (Sweden)

    Abbas Tamadon

    2018-01-01

    Full Text Available Bobbin friction stir welding (BFSW is an innovative variant for the solid state welding process whereby a rotating symmetrical tool causes a fully penetrated bond. Despite the process development, there are still unknown variables in the characterization of the process parameters which can cause uncontrolled weld defects. The entry zone and the exit zone consist of two discontinuity-defects and removing them is one of the current challenges for improving the weld quality. In the present research, the characteristic features of the entry and exit defects in the weld structure and formation mechanism of them during the BFSW processing was investigated. Using stacked layers of multi-colour plasticine the material flow, analogous to metal flow, can be visualised. By using different colours as the path markers of the analogue model, the streamline flow can be easily delineated in the discontinuity defects compared with the metal welds. AA6082-T6 aluminium plates and multi-layered plasticine slabs were employed to replicate the entry-exit defects in the metal weld and analogue samples. The fixed-bobbin tool utilized for this research was optimized by adding a thread feature and tri-flat geometry to the pin and closed-end spiral scrolls on both shoulder surfaces. Samples were processed at different rotating and longitudinal speeds to show the degree of dependency on the welding parameters for the defects. The analogue models showed that the entry zone and the exit zone of the BFSW are affected by the inhomogeneity of the material flow regime which causes the ejection or disruption of the plastic flow in the gap between the bobbin shoulders. The trial aluminium welds showed that the elimination of entry-exit defects in the weld body is not completely possible but the size of the defects can be minimized by modification of the welding parameters. For the entry zone, the flow pattern evolution suggested formation mechanisms for a sprayed tail, island zone

  5. Effect of acoustic softening on the thermal-mechanical process of ultrasonic welding.

    Science.gov (United States)

    Chen, Kunkun; Zhang, Yansong; Wang, Hongze

    2017-03-01

    Application of ultrasonic energy can reduce the static stress necessary for plastic deformation of metallic materials to reduce forming load and energy, namely acoustic softening effect (ASE). Ultrasonic welding (USW) is a rapid joining process utilizing ultrasonic energy to form a solid state joint between two or more pieces of metals. Quantitative characterization of ASE and its influence on specimen deformation and heat generation is essential to clarify the thermal-mechanical process of ultrasonic welding. In the present work, experiments were set up to found out mechanical behavior of copper and aluminum under combined effect of compression force and ultrasonic energy. Constitutive model was proposed and numerical implemented in finite element model of ultrasonic welding. Thermal-mechanical analysis was put forward to explore the effect of ultrasonic energy on the welding process quantitatively. Conclusions can be drawn that ASE increases structural deformation significantly, which is beneficial for joint formation. Meanwhile, heat generation from both frictional work and plastic deformation is slightly influenced by ASE. Based on the proposed model, relationship between ultrasonic energy and thermal-mechanical behavior of structure during ultrasonic welding was constructed. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Microstructure and failure mechanisms of refill friction stir spot welded 7075-T6 aluminum alloy joints

    International Nuclear Information System (INIS)

    Shen, Zhikang; Yang, Xinqi; Zhang, Zhaohua; Cui, Lei; Li, Tielong

    2013-01-01

    Highlights: ► There is a correlation between the void in the weld and the joint strength. ► The preferable mechanical properties can be obtained by lowering rotational speed. ► The alclad has an adverse effect on the mechanical properties. -- Abstract: In this paper, the microstructure and mechanical properties of 7075-T6 aluminum alloy joints joined by refill friction stir spot welding (RFSSW) were investigated. The keyhole was refilled successfully, and the microstructure of the weld exhibited variations in the grain sizes in the width and the thickness directions. There existed defects (hook, voids, bonding ligament, etc.) associated to the material flow in the weld. Mechanical properties of the joint have been investigated in terms of hardness and tensile/shear and cross-tension test, and the fracture mechanisms were observed by SEM (scanning electron microscope). The hardness profile of the weld exhibited a W-shaped appearance in the macroscopic level, which reached the minimum at the boundary of the sleeve and the clamping ring. The variation laws between tensile/shear and cross-tension strength and processing parameters were rather complicated. The void in the weld played an important role in determining the strength of the joint. On the whole, the preferable strength can be obtained at lower rotational speed. Shear fracture mode was observed under tensile–shear loadings, and nugget debonding, plug type fracture (on the upper sheet) and plug type fracture (on the lower sheet) modes were observed under cross-tension loadings. It was also observed that the main feature affecting the mechanical properties of the joint is the alclad between the upper and lower sheets and the connecting qualities between the stir zone and thermo-mechanically affected zone.

  7. General Mechanical Repair. Minor Automotive Maintenance, Small Engine [Repair, and] Welding: Competency Test Package.

    Science.gov (United States)

    Hamlin, Larry

    This document contains the competency test package for three sections of a general mechanical repair course: minor automotive maintenance, small engine mechanics, and welding. Following a list of the common essential elements for trade and industrial education, competency tests for the three sections are provided. Each test includes unit name,…

  8. Observation of the mechanisms causing two kinds of undercut during laser hybrid arc welding

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Jan, E-mail: jan.karlsson@ltu.se [Lulea University of Technology, Dept. TVM, SE-971 87 Lulea (Sweden); Norman, Peter; Kaplan, Alexander F.H. [Lulea University of Technology, Dept. TVM, SE-971 87 Lulea (Sweden); Rubin, Per [Rubin-Materialteknik, Gullhoenevaegen 13 97596 Lulea (Sweden); Lamas, Javier [Lulea University of Technology, Dept. TVM, SE-971 87 Lulea (Sweden); Centro Tecnoloxico do Naval Galego, Ferrol 15590 (A Coruna) (Spain); Yanez, Armando [Centro de Investigacions Tecnoloxicas, Universidade da Coruna, Ferrol 15403 (A Coruna) (Spain)

    2011-06-15

    Two different kinds of undercut were identified when laser hybrid welding hot rolled HSLA-steel in either the as-rolled condition or with the top surface mill scale removed. The presence of mill scale on the steel surface was found to give a sharp angled undercut combined with a sharp oxide inclusion at the edge of the weld which would have the same mechanical effect as a crack in this position. Removal of the surface oxides before welding resulted in the elimination of the oxide inclusions and a more rounded undercut geometry indicative of superior mechanical properties, particularly fatigue life. The mechanisms of the formation of both types of undercut have been analysed by high speed photography and SEM.

  9. Effect of friction stir welding speed on the microstructure and mechanical properties of a duplex stainless steel

    International Nuclear Information System (INIS)

    Saeid, T.; Abdollah-zadeh, A.; Assadi, H.; Malek Ghaini, F.

    2008-01-01

    The present study focuses on the effect of the welding speed on the microstructure and mechanical properties of the stir zone (SZ) in friction stir welding (FSW) of SAF 2205 duplex stainless steel. A single tool, made of a WC-base material, was used to weld 2 mm-thick plates at a constant rotational speed of 600 rpm. X-ray radiography revealed that sound welds were successfully obtained for the welding speeds in the range of 50-200 mm/min, whereas a groove-like defect was formed at the higher speed of 250 mm/min. Moreover, increasing the welding speed decreased the size of the α and γ grains in the SZ, and hence, improved the mean hardness value and the tensile strength of the SZ. These results are interpreted with respect to interplay between the welding speed and the peak temperature in FSW

  10. Mechanical Properties Of AA 6061-T6 Aluminum Alloy Friction Stir Welds

    Directory of Open Access Journals (Sweden)

    Asmaa M. Abdullah

    2015-06-01

    Full Text Available The different parameters on mechanical and microstructural properties of aluminium alloy 6061-T6 Friction stir-welded (FSW joints were investigated in the present study. Different welded specimens were produced by employing variable rotating speeds and welding speeds. Tensile strength of the produced joints was tested at room temperature and the the effecincy was assessed, it was 75% of the base metal at rotational speed 1500 rpm and weld speed 50 mm/min. Hardness of various zones of FSW welds are presented and analyzed by means of brinell hardness number . Besides to thess tests the bending properties investigated and showed good results in some specimen and not in onother the mamximum stress was 240 N/mm2 at rotational speed 1500 rpm and weld speed 50 mm/min , while the maximum stress at 1250 rpm and 75 mm/min 94 N/mm2 , hardness results shwed lower values in heat affected and nugget zones than the base metal with improving of hardness at 1500 rpm, 75 mm/min .

  11. Effect of Pin Geometry on the Mechanical Strength of Friction-Stir-Welded Polypropylene Composite Plates

    Science.gov (United States)

    Kordestani, F.; Ashenai Ghasemi, F.; Arab, N. B. M.

    2017-09-01

    Friction stir welding (FSW) is a solid-state welding process, which has successfully been applied in aerospace and automotive industries for joining materials. The friction stir tool is the key element in the FSW process. In this study, the effect of four different tool pin geometries on the mechanical properties of two types of polypropylene composite plates, with 30% glass and carbon fiber, respectively, were investigated. For this purpose, four pins of different geometry, namely, a threaded-tapered pin, square pin, four-flute threaded pin, and threaded-tapered pin with a chamfer were made and used to carry out the butt welding of 5-mm-thick plates. The standard tensile and Izod impact tests were performed to evaluate the tensile strength and impact toughness of welded specimens. The results indicated that the threaded-tapered pin with a chamfer produced welds with a better surface appearance and higher tensile and impact strengths. The tests also showed that, with the threaded-tapered pin with a chamfer, the impact strength of the glass- and carbon-fiber composite welds were about 40 and 50%, respectively, of that of the base materials.

  12. Mechanical strength of welding zones produced by material extrusion additive manufacturing.

    Science.gov (United States)

    Davis, Chelsea S; Hillgartner, Kaitlyn E; Han, Seung Hoon; Seppala, Jonathan E

    2017-08-01

    As more manufacturing processes and research institutions adopt customized manufacturing as a key element in their design strategies and finished products, the resulting mechanical properties of parts produced through additive manufacturing (AM) must be characterized and understood. In material extrusion (MatEx), the most recently extruded polymer filament must bond to the previously extruded filament via polymer diffusion to form a "weld". The strength of the weld limits the performance of the manufactured part and is controlled through processing conditions. Under-standing the role of processing conditions, specifically extruder velocity and extruder temperature, on the overall strength of the weld will allow optimization of MatEx-AM parts. Here, the fracture toughness of a single weld is determined through a facile "trouser tear" Mode III fracture experiment. The actual weld thickness is observed directly by optical microscopy characterization of cross sections of MatEx-AM samples. Representative data of weld strength as a function of printing parameters on a commercial 3D printer demonstrates the robustness of the method.

  13. Morphology, microstructure, and mechanical properties of laser-welded joints in GH909 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunming; Cai, Yuanzheng; Hu, Chongjing; Zhang, Xiong; Yan, Fei; Hu, Xiyuan [Huazhong University of Science and Technology, Wuhan (China)

    2017-05-15

    The experimental laser welding of GH909 alloy was conducted in this study. The morphology, microstructure, and mechanical properties of laser-welded joints were analyzed by scanning electron microscopy, energy diffraction spectroscopy, and other techniques. Results revealed that the microstructure of the welded joints mainly consisted of tiny cellular structures, dendritic structures, and equiaxed crystals. Pores appeared in the interdendritic regions because of the insufficient local feeding of molten metal during solidification. Nb segregation in the heat-affected zone caused liquation cracking, whereas C segregation further induced the formation of carbide precipitates along the grain boundaries during the welding thermal cycle. The instability of the keyhole significantly promoted the escape of the metal vapor/plasma from the hole; as a result, porosity defects formed in the weld. The average tensile strength of the test joints was 756 MPa, which is 93.1 % of that of the base metal. The average microhardness of the weld zone (250 HV) was higher than that of the GH909 alloy substrate (208 HV), peaking at 267 HV. Microcracks appeared along the grain boundaries, proving that the grain boundaries were the weakest areas in the joint.

  14. Mechanical properties and microstructural evaluation of AA1100 to AZ31 dissimilar friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Azizieh, M., E-mail: azizieh@gmail.com [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Sadeghi Alavijeh, A. [School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC V3T 0A3 (Canada); Abbasi, M. [High Temperature Energy Materials, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Balak, Z. [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2016-02-15

    In this paper, microstructure and mechanical properties of dissimilar friction stir welds of AA1100 and AZ31 were investigated to understand the effects of rotational and travel speed as well as pin position. The tensile results of welded samples revealed that the sound welds were formed when the stirring pin deviated from the centreline to the AZ31 side. The X-ray diffraction shows that Al{sub 3}Mg{sub 2} and Al{sub 12}Mg{sub 17} intermetallics formation occurs in the stir zone during the welding process. High hardness of these intermetallic phases increased the hardness of the stir zone to 110 Hv. The best tensile results were obtained in the sample processed in the range of 28–32 (rev/mm) rotational to travel speed ratio. - Highlights: • For Al to Mg friction stir welding, tool offset must be to Mg side. • There is an optimum rotational speed for obtain the highest strength. • Intermetallics form in any welding condition. • The volume fraction of intermetallic is directly related to FSW peak temperature.

  15. Microstructure and mechanical properties of hard zone in friction stir welded X80 pipeline steel relative to different heat input

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Hakan, E-mail: hakanay@uludag.edu.tr [Engineering and Architecture Faculty, Mechanical Engineering Department, Uludag University, 16059 Gorukle-Bursa (Turkey); Nelson, Tracy W. [Mechanical Engineering Department, Brigham Young University, 435 CTB, Provo, UT 84602 (United States)

    2013-12-01

    The study was conducted to investigate the microstructure and mechanical properties of the hard zone in friction stir welded X80 pipeline steel at different heat inputs. Microstructural analysis of the welds was carried out using optical microscopy, transmission electron microscopy, and microhardness. Heat input during friction stir welding process had a significant influence on the microstructure and mechanical properties in the hard zone along the advancing side of the weld nugget. Based on the results, the linear relationships between heat input and post-weld microstructures and mechanical properties in the hard zone of friction stir welded X80 steels were established. It can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone strength increases.

  16. Microstructure and mechanical properties of hard zone in friction stir welded X80 pipeline steel relative to different heat input

    International Nuclear Information System (INIS)

    Aydin, Hakan; Nelson, Tracy W.

    2013-01-01

    The study was conducted to investigate the microstructure and mechanical properties of the hard zone in friction stir welded X80 pipeline steel at different heat inputs. Microstructural analysis of the welds was carried out using optical microscopy, transmission electron microscopy, and microhardness. Heat input during friction stir welding process had a significant influence on the microstructure and mechanical properties in the hard zone along the advancing side of the weld nugget. Based on the results, the linear relationships between heat input and post-weld microstructures and mechanical properties in the hard zone of friction stir welded X80 steels were established. It can be concluded that with decrease in heat input the bainitic structure in the hard zone becomes finer and so hard zone strength increases

  17. Microstructures and mechanical properties of welded joints of novel 3Cr pipeline steel using an inhouse and two commercial welding wires

    International Nuclear Information System (INIS)

    Zhu, Jinyang; Xu, Lining; Chang, Wei; Hu, Lihua; Lu, Minxu

    2014-01-01

    Highlights: • Weldability of novel 3Cr pipeline steel was investigated using two commercial and an inhouse welding wires. • Mechanical properties were measured and microstructure characteristics were observed. • Fracture positions of tensile test just corresponded to the minimum hardness region of the joints. • The inhouse wire R01 can provide the highest cost-performance ratio. - Abstract: The welded joints of the novel 3Cr pipeline steel were fabricated via the gas tungsten arc welding (GTAW) technique using an inhouse welding wire labeled as R01 and two kinds of commercial wires (H08Cr3MoMnA and TGS-2CML). Microhardness, impact toughness and tensile properties of the joints were measured, and microstructure characteristics were observed by scanning electron microscopy (SEM). The results show that under selected welding procedure, the joints of R01 can achieve quite good mechanical properties without preheating and post weld heat treatment (PWHT). After thermal refining, elongation (15.2%) doubled and met the DNV-OS-F101 standard. For low carbon or super low carbon pipeline steels such as 3Cr steel, the revised formula with the carbon applicable coefficient (A(c)) was quite good for predicting the maximum hardness in heat affected zone (HAZ). Compared with these two selected commercial wires, the inhouse welding wire R01 can provide the highest cost-performance ratio

  18. TIG AISI-316 welds using an inert gas welding chamber and different filler metals: Changes in mechanical properties and microstructure

    Directory of Open Access Journals (Sweden)

    Sánchez, A.

    2010-12-01

    Full Text Available This report analyses the influence of the use of an inert gas welding chamber with a totally inert atmosphere on the microstructure and mechanical properties of austenitic AISI 316L stainless steel TIG welds, using AISI ER316L, AISI 308L and Inconel 625 as filler metals. When compared with the typical TIG process, the use of the inert gas chamber induced changes in the microstructure, mainly an increase in the presence of vermicular ferrite and ferrite stringers, what resulted in higher yield strengths and lower values of hardness. Its effect on other characteristics of the joins, such as tensile strength, depended on the filler metal. The best combination of mechanical characteristics was obtained when welding in the inert gas chamber using Inconel 625 as filler metal.

    En este estudio se analiza la influencia que el uso de una cámara de soldadura de gas inerte tiene sobre la microestructura y las propiedades mecánicas de las soldaduras TIG en el acero inoxidable austenítico AISI-316L cuando se emplean AISI ER316L, AISI 308L e Inconel 625 como materiales de aporte. Cuando se compara con el típico proceso de TIG, el uso de una cámara de gas inerte induce cambios en la microestructura, incrementando la presencia de ferrita vermicular y de laminillas de ferrita, resultando en un aumento del límite elástico y una pérdida de dureza. Su influencia sobre otras características de las soldaduras como la carga de rotura depende de la composición del material de aporte. La mejor combinación de propiedades mecánicas se obtuvo usando el Inconel 625 como material de aporte y soldando en la cámara de gas inerte.

  19. Studies on microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc welds

    Science.gov (United States)

    Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    The present work is aimed at studying the microstructure, mechanical and corrosion properties of high nitrogen stainless steel shielded metal arc (SMA) welds made with 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. Microstructures of the welds were characterized using optical microscopy (OM), field emission scanning electron microscopy (FESEM) and electron back scattered diffraction (EBSD) mainly to determine the morphology, phase analysis, grain size and orientation image mapping. Hardness, tensile and ductility bend tests were carried out to determine mechanical properties. Potentio-dynamic polarization testing was carried out to study the pitting corrosion resistance using a GillAC basic electrochemical system. Constant load type testing was carried out to study stress corrosion cracking (SCC) behaviour of welds. The investigation results shown that the selected Cr–Mn–N type electrode resulted in favourable microstructure and completely solidified as single phase coarse austenite. Mechanical properties of SMA welds are found to be inferior when compared to that of base metal and is due to coarse and dendritic structure.

  20. A comparative evaluation of microstructural and mechanical behavior of fiber laser beam and tungsten inert gas dissimilar ultra high strength steel welds

    Directory of Open Access Journals (Sweden)

    Jaiteerth R. Joshi

    2016-12-01

    Full Text Available The influence of different welding processes on the mechanical properties and the corresponding variation in the microstructural features have been investigated for the dissimilar weldments of 18% Ni maraging steel 250 and AISI 4130 steel. The weld joints are realized through two different fusion welding processes, tungsten inert arc welding (TIG and laser beam welding (LBW, in this study. The dissimilar steel welds were characterized through optical microstructures, microhardness survey across the weldment and evaluation of tensile properties. The fiber laser beam welds have demonstrated superior mechanical properties and reduced heat affected zone as compared to the TIG weldments.

  1. Fine tuning of dwelling time in friction stir welding for preventing material overheating, weld tensile strength increase and weld nugget size decrease

    Directory of Open Access Journals (Sweden)

    Mijajlović Miroslav M.

    2016-01-01

    Full Text Available After successful welding, destructive testing into test samples from Al 2024-T351 friction stir butt welds showed that tensile strength of the weld improve along the joint line, while dimensions of the weld nugget decrease. For those welds, both the base material and the welding tool constantly cool down during the welding phase. Obviously, the base material became overheated during the long dwelling phase what made conditions for creation of joints with the reduced mechanical properties. Preserving all process parameters but varying the dwelling time from 5-27 seconds a new set of welding is done to reach maximal achievable tensile strength. An analytical-numerical-experimental model is used for optimising the duration of the dwelling time while searching for the maximal tensile strength of the welds

  2. Mechanical and structural characteristics in high temperature of stainless steel welded joint

    International Nuclear Information System (INIS)

    Monteiro, S.N.; Carvalho Mota, A.F. de

    1980-01-01

    The mechanical behavior at 600 0 C of weldments made of type 304 stainless as base metal and niobium containing type 347 stainless as weld metal has been investigated. This was done through tensile and creep tests. Heat treatments at 600 0 C and up to 6000 hours permited a simultaneous follow up of the mechanical and microstructural changes. It was observed that the exposure at 600 0 C under load contributes, from the begining, to the strengthening of the weld. This is due to the acceleration of the second phase precipitation hardening. (Author) [pt

  3. The Influence of Flow and Type of Variation in The Welding Electrode SMAW Against Carbon Steel Mechanical Propertis

    Directory of Open Access Journals (Sweden)

    I Made Gatot Karohika

    2012-11-01

    Full Text Available Welding is a joining process of 2 or more metal that is widely used in industry. To obtain good welding result it is needed appropriate filler and weld parameters to avoid weld defect and wide deference of mechanic properties between welded metal and base metal.In this experiment we used different filler and current (E 6010, 7018 ? 2,5mm ? 350mm , 100 dan 130 Aand use material carbon steel AISI 1045 and SMAW welding method. Rockwell C Hardness tested in welded metal, HAZ, and base metal area.The hardness number in welded metal and HAZ is reported higher than base metal area, the hardness number of welded metal and HAZ that use current 130 is higher than that one than use current 100 A,and hardness number in base metal relatifely similar. The hardness number of welded metal that use electrode 7018 is higher than hardness number of welded metal that use electrode 6010, and hardness number of HAZ and base metal is not affected significantly by the types of electrode.

  4. Effects of solidified microstructures on J-R fracture resistances of the surge line pipe welds

    International Nuclear Information System (INIS)

    Youn, J. H.; Lee, B. S.; Yoo, W.

    2003-01-01

    The cause of the difference in J-R fracture resistances of AISI Type 347 GTAW welds which had almost same amounts of chromium carbides were investigated by the microstructural observations. As a result, the difference in the fracture resistances with the morphologies of the retained δ-ferrites in Type 347 welds were observed. The fracture resistance of the weld which had mostly vermicular type δ-ferrites was inferior to the weld which has lacy and acicular mixed type δ-ferrites. Therefore, it was deduced that the morphology of δ-ferrites affected the J-R fracture resistances of Type 347 welds

  5. Microstructure and mechanical properties of laser-welded joints of TWIP and TRIP steels

    International Nuclear Information System (INIS)

    Mujica, L.; Weber, S.; Pinto, H.; Thomy, C.; Vollertsen, F.

    2010-01-01

    With the aim of investigating a laser-welded dissimilar joint of TWIP and TRIP steel sheets, the microstructure was characterized by means of OM, SEM, and EBSD to differentiate the fusion zone, heat-affected zone, and the base material. OIM was used to differentiate between ferritic, bainitic, and martensitic structures. Compositions were measured by means of optical emission spectrometry and EDX to evaluate the effect of manganese segregation. Microhardness measurements and tensile tests were performed to evaluate the mechanical properties of the joint. Residual stresses and XRD phase quantification were used to characterize the weld. Grain coarsening and martensitic areas were found in the fusion zone, and they had significant effects on the mechanical properties of the weld. The heat-affected zone of the TRIP steel and the corresponding base material showed considerable differences in the microstructure and properties.

  6. Effects of mechanical force on grain structures of friction stir welded oxide dispersion strengthened ferritic steel

    International Nuclear Information System (INIS)

    Han, Wentuo; Kimura, Akihiko; Tsuda, Naoto; Serizawa, Hisashi; Chen, Dongsheng; Je, Hwanil; Fujii, Hidetoshi; Ha, Yoosung; Morisada, Yoshiaki; Noto, Hiroyuki

    2014-01-01

    The weldability of oxide dispersion strengthened (ODS) ferritic steels is a critical obstructive in the development and use of these steels. Friction stir welding has been considered to be a promising way to solve this problem. The main purpose of this work was to reveal the effects of mechanical force on grain structures of friction stir welded ODS ferritic steel. The grain appearances and the misorientation angles of grain boundaries in different welded zones were investigated by the electron backscatter diffraction (EBSD). Results showed that the mechanical force imposed by the stir tool can activate and promote the recrystallization characterized by the transformation of boundaries from LABs to HABs, and contribute to the grain refinement. The type of recrystallization in the stir zone can be classified as the continuous dynamic recrystallization (CDRX)

  7. Effects of mechanical force on grain structures of friction stir welded oxide dispersion strengthened ferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Han, Wentuo, E-mail: hanwentuo@hotmail.com [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kimura, Akihiko [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Tsuda, Naoto [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Serizawa, Hisashi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Chen, Dongsheng [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Je, Hwanil [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Fujii, Hidetoshi [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Ha, Yoosung [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Morisada, Yoshiaki [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Noto, Hiroyuki [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2014-12-15

    The weldability of oxide dispersion strengthened (ODS) ferritic steels is a critical obstructive in the development and use of these steels. Friction stir welding has been considered to be a promising way to solve this problem. The main purpose of this work was to reveal the effects of mechanical force on grain structures of friction stir welded ODS ferritic steel. The grain appearances and the misorientation angles of grain boundaries in different welded zones were investigated by the electron backscatter diffraction (EBSD). Results showed that the mechanical force imposed by the stir tool can activate and promote the recrystallization characterized by the transformation of boundaries from LABs to HABs, and contribute to the grain refinement. The type of recrystallization in the stir zone can be classified as the continuous dynamic recrystallization (CDRX)

  8. Effect of PWHT on Microstructure, Mechanical and Corrosion Behaviour of Gas Tungsten Arc Welds of IN718 Superalloys

    Science.gov (United States)

    Dilkush; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    The present work aims to improve corrosion resistance and mechanical behavior of the welds with suitable post weld heat treatment i.e. direct aging and solutionizing treatments (980STA, 1080STA). Gas tungsten arc welding (GTAW) has been performed on Inconel 718 (IN718) nickel based super alloy plates with 3mm thickness. The structural –property relationship of the post weld heat treated samples is judged by correlating the microstructural changes with observed mechanical behavior and pitting corrosion resistance of the welds As-recevied, direct aging (DA), 980STA,1080STA were studied. Welds were characterized for microstructure changes with scanning electron microscopy (SEM) and optical microscopy (OM).Vickers micro- hardness tester was used to measure the hardness of the weldments. Potential-dynamic polarization testing was carried out to study the pitting corrosion resistance in 3.5%NaCl (Sodium chloride) solution at 30°C.Results of the present study established that post weld heat treatments resulted in promoting the element segregation diffusion and resolve them from brittle laves particles in the matrix. Increased precipitation of strengthening phases lead to a significant increase in fusion zone hardness of 1080STA post weld heat treated condition compared to as welded, direct aged, 980STA conditions. Due to significant changes in the microstructural behavior of 1080STA condition resulted in superior pitting corrosion resistance than 980STA, direct aged and as- recevied conditions of IN718 GTA welds

  9. Effect of Friction Stir Welding Parameters on the Mechanical and Microstructure Properties of the Al-Cu Butt Joint

    Directory of Open Access Journals (Sweden)

    Sare Celik

    2016-05-01

    Full Text Available Friction Stir Welding (FSW is a solid-state welding process used for welding similar and dissimilar materials. FSW is especially suitable to join sheet Al alloys, and this technique allows different material couples to be welded continuously. In this study, 1050 Al alloys and commercially pure Cu were produced at three different tool rotation speeds (630, 1330, 2440 rpm and three different tool traverse speeds (20, 30, 50 mm/min with four different tool position (0, 1, 1.5, 2 mm by friction stir welding. The influence of the welding parameters on the microstructure and mechanical properties of the joints was investigated. Tensile and bending tests and microhardness measurements were used to determine the mechanical properties. The microstructures of the weld zone were investigated by optical microscope and scanning electron microscope (SEM and were analyzed in an energy dispersed spectrometer (EDS. Intermetallic phases were detected based on the X-ray diffraction (XRD analysis results that evaluated the formation of phases in the weld zone. When the welding performance of the friction stir welded butt joints was evaluated, the maximum value obtained was 89.55% with a 1330 rpm tool rotational speed, 20 mm/min traverse speed and a 1 mm tool position configuration. The higher tensile strength is attributed to the dispersion strengthening of the fine Cu particles distributed over the Al material in the stir zone region.

  10. Enhancement of mechanical properties and failure mechanism of electron beam welded 300M ultrahigh strength steel joints

    International Nuclear Information System (INIS)

    Zhang, Guodong; Yang, Xinqi; He, Xinlong; Li, Jinwei; Hu, Haichao

    2013-01-01

    Highlights: ► Normalizing at 970 °C plus quenching and tempering cannot refine the columnar grains. ► Ductility and toughness of conventional quenched and tempered joint are very low. ► An optimum combination of strength and ductility was obtained for the welded joints. ► Intergranular cracked columnar dendritic grains were found on the fracture surface. -- Abstract: In this study, four post-weld heat treatment (PWHT) schedules were selected to enhance the mechanical properties of electron beam welded 300M ultrahigh strength steel joints. The microstructure, mechanical properties and fractography of specimens under the four post-weld heat treatment (PWHT) conditions were investigated and also compared with the base metal (BM) specimens treated by conventional quenching and tempering (QT). Results of macro and microstructures indicate that all of the four PWHT procedures did not eliminate the coarse columnar dendritic grains in weld metal (WM). Whereas, the morphology of the weld centerline and the boundaries of the columnar dendritic grains in WM of weld joint specimens subjected to the PWHT procedure of normalizing at 970 °C for 1 h followed by conventional quenching and tempering (W-N2QT) are indistinct. The width of martensite lath in WM of W-N2QT is narrower than that of specimens subjected to other PWHT procedures. Experimental results indicate that the ductility and toughness of conventional quenched and tempered joints are very low compared with the BM specimens treated by conventional QT. However, the strength and impact toughness of the W-N2QT specimens are superior to those of the BM specimen treated by conventional QT, and the ductility is only slightly inferior to that of the latter.

  11. Effect of the weld joint configuration on stressed components, residual stresses and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Cevik, Bekir; Oezer, Alpay; Oezcatalbas, Yusuf [Gazi Univ., Ankara (Turkey)

    2014-03-01

    The effect of the weld joint configuration on components has been studied, which are under service loads, under repair or construction and the residual stresses as well as the mechanical properties of the joint have been determined. For this purpose, a horizontal positioned tensile testing device and a semi-automatic MIG welding machine have been used and then the weld joints of the plates were subjected to different elastic stresses. When the temperature of the joined elements decreased to room temperature, applied elastic stresses were released. By this means, the effects of the existing tensile stresses in the joined parts and the tensile stresses created by the welding processes were investigated. The tensile stresses occurring in the joined elements were determined by using the photo-elasticity analysis method and the hole-drilling method. Also, tensile-shear tests were applied in order to determine the effect of permanent tensile loads on the mechanical properties of the joint. Experimental results showed that the application of corner welded lap joints for components under tensile loading significantly decrease the shear strength and yielding capacities of the joint. (orig.)

  12. Thermo-Mechanical Modeling of Laser-Mig Hybrid Welding (lmhw)

    Science.gov (United States)

    Kounde, Ludovic; Engel, Thierry; Bergheau, Jean-Michel; Boisselier, Didier

    2011-01-01

    Hybrid welding is a combination of two different technologies such as laser (Nd: YAG, CO2…) and electric arc welding (MIG, MAG / TIG …) developed to assemble thick metal sheets (over 3 mm) in order to reduce the required laser power. As a matter of fact, hybrid welding is a lso used in the welding of thin materials to benefit from process, deep penetration and gap limit. But the thermo-mechanical behaviour of thin parts assembled by LMHW technology for railway cars production is far from being controlled the modeling and simulation contribute to the assessment of the causes and effects of the thermo mechanical behaviour in the assembled parts. In order to reproduce the morphology of melted and heat-affected zones, two analytic functions were combined to model the heat source of LMHW. On one hand, we applied a so-called "diaboloïd" (DB) which is a modified hyperboloid, based on experimental parameters and the analysis of the macrographs of the welds. On the other hand, we used a so-called "double ellipsoïd" (DE) which takes the MIG only contribution including the bead into account. The comparison between experimental result and numerical result shows a good agreement.

  13. Mechanical strength evaluation of the welded bellows for the ports of the JT-60 vacuum vessel

    International Nuclear Information System (INIS)

    Takatso, H.; Shimizu, M.; Yamamoto, M.

    1983-01-01

    Mechanical strength of the welded bellows for the ports of the JT-60 vacuum vessel was evaluated, laying the emphasis on the fatigue strength under the torsional electromagnetic force. The welded bellows were designed to be loaded with the forced deflection due to the relative displacement between the vacuum vessel and the external fixed point, the atmospheric pressure and the forced torsional angle due to the electromagnetic force. Stresses caused by the former two were estimated following the formulae proposed by the Kellogg Company. On the other hand, two formulae were established to estimate the stress caused by the last, after examining experimentally the behavior of the welded bellows under the torsional load; one is the shearing stress evaluation formula and the other is the axial bending stress evaluation formula. It was found that the welded bellows can easily buckle under the torsional load and the former formula corresponds to the case of non-buckling and the latter to the case of buckling. The present mechanical strength evaluation method was applied to the three kinds of the welded bellows to be used in the ports of the JT-60 vacuum vessel (neutral beam injection ports, vacuum pumping ports and the adjustable limiter ports) and it was confirmed that they have sufficient strength in the range of the design load conditions

  14. Mechanical characterization of densely welded Apache Leap tuff

    International Nuclear Information System (INIS)

    Fuenkajorn, K.; Daemen, J.J.K.

    1991-06-01

    An empirical criterion is formulated to describe the compressive strength of the densely welded Apache Leap tuff. The criterion incorporates the effects of size, L/D ratio, loading rate and density variations. The criterion improves the correlation between the test results and the failure envelope. Uniaxial and triaxial compressive strengths, Brazilian tensile strength and elastic properties of the densely welded brown unit of the Apache Leap tuff have been determined using the ASTM standard test methods. All tuff samples are tested dry at room temperature (22 ± 2 degrees C), and have the core axis normal to the flow layers. The uniaxial compressive strength is 73.2 ± 16.5 MPa. The Brazilian tensile strength is 5.12 ± 1.2 MPa. The Young's modulus and Poisson's ratio are 22.6 ± 5.7 GPa and 0.20 ± 0.03. Smoothness and perpendicularity do not fully meet the ASTM requirements for all samples, due to the presence of voids and inclusions on the sample surfaces and the sample preparation methods. The investigations of loading rate, L/D radio and cyclic loading effects on the compressive strength and of the size effect on the tensile strength are not conclusive. The Coulomb strength criterion adequately represents the failure envelope of the tuff under confining pressures from 0 to 62 MPa. Cohesion and internal friction angle are 16 MPa and 43 degrees. The brown unit of the Apache Leap tuff is highly heterogeneous as suggested by large variations of the test results. The high intrinsic variability of the tuff is probably caused by the presence of flow layers and by nonuniform distributions of inclusions, voids and degree of welding. Similar variability of the properties has been found in publications on the Topopah Spring tuff at Yucca Mountain. 57 refs., 32 figs., 29 tabs

  15. Mechanical properties of 5083 aluminium welds after manual and automatic pulsed gas metal arc welding using E5356 filler

    CSIR Research Space (South Africa)

    Mutombo, K

    2010-01-01

    Full Text Available Semi-automatic and automatic pulsed gas metal arc welding (GMAW) of aluminium alloy 5083 with ER5356 filler wire causes considerable softening in the weld. The tensile strength of dressed automatic welds approaches that of the base metal...

  16. Microstructure and mechanical properties of friction stir welded 18Cr–2Mo ferritic stainless steel thick plate

    International Nuclear Information System (INIS)

    Han, Jian; Li, Huijun; Zhu, Zhixiong; Barbaro, Frank; Jiang, Laizhu; Xu, Haigang; Ma, Li

    2014-01-01

    Highlights: • We focus on friction stir welding of 18Cr–2Mo ferritic stainless steel thick plate. • We produce high-quality joints with special tool and optimised welding parameters. • We compare microstructure and mechanical properties of steel and joint. • Friction stir welding is a method that can maintain the properties of joint. - Abstract: In this study, microstructure and mechanical properties of a friction stir welded 18Cr–2Mo ferritic stainless steel thick plate were investigated. The 5.4 mm thick plates with excellent properties were welded at a constant rotational speed and a changeable welding speed using a composite tool featuring a chosen volume fraction of cubic boron nitride (cBN) in a W–Re matrix. The high-quality welds were successfully produced with optimised welding parameters, and studied by means of optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and standard hardness and impact toughness testing. The results show that microstructure and mechanical properties of the joints are affected greatly, which is mainly related to the remarkably fine-grained microstructure of equiaxed ferrite that is observed in the friction stir welded joint. Meanwhile, the ratios of low-angle grain boundary in the stir zone regions significantly increase, and the texture turns strong. Compared with the base material, mechanical properties of the joint are maintained in a comparatively high level

  17. Effect of Activated Flux on the Microstructure, Mechanical Properties, and Residual Stresses of Modified 9Cr-1Mo Steel Weld Joints

    Science.gov (United States)

    Maduraimuthu, V.; Vasudevan, M.; Muthupandi, V.; Bhaduri, A. K.; Jayakumar, T.

    2012-02-01

    A novel variant of tungsten inert gas (TIG) welding called activated-TIG (A-TIG) welding, which uses a thin layer of activated flux coating applied on the joint area prior to welding, is known to enhance the depth of penetration during autogenous TIG welding and overcomes the limitation associated with TIG welding of modified 9Cr-1Mo steels. Therefore, it is necessary to develop a specific activated flux for enhancing the depth of penetration during autogeneous TIG welding of modified 9Cr-1Mo steel. In the current work, activated flux composition is optimized to achieve 6 mm depth of penetration in single-pass TIG welding at minimum heat input possible. Then square butt weld joints are made for 6-mm-thick and 10-mm-thick plates using the optimized flux. The effect of flux on the microstructure, mechanical properties, and residual stresses of the A-TIG weld joint is studied by comparing it with that of the weld joints made by conventional multipass TIG welding process using matching filler wire. Welded microstructure in the A-TIG weld joint is coarser because of the higher peak temperature in A-TIG welding process compared with that of multipass TIG weld joint made by a conventional TIG welding process. Transverse strength properties of the modified 9Cr-1Mo steel weld produced by A-TIG welding exceeded the minimum specified strength values of the base materials. The average toughness values of A-TIG weld joints are lower compared with that of the base metal and multipass weld joints due to the presence of δ-ferrite and inclusions in the weld metal caused by the flux. Compressive residual stresses are observed in the fusion zone of A-TIG weld joint, whereas tensile residual stresses are observed in the multipass TIG weld joint.

  18. Fabrication history and mechanical properties for ASTM A-533 Grade-B Class-2 steel weld for fully welded nuclear pressure vessels

    International Nuclear Information System (INIS)

    Pachur, D.

    1979-01-01

    Till now pressure vessels for light water reactors were made from rolled plates and forgings connected with each other by welding. The optimal quality of plates and forgings are limited in principle by the foundry technology. It is well known that in this process decomposition and segregation zones occur. Besides the heat affected zone created by the welding process is a weak link. The heat affected zone is heterogeneous and can be harbinger of risks leading to cracks. The production of a pressure vessel through shape welding is an alternative. The cylindrical container is produced by the application of one layer of welding after the other in a preshaped form. During the welding process the previously applied layers are simultaneously being tempered. The undesirable chemical residual elements are evenly distributed and segregation zones do not occur. Since we have only welding material the disadvantages of a heat affected zone are avoided. Furthermore the mechanical properties are independent of location and orientation. This shape welding process proved to be highly economical already during the experimental stay. Besides this process is applicable for vessel of any desired dimension

  19. Optimization of Thermo-mechanical Conditions in Friction Stir Welding

    DEFF Research Database (Denmark)

    Tutum, Cem Celal

    with the Seqquential Quadratic Programming (SQP) gradient-based optimization algorithm in order to find the welding speed and the heat input that would yield a prescribed average temperature close to the solidus temperature under the tool, thereby expressing a condition which is favourable for the process.......Several models for the FSW process have been applied. Initially, the thermal models were addressed since they in essence constitute the basis of all other models of FSW, be it microstructural, flow or residual stress models. Both analytical and numerical models were used and combined...

  20. Effect of the Addition of Nickel Powder and Post Weld Heat Treatment on the Metallurgical and Mechanical Properties of the Welded UNS S32304 Duplex Stainless Steel

    Directory of Open Access Journals (Sweden)

    Ali Tahaei

    Full Text Available Abstract In this research, the effect of the addition of nickel powder and the application of a post weld heat treatment (PWHT on the welding properties of the UNS S32304 lean duplex stainless steel were investigated in order to improve the microstructure and mechanical properties. Nickel powder was directly poured inside the joint gap and mixed with the filler metal during the Gas Tungsten Arc Welding (GTAW process; moreover, the solution heat treatment was performed at 1100 °C for 10 min. The joints were characterized by optical microscopy (OM and the evolution of the phase percentages in the different zones was studied by means of the image analysis technique. Tensile and hardness tests were carried out on the joints in order to evaluate the improvement of the mechanical properties. The results showed that both the addition of nickel powder during the welding process and the post weld heat treatment made it possible to improve the mechanical properties of the weld joints. PWHT had the best effect in restoring the equal percentage of ferrite and austenite compared to the addition of nickel powder.

  1. Micro–macro-characterisation and modelling of mechanical properties of gas metal arc welded (GMAW) DP600 steel

    Energy Technology Data Exchange (ETDEWEB)

    Ramazani, A., E-mail: ali.ramazani@iehk.rwth-aachen.de [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Mukherjee, K. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Abdurakhmanov, A. [Welding and Joining Institute, RWTH Aachen University, D-52072 Aachen (Germany); Prahl, U. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany); Schleser, M.; Reisgen, U. [Welding and Joining Institute, RWTH Aachen University, D-52072 Aachen (Germany); Bleck, W. [Department of Ferrous Metallurgy, RWTH Aachen University, D-52072 Aachen (Germany)

    2014-01-01

    Dual-phase (DP) steels show combined high strength and adequate formability. However, during welding, their microstructural feature of dispersion of hard martensite islands in the soft ferrite matrix is lost and the properties deteriorate. The current research aims to study the mechanical properties of the welded joint, taking into account the effect of features of all regions, such as microstructure, chemical composition and the area fraction, on the macroscopic mechanical properties of the welded joint. Hot rolled DP 600 steel was gas metal arc welded (GMAW) and tensile specimens were made with a welded joint. In the heat-affected zone (HAZ), the microstructure varied from bainite to coarse grained ferrite and tempered martensite. Chemical composition of every quantified region in the welded specimen was also identified using electron probe microanalysis (EPMA). Macromechanical FE modelling was employed to simulate the mechanical properties of the welded tensile specimen. 2D representative volume elements (RVE) for different parts of the welded region were constructed from real microstructure. 2D simulated flow curves were corrected to 3Ds using a developed correlation factor. Finally, the tensile test of welded material with inhomogeneous morphology was simulated and good agreement between experimental and predicted flow curve was achieved.

  2. Micro–macro-characterisation and modelling of mechanical properties of gas metal arc welded (GMAW) DP600 steel

    International Nuclear Information System (INIS)

    Ramazani, A.; Mukherjee, K.; Abdurakhmanov, A.; Prahl, U.; Schleser, M.; Reisgen, U.; Bleck, W.

    2014-01-01

    Dual-phase (DP) steels show combined high strength and adequate formability. However, during welding, their microstructural feature of dispersion of hard martensite islands in the soft ferrite matrix is lost and the properties deteriorate. The current research aims to study the mechanical properties of the welded joint, taking into account the effect of features of all regions, such as microstructure, chemical composition and the area fraction, on the macroscopic mechanical properties of the welded joint. Hot rolled DP 600 steel was gas metal arc welded (GMAW) and tensile specimens were made with a welded joint. In the heat-affected zone (HAZ), the microstructure varied from bainite to coarse grained ferrite and tempered martensite. Chemical composition of every quantified region in the welded specimen was also identified using electron probe microanalysis (EPMA). Macromechanical FE modelling was employed to simulate the mechanical properties of the welded tensile specimen. 2D representative volume elements (RVE) for different parts of the welded region were constructed from real microstructure. 2D simulated flow curves were corrected to 3Ds using a developed correlation factor. Finally, the tensile test of welded material with inhomogeneous morphology was simulated and good agreement between experimental and predicted flow curve was achieved

  3. Germ line mechanics – and unfinished business

    Science.gov (United States)

    Wessel, Gary M.

    2016-01-01

    Primordial germ cells are usually made early in the development of an organism. These are the mother of all stem cells that are necessary for propagation of the species, yet use highly diverse mechanisms between organisms. How they are specified, and when and where they form, are central to developmental biology. Using diverse organisms to study this development is illuminating for understanding the mechanics these cells use in this essential function, and for identifying the breadth of evolutionary changes that have occurred between species. This essay emphasizes how echinoderms may contribute to the patch-work quilt of our understanding of germ line formation during embryogenesis. PMID:26970000

  4. Evaluation of the TIG welding mechanical behavior in AISI 316 tubes for fuel rods

    International Nuclear Information System (INIS)

    Bittencourt, M.S.Q.; Carvalho Perdigao, S. de

    1985-10-01

    The effect of service temperature, the mechanical resistance and the creep behaviour of a steel which is intendend to be used as fuel rods in Nuclear Reactors was investigated. The tests were performed in seamless tubes of austenitic stainless steel, AISI 316, 20% cold worked, TIG welded. (Author) [pt

  5. General Mechanical Repair. Minor Automotive Maintenance, Small Engine [Repair, and] Welding: Curriculum Guide and Lesson Plans.

    Science.gov (United States)

    Hamlin, Larry

    This document contains a curriculum guide and lesson plans for a general mechanical repair course with three sections: minor automotive maintenance, small engine repair, and welding. The curriculum guide begins with a matrix that relates the lesson plans to essential elements of math, science, language arts, and social studies and to Texas…

  6. Microstructural characterizations and mechanical properties in underwater friction stir welding of aluminum and magnesium dissimilar alloys

    International Nuclear Information System (INIS)

    Zhao, Yong; Lu, Zhengping; Yan, Keng; Huang, Linzhao

    2015-01-01

    Highlights: • Aluminum and magnesium alloys were joined by underwater friction stir welding. • Underwater FSW was conducted to improve properties of joint with lower heat input. • Microstructures and mechanical properties of dissimilar joint were investigated. • Intermetallic compounds developed in the fracture interface were analyzed. • Fracture features of the tensile samples were analyzed. - Abstract: Formation of intermetallic compounds in the stir zone of dissimilar welds affects the mechanical properties of the joints significantly. In order to reduce heat input and control the amount and morphological characteristics of brittle intermetallic compounds underwater friction stir welding of 6013 Al alloy and AZ31 Mg alloy was carried out. Microstructures, mechanical properties, elements distribution, and the fracture surface of the joints were analyzed by optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, etc. The result shows that sound dissimilar joint with good mechanical properties can be obtained by underwater friction stir welding. Al and Mg alloys were stirred together and undergone the process of recrystallization, forming complex intercalated flow patterns in the stir zone. Tensile strength of the dissimilar joint was up to 152.3 MPa. Maximum hardness (142HV) appeared in the middle of the centerline of the specimen. Intermetallic compounds layer consisting of Al 3 Mg 2 and Mg 17 Al 12 formed in the Al/Mg interface and resulted in the fracture of the joint

  7. The Preceding Voltage Pulse and Separation Welding Mechanism of Electrical Contacts

    DEFF Research Database (Denmark)

    Yang, Xiao Cheng; Huang, Jiang; Li, Zhen Biao

    2016-01-01

    In order to obtain a better understanding of the welding mechanism in contact separation, electrical endurance tests were conducted with AgSnO2 and AgNi contacts on a simulation test device. Waveforms of contact displacement, contact voltage, and current were recorded with LabVIEW during the tests......, and changes in a contact gap and heights of pips with increases in operation cycles were observed through charge-coupled device cameras. The resultant test results show that welding in separation is accompanied with a preceding voltage pulse which represents arc rather than contact bounce arc....

  8. Effect of heat input on the microstructure and mechanical properties of gas tungsten arc welded AISI 304 stainless steel joints

    International Nuclear Information System (INIS)

    Kumar, Subodh; Shahi, A.S.

    2011-01-01

    Highlights: → Welding procedure is established for welding 6 mm thick AISI 304 using GTAW process. → Mechanical properties of the weld joints are influenced strongly by the heat input. → Highest tensile strength of 657.32 MPa is achieved by joints using low heat input. → Welding parameters affect heat input and hence microstructure of weld joints. → Extent of grain coarsening in the HAZ increases with increase in the heat input. -- Abstract: Influence of heat input on the microstructure and mechanical properties of gas tungsten arc welded 304 stainless steel (SS) joints was studied. Three heat input combinations designated as low heat (2.563 kJ/mm), medium heat (2.784 kJ/mm) and high heat (3.017 kJ/mm) were selected from the operating window of the gas tungsten arc welding process (GTAW) and weld joints made using these combinations were subjected to microstructural evaluations and tensile testing so as to analyze the effect of thermal arc energy on the microstructure and mechanical properties of these joints. The results of this investigation indicate that the joints made using low heat input exhibited higher ultimate tensile strength (UTS) than those welded with medium and high heat input. Significant grain coarsening was observed in the heat affected zone (HAZ) of all the joints and it was found that the extent of grain coarsening in the heat affected zone increased with increase in the heat input. For the joints investigated in this study it was also found that average dendrite length and inter-dendritic spacing in the weld zone increases with increase in the heat input which is the main reason for the observable changes in the tensile properties of the weld joints welded with different arc energy inputs.

  9. 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

  10. A mechanism for the formation of equiaxed grains in welds of aluminum-lithium alloy 2090

    International Nuclear Information System (INIS)

    Lin, D.C.; Wang, G.-X.; Srivatsan, T.S.

    2003-01-01

    In this technical note, the formation and presence of a zone of equiaxed grains (EQZ) along the fusion boundary of welded aluminum-lithium alloy 2090 using filler metals containing zirconium and lithium is presented and discussed. However, no EQZ was evident in welded joints of alloy 2090 using the commercial filler metals: aluminum alloy 2319 and 4145. Under identical conditions, aluminum-lithium alloy 2090 was fusion welded using several new filler metals containing various amounts of zirconium and lithium. Results reveal an increase in the width of the zone of equiaxed grains with an increase in zirconium and lithium content in the filler metal. A viable mechanism for the formation of equiaxed grains and its relationship to filler metal composition is highlighted

  11. Microstructure and anisotropic mechanical behavior of friction stir welded AA2024 alloy sheets

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhihan [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Li, Wenya, E-mail: liwy@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Li, Jinglong [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Chao, Y.J. [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Vairis, A. [Mechanical Engineering Department, TEI of Crete, Heraklion, Crete 71004 (Greece)

    2015-09-15

    The anisotropic mechanical properties of friction stir welded (FSW) AA2024-T3 alloy joints were investigated based on the uniaxial tensile tests. The joint microstructure was examined by using electron back-scattered diffraction and transmission electron microscope. Results show that the evident anisotropic failure and yielding are present in the FSW joints. With the increase of loading angle from 0° to 90° the ultimate tensile strength and elongation of the specimens consistently decrease, or at first decrease and then increase, depending on the FSW process parameters. The specimen cut from the weld direction, i.e. a loading angle of 0°, exhibits the highest strength and elongation. - Highlights: • Microstructure and anisotropy of friction stir welded joints were studied. • The evident anisotropic failure and yielding are present in joints. • The lowest yield stress and UTS are at 45° and 60° loadings, respectively. • Rotation speed heavily impact on the anisotropy of joints.

  12. Microstructure and anisotropic mechanical behavior of friction stir welded AA2024 alloy sheets

    International Nuclear Information System (INIS)

    Zhang, Zhihan; Li, Wenya; Li, Jinglong; Chao, Y.J.; Vairis, A.

    2015-01-01

    The anisotropic mechanical properties of friction stir welded (FSW) AA2024-T3 alloy joints were investigated based on the uniaxial tensile tests. The joint microstructure was examined by using electron back-scattered diffraction and transmission electron microscope. Results show that the evident anisotropic failure and yielding are present in the FSW joints. With the increase of loading angle from 0° to 90° the ultimate tensile strength and elongation of the specimens consistently decrease, or at first decrease and then increase, depending on the FSW process parameters. The specimen cut from the weld direction, i.e. a loading angle of 0°, exhibits the highest strength and elongation. - Highlights: • Microstructure and anisotropy of friction stir welded joints were studied. • The evident anisotropic failure and yielding are present in joints. • The lowest yield stress and UTS are at 45° and 60° loadings, respectively. • Rotation speed heavily impact on the anisotropy of joints

  13. Identification of mechanical properties of weld joints of AlMgSi07.F25 aluminium alloy

    Directory of Open Access Journals (Sweden)

    P. Kopas

    2017-01-01

    Full Text Available The aim of this paper is to present the analysis of selected mechanical properties of weld joints of AlMgSi07.F25 aluminium alloy. We will focus on the influence of the test bar neck shape on the tensile strength characteristics and the course of hardness in the weld joint cross-section. For the welding process using TIG (Tungsten Inert Gas technology we considered AlSi5 as the additive material. This paper also includes a short study of numerical modelling of the test bar welding.

  14. Effect of gaussian beam on microstructural and mechanical properties of dissimilarlaser welding ofAA5083 and AA6061 alloys

    Science.gov (United States)

    Srinivas, B.; Cheepu, Muralimohan; Sivaprasad, K.; Muthupandi, V.

    2018-03-01

    The present study focuses on a sheet thickness of 4 mm using different laser power and welding rate by the laser beam welding (LBW) at a beam size180 μm. The observations on the weldments are showing that thermal conductivity of the materials plays a major role on microstructural changes. The as-welded mechanical properties were studied by correlation with its microstructures. Due to the steeper temperature gradient during the laser beam welding AA6061 was showing the greater variation compares with AA5083 side in the micro hardness studies.Also, the tensile strength of 241 MPa has been reported as highest with the welds made of laser powerat 3.5 kW and welding rate at 3.5 mmin-1.

  15. Effect of Manganese on the Mechanical Properties of Welded As-Cast Aluminium Joint

    Directory of Open Access Journals (Sweden)

    Isiaka Oluwole OLADELE

    2013-11-01

    Full Text Available The effects of manganese on the mechanical properties of welded and un-weld as-cast 6063 aluminium alloy has been studied. Alloys of varying percentage of manganese from 0.019 to 0.24 were sand cast. A wooden pattern of dimensions 200×100×100mm was used, the aluminium (500g was charged into an induction furnace and heated to 750°C for 15 minutes, this was followed by the addition of weighed powdered manganese, stirred and heated at the same temperature for another 5 minutes and thereafter poured into the already prepared sand mould at a temperature of 690°C. The as-cast aluminium samples, were sectioned into two equal parts of 45mm each using power hack saw; a weld groove was created between the sides of the samples using an electric hand grinding machine, the groove served as the path along which the filler metal was deposited on the aluminium, a single v butt joint was produced from each sample and Metal Inert Gas Welding process was carried out to produce the required joint design. The different cast samples were machined to the different test pieces after which they were assessed to determine their mechanical properties (impact, hardness (welded joint and heat affected zone and tensile tests. The microstructures of the welded samples were also studied. From the results, it was observed that Sample F, which has 0.172% Mn, has the best hardness and impact strength while sample C with 0.160% Mn has the highest ultimate tensile strength.

  16. Local microstructures, Hardness and mechanical properties of a stainless steel pipe-welded joint

    International Nuclear Information System (INIS)

    Zhao Yongxiang; Gao Qing; Cai Lixun

    2000-01-01

    An experimental investigation is carefully performed into the local microstructures, hardness values and monotonic mechanical properties of the three zones (the base metal, heat affecting zone and weld metal) of 1Cr18Ni9Ti stainless steel pipe-welded joint. The local microstructures are observed by a metallurgical test and a surface replica technology, the local hardness values are measures by a random Vickers hardness test, and the local mechanical properties are characterized by the Ramberg-Osgood and modified Ramberg-Osgood stress-stain relations. The investigation reveals that there are significant differences of the three zones in the local microstructures, hardness values and monotonic mechanical properties, especially of the three zones in the local microstructure, hardness values and monotonic mechanical properties, especially of the weld metal. The weld metal exhibits the largest heterogeneity of local microstructures and monotonic mechanical properties, and the largest scatter of local hardness values. It is necessary to consider these difference and introduce the reliability method to model the scatter in the pipe analysis. In addition, it is verified that a columnar grain structure, which is made up of matrix-rich δ ferrite bands, can characterize the weld metal and the distance between the neighboring rich δ ferrite bands is an appropriate measurement of the columnar grain structure. This measurement is in accordance with the transition point between the microstructural short crack and physical small crack stages, which are generally used for characterizing the short fatigue crack behavior of materials. This indicates that the microstructure controls the fatigue damage character of the present material

  17. Metallurgy and mechanical properties variation with heat input,during dissimilar metal welding between stainless and carbon steel

    Science.gov (United States)

    Ramdan, RD; Koswara, AL; Surasno; Wirawan, R.; Faturohman, F.; Widyanto, B.; Suratman, R.

    2018-02-01

    The present research focus on the metallurgy and mechanical aspect of dissimilar metal welding.One of the common parameters that significantly contribute to the metallurgical aspect on the metal during welding is heat input. Regarding this point, in the present research, voltage, current and the welding speed has been varied in order to observe the effect of heat input on the metallurgical and mechanical aspect of both welded metals. Welding was conducted by Gas Metal Arc Welding (GMAW) on stainless and carbon steel with filler metal of ER 309. After welding, hardness test (micro-Vickers), tensile test, macro and micro-structure characterization and Energy Dispersive Spectroscopy (EDS) characterization were performed. It was observed no brittle martensite observed at HAZ of carbon steel, whereas sensitization was observed at the HAZ of stainless steel for all heat input variation at the present research. Generally, both HAZ at carbon steel and stainless steel did not affect tensile test result, however the formation of chromium carbide at the grain boundary of HAZ structure (sensitization) of stainless steel, indicate that better process and control of welding is required for dissimilar metal welding, especially to overcome this issue.

  18. Implementation of an Outer Can Welding System for Savannah River Site FB-Line

    International Nuclear Information System (INIS)

    Howard, S.R.

    2003-01-01

    This paper details three phases of testing to confirm use of a Gas Tungsten Arc (GTA) system for closure welding the 3013 outer container used for stabilization/storage of plutonium metals and oxides. The outer container/lid closure joint was originally designed for laser welding, but for this application, the gas tungsten arc (GTA) welding process has been adapted. The testing progressed in three phases: (1) system checkout to evaluate system components for operational readiness, (2) troubleshooting to evaluate high weld failure rates and develop corrective techniques, and (3) pre-installation acceptance testing

  19. High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

    Science.gov (United States)

    Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri; Field, David P.

    2018-01-01

    Friction stir welding (FSW) is a cost-effective and high-quality joining process for aluminum alloys (especially heat-treatable alloys) that is historically operated at lower joining speeds (up to hundreds of millimeters per minute). In this study, we present a microstructural analysis of friction stir welded AA7075-T6 blanks with high welding speeds up to 3 M/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. The higher welding speed results in narrower, stronger heat-affected zones (HAZs) and also higher hardness in the nugget zones. The material flow direction in the nugget zone is found to be leaning towards the welding direction as the welding speed increases. Results are coupled with welding parameters and thermal history to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high-speed processing.

  20. Thermo-Mechanical Calculations of Hybrid Rotary Friction Welding at Equal Diameter Copper Bars and Effects of Essential Parameters on Dependent Special Variables

    International Nuclear Information System (INIS)

    Parsa, M. H.; Davari, H.; Hadian, A. M.; Ahmadabadi, M. Nili

    2007-01-01

    Hybrid Rotary Friction Welding is a modified type of common rotary friction welding processes. In this welding method parameters such as pressure, angular velocity and time of welding control temperature, stress, strain and their variations. These dependent factors play an important rule in defining optimum process parameters combinations in order to improve the design and manufacturing of welding machines and quality of welded parts. Thermo-mechanical simulation of friction welding has been carried out and it has been shown that, simulation is an important tool for prediction of generated heat and strain at the weld interface and can be used for prediction of microstructure and evaluation of quality of welds. For simulation of Hybrid Rotary Friction Welding, a commercial finite element program has been used and the effects of pressure and rotary velocity of rotary part on temperature and strain variations have been investigated

  1. Thermo-Mechanical Calculations of Hybrid Rotary Friction Welding at Equal Diameter Copper Bars and Effects of Essential Parameters on Dependent Special Variables

    Science.gov (United States)

    Parsa, M. H.; Davari, H.; Hadian, A. M.; Ahmadabadi, M. Nili

    2007-05-01

    Hybrid Rotary Friction Welding is a modified type of common rotary friction welding processes. In this welding method parameters such as pressure, angular velocity and time of welding control temperature, stress, strain and their variations. These dependent factors play an important rule in defining optimum process parameters combinations in order to improve the design and manufacturing of welding machines and quality of welded parts. Thermo-mechanical simulation of friction welding has been carried out and it has been shown that, simulation is an important tool for prediction of generated heat and strain at the weld interface and can be used for prediction of microstructure and evaluation of quality of welds. For simulation of Hybrid Rotary Friction Welding, a commercial finite element program has been used and the effects of pressure and rotary velocity of rotary part on temperature and strain variations have been investigated.

  2. Performance prediction of mechanical excavators from linear cutter tests on Yucca Mountain welded tuffs

    International Nuclear Information System (INIS)

    Gertsch, R.; Ozdemir, L.

    1992-09-01

    The performances of mechanical excavators are predicted for excavations in welded tuff. Emphasis is given to tunnel boring machine evaluations based on linear cutting machine test data obtained on samples of Topopah Spring welded tuff. The tests involve measurement of forces as cutters are applied to the rock surface at certain spacing and penetrations. Two disc and two point-attack cutters representing currently available technology are thus evaluated. The performance predictions based on these direct experimental measurements are believed to be more accurate than any previous values for mechanical excavation of welded tuff. The calculations of performance are predicated on minimizing the amount of energy required to excavate the welded tuff. Specific energy decreases with increasing spacing and penetration, and reaches its lowest at the widest spacing and deepest penetration used in this test program. Using the force, spacing, and penetration data from this experimental program, the thrust, torque, power, and rate of penetration are calculated for several types of mechanical excavators. The results of this study show that the candidate excavators will require higher torque and power than heretofore estimated

  3. Microstructural and Mechanical Characterization of Electron Beam Welded Joints of High Strength S960QL and Weldox 1300 Steel Grades

    Directory of Open Access Journals (Sweden)

    Błacha S.

    2017-06-01

    Full Text Available The paper shows the results of metallographic examination and mechanical properties of electron beam welded joints of quenched and tempered S960QL and Weldox 1300 steel grades. The aim of this study was to examine the feasibility of producing good quality electron beam welded joints without filler material.

  4. Material development for waste to energy plants. Overlay welding and refractory linings. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Noergaard Hansson, A.

    2011-02-15

    Waste is an extremely corrosive fuel. In order to recover a higher percentage of the energy in waste, waste incineration plants have developed from purely heat producing units to heat and power producing units. The change in concept results in higher material temperatures and thereby faster material degradation. As a result material failures have been observed in many waste incineration plants. The purpose of this project was to develop materials with higher resistance to the corrosive elements, in order to reduce the cost of maintenance, increase the availability, and increase the efficiency. The focus is on overlay welding and refractory linings. Inconel 625, alloy 50, alloy 686, and Super 625 offer equivalent corrosion protection at panel walls. 100% overlay performs better than 50% overlay. The corrosion morphology changes with increasing temperature from pitting and general corrosion to pitting and selective corrosion (dendritic core or grain boundaries). The previously observed detrimental effect of Fe on the corrosion resistance was not confirmed. It probably depends on factors such as microstructure of the alloy and local metal temperature. Ni-overlay also reduces the corrosion rates on superheater tubes. However, the superheater environment is less aggressive than the water wall environment. Failure of refractory linings is linked to excess porosity, detrimental reactions between raw materials and other mix constituents, volume growth reactions between base material and salt depositions, and thermal stress induced crack formation. Free water and not decomposition of hydrates causes spalling and cracking during the initial heating of refractory linings. Finite Element analysis confirms the stress levels between steel and refractory with the higher stress level at the top of the panel wall tube. A number of LCC mixes were formulated, adjusted and tested. Mixes with low open porosities ({approx} 10%) and state of the art resistance to KCl were achieved. (LN)

  5. Welding mechanization in shipyard CIM; Zosen ni okeru yosetsu no jidoka robot ka CIM ka

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, T. [Hitachi Zosen Corp., Osaka (Japan)

    1997-12-01

    This paper explains development and examples of application of automated welding devices from a viewpoint of an element technology constituting computer integrated manufacturing (CIM), based on the history of modernization of shipyards that has been achieved to date. In the first step of promoting the modernization, elevating cutting accuracy in the uppermost stream process was thought a starting point of rationalization. What have been achieved therefrom are adoption of the most advanced NC plasma cutting machine, and improvement in the computer aided system for the cutting machines. In addition, a twenty-electrode line welder has been developed, which does not create angle deformation in welding longerons, and can be operated even by unskilled workers. The welder has successfully realized a construction method in which robots can be applied more easily. Further developments have been made on a robot to weld cells, advanced CAD/CAM operation techniques which are linked with data from design, an automatic one-side welding device which can achieve a speed 2.5 times greater than by conventional devices, and an automation device for three-dimensionally bent blocks, whose automation has been regarded difficult. 11 figs., 1 tab.

  6. Mechanical Behaviour of Inconel 718 Thin-Walled Laser Welded Components for Aircraft Engines

    Directory of Open Access Journals (Sweden)

    Enrico Lertora

    2014-01-01

    Full Text Available Nickel alloys are very important in many aerospace applications, especially to manufacture gas turbines and aero engine components, where high strength and temperature resistance are necessary. These kinds of alloys have to be welded with high energy density processes, in order to preserve their high mechanical properties. In this work, CO2 laser overlap joints between Inconel 718 sheets of limited thickness in the absence of postweld heat treatment were made. The main application of this kind of joint is the manufacturing of a helicopter engine component. In particular the aim was to obtain a specific cross section geometry, necessary to overcome the mechanical stresses found in these working conditions without failure. Static and dynamic tests were performed to assess the welds and the parent material fatigue life behaviour. Furthermore, the life trend was identified. This research pointed out that a full joint shape control is possible by choosing proper welding parameters and that the laser beam process allows the maintenance of high tensile strength and ductility of Inconel 718 but caused many liquation microcracks in the heat affected zone (HAZ. In spite of these microcracks, the fatigue behaviour of the overlap welds complies with the technical specifications required by the application.

  7. Joining mechanism of Ti/Al dissimilar alloys during laser welding-brazing process

    International Nuclear Information System (INIS)

    Chen Shuhai; Li Liqun; Chen Yanbin; Huang Jihua

    2011-01-01

    Research highlights: → The microstructures of interfacial zones were confirmed in detail by transmission electron microscope (TEM). Interfacial reaction layers of brazing joint were composed of α-Ti, nanosize granular Ti 7 Al 5 Si 12 and serration-shaped TiAl 3 . For the first time, obvious stacking fault structure in intermetallic phase TiAl 3 was found when the thickness of the reaction layer was very thin (approximately below 1 μm). → Metallurgical characteristics for laser welding-brazing process in the environment of far from equilibrium was expounded by microstructures of the joints, the characteristics of thermal process and element diffusion behavior. - Abstract: Joining mechanism of Ti/Al dissimilar alloys was investigated during laser welding-brazing process with automated wire feed. The microstructures of fusion welding and brazing zones were analysed in details by transmission electron microscope (TEM). It was found that microstructures of fusion welding zone consist of α-Al grains and ternary near-eutectic structure with α-Al, Si and Mg 2 Si. Interfacial reaction layers of brazing joint were composed of α-Ti, nanosize granular Ti 7 Al 5 Si 12 and serration-shaped TiAl 3 . For the first time, apparent stacking fault structure in intermetallic phase TiAl 3 was found when the thickness of the reaction layer was very thin (approximately less than 1 μm). Furthermore, crystallization behavior of fusion zone and mechanism of interfacial reaction were discussed in details.

  8. Microstructure and mechanical properties of friction stir welded 9Cr ODS steel

    International Nuclear Information System (INIS)

    Min, Hyoung Kee; Kang, Suk Hoon; Noh, Sanghoon; Lee, Jung Gu; Jang, Jinsung; Kim, Tae Kyu

    2013-01-01

    It is well known that the welding of ODS steel with a conventional melting.solidification process is not adequate to reserve nano-oxide particles in the matrix homogeneously. To reserve nano-oxide particles in the matrix homogeneously, friction stir welding (FSW) is the most promising technique to join ODS alloys. In this study, the effects of FSW on the microstructure and mechanical properties of a ODS steel were studied to apply the FSW process to 9Cr ODS steels. Microstructures were observed by means of optical microscopy, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). A tensile test and hardness test were carried out to the investigate mechanical properties. FSW could successfully produce defect-free welds on ODS plates. FSW produced a fine grain structure consisting of ferrite and martensite. Tensile strengths and elongations of the SZs were excellent at 298 K, compared to those of the BM. This study suggests that FSW might be an appropriate welding method of ODS steels. Oxide dispersion strengthened (ODS) ferritic-martensitic (FM) steel containing 9 wt%Cr is a promising candidate material for high temperature components operating in aggressive environments such as nuclear fusion and fission systems because of the excellent elevated temperature strength, corrosion and radiation resistance. These characteristics come from microstructures consisting of fine grains and nano-oxide particles dispersed in high number density. However, for more applications of ODS steel in nuclear systems, its weldability is the one of the barrier to be solved

  9. Influence of M-TIG and A-TIG Welding Process on Microstructure and Mechanical Behavior of 409 Ferritic Stainless Steel

    Science.gov (United States)

    Vidyarthy, R. S.; Dwivedi, D. K.; Vasudevan, M.

    2017-03-01

    The current study investigates the effects of activating flux tungsten inert gas welding (A-TIG) and multipass tungsten inert gas welding (M-TIG) on the weld morphology, angular distortion, microstructures and mechanical properties when welding 8-mm-thick 409 ferritic stainless steel (FSS). SiO2 was used as activating flux for A-TIG welding, while SUPERTIG ER309L was used as filler for M-TIG welding. Bead-on-plate weld trials were carried out to obtain the full penetration by using different combinations of flux coating density, welding speed and welding current. An optical microscope, field emission scanning microscope (FESEM), and x-ray diffractometer were used for the metallurgical characterizations. Vickers hardness, tensile test, Charpy toughness test, and creep behavior test were carried out to evaluate the mechanical properties of the base and weld metals. Experimental results indicate that the A-TIG process can increase the joint penetration and tends to reduce the angular distortion of the 409 FSS weldment. The A-TIG welded joint also exhibited greater mechanical strength. However, a critically low Charpy toughness was measured for the A-TIG weld fusion zone, which was later sufficiently improved after post weld heat treatment (PWHT). It was concluded that PWHT is mandatory for A-TIG welded 409 FSS.

  10. Welding lines formation in holes obtained by low pressure injection molding of ceramic parts

    Directory of Open Access Journals (Sweden)

    C. A. Costa

    Full Text Available Abstract This work presents a study to evaluate the process of producing internal holes in ceramic disks produced by low pressure injection molding (LPIM process. Two process conditions defined as pre-injection and post-injection were used to test the proposition. In the first one the pin cores that produce the holes were positioned in the cavity before the injection of the feedstock; and in the second one, the pin cores were positioned in the cavity, just after the feeding phase of the injection mold. An experimental injection mold designed and manufactured to test both processes was developed to produce ceramic disk with Ø 50 x 2 mm with four holes of Ø 5 mm, equally and radially distributed through the disk. The feedstock was composed of 86 wt% alumina (Al2O3 and 14 wt% organic vehicle based on paraffin wax. Heating and cooling systems controlled by a data acquisition system were included in the mold. The results showed that there were no welding lines with the post-injection process, proving to be an option for creating holes in the ceramic parts produced by LPIM. It was observed that best results were obtained at 58 °C mold temperature. The pins extraction temperature was about 45 °C, and the injection pressure was 170 kPa.

  11. Optimization in Friction Stir Welding - With Emphasis on Thermo-mechanical Aspects

    DEFF Research Database (Denmark)

    Tutum, Cem Celal

    combined with classical single-objective and evolutionary multi-objective optimization algorithms (i.e. SQP and NSGA-II), to find the optimum process parameters (heat input, rotational and traverse welding speeds) that would result in favorable thermo-mechanical conditions for the process.......This book deals with the challenging multidisciplinary task of combining variant thermal and thermo-mechanical simulations for the manufacturing process of friction stir welding (FSW) with numerical optimization techniques in the search for optimal process parameters. The FSW process...... is characterized by multiphysics involving solid material flow, heat transfer, thermal softening, recrystallization and the formation of residual stresses. Initially, the thermal models were addressed since they in essence constitute the basis of all other models of FSW. Following this, several integrated thermo-mechanical...

  12. 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.

  13. Influence of the welding temperature and the welding speed on the mechanical properties of friction stir welds in EN AW-2219-T87

    Science.gov (United States)

    Bachmann, A.; Krutzlinger, M.; Zaeh, M. F.

    2018-06-01

    Friction Stir Welding (FSW) is an innovative joining technique, which has proven to produce high quality joints in high strength aluminum alloys. Consequently, it is commonly used to manufacture lightweight aerospace structures with stringent requirements. For these structures, it is necessary to ensure a high ultimate tensile strength (UTS). Various studies have reported that the UTS is significantly influenced by the welding parameters. Samples welded with different parameter sets showed a considerably different UTS, despite being free from detectable welding defects (e.g. tunnel defect, voids, or lack of penetration). Based on the observations in the literature, a hypothesis was posed. The welding temperature along with the welding speed determine the UTS of the weld. This study aims to prove this hypothesis experimentally by using temperature-controlled FSW to join plates of EN AW-2219-T87 in butt joint configuration. The welded samples were examined using visual inspection, metallography, X-ray imaging, and uniaxial tensile tests. Finally, a statistical analysis was conducted. Hereby, the hypothesis was confirmed.

  14. The porosity formation mechanism in the laser-MIG hybrid welded joint of Invar alloy

    Science.gov (United States)

    Zhan, Xiaohong; Gao, Qiyu; Gu, Cheng; Sun, Weihua; Chen, Jicheng; Wei, Yanhong

    2017-10-01

    The porosity formation mechanism in the laser-metal inter gas (MIG) multi-layer hybrid welded (HW) joint of 19.05 mm thick Invar alloy is investigated. The microstructure characteristics and energy dispersive spectroscopy (EDS) are analyzed. The phase identification was conducted by the X-ray diffractometer (XRD). Experimental results show that the generation of porosity is caused by the relatively low laser power in the root pass and low current in the cover pass. It is also indicated that the microstructures of the welded joints are mainly observed to be columnar crystal and equiaxial crystal, which are closely related to the porosity formation. The EDS results show that oxygen content is significantly high in the inner wall of the porosity. The XRD results indicate that the BM and the WB of laser-MIG HW all are composed of Fe0.64Ni0.36 and γ-(Fe,Ni). When the weld pool is cooled quickly, [NiO] [FeO] and [MnO] are formed that react on C to generate CO/CO2 gases. The porosity of laser-MIG HW for Invar alloy is oxygen pore. The root source of metallurgy porosity formation is that the dissolved gases are hard to escape sufficiently and thus exist in the weld pool. Furthermore, 99.99% pure Argon is recommended as protective gas in the laser-MIG HW of Invar alloy.

  15. Influence of Friction Stir Welding on Mechanical Properties of Butt Joints of AZ61 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Seung-Ju Sun

    2017-01-01

    Full Text Available In this study, the effect of heat input on the mechanical properties and fracture behaviors of AZ61 magnesium alloy joints has been studied. Magnesium alloy AZ61 plates with thickness of 5 mm were welded at different ratios of tool rotational speed to welding speed (ω/ν. The average ultimate tensile strength of all weld conditions satisfying a ω/ν ratio of 3 reached 100% of the strength of the base material. Fractures occurred at the interface between the thermomechanical affected zone at advancing side and the stir zone in all welded specimens. From the scanning electron microscope and electron backscatter diffraction analysis, it was determined that the interface between the thermomechanical affected zone and the stir zone, which is the region where the grain orientation changes, was the weakest part; the advancing side region was relatively weaker than the retreating side region because the grain orientation change occurred more dramatically in the advancing side region.

  16. Strength analysis and optimization of welding robot mechanism in emergency stop state

    Directory of Open Access Journals (Sweden)

    Zdeněk Poruba

    2016-03-01

    Full Text Available The contribution deals with the strength analysis and optimization of the welding robot mechanism in emergency stop state. The common operational positioning of the welding robot is characterized by smooth course of speeds in the time. The resulting load does not differ significantly from the static loading. However the safety requirements given by the norm require the ability of emergency stop function. Since the course of speed in time is rather steep the higher values of acceleration and thus higher excitation force is expected. The dynamical simulation performed describes the response of the robot mechanism in the form of stress course in time, quantifies the peak values of the stress caused by the dynamical component of loading and highlights the potential risks associated with this phenomenon.

  17. Effect of friction time on the microstructure and mechanic properties of friction welded AISI 1040/Duplex stainless steel

    Directory of Open Access Journals (Sweden)

    İhsan Kırık

    2000-06-01

    Full Text Available In this study, the effect on the characteristic microstructure and mechanic properties of friction time on the couple steels AISI 1040/AISI 2205 stainless steel joining with friction welding method was experimentally investigated. Friction welding experiment were carried out in privately prepared PLC controlled continuous friction welding machine by us. Joints were carried out under 1700 rpm rotation speed, with 30MPa process friction pressure, 60MPa forging pressure, 4 second forging pressure and under 3, 5, 7, 9 and 11 second friction time, respectively. After friction welding, the bonding interface microstructures of the specimens were examined by SEM microscopy and EDS analysis. After weld microhardness and tensile strength of specimens were carried out. The result of applied tests and observations pointed out that the properties of microstructure were changed with friction time increased. The excellent tensile strength of joint observed on 1700 rpm rotation speed and 3 second friction time sample.

  18. Microstructure, crystallographic texture and mechanical properties of friction stir welded AA2017A

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.M.Z., E-mail: mohamed_ahmed4@s-petrol.suez.edu.eg [Institute for Microstructural and Mechanical Processing Engineering, University of Sheffield (IMMPETUS), Mappin Street, Sheffield S1 3JD (United Kingdom); Department of Metallurgical and Materials Engineering, Suez Canal University, Suez 43721 (Egypt); Wynne, B.P.; Rainforth, W.M. [Institute for Microstructural and Mechanical Processing Engineering, University of Sheffield (IMMPETUS), Mappin Street, Sheffield S1 3JD (United Kingdom); Threadgill, P.L. [TWI LTD, Granta Park, Great Abington, Cambridge CB21 6AL (United Kingdom)

    2012-02-15

    In this study a thick section (20 mm) friction stir welded AA2017A-T451 has been characterized in terms of microstructure, crystallographic texture and mechanical properties. For microstructural analysis both optical and scanning electron microscopes have been used. A detailed crystallographic texture analysis has been carried out using the electron back scattering diffraction technique. Crystallographic texture has been examined in both shoulder and probe affected regions of the weld NG. An entirely weak texture is observed at the shoulder affected region which is mainly explained by the effect of the sequential multi pass deformation experienced by both tool probe and tool shoulder. The texture in the probe dominated region at the AS side of the weld is relatively weak but still assembles the simple shear texture of FCC metals with B/B{sup Macron} and C components existing across the whole map. However, the texture is stronger at the RS than at the AS of the weld, mainly dominated byB/B{sup Macron} components and with C component almost absent across the map. An alternating bands between (B) components and (B{sup Macron }) component are observed only at the AS side of the weld. - Highlights: Black-Right-Pointing-Pointer Detailed investigation of microstructure and crystallographic texture. Black-Right-Pointing-Pointer The grain size is varied from the top to the bottom of the NG. Black-Right-Pointing-Pointer An entirely weak texture is observed at the shoulder affected region. Black-Right-Pointing-Pointer The texture in the probe affected region is dominated by simple shear texture.

  19. The Role of Mechanical Connection during Friction Stir Keyholeless Spot Welding Joints of Dissimilar Materials

    Directory of Open Access Journals (Sweden)

    Xiao Liu

    2017-06-01

    Full Text Available Contrast experiments of lap joints among dissimilar AZ31B Mg alloy, Mg99.50, zinc-coated DP600 sheet, and non-zinc-coated DP600 sheet were made by friction stir keyholeless spot welding (FSKSW and vacuum diffusion welding (VDW, respectively. Scanning electron microscopy (SEM and energy disperse spectroscopy (EDS were used to investigate the microstructures and components of the joints welded. The experimental results show that the FSKSW bonding method is a kind of compound mode that contains a mechanical connection and element diffusion fusion connection, in which mechanical connection has the main decisive function on joints of Mg/steel. Elements diffusion exists in the interfacial region of the joints and the elements diffusion extent is basically the same to that of VDW. The elements’ diffusion in Mg/steel using FSKSW is defined in the reaction between small amounts elements of the base metal and zinc-coated metals. The intermetallic compounds and composite oxide perform some reinforcement on the mechanical connection strength.

  20. Effects of heat input on mechanical properties of metal inert gas welded 1.6 mm thick galvanized steel sheet

    International Nuclear Information System (INIS)

    Rafiqul, M I; Ishak, M; Rahman, M M

    2012-01-01

    It is usually a lot easier and less expensive to galvanize steel before it is welded into useful products. Galvanizing afterwards is almost impossible. In this research work, Galvanized Steel was welded by using the ER 308L stainless steel filler material. This work was done to find out an alternative way of welding and investigate the effects of heat input on the mechanical properties of butt welded joints of Galvanized Steel. A 13.7 kW maximum capacity MIG welding machine was used to join 1.6 mm thick sheet of galvanized steel with V groove and no gap between mm. Heat inputs was gradually increased from 21.06 to 25.07 joules/mm in this study. The result shows almost macro defects free welding and with increasing heat input the ultimate tensile strength and welding efficiency decrease. The Vickers hardness also decreases at HAZ with increasing heat input and for each individual specimen; hardness was lowest in heat affected zone (HAZ), intermediate in base metal and maximum in welded zone. The fracture for all specimens was in the heat affected zone while testing in the universal testing machine.

  1. Effects of heat input on mechanical properties of metal inert gas welded 1.6 mm thick galvanized steel sheet

    Science.gov (United States)

    Rafiqul, M. I.; Ishak, M.; Rahman, M. M.

    2012-09-01

    It is usually a lot easier and less expensive to galvanize steel before it is welded into useful products. Galvanizing afterwards is almost impossible. In this research work, Galvanized Steel was welded by using the ER 308L stainless steel filler material. This work was done to find out an alternative way of welding and investigate the effects of heat input on the mechanical properties of butt welded joints of Galvanized Steel. A 13.7 kW maximum capacity MIG welding machine was used to join 1.6 mm thick sheet of galvanized steel with V groove and no gap between mm. Heat inputs was gradually increased from 21.06 to 25.07 joules/mm in this study. The result shows almost macro defects free welding and with increasing heat input the ultimate tensile strength and welding efficiency decrease. The Vickers hardness also decreases at HAZ with increasing heat input and for each individual specimen; hardness was lowest in heat affected zone (HAZ), intermediate in base metal and maximum in welded zone. The fracture for all specimens was in the heat affected zone while testing in the universal testing machine.

  2. Mechanical Property Analysis in the Retracted Pin-Tool (RPT) Region of Friction Stir Welded (FSW) Aluminum Lithium 2195

    Science.gov (United States)

    Ding, R. Jeffrey; Oelgoetz, Peter A.

    1999-01-01

    The "Auto-Adjustable Pin Tool for Friction Stir Welding", was developed at The Marshall Space Flight Center to address process deficiencies unique to the FSW process. The auto-adjustable pin tool, also called the retractable pin-tool (R.PT) automatically withdraws the welding probe of the pin-tool into the pin-tool's shoulder. The primary function of the auto-adjustable pin-tool is to allow for keyhole closeout, necessary for circumferential welding and localized weld repair, and, automated pin-length adjustment for the welding of tapered material thickness. An overview of the RPT hardware is presented. The paper follows with studies conducted using the RPT. The RPT was used to simulate two capabilities; welding tapered material thickness and closing out the keyhole in a circumferential weld. The retracted pin-tool regions in aluminum- lithium 2195 friction stir weldments were studied through mechanical property testing and metallurgical sectioning. Correlation's can be =de between retractable pin-tool programmed parameters, process parameters, microstructure, and resulting weld quality.

  3. Metallurgical and Mechanical Characterization of High Temperature Titanium Alloys Joined by Friction Stir Welding

    Science.gov (United States)

    Gangwar, Kapil Dev

    In the world of joining, riveting and additive manufacturing, weight reduction, and omission of defects (at both macro and micro level) remain of paramount. Therefore, in the wake of ubiquitous fusion welding (FW) and widely accepted approach of riveting using Inconel bolts to resist corrosion at higher temperature, friction stir welding (FSW) has emerged as a novice jewel in friction based additive manufacturing industry. With advancements in automation of welding process and tool material, FSW of materials with higher work hardening such as steel and titanium has also become probable. Process and property relations associated with FSW are inevitable in case of dissimilar titanium alloys, due to presence of heterogeneity (whether atrocious or advantageous) in and around the weld nugget. These process property relationships are needed to be studied and addressed properly in order to optimize the processing window for improved mechanical and metallurgical properties. In this study FSWed similar and dissimilar butt joints of α+β, and near α titanium, alloys have been produced for varying processing conditions in order to study the effect of rotation speed (rpm) and traverse speed (TS; mm-min-1). The aim of this study is to assess the effect of tool geometry, tool rpm, TS on microstructure and mechanical properties of most widely used α+β titanium alloy, Ti-6Al-4V (Ti-64), standard grain and fine grain in addition to α+β,Ti-5Al-4V (T-54M), standard grain, and near α, Ti-6Al-2Mo-4Zr-2Sn (Ti-6242), standard grain (SG) and fine grain (FG). During FSW, a unique α+β fine-grained microstructure has been formed depending on whether or not the peak temperature in the weld nugget (WN) reached above or below β transus temperature. The resulting microstructure consists of acicular α+β, emanating from the prior β grain boundary as the weld cools off. The changes in the microstructure are observed by optical microscopy (OM). Later, a detailed analysis of material

  4. Vapor plume oscillation mechanisms in transient keyhole during tandem dual beam fiber laser welding

    Science.gov (United States)

    Chen, Xin; Zhang, Xiaosi; Pang, Shengyong; Hu, Renzhi; Xiao, Jianzhong

    2018-01-01

    Vapor plume oscillations are common physical phenomena that have an important influence on the welding process in dual beam laser welding. However, until now, the oscillation mechanisms of vapor plumes remain unclear. This is primarily because mesoscale vapor plume dynamics inside a millimeter-scale, invisible, and time-dependent keyhole are difficult to quantitatively observe. In this paper, based on a developed three-dimensional (3D) comprehensive model, the vapor plume evolutions in a dynamical keyhole are directly simulated in tandem dual beam, short-wavelength laser welding. Combined with the vapor plume behaviors outside the keyhole observed by high-speed imaging, the vapor plume oscillations in dynamical keyholes at different inter-beam distances are the first, to our knowledge, to be quantitatively analyzed. It is found that vapor plume oscillations outside the keyhole mainly result from vapor plume instabilities inside the keyhole. The ejection velocity at the keyhole opening and dynamical behaviors outside the keyhole of a vapor plume both violently oscillate with the same order of magnitude of high frequency (several kHz). Furthermore, the ejection speed at the keyhole opening and ejection area outside the keyhole both decrease as the beam distance increases, while the degree of vapor plume instability first decreases and then increases with increasing beam distance from 0.6 to 1.0 mm. Moreover, the oscillation mechanisms of a vapor plume inside the dynamical keyhole irradiated by dual laser beams are investigated by thoroughly analyzing the vapor plume occurrence and flow process. The vapor plume oscillations in the dynamical keyhole are found to mainly result from violent local evaporations and severe keyhole geometry variations. In short, the quantitative method and these findings can serve as a reference for further understanding of the physical mechanisms in dual beam laser welding and of processing optimizations in industrial applications.

  5. Mechanical properties of API X80 steel pipe joints welded by Flux Core Arc Weld Process; Propriedades mecanicas de juntas de tubos de aco API X80 soldadas com arame tubulares

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez, Robert E. Cooper; Silva, Jose Hilton F.; Trevisan, Roseana E. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Fabricacao

    2003-07-01

    Flux Core Arc Welding processes (FCAW) are beginning to be applied in pipeline welds, however, very limited experimental data regarding mechanical properties of pipeline weld joints with these processes are available in the literature. In this paper, the effects of preheat temperature and type of FCAW on mechanical properties (microhardness and tensile strength) of API X80 weld joint steel are presented. FCAW processes with gas protection and self-shielded were used. Multipasses welding were applied in 30'' diameter and 0,625'' thickness tubes. Influence factors were: FCAW type and preheat temperature. Acceptance criteria of welded joints were evaluated by API 1104 standard for tensile strength test and ASTM E384-99 for microhardness test. The results obtained showed that FCAW type and preheat temperature have no influence on mechanical properties of API X80 joint steel. (author)

  6. Microstructure, local mechanical properties and stress corrosion cracking susceptibility of an SA508-52M-316LN safe-end dissimilar metal weld joint by GTAW

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Hongliang; Zhu, Ruolin [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049 (China); Zhang, Zhiming [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Jianqiu, E-mail: wangjianqiu@imr.ac.cn [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Han, En.-Hou.; Ke, Wei [Key Laboratory of Nuclear Materials and Safety Assessment, Liaoning KeyLaboratory for Safety and Assessment Technique of Nuclear Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Su, Mingxing [Shanghai Research Center for Weld and Detection Engineering Technique of Nuclear Equipment, Shanghai 201306 (China)

    2016-07-04

    The microstructure, local mechanical properties and local stress corrosion cracking susceptibility of an SA508-52M-316LN domestic dissimilar metal welded safe-end joint used for AP1000 nuclear power plant prepared by automatic gas tungsten arc welding was studied in this work by optical microscopy, scanning electron microscopy (with electron back scattering diffraction and an energy dispersive X-ray spectroscopy system), micro-hardness testing, local mechanical tensile testing and local slow strain rate tests. The micro-hardness, local mechanical properties and stress corrosion cracking susceptibility across this dissimilar metal weld joint vary because of the complex microstructure across the fusion area and the dramatic chemical composition change across the fusion lines. Briefly, Type I boundaries and Type II boundaries exist in 52Mb near the SA508-52Mb interface, a microstructure transition was found in SA508 heat affected zone, the residual strain and grain boundary character distribution changes as a function of the distance from the fusion boundary in 316LN heat affected zone, micro-hardness distribution and local mechanical properties along the DMWJ are heterogeneous, and 52Mw-316LN interface has the highest SCC susceptibility in this DMWJ while 316LN base metal has the lowest one.

  7. Microstructure and mechanical properties of aluminum 5083 weldments by gas tungsten arc and gas metal arc welding

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yao [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wang Wenjing [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Xie Jijia [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Sun Shouguang [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Wang Liang [College of Metallurgy and Material Engineering, Chongqing University of Science and Technology, Chongqing 401331 (China); Qian Ye; Meng Yuan [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Wei Yujie, E-mail: yujie_wei@lnm.imech.ac.cn [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer Welding zones by GTAW and GMAW are softer than the parent material Al5083. Black-Right-Pointing-Pointer GTAW for Al5083 are mechanically more reliable than that welded by GMAW. Black-Right-Pointing-Pointer GTAW welds fail by shear, but GMAW welds show mixed shear and normal failure. - Abstract: The mechanical properties and microstructural features of aluminum 5083 (Al5083) weldments processed by gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) are investigated. Weldments processed by both methods are mechanically softer than the parent material Al5083, and could be potential sites for plastic localization. It is revealed that Al5083 weldments processed by GTAW are mechanical more reliable than those by GMAW. The former bears higher strength, more ductility, and no apparent microstructure defects. Perceivable porosity in weldments by GMAW is found, which could account for the distinct mechanical properties between weldments processed by GTAW and GMAW. It is suggested that caution should be exercised when using GMAW for Al5083 in the high-speed-train industry where such light weight metal is broadly used.

  8. Microstructure and mechanical properties of aluminum 5083 weldments by gas tungsten arc and gas metal arc welding

    International Nuclear Information System (INIS)

    Liu Yao; Wang Wenjing; Xie Jijia; Sun Shouguang; Wang Liang; Qian Ye; Meng Yuan; Wei Yujie

    2012-01-01

    Highlights: ► Welding zones by GTAW and GMAW are softer than the parent material Al5083. ► GTAW for Al5083 are mechanically more reliable than that welded by GMAW. ► GTAW welds fail by shear, but GMAW welds show mixed shear and normal failure. - Abstract: The mechanical properties and microstructural features of aluminum 5083 (Al5083) weldments processed by gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) are investigated. Weldments processed by both methods are mechanically softer than the parent material Al5083, and could be potential sites for plastic localization. It is revealed that Al5083 weldments processed by GTAW are mechanical more reliable than those by GMAW. The former bears higher strength, more ductility, and no apparent microstructure defects. Perceivable porosity in weldments by GMAW is found, which could account for the distinct mechanical properties between weldments processed by GTAW and GMAW. It is suggested that caution should be exercised when using GMAW for Al5083 in the high-speed-train industry where such light weight metal is broadly used.

  9. Mean load effect on fatigue of welded joints using structural stress and fracture mechanics approach

    International Nuclear Information System (INIS)

    Kim, Jong Sung; Kim, Cheol; Jin, Tae Eun; Dong, P.

    2006-01-01

    In order to ensure the structural integrity of nuclear welded structures during design life, the fatigue life has to be evaluated by fatigue analysis procedures presented in technical codes such as ASME B and PV Code Section III. However, existing fatigue analysis procedures do not explicitly consider the presence of welded joints. A new fatigue analysis procedure based on a structural stress/fracture mechanics approach has been recently developed in order to reduce conservatism by erasing uncertainty in the analysis procedure. A recent review of fatigue crack growth data under various mean loading conditions using the structural stress/fracture mechanics approach, does not consider the mean loading effect, revealed some significant discrepancies in fatigue crack growth curves according to the mean loading conditions. In this paper, we propose the use of the stress intensity factor range ΔK characterized with loading ratio R effects in terms of the structural stress. We demonstrate the effectiveness in characterizing fatigue crack growth and S-N behavior using the well-known data. It was identified that the S-N data under high mean loading could be consolidated in a master S-N curve for welded joints

  10. Phase transformation and mechanical behavior in annealed 2205 duplex stainless steel welds

    International Nuclear Information System (INIS)

    Badji, Riad; Bouabdallah, Mabrouk; Bacroix, Brigitte; Kahloun, Charlie; Belkessa, Brahim; Maza, Halim

    2008-01-01

    The phase transformations and mechanical behaviour during welding and subsequent annealing treatment of 2205 duplex stainless steel have been investigated. Detailed microstructural examination showed the presence of higher ferrite amounts in the heat affected zone (HAZ), while higher amounts of austenite were recorded in the centre region of the weld metal. Annealing treatments in the temperature range of 800-1000 deg. C resulted in a precipitation of σ phase and M 23 C 6 chromium carbides at the γ/δ interfaces that were found to be preferential precipitation sites. Above 1050 deg. C, the volume fraction of δ ferrite increases with annealing temperature. The increase of δ ferrite occurs at a faster rate in the HAZ than in the base metal and fusion zone. Optimal mechanical properties and an acceptable ferrite/austenite ratio throughout the weld regions corresponds to annealing at 1050 deg. C. Fractographic examinations showed that the mode of failure changed from quasi-cleavage fracture to dimple rupture with an increase in the annealing temperature from 850 to 1050 deg. C

  11. Microstructure and mechanical performance of autogenously fibre laser beam welded Ti-6242 butt joints

    Energy Technology Data Exchange (ETDEWEB)

    Kashaev, Nikolai, E-mail: nikolai.kashaev@hzg.de; Pugachev, Dmitry; Ventzke, Volker; Fomin, Fedor; Burkhardt, Irmela; Enz, Josephin; Riekehr, Stefan

    2017-05-10

    This work deals with the effects of laser beam power, focus position and advance speed on the geometry, microstructure and mechanical properties such as the tensile strength and microhardness of autogenously fibre laser beam welded Ti-6Al-2Sn-4Zr-2Mo (denoted as Ti-6242) butt joints used for high temperature applications. The Ti-6242 sheet employed here is characterized by a globular (α+β) microstructure. Laser beam welded butt joints consisted of a martensitic fusion zone, inhomogeneous heat affected zones and equiaxed base materials. The microhardness increased from 330 HV 0.3 in base material to 430 HV 0.3 in fusion zone due to the martensitic transformation. Butt joints showed the base material level of strength in tensile test. The local increase in microhardness provided a shielding effect that protected the Ti-6242 butt joint against mechanical damage during the static tensile load test. The predicted critical total underfill depth that does not reduce the tensile strength of the weld was determined to be 25% of the specimen thickness. - Highlights: • Autogenous fibre LBW of Ti-6242 was successfully achieved. • Butt joints showed low levels of porosity and an appropriate seam geometry. • Base material level of strength achieved for tensile strength. • Predicted critical underfill depth is 25% of the specimen thickness.

  12. Study on Welding Mechanism Based on Modification of Polypropylene for Improving the Laser Transmission Weldability to PA66

    Science.gov (United States)

    Liu, Huixia; Jiang, Hairong; Guo, Dehui; Chen, Guochun; Yan, Zhang; Li, Pin; Zhu, Hejun; Chen, Jun; Wang, Xiao

    2015-01-01

    Polypropylene and PA66 are widely used in our daily life, but they cannot be welded by laser transmission welding (LTW) because of polar differences and poor compatibility. In this paper, grafting modification technology is used to improve the welding performance between polypropylene and PA66. Firstly, the strong reactive and polar maleic-anhydride (MAH) is grafted to polypropylene and infrared spectrometer is used to prove that MAH has been grafted to polypropylene. At the same time, the mechanical and thermal properties of the graft modified polypropylene (TGMPP) are tested. The results prove that the grafting modification has little influence on them. Also, the optical properties of TGMPP are measured. Then, the high welding strength between TGMPP and PA66 is found and the mechanism of the weldability is researched, which shows that there are two reasons for the high welding strength. By observing the micro morphology of the welding zone, one reason found is that the modification of polypropylene can improve the compatibility between polypropylene and PA66 and make them easy to diffuse mutually, which causes many locking structures formed in the welding region. The other reason is that there are chemical reactions between TGMPP and PA66 proved by the X-ray photoelectron spectrometer. PMID:28793484

  13. Microstructure and mechanical properties of newly developed aluminum–lithium alloy 2A97 welded by fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Banglong [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials Ministry of Education, Shandong University, Jinan 250061 (China); Qin, Guoliang, E-mail: glqin@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials Ministry of Education, Shandong University, Jinan 250061 (China); Meng, Xiangmeng; Ji, Yang; Zou, Yong [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials Ministry of Education, Shandong University, Jinan 250061 (China); Lei, Zhen [Harbin Welding Institute, Harbin 150028 (China)

    2014-11-03

    The newly developed aluminum–lithium alloy 2A97 was for the first time joined by laser beam welding in order to meet the ever-increased long-term requirements of aerospace, aviation and armament industries. The weld appearance, microstructure, solute segregation, precipitate behavior, and their relationships with mechanical properties of welded joints were investigated. Sound joints with no crack and a few small porosities are obtained under appropriate heat inputs. As a result of heterogeneous nucleation involving the effect of Zr and Li, a non-dendritic equiaxed zone forms between partially melted zone and fusion zone. The crystal morphologies in fusion zone vary from columnar dendrite to equiaxed dendrite, with the increase of constitutional supercooling. Solute segregation leads to the variations of Cu content in grain interior and boundary, as well as the weak ability of re-precipitation of fusion zone. Most precipitates in the base metal dissolve during welding, and fusion zone contains a decreased quantity of δ′, β′, θ′, and T{sub 1}. The ultimate tensile strength of laser welded joints is 83.4% of that of the base metal, and can meet the application requirements from related industries, but the ductility still needs to be improved. Welding defects and loss of solid solution/precipitation hardened structure lead to the degradation of mechanical properties. Tensile fracture occurs in weld with the brittle intergranular dominated mode and premature failure occurs and extends in the equiaxed zone.

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

    African Journals Online (AJOL)

    HOD

    mechanical properties (hardness, tensile and impact) of type 304 austenitic stainless steel (ASS) immersed in 0.5M hydrochloric acid at ... The increasing high demand on stainless steel usage in industry as a ... materials prices of major alloying additions such as nickel ..... Microstructure of Cast Fibre-Polyester/Iron Filings.

  15. Microstructural and mechanical properties on friction welding of dissimilar metals used in motor vehicles

    Science.gov (United States)

    Jesudoss Hynes, N. Rajesh; Shenbaga Velu, P.

    2018-02-01

    In the last two decades, major car manufacturing companies are exploring the possibilities of joining magnesium with aluminium, via friction welding technique for many crucial automotive applications. Our primary objective, is to carry out an experimental investigation in order to study the behaviour of dissimilar joints. The microscopic structure at the welded joint interface was analysed using an optical microscopy and scanning electron microscope. It was found that, by increasing the value of friction time, the value of the tensile strength increases and the result of tensile strength is found to be 120 MPa at a friction time of 10 s. Micro hardness was found to be higher at the interface of the weldment due to the development of a brittle intermetallic compound. Micro structural studies using SEM reveals, distinct zones such as an unaffected parent metal zone, the heat affected zone, a thermo-mechanically affected zone and a fully deformed plasticised zone.

  16. TIG and MIG welding of 6061 and 7020 aluminium alloys. Microstructural studies and mechanical properties

    International Nuclear Information System (INIS)

    Gomez de Salazar, J.M.; Urena, A.; Villauriz, E.; Manzanedo, S.; Barrena, I.

    1998-01-01

    The aluminium alloys of the 6XXX and 7XXX series, are actually considered of medium and high strength, and are been profusely used in different industries such as aeronautical, automotive, etc.However, its wide application as structural material needs of the proper development of their joining process. The present work describes the results obtained from the microstructural evaluation, both with optical and scanning electronic micros copies (OM) and SEM), and of the mechanical one (hardness changes) of the weld produced in the alloys using different arc welding techniques: FTAW (TIG) and GMAW (MIG). For the last one, a filler metal with a composition of Al-5Mg, AWS denomination A5.10-92 (AA5356), has been used. (Author) 5 refs

  17. Metallurgical and mechanical examinations of steel–copper joints arc welded using bronze and nickel-base superalloy filler materials

    International Nuclear Information System (INIS)

    Velu, M.; Bhat, Sunil

    2013-01-01

    Highlights: ► Optical and scanning electron microscopy show defect free weld interfaces. ► Energy dispersive spectroscopy shows low dilution level of the weld by Fe. ► XRD studies show no brittle intermetallic phases in the weld interfaces. ► Weld interfaces did not fail during tensile, transverse bending and impact tests. ► The joint exhibits superior strength properties than that of bronze filler. - Abstract: The paper presents metallurgical and mechanical examinations of joints between dissimilar metals viz. copper (UNSC11000) and alloy steel (En31) obtained by Shielded Metal Arc Welding (SMAW) using two different filler materials, bronze and nickel-base super alloy. The weld bead of the joint with bronze-filler displayed porosity, while that with nickel-filler did not. In tension tests, the weldments with bronze-filler fractured in the centre of the weld, while those with nickel-filler fractured in the heat affected zone (HAZ) of copper. Since the latter exhibited higher strength than the former, all the major tests were undertaken over the joints with nickel-filler alone. Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) indicated corrugated weld interfaces and favorable elemental diffusions across them. X-ray diffraction (XRD) studies around the weld interfaces did not reveal any detrimental intermetallic compounds. Transverse bending tests showed that flexural strengths of the weldments were higher than the tensile strengths. Transverse side bend tests confirmed good ductility of the joints. Shear strength of the weld-interface (Cu–Ni or Ni–steel) was higher than the yield strength of weaker metal. Microhardness and Charpy impact values were measured at all the important zones across the weldment

  18. On the effect of β phase on the microstructure and mechanical properties of friction stir welded commercial brass alloys.

    Science.gov (United States)

    Heidarzadeh, Akbar; Saeid, Tohid

    2015-12-01

    Conventional fusion welding of brass (Cu-Zn) alloys has some difficulties such as evaporation of Zn, toxic behavior of Zn vapor, solidification cracking, distortion, and oxidation [1], [2], [3]. Fortunately, friction stir welding (FSW) has been proved to be a good candidate for joining the brass alloys, which can overcome the fusion welding short comes [4], [5], [6], [7]. The data presented here relates to FSW of the single and double phase brass alloys. The data is the microstructure and mechanical properties of the base metals and joints.

  19. Mechanical properties of a 316L/T91 weld joint tested in lead-bismuth liquid

    International Nuclear Information System (INIS)

    Serre, Ingrid; Vogt, Jean-Bernard

    2009-01-01

    The mechanical strength of T91/316L weld joint assembled by electron beam process is investigated in air and in a liquid lead bismuth bath at 300 and 380 o C using the small punch test. It is shown that the mechanical response in air of the weld joint is similar to that of the T91 base material. The plastic deformation is mainly concentrated in the T91 part of the weld joint which promotes cracking in this material. Testing in liquid lead bismuth bath results in a reduction in ductility and the formation of brittle cracks. The T91/weld interface is found to be rather resistant as it cracks late in the test and after a large crack propagated in the T91 steel.

  20. Microstructural and mechanical property characterization of Er modified Al-Mg-Mn alloy Tungsten Inert Gas welds

    International Nuclear Information System (INIS)

    Yang, Dongxia; Li, Xiaoyan; He, Dingyong; Nie, Zuoren; Huang, Hui

    2012-01-01

    Highlights: → The microstructural characterization of TIG welded Al-Mg-Mn-Zr-Er alloy is studied. → A typical equaixed zone (EQZ) with finer grains is observed in the weld metal at the fusion boundary. → The dissolution of non-primary Al 3 Er particles in Al matrix is one reason of the weakness of TIG welded joint. →The relationship between mechanical properties and microstructure of welded joints is evaluated. →Reasons for joint softening are given from work-hardening, precipitation strengthening and solution strengthening. -- Abstract: Samples of Al-Mg-Mn-Zr-Er alloys have been welded using the method of TIG welding. Microstructures characterization was performed by optical microscopy (OM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM), respectively. In addition, tensile and hardness test was conducted. The relationship between mechanical properties and microstructure of welded joints is evaluated. Results indicate that the ultimate tensile strength of the joints is 72% of that of the base metal. The base metal consists of a typical rolled structure, and the fusion zone (FZ) is mainly made up of dendrite grains. A characteristic equiaxed zone (EQZ) is obtained at the fusion boundary between the base metal and fusion zone. Fine dispersion of coherent Al 3 Er precipitates was found in the base metal, however, the quantity of these particles dropped significantly in the fusion zone. The hardness test results indicate that the microhardness in the fusion zone is lower than that of the base metal, due to the as-cast structure in this region. Based on the present work, it is concluded that TIG welding is the suitable welding procedure for joining this new type Er-containing aluminum alloy.

  1. Friction Stir Welding of Low-Carbon AISI 1006 Steel: Room and High-Temperature Mechanical Properties

    Science.gov (United States)

    Shunmugasamy, Vasanth C.; Mansoor, Bilal; Ayoub, Georges; Hamade, Ramsey

    2018-03-01

    Friction stir welding (FSW) is an ecologically benign solid-state joining process. In this work, FSW of low-carbon AISI 1006 steel was carried out to study the microstructure and mechanical properties of the resulting joints at both room temperature (RT) and 200 °C. In the parameter space investigated here, a rotational tool speed and translation feed combination of 1200 rpm and 60 mm/min produced a defect-free weld with balanced mechanical properties and a superior Vickers microhardness profile compared to all other conditions and to base metal (BM). At faster translation feeds (100 and 150 mm/min), wormhole defects were observed in the weld microstructure and were attributed to higher strain rate experienced by the weld zone. Under tensile loading, welded material exhibited yield strength that was up to 86 and 91% of the BM at RT and 200 °C, respectively. On the other hand, tensile strength of welded material was nearly similar to that of the base metal at both RT and 200 °C. However, at both temperatures the tensile ductility of the welded joints was observed to be significantly lower than the BM. Annealing of the 1200 rpm and 60 mm/min FSW specimen resulted in tensile strength of 102% compared to base material and 47% increase in the strain at failure compared to the as-welded specimen. The Charpy impact values revealed up to 62 and 53% increase in the specific impact energy for the 1200 rpm and 60 mm/min welded joints as compared with the BM.

  2. Studies on mechanical properties, microstructure and fracture morphology details of laser beam welded thick SS304L plates for fusion reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Buddu, Ramesh Kumar, E-mail: buddu@ipr.res.in [Fusion Reactor Materials Development and Characterization Division, Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Chauhan, N.; Raole, P.M. [Fusion Reactor Materials Development and Characterization Division, Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Natu, Harshad [Magod Laser Machining Pvt. Ltd, Jigani, Bengaluru 560105 (India)

    2015-06-15

    Highlights: • CO{sub 2} laser welding of 8 mm thick SS304L plates has been carried out and full penetration welds fabricated and characterized for mechanical properties and microstructure details. • Welded samples have shown tensile properties comparable to base indicating good weld quality joints. • Impact fracture tests of weld zone and heat affected zone samples have shown poor toughness compared to the base metal. • SEM analysis of fracture samples of tensile and impact specimens indicated the complex microstructure features in weld zone and combined ductile and brittle fracture features. • Combined features of dendrite and cellular structures are observed in weld microstructures with narrow HAZ and delta ferrite is found in the welds and further confirmed by higher Ferrite Number data. - Abstract: Austenitic stainless steel is widely used structural material for the fabrication of the fusion reactor components. Laser welding is high power density process which offers several advantages over the other conventional processes like Tungsten Inert Gas welding. The features like low distortion, narrow heat affected zone, deep penetration in single pass, good mechanical properties are some of the advantages of laser welding process. The laser weld process parameters optimization has several challenges in terms of overcoming the weld defects like voids due to lack of penetration over depth, undercuts and porosity. The present paper reports the studies carried out with CO{sub 2} laser welding of 8 mm thick austenitic stainless steel SS304L plates and their characterization of mechanical properties, microstructure and fracture morphology details. The weld process parameter optimization towards defect free welds with full penetration welding has been carried out. The welded samples have shown tensile properties comparable to base metal, bend tests are successfully passed. The hardness measurements have shown slightly higher for weld zone compared to base metal

  3. Studies on mechanical properties, microstructure and fracture morphology details of laser beam welded thick SS304L plates for fusion reactor applications

    International Nuclear Information System (INIS)

    Buddu, Ramesh Kumar; Chauhan, N.; Raole, P.M.; Natu, Harshad

    2015-01-01

    Highlights: • CO 2 laser welding of 8 mm thick SS304L plates has been carried out and full penetration welds fabricated and characterized for mechanical properties and microstructure details. • Welded samples have shown tensile properties comparable to base indicating good weld quality joints. • Impact fracture tests of weld zone and heat affected zone samples have shown poor toughness compared to the base metal. • SEM analysis of fracture samples of tensile and impact specimens indicated the complex microstructure features in weld zone and combined ductile and brittle fracture features. • Combined features of dendrite and cellular structures are observed in weld microstructures with narrow HAZ and delta ferrite is found in the welds and further confirmed by higher Ferrite Number data. - Abstract: Austenitic stainless steel is widely used structural material for the fabrication of the fusion reactor components. Laser welding is high power density process which offers several advantages over the other conventional processes like Tungsten Inert Gas welding. The features like low distortion, narrow heat affected zone, deep penetration in single pass, good mechanical properties are some of the advantages of laser welding process. The laser weld process parameters optimization has several challenges in terms of overcoming the weld defects like voids due to lack of penetration over depth, undercuts and porosity. The present paper reports the studies carried out with CO 2 laser welding of 8 mm thick austenitic stainless steel SS304L plates and their characterization of mechanical properties, microstructure and fracture morphology details. The weld process parameter optimization towards defect free welds with full penetration welding has been carried out. The welded samples have shown tensile properties comparable to base metal, bend tests are successfully passed. The hardness measurements have shown slightly higher for weld zone compared to base metal and the

  4. Effect of groove design on mechanical and metallurgical properties of quenched and tempered low alloy abrasion resistant steel welded joints

    International Nuclear Information System (INIS)

    Sharma, Varun; Shahi, A.S.

    2014-01-01

    Highlights: • Effect of weld groove design on Q and T steel welded joints is investigated. • Groove design influences heat dissipation characteristics of welded joints. • Double-V groove joint possesses maximum yield strength and UTS. • C-groove joint possesses highest impact energy, both at room temperature and 0 °C. • A wide variation in microhardness exists across different zone of the weldments. - Abstract: Experimental investigations were carried out to study the influence of three different groove designs on mechanical and metallurgical properties of 15 mm thick Q and T (quenched and tempered) steel welded joints. Welding heat input variation corresponding to each joint configuration was kept to a minimal such that the objective of investigating, exclusively, the effect of varied weld volume on the mechanical and metallurgical performance of these joints could be accomplished. Mechanical performance of these joints was evaluated by subjecting them to transverse tensile testing, and Charpy V-notch impact testing of the weld zones at room temperature and 0 °C. The results of this study reveal that among all types of groove formations used for welding, double-V groove joint possessed maximum YS (yield strength) and UTS (ultimate tensile strength), besides maximum strength ratio (YS/UTS) that was followed by U-groove joint and C-groove joint, respectively. However, weld zone tested individually, for the cover as well as the root pass of the C-groove joint possessed highest CVN (Charpy V-notch) values, both at room temperature and 0 °C. Extensive microhardness studies of these weldments showed a wide variation in the microhardness values of the weld zone and the HAZ (heat affected zone). It was concluded that each groove formation/design exerted a significant influence on the heat dissipation characteristics of these joints, which is evident from different morphological features as revealed through optical microscopy. Scanning electron microscopic

  5. Fracture Mechanics Approach to X-Ray Diffraction Method for Spot Welded Lap Joint Structure of Rolled Steel Considered Residual Stress

    International Nuclear Information System (INIS)

    Baek, Seung Yeb; Bae, Dong Ho

    2011-01-01

    Cold and hot-rolled carbon steel sheets are commonly used in railroad cars or commercial vehicles such as the automobile. The sheets used in these applications are mainly fabricated by spot welding, which is a type of electric resistance welding. However, the fatigue strength of a spot-welded joint is lower than that of the base metal because of high stress concentration at the nugget edge of the spot-welded part. In particular, the fatigue strength of the joint is influenced by not only geometrical and mechanical factors but also the welding conditions for the spot-welded joint. Therefore, there is a need for establishing a reasonable criterion for a long-life design for spot-welded structures. In this thesis, ΔP-N f relation curves have been used to determine a long-life fatigue-design criterion for thin-sheet structures. However, as these curves vary under the influence of welding conditions, mechanical conditions, geometrical factors, etc. It is very difficult to systematically determine a fatigue-design criterion on the basis of these curves. Therefore, in order to eliminate such problems, the welding residual stresses generated during welding and the stress distributions around the weld generated by external forces were numerically and experimentally analyzed on the basis of the results, reassessed fatigue strength of gas welded joints

  6. Friction stir welding (FSW process of copper alloys

    Directory of Open Access Journals (Sweden)

    M. Miličić

    2016-01-01

    Full Text Available The present paper analyzes the structure of the weld joint of technically pure copper, which is realized using friction stir welding (FSW. The mechanism of thermo-mechanical processes of the FSW method has been identified and a correlation between the weld zone and its microstructure established. Parameters of the FSW welding technology influencing the zone of the seam material and the mechanical properties of the resulting joint were analyzed. The physical joining consists of intense mixing the base material along the joint line in the “doughy” phase. Substantial plastic deformations immediately beneath the frontal surface of tool provide fine-grained structure and a good quality joint. The optimum shape of the tool and the optimum welding regime (pressure force, rotation speed and the traverse speed of the tool in the heat affected zone enable the achievement of the same mechanical properties as those of the basic material, which justifies its use in welding reliable structures.

  7. The use of field indentation microprobe in measuring mechanical properties of welds

    International Nuclear Information System (INIS)

    Haggag, F.M.; Wong, H.; Alexander, D.J.; Nanstad, R.K.

    1989-01-01

    A field indentation microprobe (FIM) was conceived for evaluating the structural integrity of metallic components (including base metal, welds, and heat-affected zones) in situ in a nondestructive manner. The FIM consists of an automated ball indentation (ABI) unit for determining the mechanical properties (yield strength, flow properties, estimates of fracture toughness, etc.) and a nondestructive evaluation (NDE) unit (consisting of ultrasonic transducers and a video camera) for determining the physical properties such as crack size, material pileup around indentation, and residual stress presence and orientation. The laboratory version used in this work performs only ABI testing. ABI tests were performed on stainless steel base metal (type 316L), heat-affected zone, and welds (type 308). Excellent agreement was obtained between yield strength and flow properties (true-stress/true-plastic-strain curve) measured by the ABI tests and those from uniaxial tensile tests conducted on 308 stainless steel welds, thermally aged at 343/degree/C for different times, and on the base material. 4 refs., 17 figs

  8. A study on the mechanical stress relieving and safety assessment without post-weld heat treatment

    International Nuclear Information System (INIS)

    Xu Jijin; Chen Ligong; Ni Chunzhen

    2007-01-01

    For full welded body valve, the temperature of grommet cannot exceed 150 deg. C in order to prevent it from damaging and assure the tightness and the service life of valve. Therefore, post-weld heat treatment (PWHT) cannot be used to relieve the residual stresses. In this study, the effect of the mechanical stress relieving (MSR) treatment on the residual stresses was studied by the finite element method and experimental work. A pressure and time diagram of MSR treatment was established. A two-dimensional axisymmetric finite element model was used to simulate the residual stresses field. Before and after MSR treatment, the residual stresses on the outer surface were measured by the blind hole drilling method. Finally, the fracture toughness behaviors of weld zone (WZ) and heat affected zone (HAZ) were investigated in terms of crack tip opening displacement (CTOD) according to BS7448 and DNV-OS-C401 fracture toughness tests standards. The safety of the valve in active service was assessed without PWHT. Through comparison and analysis, the axial residual stresses and the hoop residual stresses on the outer surface of valve are mainly tensile. The peak value of tensile stress occurs nearer to the outer surface of the valve. MSR treatment can decrease the peak value of axial residual stresses and hoop residual stresses on the outer surface obviously and make the residual stresses distribution more uniform. The safety of the valve in active service is reliable without PWHT

  9. Effect of vibration on microstructures and mechanical properties of 304 stainless steel GTA welds

    Science.gov (United States)

    Hsieh, Chih-Chun; Lai, Chien-Hong; Wu, Weite

    2013-07-01

    This study investigates the microstructures and mechanical properties of 304 stainless steel at various vibration frequencies during simultaneous vibration welding. The experimental results demonstrated that simultaneous vibration welding could accelerate the nucleation and grain refinement of the microstructures. The effect of the grain refinement was more evident at the resonant frequency (375 Hz) and a minimum content of residual δ-ferrite (4.0%). The γ phase grew in the preferential orientation of the (111) direction with and without vibration. The full width at half maximum of the diffraction peak widened after the vibration, which was attributed to the grain refinement. The residual stress could be efficiently removed through simultaneous vibration welding when the amplitude of the vibration was increased. Furthermore, the lowest residual stress (139 MPa) was found when the vibration frequency was 375 Hz. The hardness and Young's modulus exhibited slight increases with low and medium frequencies. The hardness values were increased by 7.6% and Young's modulus was increased by 15% when the vibration frequency was resonant (375 Hz).

  10. Microstructural and Mechanical Properties of Welded High Strength Steel Plate Using SMAW and SAW Method for LPG Storage Tanks

    Science.gov (United States)

    Winarto, Winarto; Riastuti, Rini; Kumeidi, Nur

    2018-03-01

    Indonesian government policy to convert energy consumption for domestic household from kerosene to liquefied petroleum gas (LPG) may lead to the increasing demand for LPG storage tank. LPG storage tank with a large capacity generally used the HSLA steel material of ASTM A516 Grade 70 joined by SMAW or combination between SMAW and SAW method. The heat input can affect the microstructure and mechanical properties of the weld area. The input heat is proportional to the welding current and the arc voltage, but inversely proportional to its welding speed. The result shows that the combination of SMAW-SAW process yield the lower hardness in the HAZ and the fusion zone compared to the singe SMAW process. PWHT mainly applied to reduce residual stress of welded joint. The result shows that PWHT can reduce the hardness in the HAZ and the fusion zone in comparing with the singe SMAW process. The microstructure of weld joint shows a coarser structure in the combined welding process (SMAW-SAW) comparing with the single welding process (SMAW).

  11. Effects of Sc and Zr on mechanical property and microstructure of tungsten inert gas and friction stir welded aerospace high strength Al–Zn–Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Ying, E-mail: csudengying@163.com [School of Metallurgy and Environment, Central South University, Hunan, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China); State Key Laboratory for Power Metallurgy, Central South University, Hunan, Changsha 410083 (China); Peng, Bing [School of Metallurgy and Environment, Central South University, Hunan, Changsha 410083 (China); Xu, Guofu, E-mail: csuxgf66@csu.edu.cn [School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China); State Key Laboratory for Power Metallurgy, Central South University, Hunan, Changsha 410083 (China); Pan, Qinglin; Yin, Zhimin; Ye, Rui [School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China); Wang, Yingjun; Lu, Liying [Northeast Light Alloy Co. Ltd., Hei Longjiang, Harbin 150060 (China)

    2015-07-15

    New aerospace high strength Al–Zn–Mg and Al–Zn–Mg–0.25Sc–0.10Zr (wt%) alloys were welded by tungsten inert gas (TIG) process using a new Al–6.0Mg–0.25Sc–0.10Zr (wt%) filler material, and friction stir welding (FSW) process, respectively. Mechanical property and microstructure of the welded joints were investigated comparatively by tensile tests and microscopy methods. The results show that Sc and Zr can improve the yield strength and ultimate tensile strength of Al–Zn–Mg alloy by 59 MPa (23.3%) and 16 MPa (4.0%) in TIG welded joints, and by 77 MPa (23.8%) and 54 MPa (11.9%) in FSW welded joints, respectively. The ultimate tensile strength and elongation of new Al–Zn–Mg–Sc–Zr alloy FSW welded joint are 506±4 MPa and 6.34±0.2%, respectively, showing superior post welded performance. Mechanical property of welded joint is mainly controlled by its “weakest microstructural zone”. TIG welded Al–Zn–Mg and Al–Zn–Mg–Sc–Zr alloys reinforced with weld bead both failed at fusion boundaries. Secondary Al{sub 3}Sc{sub x}Zr{sub 1−x} particles originally present in parent alloy coarsen during TIG welding process, but they can restrain the grain growth and recrystallization here, thus improving welding performance. For two FSW welded joints, fracture occurred in weld nugget zone. Secondary Al{sub 3}Sc{sub x}Zr{sub 1−x} nano-particles almost can keep unchangeable size (20–40 nm) across the entire FSW welded joint, and thus provide effective Orowan strengthening, grain boundary strengthening and substructure strengthening to strengthen FSW joints. The positive effect from Sc and Zr additions into base metals can be better preserved by FSW process than by TIG welding process.

  12. Effects of Sc and Zr on mechanical property and microstructure of tungsten inert gas and friction stir welded aerospace high strength Al–Zn–Mg alloys

    International Nuclear Information System (INIS)

    Deng, Ying; Peng, Bing; Xu, Guofu; Pan, Qinglin; Yin, Zhimin; Ye, Rui; Wang, Yingjun; Lu, Liying

    2015-01-01

    New aerospace high strength Al–Zn–Mg and Al–Zn–Mg–0.25Sc–0.10Zr (wt%) alloys were welded by tungsten inert gas (TIG) process using a new Al–6.0Mg–0.25Sc–0.10Zr (wt%) filler material, and friction stir welding (FSW) process, respectively. Mechanical property and microstructure of the welded joints were investigated comparatively by tensile tests and microscopy methods. The results show that Sc and Zr can improve the yield strength and ultimate tensile strength of Al–Zn–Mg alloy by 59 MPa (23.3%) and 16 MPa (4.0%) in TIG welded joints, and by 77 MPa (23.8%) and 54 MPa (11.9%) in FSW welded joints, respectively. The ultimate tensile strength and elongation of new Al–Zn–Mg–Sc–Zr alloy FSW welded joint are 506±4 MPa and 6.34±0.2%, respectively, showing superior post welded performance. Mechanical property of welded joint is mainly controlled by its “weakest microstructural zone”. TIG welded Al–Zn–Mg and Al–Zn–Mg–Sc–Zr alloys reinforced with weld bead both failed at fusion boundaries. Secondary Al 3 Sc x Zr 1−x particles originally present in parent alloy coarsen during TIG welding process, but they can restrain the grain growth and recrystallization here, thus improving welding performance. For two FSW welded joints, fracture occurred in weld nugget zone. Secondary Al 3 Sc x Zr 1−x nano-particles almost can keep unchangeable size (20–40 nm) across the entire FSW welded joint, and thus provide effective Orowan strengthening, grain boundary strengthening and substructure strengthening to strengthen FSW joints. The positive effect from Sc and Zr additions into base metals can be better preserved by FSW process than by TIG welding process

  13. Comparing the Structure and Mechanical Properties of Welds on Ductile Cast Iron (700 MPa under Different Heat Treatment Conditions

    Directory of Open Access Journals (Sweden)

    Ronny M. Gouveia

    2018-01-01

    Full Text Available The weldability of ductile iron, as widely known, is relatively poor, essentially due to its typical carbon equivalent value. The present study was developed surrounding the heat treatability of welded joints made with a high strength ductile cast iron detaining an ultimate tensile strength of 700 MPa, and aims to determine which heat treatment procedures promote the best results, in terms of microstructure and mechanical properties. These types of alloys are suitable for the automotive industry, as they allow engineers to reduce the thickness of parts while maintaining mechanical strength, decreasing the global weight of vehicles and providing a path for more sustainable development. The results allow us to conclude that heat treatment methodology has a large impact on the mechanical properties of welded joints created from the study material. However, the thermal cycles suffered during welding promote the formation of ledeburite areas near the weld joint. This situation could possibly be dealt through the implementation of post-welding heat treatments (PWHT with specific parameters. In contrast to a ductile cast iron tested in a previous work, the bull-eye ductile cast iron with 700 MPa ultimate tensile strength presented better results during the post-welding heat treatment than during preheating.

  14. The Effects of Nitrogen Gas on Microstructural and Mechanical Properties of TIG Welded S32205 Duplex Stainless Steel

    Directory of Open Access Journals (Sweden)

    Aziz Barış Başyiğit

    2018-04-01

    Full Text Available Duplex stainless steels are gaining greater interest due to their increasing amounts of application fields. Accordingly, there is a need for awareness of problems associated with improper microstructural distributions such as δ-ferrite (delta-ferrite, austenite and other important intermetallic phases that may form in these steel weldments. Since δ-ferrite versus austenite ratio profoundly influences corrosion and mechanical properties, optimum δ-ferrite ratios must be kept approximately within 35–65 vol % and balance austenite to maintain satisfactory corrosion and mechanical properties on welding of these steels. Cooling rates of welds and alloying elements in base metal are the major factors that determine the final microstructure of these steels. In this work, 3 mm thickness of 2205 duplex stainless-steel plates were TIG (Tungsten Inert Gas welded with various amounts of nitrogen gas added to argon shielding gas. Specimens were joined within the same welding parameters and cooling conditions. As nitrogen is a potential austenite stabilizer and an interstitial solid solution hardener, the effects of nitrogen on mechanical properties such as hardness profiles, grain sizes and microstructural modifications are investigated thoroughly by changing the welding shielding gas compositions. Increasing the nitrogen content in argon shielding gas also increases the amount of austenitic phase while δ-ferrite ratios decreases. Nitrogen spherodized the grains of austenitic structure much more than observed in δ-ferrite. The strength values of specimens that welded with the addition of nitrogen gas into the argon shielding gas are increased more in both austenitic and delta-ferritic structure as compared to specimens that welded with plain argon shielding gas. The addition of 1 vol % of nitrogen gas into argon shielding gas provided the optimum phase balance of austenite and δ-ferrite in S32205 duplex stainless-steel TIG-welded specimens.

  15. Fracture mechanics characterisation of the WWER-440 reactor pressure vessel beltline welding seam of Greifswald unit 8

    International Nuclear Information System (INIS)

    Viehrig, Hans-Werner; Schuhknecht, Jan

    2008-01-01

    WWER-440 second generation (V-213) reactor pressure vessels (RPV) were produced by IZHORA in Russia and by SKODA in the former Czechoslovakia. The surveillance Charpy-V and fracture mechanics SE(B) specimens of both producers have different orientations. The main difference is the crack extension direction which is through the RPV thickness and circumferential for ISHORA and SKODA RPV, respectively. In particular for the investigation of weld metal from multilayer submerged welding seams the crack extension direction is of importance. Depending on the crack extension direction in the specimen there are different welding beads or a uniform structure along the crack front. The specimen orientation becomes more important when the fracture toughness of the weld metal is directly determined on surveillance specimens according to the Master Curve (MC) approach as standardised in the ASTM Standard Test Method E1921. This approach was applied on weld metal of the RPV beltline welding seam of Greifswald Unit 8 RPV. Charpy size SE(B) specimens from 13 locations equally spaced over the thickness of the welding seam were tested. The specimens are in TL and TS orientation. The fracture toughness values measured on the SE(B) specimens with both orientations follow the course of the MC. Nearly all values lie within the fracture toughness curves for 5% and 95% fracture probability. There is a strong variation of the reference temperature T 0 though the thickness of the welding seam, which can be explained with structural differences. The scatter is more pronounced for the TS SE(B) specimens. It can be shown that specimens with TS and TL orientation in the welding seam have a differentiating and integrating behaviour, respectively. The statistical assumptions behind the MC approach are valid for both specimen orientations even if the structure is not uniform along the crack front. By comparison crack extension, JR, curves measured on SE(B) specimens with TL and TS orientation show

  16. Some studies on mechanical properties and microstructural characterization of automated TIG welding of thin commercially pure titanium sheets

    Energy Technology Data Exchange (ETDEWEB)

    Karpagaraj, A.; Siva shanmugam, N., E-mail: nsiva@nitt.edu; Sankaranarayanasamy, K.

    2015-07-29

    Gas Tungsten Arc Welding (GTAW) is a commonly used welding process for welding Titanium materials. Welding of titanium and its alloys poses several intricacies to the designer as they are prone to oxidation phenomenon. To overcome this contamination, a relatively new type of shielding arrangement is experimented. The proposed design and arrangement have been employed for joining commercially pure titanium sheets with variations in the GTAW process parameters namely the welding current and travel speed. Bead on plate (BoP) trials were conducted on thin sheets of 2 mm thickness by varying the process parameters. Subsequently, the macro structure images were captured. Based on these results, the process parameters are chosen for carrying out full penetration butt joints on 1.6 mm and 2 mm thick titanium sheets. The influences of these parameters of GTAW on the microstructure, mechanical properties and surface morphology at the fractured locations of the welded joints are examined. The microstructural properties of base metal, heat affected zone and fusion zone are analyzed through optical microscopy. The welded joints showed an ultimate tensile strength of about 383 MPa with 15.7% elongation. The hardness value at fusion zone and base metal are typically observed to be 191 and 153 HV-0.5, respectively. X-ray diffraction study is conducted to examine the chemical composition in the parent metal and fusion zone of the weld. Fractured surface is examined using Scanning Electron Microscopy which revealed dimple kind of rupture present at the fractured surfaces owing to insufficient or excessive heat with slight impurities that prevents the accomplishment of stronger micro-level weld integrity.

  17. Some studies on mechanical properties and microstructural characterization of automated TIG welding of thin commercially pure titanium sheets

    International Nuclear Information System (INIS)

    Karpagaraj, A.; Siva shanmugam, N.; Sankaranarayanasamy, K.

    2015-01-01

    Gas Tungsten Arc Welding (GTAW) is a commonly used welding process for welding Titanium materials. Welding of titanium and its alloys poses several intricacies to the designer as they are prone to oxidation phenomenon. To overcome this contamination, a relatively new type of shielding arrangement is experimented. The proposed design and arrangement have been employed for joining commercially pure titanium sheets with variations in the GTAW process parameters namely the welding current and travel speed. Bead on plate (BoP) trials were conducted on thin sheets of 2 mm thickness by varying the process parameters. Subsequently, the macro structure images were captured. Based on these results, the process parameters are chosen for carrying out full penetration butt joints on 1.6 mm and 2 mm thick titanium sheets. The influences of these parameters of GTAW on the microstructure, mechanical properties and surface morphology at the fractured locations of the welded joints are examined. The microstructural properties of base metal, heat affected zone and fusion zone are analyzed through optical microscopy. The welded joints showed an ultimate tensile strength of about 383 MPa with 15.7% elongation. The hardness value at fusion zone and base metal are typically observed to be 191 and 153 HV-0.5, respectively. X-ray diffraction study is conducted to examine the chemical composition in the parent metal and fusion zone of the weld. Fractured surface is examined using Scanning Electron Microscopy which revealed dimple kind of rupture present at the fractured surfaces owing to insufficient or excessive heat with slight impurities that prevents the accomplishment of stronger micro-level weld integrity

  18. Effect of filler metals and heat treatment on mechanical properties of welded joints of the VT20L and VT6L titanium cast alloys

    International Nuclear Information System (INIS)

    Abramova, V.N.; Polyakov, D.A.; Vas'kin, Yu.V.; Kulikov, F.R.; Prostov, I.A.; Yasinskij, K.K.

    1979-01-01

    Developed is a technology of welding and heat treatment of the VT20L and VT6L alloys, providing the mechanical properties of welds on the base metal level. It is found, that for residual stress relieving it is quite enough to anneal the alloys at 650 deg C. Welding of the investigated alloys up to 20 mm thick using SPT-2 additional wire provides the welded joint strength on a level of 0.8 σsub(u) of base metal. Usage of additional wire of base metal provides equal strength of welds and base metal

  19. Forming mechanism and avoiding measures of blue-ring on electronic beam welding sample after water corrosion

    International Nuclear Information System (INIS)

    Ren Defang; Luo Xiandian; Tong Shenxiu; Guo Xulin; Peng Haiqing

    2001-01-01

    After water corrosion in compliance with ASTM G2, the blue ring appears on the nuclear fuel rod samples of AFA 2G welded by using a Big Chamber Electron Beam Welder made in Russia. The characteristics, appearance, chemical composition, microstructure of b lue ring a nd some condition test are described. The mechanism of forming blue ring may be depicted as following: welding metal vapor and the splash produced by secondary and scatter electrons on metal clamp and gun body deposit in the area between HAZ and substrate because of the water cooling down effects on the clamp; these deposits, after water corrosion, appears as blue ring on the fuel rod surface. Avoiding measure is that the side of the clamp closing to weld seal is chamfered, while making the welding chamber cleaner

  20. Very High Cycle Fatigue Crack Initiation Mechanism in Nugget Zone of AA 7075 Friction Stir Welded Joint

    Directory of Open Access Journals (Sweden)

    Chao He

    2017-01-01

    Full Text Available Very high cycle fatigue behavior of nugget zone in AA 7075 friction stir welded joint was experimentally investigated using ultrasonic fatigue testing system (20 kHz to clarify the crack initiation mechanism. It was found that the fatigue strength of nugget zone decreased continuously even beyond 107 cycles with no traditional fatigue limits. Fatigue cracks initiated from the welding defects located at the bottom side of the friction stir weld. Moreover, a special semicircular zone could be characterized around the crack initiation site, of which the stress intensity factor approximately equaled the threshold of fatigue crack propagation rate. Finally, a simplified model was proposed to estimate the fatigue life by correlating the welding defect size and applied stress. The predicted results are in good agreement with the experimental results.

  1. Examination of structure and mechanical properties of hard-to-weld metal joints obtained with the laser method

    International Nuclear Information System (INIS)

    Czujko, T.; Przetakiewicz, W.; Jozwiak, S.; Hoffman, J.; Kalita, W.

    1995-01-01

    Metal joints of stainless of type X6CrNiMoTi1722 (according to DIN) and high conductivity (HC) copper, and joints of transformer steel containing about 3.5% of silicon were obtained using metal sheets 2 mm in thickness. The microstructure and the distribution of microhardness in the area of the joint, and the changes of the strength and elongation caused by the process of laser welding were examined with reference to the properties of the native metal; and, in the case of transformer steel-joints, the effects of welding by means of the TIG method were also analyzed. A probable mechanism of the formation of the steel-copper joint was presented, the strength of which is comparable with that of copper. The superiority of laser welding over TIG welding was also demonstrated. (author). 11 refs, 4 figs, 1 tab

  2. Study on production mechanism of welding residual stress at the juncture of a pipe penetrating a thick plate

    International Nuclear Information System (INIS)

    Mochizuki, Masahito; Enomoto, Kunio; Okamoto, Noriaki; Saitoh, Hideyo; Hayashi, Eisaku.

    1994-01-01

    This paper studies welding residual stresses at the intersection of a small diameter pipe penetrating a thick plate. The pipe is welded to the plate, and Tungsten Innert Gas (TIG) cladding is melted on the inner surface of the pipe to protect it from stress corrosion cracking due to long operation in nuclear power plants. Stresses are calculated by heat conduction analysis and thermal elasto-plastic analysis, and also measured by strain gauges. Welding residual stresses are shown to have no corrosive influence on the inner pipe surface, and the stresses are compressed enough to protect the pipe against stress corrosion cracking on the outer surface. It was also studied to make clear the production mechanism of the residual stresses which were generated by welding processes at the pipe. (author)

  3. Effects of Different Filler Metals on the Mechanical Behaviors of GTA Welded AA7A52(T6)

    Science.gov (United States)

    Shu, Fengyuan; Lv, Yaohui; Liu, Yuxin; Lin, Jianjun; Sun, Zhe; Xu, Binshi; He, Peng

    2014-06-01

    ER4043, ER5356, and AA7A52 on behalf of the Al-Si, Al-Mg, and Al-Zn-Mg-based welding material, respectively, were chosen as the filler metal to weld AA7A52(T6) plates by GTAW. The variance in mechanical performances of the joints caused by the various filler materials was investigated with reference to the SEM and EDS test results for the weld seam and the fracture surface. Failure was found in the seam for all the welded joints. With regard to the joint obtained with ER4043 welding wire, the total elongation was limited by the brittle intergranular compound Mg2Si of which Mg was introduced by convection mass transfer. As for the other two welds, the content ratio of Zn and Mg was found to play the dominant role in deciding the mechanical properties of the intergranular Mg-Zn compounds which were responsible for the tensile behavior of the joints. The content ratio (wt.%) of beyond 2:1 gave birth to the strengthening phase MgZn2 leading to a ductile fracture. Cr in the seam obtained with AA7A52 filler metal was found to enhance the strength of the joint through isolated particles.

  4. The Effect of Tool Profiles on Mechanical Properties of Friction Stir Welded Al5052 T-Joints.

    Science.gov (United States)

    Kim, Byeong-Jin; Bang, Hee-Seon; Bang, Han-Sur

    2018-03-01

    Al5052 T butt joints with two skins (5 mm) and one stringer (3 mm) has been successfully welded by friction stir welding (FSW). Notably, this paper has been investigated the effect of tool shape on welded formation mechanism and mechanical properties. The used shapes of tool pin are two types which are cylinder (type 1) and frustum (type 2). Dimension on two types of tool pin shape is respectively pin length of 4.7 mm and pin diameter of frustum type of top (5 mm) and bottom (3 mm). The results of experiment show that inner defects in FSWed T-joints increase significantly in accordance with traverse speed. The maximum tensile strength of welded joint fabricated using type 1 is equivalent to 85% that of the base metal, which is approximately 10% higher than that of type 2. Because welded joint of type 1 has more smoothly plastic flow in comparison with type 2. Consequently, the results show that type 1 is better appropriate for friction stir welded Al5052 T butt joints than type 2.

  5. The application of linear elastic fracture mechanics to thermally stressed welded components

    International Nuclear Information System (INIS)

    Green, D.

    1981-01-01

    Linear Elastic Fracture Mechanics techniques are applied to components constructed from brittle materials and operating at low or ambient temperatures. It is argued that these techniques can justifiably be applied to components at high temperature provided that stresses are thermally induced, self-equilibrating and cyclic. Such loading conditions occur for example in an LMFBR and a simple welded detail containing a crevice is taken as an example. Theoretical and experimental estimates of crack growth in this component are compared and good agreement is shown. (author)

  6. Effect of scandium additions on microstructure and mechanical properties of Al-Zn-Mg alloy welds

    International Nuclear Information System (INIS)

    Dev, Selvi; Stuart, A. Archibald; Kumaar, R.C. Ravi Dev; Murty, B.S.; Rao, K. Prasad

    2007-01-01

    The microstructure and mechanical properties of fusion zones of medium strength Al-Zn-Mg alloy (RDE-40) welds obtained by using different fillers containing various amount of scandium was investigated. It was observed that addition of scandium led to very significant grain refinement in the fusion zone especially for scandium levels greater than the eutectic composition (0.55 wt%). The grain refinement led to the reduction in solidification cracking and improved the tensile properties of fusion zone compared to the ones obtained by the commercial AA5556 filler

  7. Mechanism of formation and methods of removing magnetic blowing in welding

    International Nuclear Information System (INIS)

    Korol'kov, P.

    1998-01-01

    All welding processes using the electric arc or electron beams are characterised by the detrimental effect of magnetic fields: the electrons of the welding arc are subjected to the effect of the magnetic force distorting their trajectory. In most cases, the arc is deflected along the area of preparation for welding but, in this case, a natural magnetic field forms around the are and, consequently, arc in his unstable and, under severe conditions, the arc breaks up. The effect of the magnetic field of the welding are depends not only on its strength but also the shape and the depth of the area of preparation for welding, the specific pass in welding and arc voltage. Thus, the effect of the magnetic fields is the strongest in the deep and narrow areas of preparation for welding. In most cases, this effect is stronger in welding the weld root, and in subsequent passes the magnetic flux is shunted by the deposited metal. (author)

  8. Sequential ultrasonic spot welding of thermoplastic composites : An experimental study on the welding process and the mechanical behaviour of (multi-)spot welded joints

    NARCIS (Netherlands)

    Zhao, T.

    2018-01-01

    The popularity of thermoplastic composites (TPCs) has been growing steadily in the last decades in the aircraft industry. This is not only because of their excellent material properties, but also owing to their fast and cost-effective manufacturing process. Fusion bonding, or welding, is a typical

  9. Microstructure and mechanical properties of weld-bonded and resistance spot welded magnesium-to-steel dissimilar joints

    International Nuclear Information System (INIS)

    Xu, W.; Chen, D.L.; Liu, L.; Mori, H.; Zhou, Y.

    2012-01-01

    Highlights: ► Adhesive reduces shrinkage porosity and stress concentration around the weld nugget. ► Adhesive promotes the formation of intermetallic compounds during weld bonding. ► In Mg/steel joints fusion zone appears only at the Mg side with dendritic structures. ► Weld-bonded Mg/steel joints are considerably stronger than RSW Mg/steel joints. ► Fatigue strength is three-fold higher for weld-bonded joints than for RSW joints. - Abstract: The aim of this study was to evaluate microstructures, tensile and fatigue properties of weld-bonded (WB) magnesium-to-magnesium (Mg/Mg) similar joints and magnesium-to-steel (Mg/steel) dissimilar joints, in comparison with resistance spot welded (RSW) Mg/steel dissimilar joints. In the WB Mg/Mg joints, equiaxed dendritic and divorced eutectic structures formed in the fusion zone (FZ). In the dissimilar joints of RSW and WB Mg/steel, FZ appeared only at Mg side with equiaxed and columnar dendrites. At steel side no microstructure changed in the WB Mg/steel joints, while the microstructure in the RSW Mg/steel joints consisted of lath martensite, bainite, pearlite and retained austenite leading to an increased microhardness. The relatively low cooling rate suppressed the formation of shrinkage porosity but promoted the formation of MgZn 2 and Mg 7 Zn 3 in the WB Mg/steel joints. The added adhesive layer diminished stress concentration around the weld nugget. Both WB Mg/Mg and Mg/steel joints were significantly stronger than RSW Mg/steel joints in terms of the maximum tensile shear load and energy absorption, which also increased with increasing strain rate. Fatigue strength was three-fold higher for WB Mg/Mg and Mg/steel joints than for RSW Mg/steel joints. Fatigue failure in the RSW Mg/steel joints occurred from the heat-affected zone near the notch root at lower load levels, and in the mode of interfacial fracture at higher load levels, while it occurred in the Mg base metal at a maximum cyclic load up to ∼10 kN in

  10. A metallurgical and mechanical study on dissimilar Friction Stir welding of aluminum 1050 to brass (CuZn30)

    International Nuclear Information System (INIS)

    Esmaeili, A.; Givi, M.K. Besharati; Rajani, H.R. Zareie

    2011-01-01

    Highlights: → Brass and aluminum 1050 are joined for the first time through Friction Stir welding. → Welding parameters are optimized to obtain a sound joint. → The ultimate tensile strength of the sound joint reaches 80% of aluminum base metal. → The effect of interfacial intermetallic compounds on mechanical properties is probed. → CuZn, Cu9Al4 and CuAl2 form the majority of observed intermetallic compounds. - Abstract: In this research, the effect of Friction Stir welding parameters on mechanical and metallurgical properties of aluminum 1050/brass (70%Cu-30%Zn) joints was investigated. Optical microscopy, SEM, X-ray diffraction analysis and EDS analysis were used to probe microstructures and chemical compositions. In order to examine mechanical properties, besides hardness test, tensile strength of the welds was measured. The main parameters in this study were the tool rotational speed, offset, welding speed, and depth of the sinking pin. The maximum ultimate tensile strength of the joint reached in this research was 80% of the base metal (aluminum). Results show that the optimum parameters will yield a defect free joint arisen from a suitable material flow and a narrow multilayer intermetallic compound at interface in addition to a composite structure in the stir zone which all result in a strong joint. Also, by leaving the optimized condition, occurrence of large brass fragments and weld defects lower weld strength besides shifting fracture path from interface to the stir zone. Also, according to the results, using low rotation speed is accompanied by disappearance of interfacial intermetallic layer, whereas fast rotation will thicken this layer. Moreover, severe mechanical twining is observed in TMAZ of brass which leads to high values of hardness in this region.

  11. Analysis of residual stress relief mechanisms in post-weld heat treatment

    International Nuclear Information System (INIS)

    Dong, Pingsha; Song, Shaopin; Zhang, Jinmiao

    2014-01-01

    This paper presents a recent study on weld residual stress relief mechanisms associated with furnace-based uniform post-weld heat treatment (PWHT). Both finite element and analytical methods are used to quantitatively examine how plastic deformation and creep relaxation contribute to residual stress relief process at different stages of PWHT process. The key contribution of this work to an improved understanding of furnace based uniform PWHT can be summarized as follows: (1)Plastic deformation induced stress relief during PWHT can be analytically expressed by the change in material elastic deformation capacity (or elastic deformation limit) measured in terms of material yield strength to Young's modulus ratio, which has a rather limited role in overall residual stress relief during furnace based uniform PWHT. (2)The most dominant stress relief mechanism is creep strain induced stress relaxation, as expected. However, a rapid creep strain development accompanied by a rapid residual stress reduction during heating stage before reaching PWHT temperature is shown to contribute to most of the stress relief seen in overall PWHT process, suggesting PWHT hold time can be significantly reduced as far as residual stress relief is concerned. (3)A simple engineering scheme for estimating residual stress reduction is proposed based on this study by relating material type, PWHT temperature, and component wall thickness. - Highlights: • The paper clarified effects of plastic deformation and creep relaxation on weld residual stress relief during uniform PWHT. • Creep strain development is far more important than plastic strain, mostly completed even before hold time starts. • Plastic strain development is insignificant and be analytically described by a material elastic deformation capacity parameter. • An engineering estimation scheme is proposed for determining residual stress reduction resulted from furnace based PWHT

  12. Grain boundary defects initiation at the outer surface of dissimilar welds: corrosion mechanism studies

    International Nuclear Information System (INIS)

    De Bouvier, O.; Yrieix, B.

    1995-11-01

    Dissimilar welds located on the primary coolant system of the French PWR I plants exhibit grain boundary defects in the true austenitic zones of the first buttering layer. If grain boundaries reach the interface, they can extend to the martensitic band. Those defects are filled with compact oxides. In addition, the ferritic base metal presents some pits along the interface. Nowadays, three mechanisms are proposed to explain the initiation of those defects: stress corrosion cracking, intergranular corrosion and high temperature intergranular oxidation. This paper is dealing with the study of the mechanisms involved in the corrosion phenomenon. Intergranular corrosion tests performed on different materials show that only the first buttering layer, even with some δ ferrite, is sensitized. The results of stress corrosion cracking tests in water solutions show that intergranular cracking is possible on a bulk material representative of the first buttering layer. It is unlikely on actual dissimilar welds where the ferritic base metal protects the first austenitic layer by galvanic coupling. Therefore, the stress corrosion cracking assumption cannot explain the initiation of the defects in aqueous environment. The results of the investigations and of the corrosion studies led to the conclusion that the atmosphere could be the only possible aggressive environment. This conclusion is based on natural atmospheric exposure and accelerated corrosion tests carried out with SO 2 additions in controlled atmosphere. They both induce a severe intergranular corrosion on true sensitized austenitic materials. This corrosion studies cannot conclude definitively on the causes of the defect initiation on field, but they show that the atmospheric corrosion could produce intergranular attacks in the pure austenitic zones of the first buttering layer of the dissimilar welds and that this corrosion is stress assisted. (author). 1 ref., 6 figs., 4 tabs

  13. Repair welding of cracked steam turbine blades

    International Nuclear Information System (INIS)

    Bhaduri, A.K.; Gill, T.P.S.; Albert, S.K.; Shanmugam, K.; Iyer, D.R.

    1999-01-01

    The procedure for repair welding of cracked steam turbine blades made of martensitic stainless steels has been developed using the gas tungsten arc welding process. Weld repair procedures were developed using both ER316L austenitic stainless steel filler wire and ER410 martensitic stainless steel filler wire. The repair welding procedure with austenitic filler wire was developed to avoid preheating of the blade as also hydrogen induced cold cracking, and involved evaluation of three different austenitic filler wires, viz. ER309L, ER316L and ERNiCr-3. The overall development of the repair welding procedure included selection of welding consumables (for austenitic filler metal), optimisation of post weld heat treatment parameters, selection of suitable method for local pre-heating and post-weld heat treatment (PWHT) of the blades, determination of mechanical properties of weldments in as-welded and PWHT conditions, and microstructural examination. After various trials using different procedures, the procedure of local PWHT using electrical resistance heating on the top surface of the weldment and monitoring the temperature by placing a thermocouple at the bottom of the weld, was found to give the most satisfactory results. A similar procedure was used for preheating while using ER410 filler metal. Mechanical testing of weldments before and after PWHT involved tensile tests at room temperature, face and root bend tests, and microhardness measurements across the fusion line and heat affected zone. During procedure qualification, mock-ups and actual repair welding, dye penetrant testing was used at different stages and where ever possible radiography was carried out. These procedures were developed for repair welding of cracked blades in the low-pressure (LP) steam turbines of Indian nuclear power plants. The procedure with ER316 L filler wire has so far been applied for repair welding of 2 cracked blades (made of AISI 410 SS) of LP steam turbines, while the procedure

  14. Mechanical design of injection line for VEC

    International Nuclear Information System (INIS)

    Nandi, C.; Bandopadhyay, D.K.; Pal, G.; Sharma, R.N.; Mallik, C.; Chaudhuri, J.; Bhandari, R.K.

    2003-01-01

    A 14.5 GHz ECR ion source along with its analyzing section was earlier installed at VECC for injecting multiply charged gaseous and metallic ions into the existing K 130 cyclotron. The injection line from this ECR ion source was connected to the vertical section of the existing injection line for integrating it with the K 130 cyclotron. The injection line comprises two solenoid magnets, a steering magnet, and a bending magnet. In between the solenoid magnets a length about 1.5 metres has been provided for future atomic physics experimental applications. Two gate valves are used to isolate this area. For beam diagnostics, two Faraday cups, designed and fabricated in this centre, have been installed

  15. Weldability and mechanical property characterization of weld clad alloy 800H tubesheet forging

    International Nuclear Information System (INIS)

    King, J.F.; McCoy, H.E.

    1984-09-01

    The weldability of an alloy 800H forging that simulates a steam generator tubesheet is studied. Weldability was of concern because a wide range of microstructures was present in this forging. The top and portions of the bottom were weld clad with ERNiC-3 weld metal to a thickness of 19 mm similar to that anticipated for HTGR steam generators. Examinations of the clad fusion line in various regions revealed no weldability problems except possibly on the bottom portion, which contained large grains and some as-cast structure. A few microfissures were evident in this region, but no excessive hot cracking tendency was observed. The tensile properties in all areas of the clad forging were reasonable and not influenced greatly by the microstructure. The elevated-temperature tests showed strong tendency for fracture in the heat-affected zone of the alloy 800H. Creep failure at 649 0 C consistently occurred in the heat-affected zone of the alloy 800H, but the creep strength exceeded the expected values for alloy 800H

  16. NDE and fracture mechanics evaluation of bottom-head weld indications in a BWR reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Brickstad, B [Swedish Plant Inspectorate, Stockholm (Sweden)

    1988-12-31

    This document deals with the Non Destructive Examination (NDE) and the fracture mechanics evaluation of bottom head welds in a BWR. The NDE equipment is presented, together with the geometry of evaluated flaw regions. After the fracture mechanics evaluation, it appeared that the plant results fulfilled the usual conditions, and the plant was allowed to operate one more year. (TEC).

  17. Enhancement of mechanical properties and corrosion resistance of friction stir welded joint of AA2014 using water cooling

    Energy Technology Data Exchange (ETDEWEB)

    Sinhmar, S., E-mail: sinhmarsunil88@gmail.com; Dwivedi, D.K.

    2017-01-27

    An investigation on the microstructure, mechanical properties, and corrosion behavior of friction stir welded joint of AA2014 in natural cooled (NC) and water cooled (WC) conditions have been reported. Optical microscopy, field emission scanning electron microscopy (FESEM) with Energy dispersive X-ray spectroscopy (EDS), Vicker's microhardness, tensile testing, X-ray diffraction (XRD), and electrochemical potentiodynamic polarization corrosion test (Tafel curve) were carried out to characterize the friction stir weld joints in both the cooling conditions. Water cooling resulted in higher strength and microhardness of friction stir weld joint compared to the natural cooling. The width of heat affected zone was reduced by the use of water cooling during friction stir welding (FSW) and minimum hardness zone was shifted towards weld center. The corrosion test was performed in 3.5% NaCl solution. Corrosion resistance of water cooled joint was found higher than natural cooled FSW joint. The precipitation behavior of weld nugget and heat affected zone impacts the corrosion resistance of FSW joint of AA 2014. Hardness, tensile, and corrosion properties of FSW joints produced under NC and WC conditions have been discussed in the light of microstructure.

  18. Effect of Friction Stir Welding Parameters on the Microstructure and Mechanical Properties of AA2024-T4 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    A. W. El-Morsy

    2018-02-01

    Full Text Available In this work, the effects of rotational and traverse speeds on the 1.5 mm butt joint performance of friction stir welded 2024-T4 aluminum alloy sheets have been investigated. Five rotational speeds ranging from 560 to 1800 rpm and five traverse speeds ranging from 11 to 45 mm/min have been employed. The characterization of microstructure and the mechanical properties (tensile, microhardness, and bending of the welded sheets have been studied. The results reveal that by varying the welding parameters, almost sound joints and high performance welded joints can be successfully produced at the rotational speeds of 900 rpm and 700 rpm and the traverse speed of 35 mm/min. The maximum welding performance of joints is found to be 86.3% with 900 rpm rotational speed and 35 mm/min traverse speed. The microhardness values along the cross-section of the joints show a dramatic drop in the stir zone where the lowest value reached is about 63% of the base metal due to the softening of the welded zone caused by the heat input during joining.

  19. Enhancement of mechanical properties and corrosion resistance of friction stir welded joint of AA2014 using water cooling

    International Nuclear Information System (INIS)

    Sinhmar, S.; Dwivedi, D.K.

    2017-01-01

    An investigation on the microstructure, mechanical properties, and corrosion behavior of friction stir welded joint of AA2014 in natural cooled (NC) and water cooled (WC) conditions have been reported. Optical microscopy, field emission scanning electron microscopy (FESEM) with Energy dispersive X-ray spectroscopy (EDS), Vicker's microhardness, tensile testing, X-ray diffraction (XRD), and electrochemical potentiodynamic polarization corrosion test (Tafel curve) were carried out to characterize the friction stir weld joints in both the cooling conditions. Water cooling resulted in higher strength and microhardness of friction stir weld joint compared to the natural cooling. The width of heat affected zone was reduced by the use of water cooling during friction stir welding (FSW) and minimum hardness zone was shifted towards weld center. The corrosion test was performed in 3.5% NaCl solution. Corrosion resistance of water cooled joint was found higher than natural cooled FSW joint. The precipitation behavior of weld nugget and heat affected zone impacts the corrosion resistance of FSW joint of AA 2014. Hardness, tensile, and corrosion properties of FSW joints produced under NC and WC conditions have been discussed in the light of microstructure.

  20. Study on microstructure and mechanical properties of Al–Mg–Mn–Er alloy joints welded by TIG and laser beam

    International Nuclear Information System (INIS)

    Yang, Dongxia; Li, Xiaoyan; He, Dingyong; Huang, Hui; Zhang, Liang

    2012-01-01

    Highlights: ► The microstructural characterization of the TIG and laser welded Al–Mg–Mn–Er alloy is studied. ► Transition zone and HAZ are found to disappear near the fusion boundaries in LBW joint. ► Primary Al 3 Er in LBW weld provides more nucleation sites and lead to the grain refinement. ► The evaporation of alloying element Mg in TIG and LBW joints is investigated. ► Reasons for high strength of LBW joint are fine-grain strengthening and solution strengthening. -- Abstract: Al-4.7Mg-0.7Mn-0.3Er alloy plates were welded by laser beam welding (LBW) and tungsten inert gas (TIG). Mechanical properties and microstructures of both welded joints were analyzed. The results showed that the tensile strength of LBW joint was 315 MPa, which was approximately 10% higher than that of TIG welded joint. This was attributed to the fine grains, dispersed primary Al 3 Er phase and low Mg evaporation in LBW weld. Equiaxed grains with average size of 30 μm were obtained in the fusion zone, which were much smaller than that of 90 μm in the fusion zone of TIG joint, due to the low heat input during LBW process. Moreover, finer primary Al 3 Er particles were uniformly distributed in the LBW joints, which resulted in a substantial increase of nucleation rate in LBW welds. In addition, it was also found that Mg concentrations in the fusion zones, in both TIG and LBW joints, were lower than that of the base one tested by EPMA. The burning loss rates of Mg in TIG and LBW joints were 36% and 22%, respectively.

  1. Computer-based mechanical design of overhead lines

    Science.gov (United States)

    Rusinaru, D.; Bratu, C.; Dinu, R. C.; Manescu, L. G.

    2016-02-01

    Beside the performance, the safety level according to the actual standards is a compulsory condition for distribution grids’ operation. Some of the measures leading to improvement of the overhead lines reliability ask for installations’ modernization. The constraints imposed to the new lines components refer to the technical aspects as thermal stress or voltage drop, and look for economic efficiency, too. The mechanical sizing of the overhead lines is after all an optimization problem. More precisely, the task in designing of the overhead line profile is to size poles, cross-arms and stays and locate poles along a line route so that the total costs of the line's structure to be minimized and the technical and safety constraints to be fulfilled.The authors present in this paper an application for the Computer-Based Mechanical Design of the Overhead Lines and the features of the corresponding Visual Basic program, adjusted to the distribution lines. The constraints of the optimization problem are adjusted to the existing weather and loading conditions of Romania. The outputs of the software application for mechanical design of overhead lines are: the list of components chosen for the line: poles, cross-arms, stays; the list of conductor tension and forces for each pole, cross-arm and stay for different weather conditions; the line profile drawings.The main features of the mechanical overhead lines design software are interactivity, local optimization function and high-level user-interface

  2. The Effect of Cu Powder During Friction Stir Welding on Microstructure and Mechanical Properties of AA3003-H18

    Science.gov (United States)

    Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.

    2014-08-01

    Friction stir welding (FSW) was used to join 3003-H18 non-heat-treatable aluminum alloy plates by adding copper powder. The copper powder was first added to the gap (0.1 and 0.2 mm) between two plates and then the FSW was performed. The specimens were joined at various rotational speeds of 800, 1000, and 1200 rpm at traveling speeds of 70 and 100 mm/min. The effects of rotational speed, second pass of FSW, and direction of second pass also were studied on copper particle distribution and formation of Al-Cu intermetallic compounds in the stir zone. The second pass of FSW was carried out in two ways; in line with the first pass direction (2F) and in the reverse direction of the first pass (FB). The microstructure, mechanical properties, and formation of intermetallic compounds type were investigated. In high copper powder compaction into the gap, large clusters were formed in the stir zone, while fine clusters and sound copper particles distribution were obtained in low powder compaction. The copper particle distribution and amount of Al-Cu intermetallic compounds were increased in the stir zone with increasing the rotational speed and applying the second pass. Al2Cu and AlCu intermetallic phases were formed in the stir zone and consequently the hardness was significantly increased. The copper particles and in situ intermetallic compounds were symmetrically distributed in both advancing and retreating sides of weld zone after FB passes. Thus, the wider area was reinforced by the intermetallic compounds. Also, the tensile test specimens tend to fracture from the coarse copper aggregation at the low rotational speeds. At high rotational speeds, the fracture locations are placed in HAZ and TMAZ.

  3. Effects of various tool pin profiles on mechanical and metallurgical properties of friction stir welded joints of cryorolled AA2219 aluminium alloy

    Science.gov (United States)

    Kamal Babu, Karupannan; Panneerselvam, Kavan; Sathiya, Paulraj; Noorul Haq, Abdul Haq; Sundarrajan, Srinivasan; Mastanaiah, Potta; Srinivasa Murthy, Chunduri Venkata

    2018-02-01

    Friction stir welding (FSW) process was conducted on cryorolled (CR) AA2219 plate using different tool pin profiles such as cylindrical pin, threaded cylindrical pin, square pin and hexagonal pin profiles. The FSW was carried out with pairs of 6 mm thick CR aluminium plates with different tool pin profiles. The different tool pin profile weld portions' behaviors like mechanical (tensile strength, impact and hardness) and metallurgical characteristics were analyzed. The results of the mechanical analysis revealed that the joint made by the hexagonal pin tool had good strength compared to other pin profiles. This was due to the pulsating action and material flow of the tool resulting in dynamic recrystallization in the weld zone. This was confirmed by the ultra fine grain structure formation in Weld Nugget (WN) of hexagonal pin tool joint with a higher percentage of precipitate dissolution. The fractograph of the hexagonal tool pin weld portion confirmed the finer dimple structure morphology without having any interior defect compared to other tool pin profiles. The lowest weld joint strength was obtained from cylindrical pin profile weld joint due to insufficient material flow during welding. The Transmission Electron Microscope and EDX analysis showed the dissolution of the metastable θ″, θ' (Al2Cu) partial precipitates in the WN and proved the influence of metastable precipitates on enhancement of mechanical behavior of weld. The XRD results also confirmed the Al2Cu precipitation dissolution in the weld zone.

  4. Microstructure and Mechanical Properties of Inconel 625 Alloy on Low Carbon Steel by Heat Treatment after Overlay Welding

    International Nuclear Information System (INIS)

    Kim, Seungpil; Jang, Jaeho; Kim, Jungsoo; Kim, Byung Jun; Sohn, Keun Yong; Nam, Dae-Geun

    2016-01-01

    Overlay welding technique is one of methods used to improve metal mechanical properties such as strength, toughness and corrosion resistance. Generally, Inconel 625 alloy is used for overlay welding layer on low carbon steels for economic consideration. However, the method produces some problems in the microstructure of the cast structure and some defects, caused by the elevated temperatures of the overlay process. To resolve these problems, heat treatments are required. In this study, Inconel 625 alloy was welded on a low carbon steel by the overlay welding process to investigate the resulting microstructure and mechanical properties. A double heat treatment was performed to improve the mechanical properties of the welding and substrate layers. It was found that Inconel 625 alloy had an austenite microstructure after the first heat treatment, but the low carbon steel had a ferrite-pearlite microstructure after the second heat treatment. After the double heat treatment, the sample showed the optimum hardness because of grain refinement and homogenization of the microstructure.

  5. Microstructure and Mechanical Properties of Inconel 625 Alloy on Low Carbon Steel by Heat Treatment after Overlay Welding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seungpil; Jang, Jaeho; Kim, Jungsoo; Kim, Byung Jun; Sohn, Keun Yong; Nam, Dae-Geun [Korea Institute of Industrial Technology, Busan (Korea, Republic of)

    2016-08-15

    Overlay welding technique is one of methods used to improve metal mechanical properties such as strength, toughness and corrosion resistance. Generally, Inconel 625 alloy is used for overlay welding layer on low carbon steels for economic consideration. However, the method produces some problems in the microstructure of the cast structure and some defects, caused by the elevated temperatures of the overlay process. To resolve these problems, heat treatments are required. In this study, Inconel 625 alloy was welded on a low carbon steel by the overlay welding process to investigate the resulting microstructure and mechanical properties. A double heat treatment was performed to improve the mechanical properties of the welding and substrate layers. It was found that Inconel 625 alloy had an austenite microstructure after the first heat treatment, but the low carbon steel had a ferrite-pearlite microstructure after the second heat treatment. After the double heat treatment, the sample showed the optimum hardness because of grain refinement and homogenization of the microstructure.

  6. Microstructural Characterization and Mechanical Properties Analysis of Weld Metals with Two Ni Contents During Post-Weld Heat Treatments

    Science.gov (United States)

    Wu, Da-yong; Han, Xiu-lin; Tian, Hong-tao; Liao, Bo; Xiao, Fu-ren

    2015-05-01

    This study designed post-weld heat treatments, including reheating and tempering, associated with hot bending to investigate the microstructures, toughness, and hardness of two weld metals with different Ni contents (transformation temperature and increased the proportion of acicular ferrite (AF). Furthermore, a high Ni content promoted the martensite/austenite (M/A) constituent formation after reheating. The promotion of the M/A formation increased the number of cementite particles, and accelerated cementite coarsening during tempering. The large-angle grain boundary density from the AF improved the toughness despite the negative effect of cementite. The strengthening contributions were calculated, and the grain refinement was the greatest. The high Ni content decreased the effective grain size with a 2 deg tolerance angle, thus enhancing the grain refinement contribution.

  7. An assessment of microstructure, mechanical properties and corrosion resistance of dissimilar welds between Inconel 718 and 310S austenitic stainless steel

    International Nuclear Information System (INIS)

    Mortezaie, A.; Shamanian, M.

    2014-01-01

    In the present study, dissimilar welding between Inconel 718 nickel-base superalloy and 310S austenitic stainless steel using gas tungsten arc welding process was performed to determine the relationship between the microstructure of the welds and the resultant mechanical and corrosion properties. For this purpose, three filler metals including Inconel 625, Inconel 82 and 310 stainless steel were used. Microstructural observations showed that weld microstructures for all filler metals were fully austenitic. In tension tests, welds produced by Inconel 625 and 310 filler metals displayed the highest and the lowest ultimate tensile strength, respectively. The results of Charpy impact tests indicated that the maximum fracture energy was related to Inconel 82 weld metal. According to the potentiodynamic polarization test results, Inconel 82 exhibited the highest corrosion resistance among all tested filler metals. Finally, it was concluded that for the dissimilar welding between Inconel 718 and 310S, Inconel 82 filler metal offers the optimum properties at room temperature. - Highlights: • Three filler metals including Inconel 625, Inconel 82 and 310 SS were used. • A columnar to equiaxed dendritic structure was seen for IN-625 weld metal. • A granular austenitic microstructure obtained for Inconel 82 weld metal. • Microstructure of 310 weld metal includes solidification cracks along SSGB. • IN-82 weld metal showed the highest corrosion potential

  8. Microstructure and mechanical properties of China low activation martensitic steel joint by TIG multi-pass welding with a new filler wire

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Bo [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Zhang, Junyu [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); University of Science and Technology of China, Hefei, Anhui, 230027 (China); Wu, Qingsheng, E-mail: qingsheng.wu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China)

    2017-07-15

    Tungsten Inner Gas (TIG) welding is employed for joining of China low activation martensitic (CLAM) steel. A new filler wire was proposed, and the investigation on welding with various heat input and welding passes were conducted to lower the tendency towards the residual of δ ferrite in the joint. With the optimized welding parameters, a butt joint by multi-pass welding with the new filler wire was prepared to investigate the microstructure and mechanical properties. The microstructure of the joint was observed by optical microscope (OM) and scanning electron microscope (SEM). The hardness, Charpy impact and tensile tests of the joint were implemented at room temperature (25 °C). The results revealed that almost full martensite free from ferrite in the joints were obtained by multipass welding with the heat input of 2.26 kJ/mm. A certain degree of softening occurred at the heat affected zone of the joint according to the results of tensile and hardness tests. The as welded joints showed brittle fracture in the impact tests. However, the joints showed toughness fracture after tempering and relatively better comprehensive performance were achieved when the joints were tempered at 740 °C for 2 h. - Highlights: •A new filler material was proposed to control ferrite content in CLAM weld metal. •Heat input affected ferrite content through influencing cooling rate during welding. •Multipass welding was a promising way to eliminate the ferrite in the weld.

  9. Effect of Interfacial Reaction on the Mechanical Performance of Steel to Aluminum Dissimilar Ultrasonic Spot Welds

    Science.gov (United States)

    Xu, Lei; Wang, Li; Chen, Ying-Chun; Robson, Joe D.; Prangnell, Philip B.

    2016-01-01

    The early stages of formation of intermetallic compounds (IMC) have been investigated in dissimilar aluminum to steel welds, manufactured by high power (2.5 kW) ultrasonic spot welding (USW). To better understand the influence of alloy composition, welds were produced between a low-carbon steel (DC04) and two different aluminum alloys (6111 and 7055). The joint strengths were measured in lap shear tests and the formation and growth behavior of IMCs at the weld interface were characterized by electron microscopy, for welding times from 0.2 to 2.4 seconds. With the material combinations studied, the η (Fe2Al5) intermetallic phase was found to form first, very rapidly in the initial stage of welding, with a discontinuous island morphology. Continuous layers of η and then θ (FeAl3) phase were subsequently seen to develop on extending the welding time to greater than 0.7 second. The IMC layer formed in the DC04-AA7055 combination grew thicker than for the DC04-AA6111 welds, despite both weld sets having near identical thermal histories. Zinc was also found to be dissolved in the IMC phases when welding with the AA7055 alloy. After post-weld aging of the aluminum alloy, fracture in the lap shear tests always occurred along the joint interface; however, the DC04-AA6111 welds had higher fracture energy than the DC04-AA7055 combination.

  10. Simulation of Weld Mechanical Behavior to Include Welding Induced Residual Stress and Distortion: Coupling of SYSWELD and Abaqus Codes

    Science.gov (United States)

    2015-11-01

    able to investigate how the welding process modifies the resultant fracture and fatigue behavior for structural components on its vessels. NSWCCD-61...Investigation of the Strain Rate and Temperature Effects on the Plastic Flow Stress and Ductile Failure Strain of Aluminum Alloys 5083- H116, 6082-T6, and a...883-895. 4. Xiaosheng Gao, Tingting Zhang, Matthew Hayden, and Charles Roe, Effects of the Stress State on Plasticity and Ductile Failure of an

  11. Thermomechanical Modelling of Friction Stir Welding

    DEFF Research Database (Denmark)

    Hattel, Jesper Henri; Schmidt, Henrik Nikolaj Blicher; Tutum, Cem Celal

    2009-01-01

    Friction Stir Welding (FSW) is a fully coupled thermomechanical process and should in general be modelled as such. Basically, there are two major application areas of thermomechanical models in the investigation of the FSW process: i) Analysis of the thermomechanical conditions such as e.g. heat...... generation and local material deformation (often referred to as flow) during the welding process itself. ii) Prediction of the residual stresses that will be present in the joint structure post to welding. While the former in general will call for a fully-coupled thermomechanical procedure, however...... for the FSW process at hand, the heat generation must either be prescribed analytically or based on a fully coupled analysis of the welding process itself. Along this line, a recently proposed thermal-pseudo-mechanical model is presented in which the temperature dependent yield stress of the weld material...

  12. Al/Cu Dissimilar Friction Stir Welding with Ni, Ti, and Zn Foil as the Interlayer for Flow Control, Enhancing Mechanical and Metallurgical Properties

    Science.gov (United States)

    Sahu, Prakash Kumar; Pal, Sukhomay; Pal, Surjya K.

    2017-07-01

    This research investigates the effects of Ni, Ti, and Zn foil as interlayer, inserted between the faying edges of Al and Cu plates, for controlled intermetallic compound (IMC) formation. The weld tensile strength with Ti and Zn as interlayer is superior to Al base metal strength. This is due to controlled flow of IMCs by diffused Ti interlayer and thin, continuous, and uniform IMC formation in the case of Zn interlayer. Improved flexural stress was observed with interlayer. Weld microhardness varied with different interlayers and purely depends on IMCs present at the indentation point, flow of IMCs, and interlayer hardness. Specimens with interlayer failed at the interface of the nugget and thermomechanical-affected zone (TMAZ) with complete and broken three-dimensional (3-D) grains, indicating transgranular fracture. Phase analysis revealed that Al/Cu IMCs are impeded by Ni and Ti interlayer. The minor binary and ternary IMC phases form adjacent to the interlayer due to diffusion of the material with Al/Cu. Line scan and elemental mapping indicate thin, continuous, and uniform IMCs with enhanced weld metallurgical and mechanical properties for the joints with Zn interlayer. Macrostructural analysis revealed IMC flow variations with and without interlayer. Variation in grain size at different zones is also observed for different interlayers.

  13. The Effects of Shielded Metal Arc Welding (Smaw) Welding On The Mechanical Characteristics With Heating Treatment inn S45c Steel

    Science.gov (United States)

    Munawar; Abbas, Hammada; Yusran Aminy, Ahmad

    2018-02-01

    Steel material has been used mainly for making tooling, automotive components, other household needs, power generators to frame buildings and bridges. This study aimed (1) to analyze the mechanical Characteristics of S45C steel with and without heating treatments, and (2) to analyze the temperature of heating treatment which could result in the maximal strength of S45C steel after the welding process. The research was conducted in the laboratory of mechanical engineering study program, Departement of mechanical Engineering, Christian university of indonesia paulus, makassar. The method used materials, instruments, and the dimensions determination of specimen based on the proposed testing standard, Next, was to determine the mechanical caracteristics of the S45C steel wich had been welded and heated.The tensile specimens, the hardness specimen, the impact specimen, and microstructures of which,each of the 3 specimens was the specimens was the specimen without treatment, the spesimen with the welding wthout heating and the specimen of 150°C, 250° C, 300° C. The research results indicated that the treatment process of 150°C, 250°C and 300°C produced the changes of mechanic charateristics with the tensile strength of 42 kgf/mm2 when the temperature had reached 300°C, but at the temperature 300°C, the its toughness would decrease to Hi = 0.836 j/m2 and its hardness would increase to 40.83 at the temperature of 300°C. The value of the maximum strengs was reached at the heating temperature of 300°C for the tensile strength and the hardness, while at the temperature of 300°C its impact value would decrease.

  14. Effect of welding parameters on mechanical properties of GTAW of UNS S31803 and UNS S32750 weldments

    Directory of Open Access Journals (Sweden)

    Paulraj Prabhu

    2015-01-01

    Full Text Available Duplex Stainless Steel (DSS and Super Duplex Stainless Steel (SDSS pipes were welded by Gas Tungsten Arc Welding (GTAW process. The effect of welding parameters such as heat input, cooling rate, shielding/purging gas composition and interpass temperature on tensile strength, hardness and impact toughness were studied. The microstructure analysis revealed presence of intermetallic phases at root region of the weldments. All mechanical properties were improved at lower heat input and high cooling rate due to grain refinement and balanced microstructure [ferrite and austenite]. All weldments exhibited higher strength than base materials. Weld root region was harder than centre and cap region. SDSS is more susceptible to sigma phase formation due to higher alloying elements and weld thermal cycles, which lead to considerable loss of toughness. Higher nitrogen contents in shielding and purging gas resulted strengthening of austenite phase and restriction of dislocations, which ultimately improved mechanical properties. Higher interpass temperature caused reduction in strength and toughness because of grain coarsening and secondary phase precipitation.

  15. Effects of aging treatment and heat input on the microstructures and mechanical properties of TIG-welded 6061-T6 alloy joints

    Science.gov (United States)

    Peng, Dong; Shen, Jun; Tang, Qin; Wu, Cui-ping; Zhou, Yan-bing

    2013-03-01

    Aging treatment and various heat input conditions were adopted to investigate the microstructural evolution and mechanical properties of TIG welded 6061-T6 alloy joints by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone (HAZ) increases and grains in the fusion zone (FZ) coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175°C for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.

  16. Effect of Welding Parameters on Microstructure and Mechanical Properties of Cast Fe-40Al Alloy

    Directory of Open Access Journals (Sweden)

    Osman Torun

    2016-09-01

    Full Text Available Friction welding of cast Fe-40Al alloy was carried out at 1000 rmp for various friction times, friction pressures, and forging pressures. The microstructures of the interface of welded samples were analyzed by optical and scanning electron microscopy (SEM. Micrographs demonstrated that excellent welding formed continuously along the interface, except for samples welded for 3 s. Chemical compositions of the interface of the friction welded samples and of the fractured surface of all the specimens were determined using energy dispersive spectroscopy (EDS. After the welding process, shear tests were applied to the welded samples to determine the shear strength of joints. Test results indicated that the maximum shear strength was 469.5 MPa.

  17. Study of process parameters effect on the filling phase of micro injection moulding using weld lines as flow markers

    DEFF Research Database (Denmark)

    Tosello, Guido; Gava, Alberto; Hansen, Hans Nørgaard

    2010-01-01

    , the relationships between the filling pattern and the different process parameter settings have to be established. In this paper, a novel approach based on the use of weld lines as flow markers to trace the development of the flow front during the filling is proposed. The effects on the filling stage of process......Micro-injection moulding (micro-moulding) is a process which enables the mass production of polymer microproducts. In order to produce high-quality injection moulded micro-parts, a crucial aspect to be fully understood and optimised is the filling of the cavity by the molten polymer. As a result...... manufactured by micro-electrodischarge machining. A commercially available polystyrene grade polymer has been moulded using a high-speed injection moulding machine. The design of experiment technique was employed to determine the effect of the process parameters on the filling phase of the micro...

  18. Study of the mechanical properties of welded joints by wet sub sea welding technique with tubular electrode; Estudo das propriedades mecanicas de juntas soldadas pela tecnica de soldagem subaquatica molhada com eletrodo tubular

    Energy Technology Data Exchange (ETDEWEB)

    Teichmann, Erwin Werner; Baixo, Carlos Eduardo Iconomos; Dutra, Jair Carlos [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica. Lab. de Soldagem e Mecatronica - LABSOLDA]. E-mail: erwin@labsolda.ufsc.br; Santos, Valter Rocha dos [Centro Federal de Educacao Tecnologica (CEFET), Rio de Janeiro, RJ (Brazil); Teixeira, Jose Claudio [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    1997-07-01

    Some experiments conducted at LABSOLDA/UFSC - a welding laboratory of Santa Catarina Univ., Florianopolis, Brazil - in order to identify mechanical properties, weld bead geometry and the quantity and dimensions of pores in weld beads produced by sub sea wet FCAW are described. Welding in shallow water with power source adjusted to operate in constant current characteristic mode and a set of parameters to establish an open arc transfer mode it was obtained weld beads with regular geometry and an acceptable profile, with low level of defects incidence, no pores and crack free. The tenacity measured by Charpy tests (0C) was 34 J and hardness of 119 HV-10 measured by Vickers tests. The methodology used in the experiments and the results obtained are discussed in the paper. (author)

  19. Automatization of welding

    International Nuclear Information System (INIS)

    Iwabuchi, Masashi; Tomita, Jinji; Nishihara, Katsunori.

    1978-01-01

    Automatization of welding is one of the effective measures for securing high degree of quality of nuclear power equipment, as well as for correspondence to the environment at the site of plant. As the latest ones of the automatic welders practically used for welding of nuclear power apparatuses in factories of Toshiba and IHI, those for pipes and lining tanks are described here. The pipe welder performs the battering welding on the inside of pipe end as the so-called IGSCC countermeasure and the succeeding butt welding through the same controller. The lining tank welder is able to perform simultaneous welding of two parallel weld lines on a large thin plate lining tank. Both types of the welders are demonstrating excellent performance at the shops as well as at the plant site. (author)

  20. TIG welding of 22-05 duplex stainless steels (Uranus 45 N and Avesta). Microstructural studies and mechanical properties

    International Nuclear Information System (INIS)

    Gomez de Salazar, J.M.; Urena, A.; Cobollo, M.; Barranco, V.; Alvarez, M.J.

    1998-01-01

    TIG welding of two different duplex stainless steels is carried out. Are-discharge on base-material plates by means of the TIG technique without filler metal and varying the energetic conditions (E.N.A.) has been performed. A comparative study concerning the microstructural evolution as well as mechanical properties is carried out. The relation between hardness profiles, the microstructural variations and the ferrite δ concentration is established. Further, the above mentioned properties are related to the E.N.A. for each welded joint. (Author) 8 refs

  1. On the Similarity of Deformation Mechanisms During Friction Stir Welding and Sliding Friction of the AA5056 Alloy

    Science.gov (United States)

    Kolubaev, A. V.; Zaikina, A. A.; Sizova, O. V.; Ivanov, K. V.; Filippov, A. V.; Kolubaev, E. A.

    2018-04-01

    A comparative investigation of the structure of an aluminum-manganese alloy is performed after its friction stir welding and sliding friction. Using the methods of optical and electron microscopy, it is shown that during friction identical ultrafine-grained structures are formed in the weld nugget and in the surface layer, in which the grains measure 5 μm irrespective of the initial grain size of the alloy. An assumption is made that the microstructure during both processes under study is formed by the mechanism of rotational plasticity.

  2. High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri; Field, David P.

    2017-11-20

    Friction-stir-welding (FSW) is a cost-effective and high quality joining process for aluminum alloys (especially heat-treatable allo ys) that has been applied successfully in the aerospace industry. However, the full potential of FSW on more cost-sensitive applications is still limited by the production rate, namely the welding speed of the process. The majority of literature evaluating FSW of aluminum alloys is based on welds made in the range of welding speeds around hundreds of millimeters per minute, and only a handful are at a moderate speed of 1 m/min. In this study we present a microstructural analysis of friction stir welded AA7075-T6 blanks with welding speeds up to 3 m/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. Results are coupled with welding parameters to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high speed processing.

  3. ICT diagnostic method of beryllium welding quality

    International Nuclear Information System (INIS)

    Sun Lingxia; Wei Kentang; Ye Yunchang

    2002-01-01

    To avoid the interference of high density material for the quality assay of beryllium welding line, a slice by slice scanning method was proposed based upon the research results of the Industrial Computerized Tomography (ICT) diagnostics for weld penetration, weld width, off-centered deviation and weld defects of beryllium-ring welding seam with high density material inside

  4. Modified Welding Technique of a Hypo-Eutectic Al-Cu Alloy for Higher Mechanical Properties

    Science.gov (United States)

    Ghosh, B. R.; Gupta, R. K.; Biju, S.; Sinha, P. P.

    GTAW process is used for welding of pressure vessels made of hypo-eutectic Al-Cu alloy AA2219 containing 6.3% Cu. As welded Yield strength of the alloy was found to be in the range of 140-150 MPa, using conventional single pass GTAW technique on both AC and DCSP modes. Interestingly, it was also found that weld-strength decreased with increase in thickness of the weld coupons. Welding metallurgy of AA2219 Al alloy was critically reviewed and factors responsible for lower properties were identified. Multipass GTAW on DCSP mode was postulated to improve the weld strength of this alloy. A systematic experimentation using 12 mm thick plates was carried out and YS of 200 MPa has been achieved in the as welded condition. Thorough characterization including optical and electron microscopy was conducted to validate the metallurgical phenomena attributable to improvement in weld strength. This paper presents the conceptual understanding of welding metallurgy of AA2219 alloy and validation by experiments, which could lead to better weld properties using multipass GTAW on DCSP mode.

  5. Microstructure and Mechanical Properties of Laser Welded Joints of DZ125L and IN718 Nickel Base Superalloys

    Science.gov (United States)

    Liang, Taosha; Wang, Lei; Liu, Yang; Song, Xiu

    2018-05-01

    The microstructure and mechanical properties of the laser welded joint of DZ125L and IN718 nickel base superalloys were investigated. The results show that the fusion zone (FZ) mainly consists of fine dendrite structure with fine γ', Laves phases and MC carbides inhomogeneously distributed. The high welding temperature induces the partial dissolution of γ' in the heat-affected zone (HAZ) of DZ125L and liquation of grain boundaries in both of the HAZs. After post-weld heat treatment (PWHT), fine γ″ and γ' phases precipitate in the FZ, IN718 HAZ and IN718 base metal (BM), and fine γ' precipitate in the γ channel of the HAZ and BM of DZ125L. With tensile testing, the joints after PWHT show higher strengths than that of the weaker DZ125L alloy. Plastic deformation mainly concentrates in the weaker DZ125L and the joint finally fails in the DZ125L BM.

  6. Effects of the Heterogeneity in the Electron Beam Welded Joint on Mechanical Properties of Ti6Al4V Alloy

    Science.gov (United States)

    Liu, Jing; Gao, Xiao-Long; Zhang, Lin-Jie; Zhang, Jian-Xun

    2015-01-01

    The aim of this investigation was to evaluate the effect of microstructure heterogeneity on the tensile and low cycle fatigue properties of electron beam welded (EBW) Ti6Al4V sheets. To achieve this goal, the tensile and low cycle fatigue property in the EBW joints and base metal (BM) specimens is compared. During the tensile testing, digital image correlation technology was used to measure the plastic strain field evolution within the specimens. The experimental results showed that the tensile ductility and low cycle fatigue strength of EBW joints are lower than that of BM specimens, mainly because of the effect of microstructure heterogeneity of the welded joint. Moreover, the EBW joints exhibit the cyclic hardening behavior during low fatigue process, while BM specimens exhibit the cyclic softening behavior. Compared with the BM specimens with uniform microstructure, the heterogeneity of microstructure in the EBW joint is found to decrease the mechanical properties of welded joint.

  7. Statistical mechanics of flux lines in high-temperature superconductors

    International Nuclear Information System (INIS)

    Dasgupta, C.

    1992-01-01

    The shortness of the low temperature coherence lengths of high T c materials leads to new mechanisms of pinning of flux lines. Lattice periodic modulations of the order parameters itself acts to pin vortex lines in regions of the unit cell were the order parameter is small. A presentation of flux creep and flux noise at low temperature and magnetic fields in terms of motion of simple metastable defects on flux lines is made, with a calculation of flux lattice melting. 12 refs

  8. The effect of neutron irradiation on the mechanical properties of welded zircaloy-2

    Energy Technology Data Exchange (ETDEWEB)

    Evans, D G

    1962-07-15

    Zircaloy-2 tensile specimens, subsize impact bars and representative spigot welds were subjected to three NRX cycles in the X-5 loop. Average loop temperature was 260{sup o}C over the three cycles. One group of tensile specimens was heat-treated in vacuum at 900{sup o}C for 40 minutes, another group contained welded areas in the centre of the gauge length and a third group was hydrided after welding. Notches of the impact specimens were located in the fusion zone of the weld, Spigot welds were made on autoclaved and unautoclaved simulated production assemblies. The transition temperature of Zircaloy-2 increased appreciably upon welding. This was accompanied by a decrease in absorbed energy values for all temperatures between 0{sup o} and 300{sup o}C. Neutron irradiation had no effect on the impact properties of welded. Zircaloy-2. Welding decreased the uniform and total elongation at room temperature and at 260{sup o}C, and increased the 260{sup o}C PL, YS and UTS. Hydriding to a nominal 100 ppm hydrogen had no effect on the unirradiated tensile properties at either test temperature. The heat treatment decreased the strength properties but did not affect the ductility. Neutron irradiation increased the YS of the welded and hydrided material by 20% and the heat treated YS by 40%. Irradiation also increased the 260{sup o}C strength properties of the as-welded material. It was found that the unautoclaved spigot welds had a generally higher tensile strength than the autoclaved and welded specimens. For specimens welded in either condition, the outer welds of the 19-element bundle had a lower average breaking load than the inner welds. Neutron irradiation had no effect on the tensile strength of these welds. It was also demonstrated that a cup-and-cone type of fracture could be produced in a bend test. These fractures were similar to those observed in irradiated fuel bundles which had been damaged during transfer operations. A large amount of scatter rendered some

  9. Corrosion Resistance and Mechanical Properties of TIG and A-TIG Welded Joints of Lean Duplex Stainless Steel S82441 / 1.4662

    Directory of Open Access Journals (Sweden)

    Brytan Z.

    2016-06-01

    Full Text Available This paper presents results of pitting corrosion resistance of TIG (autogenous and with filler metal and A-TIG welded lean duplex stainless steel S82441/1.4662 evaluated according to ASTM G48 method, where autogenous TIG welding process was applied using different amounts of heat input and shielding gases like pure Ar and Ar+N2 and Ar+He mixtures. The results of pitting corrosion resistance of the welded joints of lean duplex stainless steel S82441 were studied in as weld conditions and after different mechanical surface finish treatments. The results of the critical pitting temperature (CPT determined according to ASTM G48 at temperatures of 15, 25 and 35°C were presented. Three different surface treatment after welding were applied: etching, milling, brushing + etching. The influence of post weld surface treatment was studied in respect to the pitting corrosion resistance, basing on CPT temperature.

  10. Effect of tool offsetting on microstructure and mechanical properties dissimilar friction stir welded Mg-Al alloys

    Science.gov (United States)

    Baghdadi, Amir Hossein; Fazilah Mohamad Selamat, Nor; Sajuri, Zainuddin

    2017-09-01

    Automotive and aerospace industries are attempting to produce lightweight structure by using materials with low density such as aluminum and magnesium alloys to increase the fuel efficiency and consequently reduce the environmental pollution. It can be beneficial to join Mg to Al to acquire ideal performance in special applications. Friction stir welding (FSW) is solid state welding processes and relatively lower temperature of the process compared to fusion welding processes. This makes FSW a potential joining technique for joining of the dissimilar materials. In this study, Mg-Al butt joints were performed by FSW under different tool offset conditions, rotation rates (500-600 rpm) and traverse speeds (20 mm/min) with tool axis offset 1 mm shifted into AZ31B or Al6061 (T6), and without offset. During the welding process AZ31B was positioned at the advancing side (AS) and Al6061 (T6) was located at the retreating side (RS). Defect free AZ31B-Al6061 (T6) dissimilar metal FSW joints with good mechanical properties were obtained with the combination of intermediate rotation rate and low traverse speed pin is in the middle. When tool positioned in -1 mm or +1 mm offsetting, some defects were found in SZ of dissimilar FSWed joints such as cavity, tunnel, and crack. Furthermore, a thin layer of intermetallic compounds was observed in the stir zone at the interface between Mg-Al plates. The strength of the joint was influenced by FSW parameters. Good mechanical properties obtained with the combination of intermediate rotational speed of 600 rpm and low travelling speed of 20 mm/min by locating Mg on advancing side when pin is in the middle. Also, Joint efficiency of the welds prepared in the present study was between 29% and 68% for the different welding parameters.

  11. Instructional Guidelines. Welding.

    Science.gov (United States)

    Fordyce, H. L.; Doshier, Dale

    Using the standards of the American Welding Society and the American Society of Mechanical Engineers, this welding instructional guidelines manual presents a course of study in accordance with the current practices in industry. Intended for use in welding programs now practiced within the Federal Prison System, the phases of the program are…

  12. Characterisation of girth pipe weld for primary heat transport system of pressurised heavy water reactors

    International Nuclear Information System (INIS)

    Singh, P.K.; Vaze, K.K.; Kushwaha, H.S.

    2002-01-01

    The weld and heat affected zone (HAZ) associated with the girth weld are most vulnerable regions of the piping system. The different regions of the weld joint such as the weld metal, HAZ and base metal lead to heterogeneous mechanical and metallurgical properties of the joints. Due to their different metallurgical and mechanical properties, the amounts of damage produced in these regions are different when the component is subjected to service condition. Thus, it is imperative to know the characteristics of these regions of a pipe weld in order to identify the weakest zone for safe designing of high energy piping components. In view of this necessity the present study has been planned to carry out complete characterisation of the weld joint of SA 333 Gr.6 steel pipe, in terms of its metallurgical, mechanical and fracture properties. The mechanical and fracture mechanics properties of the base metal, weld deposit and HAZ have been compared and correlated with reference to their microstructures. Weld joints of SA 333 Gr.6 steel pipe have been prepared by using GTAW root pass and SMAW filling of V-grove as per recommended welding procedure specifications (WPS) conforming to ASME Sec IX commonly used to fabricate nuclear piping system components. The emphasis of the study is to characterise base, weld and HAZ of the pipe weld in terms of chemical, metallurgical, mechanical and fracture mechanics properties. The fracture toughness behaviour of the welds and HAZ has been characterised by J-integral parameters. The fatigue crack growth rate has been characterised by Paris Law. Stretched zone width (SZW) has been measured under SEM to evaluate initiation fracture toughness. The estimated initiation fracture toughness based on SZW and blunting line given by EGF recommendation have been compared. The fracture mechanics properties of base, weld and HAZ has been determined and compared. The fracture mechanics properties of the weld and HAZ have been correlated to their

  13. Micro friction stir lap welding of AISI 430 ferritic stainless steel: a study on the mechanical properties, microstructure, texture and magnetic properties

    Science.gov (United States)

    Mostaan, Hossein; Safari, Mehdi; Bakhtiari, Arash

    2018-04-01

    In this study, the effect of friction stir welding of AISI 430 (X6Cr17, material number 1.4016) ferritic stainless steel is examined. Two thin sheets with dimensions of 0.4 × 50 × 200 mm3 are joined in lap configuration. Optical microscopy and field emission electron microscopy were used in order to microstructural evaluations and fracture analysis, respectively. Tensile test and microhardness measurements are employed in order to study the mechanical behaviors of welds. Also, vibrational sample magnetometry (VSM) is employed for characterizing magnetic properties of welded samples. Texture analysis is carried out in order to clarify the change mechanism of magnetic properties in the welded area. The results show that AISI 430 sheets are successfully joined considering both, the appearance of the welding bead and the strength of the welded joint. It is found that by friction stir welding of AISI 430 sheets, texture components with easy axes magnetization have been replaced by texture components with harder magnetization axes. VSM analysis showed that friction stir welding leads to increase in residual induction (Br) and coercivity (Hc). This increase is attributed to the grain refining due the friction stir welding and formation of texture components with harder axes of magnetizations.

  14. Mechanical properties of electron beam welds of 316LN austenitic steels at low temperature for ITER gravity support system

    International Nuclear Information System (INIS)

    Lee, P.Y.; Huo, B.L.; Kuai, K.W.

    2007-01-01

    The gravity support system in ITER not only sustains magnet system, the vacuum vessel and in-vessel components, but also endures several large forces, such as electromagnetic force, thermal load and seismic loads. Based on the ITER design report, the maximum displacement of the gravity support system is estimated to be 32 mm in radial direction at the top flange of the flexible plates during the TF coil cool down from room temperature to 80 k. Welds are located in the peak stress region and subject to cyclic loads in the top flange is a potential problem. Therefore, the mechanical properties of the welds are extremely important for this system. 316LN austenitic stainless steel has been selected as the gravity support structure materials. However, there is still lack of the related mechanical data of the welding components of 316LN stainless steel at present. In this study, we are systematically investigated the mechanical properties of the welding components at low temperature. (authors)

  15. Thermo-Mechanical Characterization of Friction Stir Spot Welded AA7050 Sheets by Means of Experimental and FEM Analyses.

    Science.gov (United States)

    D'Urso, Gianluca; Giardini, Claudio

    2016-08-11

    The present study was carried out to evaluate how the friction stir spot welding (FSSW) process parameters affect the temperature distribution in the welding region, the welding forces and the mechanical properties of the joints. The experimental study was performed by means of a CNC machine tool obtaining FSSW lap joints on AA7050 aluminum alloy plates. Three thermocouples were inserted into the samples to measure the temperatures at different distance from the joint axis during the whole FSSW process. Experiments was repeated varying the process parameters, namely rotational speed, axial feed rate and plunging depth. Axial welding forces were measured during the tests using a piezoelectric load cell, while the mechanical properties of the joints were evaluated by executing shear tests on the specimens. The correlation found between process parameters and joints properties, allowed to identify the best technological window. The data collected during the experiments were used to validate a simulation model of the FSSW process, too. The model was set up using a 2D approach for the simulation of a 3D problem, in order to guarantee a very simple and practical solution for achieving results in a very short time. A specific external routine for the calculation of the thermal energy due to friction acting between pin and sheet was developed. An index for the prediction of the joint mechanical properties using the FEM simulations was finally presented and validated.

  16. Thermo-Mechanical Characterization of Friction Stir Spot Welded AA7050 Sheets by Means of Experimental and FEM Analyses

    Directory of Open Access Journals (Sweden)

    Gianluca D’Urso

    2016-08-01

    Full Text Available The present study was carried out to evaluate how the friction stir spot welding (FSSW process parameters affect the temperature distribution in the welding region, the welding forces and the mechanical properties of the joints. The experimental study was performed by means of a CNC machine tool obtaining FSSW lap joints on AA7050 aluminum alloy plates. Three thermocouples were inserted into the samples to measure the temperatures at different distance from the joint axis during the whole FSSW process. Experiments was repeated varying the process parameters, namely rotational speed, axial feed rate and plunging depth. Axial welding forces were measured during the tests using a piezoelectric load cell, while the mechanical properties of the joints were evaluated by executing shear tests on the specimens. The correlation found between process parameters and joints properties, allowed to identify the best technological window. The data collected during the experiments were used to validate a simulation model of the FSSW process, too. The model was set up using a 2D approach for the simulation of a 3D problem, in order to guarantee a very simple and practical solution for achieving results in a very short time. A specific external routine for the calculation of the thermal energy due to friction acting between pin and sheet was developed. An index for the prediction of the joint mechanical properties using the FEM simulations was finally presented and validated.

  17. Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

    Science.gov (United States)

    Silva, Cleiton Carvalho; de Albuquerque, Victor Hugo C.; Miná, Emerson Mendonça; Moura, Elineudo P.; Tavares, João Manuel R. S.

    2018-03-01

    The aim of this work was to evaluate the different phases formed during solidification and after thermal aging of the as-welded 625 nickel-based alloy, as well as the influence of microstructural changes on the mechanical properties. The experiments addressed aging temperatures of 650 and 950 °C for 10, 100, and 200 hours. The samples were analyzed by electron microscopy, microanalysis, and X-ray diffraction in order to identify the secondary phases. Mechanical tests such as hardness, microhardness, and Charpy-V impact test were performed. Nondestructive ultrasonic inspection was also conducted to correlate the acquired signals with mechanical and microstructural properties. The results show that the alloy under study experienced microstructural changes when aged at 650 °C. The aging was responsible by the dissolution of the Laves phase formed during the solidification and the appearance of γ″ phase within interdendritic region and fine carbides along the solidification grain boundaries. However, when it was aged at 950 °C, the Laves phase was continuously dissolved and the excess Nb caused the precipitation of the δ-phase (Ni3Nb), which was intensified at 10 hours of aging, with subsequent dissolution for longer periods such as 200 hours. Even when subjected to significant microstructural changes, the mechanical properties, especially toughness, were not sensitive to the dissolution and/or precipitation of the secondary phases.

  18. Use of servo controlled weld head for end closure welding

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, S.K.; Setty, D.S.; Rameswara Rao, A.; Hemantha Rao, G.V.S.; Jayaraj, R.N. [Nuclear Fuel Complex, Dept. of Atomic Energy, Hyderabad (India)

    2010-07-01

    In the PHWR fuel fabrication line resistance welding processes are used for joining various zirconium based alloy components to fuel tube of similar material. The quality requirement of these welding processes is very stringent and has to meet all the product requirements. At present these welding processes are being carried out by using standard resistance welding machines. In the resistance welding process in addition to current and time, force is one of the critical and important parameter, which influences the weld quality. At present advanced feed back type fast response medium frequency weld controllers are being used. This has upslope/down slope, constant and repetitive weld pattern selection features makes this critical welding process more reliable. Compared to weld controllers, squeeze force application devices are limited and normally standard high response pneumatic cylinders are used in the welding process. With this type of devices the force is constant during welding process and cannot be varied during welding process as per the material deformation characteristics. Similarly due to non-availability of feed back systems in the squeeze force application systems restricts the accuracy and quality of the welding process. In the present paper the influence of squeeze force pattern on the weld quality using advanced feed back type servo based force control system was studied. Different squeeze forces were used during pre and post weld heat periods along with constant force and compared with the weld quality. (author)

  19. 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.

  20. Mechanical properties of similar and dissimilar weldments of RAFMS and AISI 316L (N) SS prepared by electron beam welding process

    Energy Technology Data Exchange (ETDEWEB)

    Albert, S.K., E-mail: shaju@igcar.gov.in [Indira Gandhi Center for Atomic Research, Kalpakkam 603 102 (India); Das, C.R. [Indira Gandhi Center for Atomic Research, Kalpakkam 603 102 (India); Sam, Shiju [Institute of Plasma Research, Gandhi Nagar (India); Mastanaiah, P.; Patel, M. [Defence Research and Development Laboratory, Hyderabad (India); Bhaduri, A.K.; Jayakumar, T. [Indira Gandhi Center for Atomic Research, Kalpakkam 603 102 (India); Murthy, C.V.S. [Defence Research and Development Laboratory, Hyderabad (India); Kumar, Rajendra [Institute of Plasma Research, Gandhi Nagar (India)

    2014-10-15

    Highlights: • Increase of W content in RAFM steel can result in retention of delta ferrite in the EB weld of the steel. • Presence of delta ferrite seems to affect the ductile brittle transition temperature of the weld metal. • There is improper mixing of the two base metals in the fusion zone dissimilar welds of RAFM steel and austenitic stainless steel made by EB welding. - Abstract: Effect of weld metal composition on microstructure and toughness of weld metal is studied in this paper. Weld joints of reduced activation ferritic/martensitic (RAFM) steel containing 1.0 and 1.4 wt.% W were prepared using electron beam welding (EBW) process. Dissimilar weld joints between 1.0 wt.% W RAFM steel and AISI 316L (N) SS were also prepared using EBW process. The effect of post weld heat treatment (PWHT) temperatures on microstructure and mechanical properties was also studied. Microstructural observation reveals delta–ferrite in 1.4 wt.% W containing weld metal, which is absent in 1.0 wt.% W weld metal. In the case of the dissimilar weld metal, microstructure shows presence of lath martensite and retained austenite. Austenite was stable even after PWHT and its presence is attributed to high nickel (5–6 wt.%) content in the dissimilar weld metal. Hardness of RAFM steel weld metal was found to be 270–290 VHN after PWHT at 750 °C for 2 h. Impact toughness of both 1.0 and 1.4 wt.% W RAFM steel is high (>250 J) at ambient temperature. However, after PWHT, variation of toughness with temperature is more drastic for 1.4 wt.% W RAFM steel weld metal than the other. As a result, ductile brittle transition temperature (DBTT) for the 1.4 wt.% steel weld metal is close to 0 °C while that of the 1.0 wt.% W steel is close to that of the base metal (∼−80 °C)

  1. Influence of groove size and reinforcements addition on mechanical properties and microstructure of friction stir welded joints

    Science.gov (United States)

    Reddy Baridula, Ravinder; Ibrahim, Abdullah Bin; Yahya, Che Ku Mohammad Faizal Bin Che Ku; Kulkarni, Ratnakar; Varma Ramaraju, Ramgopal

    2018-03-01

    The butt joints fabricated by friction stir welding were found to have more strength than the joints obtained by conventional joining process. The important outcome of this process is the successful fabrication of surface composites with improved properties. Thus in order to further enhance the strength of the dissimilar alloy joints the reinforcements can be deposited in to the aluminium matrix during the process of friction stir welding. In the present study the multi-walled carbon nanotubes were embedded in to the groove by varying the width during joining of dissimilar alloys AA2024 and AA7075. Four widths were selected with constant depth and optimum process parameters were selected to fabricate the sound welded joints. The results show that the mechanical properties of the fabricated butt joints were influenced by the size of the groove, due to variation in the deposition of reinforcement in the stir zone. The microstructural study and identification of the elements of the welded joints show that the reinforcements deposition is influenced by the size of the groove. It has also been observed that the groove with minimum width is more effective than higher width. The mechanical properties are found to be improved due to the pinning of grain boundaries.

  2. Study on the Effect of Laser Welding Parameters on the Microstructure and Mechanical Properties of Ultrafine Grained 304L Stainless Steel

    Directory of Open Access Journals (Sweden)

    Reihane Nafar Dehsorkhi

    2016-12-01

    Full Text Available In the present study, an ultrafine grained (UFG 304L stainless steel with the average grain size of 300 nm was produced by a combination of cold rolling and annealing. Weldability of the UFG sample was studied by Nd: YAG laser welding under different welding conditions. Taguchi experimental design was used to optimize the effect of frequency, welding time, laser current and laser pulse duration on the resultant microstructure and mechanical properties. X-ray Diffraction (XRD, Optical Microscope (OM, Scanning Electron Microscope (SEM, Transmission Electron Microscope (TEM, microhardness measurements and tension tests were conducted to characterize the sample after thermomechanical processing and laser welding. The results showed that the ultrafine grained steel had the yield strength of 1000 Mpa and the total elongation of 48%, which were almost three times higher than those of the as-received sample. The microstructure of the weld zone was shown to be a mixture of austenite and delta ferrite. The microhardness of the optimized welded sample (315 HV0.5 was found to be close to the UFG base metal (350 HV. It was also observed that the hardness of the heat affected zone (HAZ was  lower than that of the weld zone, which was related to the HAZ grain growth during laser welding. The results of optimization also showed that the welding time was the most important parameter affecting the weld strength. Overall, the study showed that laser welding could be an appropriate and alternative welding technique for the joining of UFG steels.

  3. TIGER/Line Shapefile, 2013, county, Weld County, CO, Current Address Ranges Relationship File

    Data.gov (United States)

    US Census Bureau, Department of Commerce — The TIGER/Line shapefiles and related database files (.dbf) are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master...

  4. Microstructure and Mechanical Properties of Ultrasonic Spot Welded Mg/Al Alloy Dissimilar Joints

    Directory of Open Access Journals (Sweden)

    He Peng

    2018-04-01

    Full Text Available Lightweight structural applications of magnesium and aluminum alloys inevitably necessitate welding and joining, especially dissimilar welding between these alloys. The objective of this study was to examine the feasibility of joining ZEK100 Mg alloy to Al6022 alloy via ultrasonic spot welding, focusing on effects of welding energy. An interface diffusion layer consisting of α-Mg and Al12Mg17 eutectic structure was observed to form, with its thickness increased from ~0.5 µm to ~30 µm with increasing welding energy from 500 J to 2000 J. The tensile lap shear peak load or strength and critical stress intensity of the welded joints first increased and then decreased with increasing welding energy, with their peak values achieved at 750 J. Fatigue life of the joints made at 750 J and 2000 J was equivalent at the lower cyclic loading levels, while it was longer for the joints made at 750 J at the higher cyclic loading levels. Fatigue fracture mode changed from interfacial failure to mainly transverse-through-thickness crack growth with decreasing cyclic loading level, which corresponded well to the bi-linear characteristic of S-N curves. Crack initiation basically occurred at the weld nugget border and at the interface between the two sheets, which can be understood via a theoretical stress analysis.

  5. Microstructure and Mechanical Properties of J55ERW Steel Pipe Processed by On-Line Spray Water Cooling

    Directory of Open Access Journals (Sweden)

    Zejun Chen

    2017-04-01

    Full Text Available An on-line spray water cooling (OSWC process for manufacturing electric resistance welded (ERW steel pipes is presented to enhance their mechanical properties and performances. This technique reduces the processing needed for the ERW pipe and overcomes the weakness of the conventional manufacturing technique. Industrial tests for J55 ERW steel pipe were carried out to validate the effectiveness of the OSWC process. The microstructure and mechanical properties of the J55 ERW steel pipe processed by the OSWC technology were investigated. The optimized OSWC technical parameters are presented based on the mechanical properties and impact the performance of steel pipes. The industrial tests show that the OSWC process can be used to efficiently control the microstructure, enhance mechanical properties, and improve production flexibility of steel pipes. The comprehensive mechanical properties of steel pipes processed by the OSWC are superior to those of other published J55 grade steels.

  6. Microstructure and mechanical characterization of friction stir welded high strength low alloy steels

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh, R., E-mail: rameshsmit@gmail.com [Department of Mechanical Engineering, PSG College of Technology, Coimbatore 641004, Tamilnadu (India); Dinaharan, I., E-mail: dinaweld2009@gmail.com [Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park Kingsway Campus, Johannesburg 2006, Gauteng (South Africa); Kumar, Ravi, E-mail: nvrk@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamilnadu (India); Akinlabi, E.T., E-mail: etakinlabi@uj.ac.za [Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park Kingsway Campus, Johannesburg 2006, Gauteng (South Africa)

    2017-02-27

    Friction stir welding (FSW) is a promising technique to join HSLA steels without the problems encountered during fusion based welding processes. In the present work, 3 mm thick HSLA plates were successfully welded using FSW. A tool made of tungsten-rhenium alloy was used in this work. The relationship between microstructure and tensile strength was studied under various welding conditions i.e. change in traverse speed (57–97 mm/min). The microstructure of the weld nugget revealed the presence of upper bainite and fine ferrite phases. The amount of upper bainite reduced with increase in traverse speed. EBSD images showed a reducing trend for grain size. The details of hardness, tensile strength and bending test were reported.

  7. Microstructure and mechanical characterization of friction stir welded high strength low alloy steels

    International Nuclear Information System (INIS)

    Ramesh, R.; Dinaharan, I.; Kumar, Ravi; Akinlabi, E.T.

    2017-01-01

    Friction stir welding (FSW) is a promising technique to join HSLA steels without the problems encountered during fusion based welding processes. In the present work, 3 mm thick HSLA plates were successfully welded using FSW. A tool made of tungsten-rhenium alloy was used in this work. The relationship between microstructure and tensile strength was studied under various welding conditions i.e. change in traverse speed (57–97 mm/min). The microstructure of the weld nugget revealed the presence of upper bainite and fine ferrite phases. The amount of upper bainite reduced with increase in traverse speed. EBSD images showed a reducing trend for grain size. The details of hardness, tensile strength and bending test were reported.

  8. Formation mechanism for the nanoscale amorphous interface in pulse-welded Al/Fe bimetallic systems

    International Nuclear Information System (INIS)

    Li, Jingjing; Yu, Qian; Zhang, Zijiao; Xu, Wei; Sun, Xin

    2016-01-01

    Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the subsequent recrystallization occurred on the aluminum side of the interface.

  9. Formation mechanism for the nanoscale amorphous interface in pulse-welded Al/Fe bimetallic systems

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jingjing [Department of Mechanical Engineering, The University of Hawaii at Manoa, Honolulu, Hawaii 96822 (United States); Yu, Qian; Zhang, Zijiao [Department of Materials Science and Engineering, Center for Electron Microscope, Zhejiang University, Hangzhou 310027 (China); Xu, Wei; Sun, Xin, E-mail: xin.sun@pnnl.gov [Pacific Northwest National Laboratory, Richland, Washington 99354 (United States)

    2016-05-16

    Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the subsequent recrystallization occurred on the aluminum side of the interface.

  10. Mechanical properties and long-range behaviour of TZM-welding joints

    International Nuclear Information System (INIS)

    Jakobeit, W.; Eck, R.; Ullrich, G.

    1987-01-01

    In order to utilize the known excellent high temperature properties of TZM (Mo-0,5Ti-0,08Zr) for construction of components with thick sections (sheets of 8 mm wall thickness, bars of 25 mm diameter) the testing of suitable joining techniques was necessary. Based on the present state of the art the EB- and TIG-welding as well as the friction welding seemed to be the qualified methods. The investigations of the welded specimens covered non-destructive tests and metallographic evaluations as well as tensile tests, long term creep rupture tests at 850 0 C and fatigue tests unter tension-compression stresses at room temperature and 850 0 C. EB- and TIG-weldments showed coarse grained weld and heat affected zones. Due to higher gas contents, the EB-welded specimens produced by P/M process were interspersed with pores while the joints of the ARC-cast TZM material were uniform. However, TIG-welds of both variants were affected with porosity and cracks. The friction welds were almost perfect. In the tensile tests, all the joints containing recrystallized microstructure zones ruptured in the welds at strength values equivalent to recrystallized TZM. The strength of friction welds exhibited significant higher values. At room temperature the tensile ductility of all weldments was inadequate, the friction welded specimens showed the lowest values. At 850 0 C the tensile ductility was adequate in all variants. The creep rupture tests at 850 0 C exhibit up to 10 000 h that the strength of the friction weldments exceed those of the EB-weldments. (orig./IHOE) [de

  11. PLANAR MECHANISMS USED FOR GENERATING CURVE LINE TRANSLATION MOTION

    Directory of Open Access Journals (Sweden)

    Ovidiu ANTONESCU

    2015-05-01

    Full Text Available The curve line translation motion can be generated in the particular form of the circular translation, through mono-mobile mechanisms with articulated links of simple parallelogram type (with a fixed side or through transmission with toothed belt with a fixed wheel. Also, the circular translation can be generated through planar mechanisms with two cylindrical gears with a fixed central wheel. It is mentioned that the two cylindrical gearings of the Fergusson mechanisms are both exterior and interior.

  12. Analysis of stratification effects on mechanical integrity of pressurizer surge line

    International Nuclear Information System (INIS)

    Thomas-Solgadi, E.; Taupin, P.; Ensel, C.

    1992-01-01

    Unexpected thermal movements in pressurizer surge lines have been reported by several PWR operating utilities. Sometimes gaps between pipe and pipe whip restraints can become closed and plastic deformations could result. Moreover these movements, which have not been considered at conception, can induce additional stresses, and design limits on fatigue and stresses may be exceeded. These piping movements are caused by thermal stratification phenomenon in the horizontal part of the surge line (difference of temperature between hot leg and pressurizer varying from 30 C to above 160 C). To assess the mechanical consequences of this 3-dimensional phenomenon, FRAMATOME has developed a computer program using simplified models (1 and 2-dimensional). This method integrates past investigations on thermal-hydraulic variation of the stratification based on plant monitoring programs carried out by FRAMATOME since 1981, and based also on thermal-hydraulic tests and thermal-hydraulic computer code results. The methodology developed by FRAMATOME permits the following calculations: movements of the line in the elastic and plastic domains; stresses (Mises criterion -- calculations in compliance with ASME or RCC-M codes); usage factors in different components (elbows, welds, ...); crack propagation taking into account stratification and plastic shakedown

  13. GMAW (Gas Metal Arc Welding) process development for girth welding of high strength pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Rajan, Vaidyanath; Daniel, Joe; Quintana, Marie [The Lincoln Electric Company, Cleveland, OH (United States); Chen, Yaoshan [Center for Reliable Energy Systems (CRES), Dublin, OH (United States); Souza, Antonio [Lincoln Electric do Brasil, Guarulhos, SP (Brazil)

    2009-07-01

    This paper highlights some of the results and findings from the first phase of a consolidated program co-funded by US Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA) and Pipeline Research Council Inc (PRCI) to develop pipe weld assessment and qualification methods and optimize X 100 pipe welding technologies. One objective of the program is to establish the range of viable welding options for X 100 line pipe, and define the essential variables to provide welding process control for reliable and consistent mechanical performance of the weldments. In this first phase, a series of narrow gap girth welds were made with pulsed gas metal arc welding (GMAW), instrumented with thermocouples in the heat affected zone (HAZ) and weld metal to obtain the associated thermal profiles, and instrumented to measure true energy input as opposed to conventional heat input. Results reveal that true heat input is 16%-22% higher than conventional heat input. The thermal profile measurements correlate very well with thermal model predictions using true energy input data, which indicates the viability of treating the latter as an essential variable. Ongoing microstructural and mechanical testing work will enable validation of an integrated thermal-microstructural model being developed for these applications. Outputs from this model will be used to correlate essential welding process variables with weld microstructure and hardness. This will ultimately enable development of a list of essential variables and the ranges needed to ensure mechanical properties are achieved in practice, recommendations for controlling and monitoring these essential variables and test methods suitable for classification of welding consumables. (author)

  14. 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.

  15. Transition welds in welding of two-ply steels

    International Nuclear Information System (INIS)

    Fartushnyj, V.G.; Evsyukov, Yu.G.

    1977-01-01

    Studied were physico-mechanical properties of welds made by various welding wires of chromium-nickel and nickel-chromium steels in submerged arc welding of double-layer steels with main layer of the VSt.3sp. carbon steel. It is shown that service-reliable structures welded of two-layer steels are obtained by providing the content from 11 to 20 % Ni in the automatically welded transition layer

  16. Inversion mechanisms for OH main lines astrophysical masers

    International Nuclear Information System (INIS)

    Elitzur, M.

    1977-01-01

    Excitation processes that can lead to inversion of the main lines of the OH ground state are discussed. Due to the frequency dependence of the emission coefficient of dust, far-IR emitted by warm enough dust can excite the upper halves of the Λ-doublets of rotational levels more strongly than the lower halves. The cascade back to the ground state will then invert the main lines and it is shown that this mechanism can explain rather well the main lines emission from OH-IR stars. The main lines masers associated with compact HII regions are discussed extensively. It is argued that the most plausible explanation for them is a model based on the mechanism suggested some time ago by Johnston where the inversion is due to collisional excitation by streams of uni-directional electrons. (author)

  17. Microstructural, mechanical and weldability assessments of the dissimilar welds between γ′- and γ″-strengthened nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Naffakh Moosavy, Homam, E-mail: homam_naffakh@iust.ac.ir [School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Tehran 16846-13114 (Iran, Islamic Republic of); Aboutalebi, Mohammad-Reza; Seyedein, Seyed Hossein [School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Tehran 16846-13114 (Iran, Islamic Republic of); Mapelli, Carlo [Dipartimento di Meccanica, Politecnico di Milano, Via La Massa 34, Milan 20156 (Italy)

    2013-08-15

    Dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys has been investigated to identify the relationship between the microstructure of the welds and the resultant mechanical and weldability characteristics. γ′-Strengthened nickel-base Alloy 500 and γ″-strengthened nickel-base Alloy 718 were used for dissimilar welding. Gas tungsten arc welding operations were utilized for performing the autogenous dissimilar welding. Alloy 500 and Alloy 718 base metals showed various types of phases, carbides, intermetallics and eutectics in their microstructure. The results for Alloy 500 weld metal showed severe segregation of titanium to the interdendritic regions. The Alloy 718 weld metal compositional analysis confirmed the substantial role of Nb in the formation of low-melting eutectic-type morphologies which can reduce the weldability. The microstructure of dissimilar weld metal with dilution level of 65% wt.% displayed semi-developed dendritic structure. The less segregation and less formation of low-melting eutectic structures caused to less susceptibility of the dissimilar weld metal to the solidification cracking. This result was confirmed by analytic modeling achievements. Dissolution of γ″-Ni{sub 3}Nb precipitations took place in the Alloy 718 heat-affected zone leading to sharp decline of the microhardness in this region. Remelted and resolidified regions were observed in the partially-melted zone of Alloy 500 and Alloy 718. Nevertheless, no solidification and liquation cracking happened in the dissimilar welds. Finally, this was concluded that dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys can successfully be performed. - Highlights: • Dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys is studied. • Microstructural, mechanical and weldability aspects of the welds are assessed. • Microstructure of welds, bases and heat-affected zones is characterized in detail. • The type

  18. Effects of delta ferrite content on the mechanical properties of E308-16 stainless steel weld metal

    Energy Technology Data Exchange (ETDEWEB)

    Edmonds, D. P.; Vandergriff, D. M.; Gray, R. J.

    1978-01-01

    The effects of ferrite content on the properties of type 308 stainless steel shielded metal-arc (SMA) welds were investigated. Welds were made at four levels of ferrite content ranging from 2 to 15 FN (Ferrite Number). Creep and tensile tests were performed. Specimens were aged at 1100/sup 0/C (593/sup 0/C) for times up to 10,000 h (36 Ms) and Charpy V-notch impact tests were performed. Chemical analysis of the original deposits, Magne-gage evaluations, and metallographic evaluation of tested specimens were made. The E308-16 stainless steel electrodes were formulated to produce SMA welds with 2, 5, 9, and 15 FN. The ferrite number was made to vary by varying the nickel and chromium concentrations. Magne-gage determinations revealed that as-welded structures contained an average of 1.8, 4.2, 9.6, and 14.5 FN, respectively. Chemical anslysis of these deposits revealed no unusually high concentrations of tramp elements that would significantly affect mechanical properties. The extra low-ferrite electrodes were made with a different core wire, which produced deposits with slightly higher molybdenum concentrations. This variation in molybdenum should affect properties only minimally. From these chemical analyses and a constitutional diagram, ferrite concentrations were calculated, and the results correlated with the Magne-gage values

  19. Mechanical behaviour of SFR materials: proposition of fatigue weld joint coefficient for MOD9CR-1MO

    International Nuclear Information System (INIS)

    Ancelet, O.; Matheron, Ph.

    2012-01-01

    Mod 9Cr-1Mo steel (T91) is a candidate material for steam generator of SFR (Sodium Fast Reactors). In order to validate this choice, it is necessary, firstly to verify that it is able to withstand the planned environmental and operating conditions, and secondly to check if it is covered by the existing design codes, concerning its procurement, fabrication, welding, examination methods and mechanical design rules. A large R and D program on mod9Cr-1Mo steel has been undertaken at CEA in order to characterize the behavior of this material and of its welded junctions. In this program, the role of the Laboratory for structural Integrity and Standards (LISN) is to develop high temperature defect assessment procedures under fatigue and creep loadings. In this frame, complementary studies are conducted in order to validate the existing methods (developed for the fast reactors) and to get new experimental data on Mod9Cr-1Mo steel. In particular, some new experiments are conducted on specimen with a weld joint and compared with classical experiments on base metal specimen. These results associated with finite element modeling allow to propose a weld joint coefficient at 550 degrees C for the Mod9Cr1Mo steel. (authors)

  20. Effects of Heat Input on the Mechanical and Metallurgical Characteristics of Tig Welded Incoloy 800Ht Joints

    Directory of Open Access Journals (Sweden)

    Kumar S. Arun

    2017-09-01

    Full Text Available This study focuses on the effect of heat input on the quality characteristics of tungsten inert arc gas welded incoloy 800HT joints using inconel-82 filler wire. Butt welding was done on specimens with four different heat inputs by varying the process parameters like welding current and speed. The result indicated that higher heat input levels has led to the formation of coarser grain structure, reduced mechanical properties and sensitization issues on the weldments. The formation of titanium nitrides provided resistance to fracture and increased the tensile strength of the joints at high temperatures. Further aging was done on the welded sample at a temperature of 750°C for 500 hours and the metallographic result showed formation of carbides along the grain boundaries in a chain of discrete and globular form which increased the hardness of the material. The formation of spinel NiCr2O4 provided oxidation resistance to the material during elevated temperature service.

  1. Low-Temperature Aging of Delta-Ferrite in 316L SS Welds; Changes in Mechanical Properties and Etching Properties

    Science.gov (United States)

    Abe, Hiroshi; Shimizu, Keita; Watanabe, Yutaka

    Thermal aging embrittlement of LWR components made of stainless cast (e.g. CF-8 and CF-8M) is a potential degradation issue, and careful attention has been paid on it. Although welds of austenitic stainless steels (SSs) have γ-δ duplex microstructure, which is similar to that of the stainless cast, examination on thermal aging characteristics of the SS welds is very limited. In order to evaluate thermal aging behavior of weld metal of austenitic stainless steel, the 316L SS weld metal has been prepared and changes in mechanical properties and in etching properties at isothermal aging at 335°C have been investigated. The hardness of the ferrite phase has increased with aging, while the hardness of austenite phase has stayed same. It has been suggested that spinodal decomposition has occurred in δ-ferrite by the 335°C aging. The etching rates of δ-ferrite at immersion test in 5wt% hydrochloric acid solution have been also investigated using an AFM technique. The etching rate of ferrite phase has decreased consistently with the increase in hardness of ferrite phase. It has been thought that this characteristic is also caused by spinodal decomposition of ferrite into chromium-rich (α') and iron-rich (α).

  2. Mechanical Properties of Laser Beam Welded Ultra-high Strength Chromium Steel with Martensitic Microstructure

    Science.gov (United States)

    Dahmen, Martin; Janzen, Vitalij; Lindner, Stefan; Wagener, Rainer

    A new class of steels is going to be introduced into sheet manufacturing. Stainless ferritic and martensitic steels open up opportunities for sheet metal fabrication including hot stamping. A strength of up to 2 GPa at a fracture strain of 15% can be attained. Welding of these materials became apparently a challenge. Energy-reduced welding methods with in-situ heat treatment are required in order to ensure the delicate and complex heat control. Laser beam welding is the joining technique of choice to supply minimum heat input to the fusion process and to apply an efficient heat control. For two application cases, production of tailored blanks in as-rolled condition and welding in assembly in hot stamped conditions, welding processes have been developed. The welding suitability is shown in metallurgical investigations of the welds. Crash tests based on the KSII concept as well as fatigue tests prove the applicability of the joining method. For the case of assembly also joining with deep drawing and manganese boron steel was taken into consideration. The strength of the joint is determined by the weaker partner but can benefit from its ductility.

  3. Modeling of the fracture behavior of spot welds using advanced micro-mechanical damage models

    International Nuclear Information System (INIS)

    Sommer, Silke

    2010-01-01

    This paper presents the modeling of deformation and fracture behavior of resistance spot welded joints in DP600 steel sheets. Spot welding is still the most commonly used joining technique in automotive engineering. In overloading situations like crash joints are often the weakest link in a structure. For those reasons, crash simulations need reliable and applicable tools to predict the load bearing capacity of spot welded components. Two series of component tests with different spot weld diameters have shown that the diameter of the weld nugget is the main influencing factor affecting fracture mode (interfacial or pull-out fracture), load bearing capacity and energy absorption. In order to find a correlation between nugget diameter, load bearing capacity and fracture mode, the spot welds are simulated with detailed finite element models containing base metal, heat affected zone and weld metal in lap-shear loading conditions. The change in fracture mode from interfacial to pull-out or peel-out fracture with growing nugget diameter under lap-shear loading was successfully modeled using the Gologanu-Leblond model in combination with the fracture criteria of Thomason and Embury. A small nugget diameter is identified to be the main cause for interfacial fracture. In good agreement with experimental observations, the calculated pull-out fracture initiates in the base metal at the boundary to the heat affected zone.

  4. Effect of tool pin profile on microstructure and mechanical properties of friction stir welded AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Motalleb-nejad, P.; Saeid, T.; Heidarzadeh, A.; Darzi, Kh.; Ashjari, M.

    2014-01-01

    Highlights: • FSW conditions for defect free joints of AZ31B magnesium alloy were reached. • The effect of FSW factors such pin design on the features of the welds was studied. • Taper pin caused to finest grains and highest mechanical properties. • The superior properties of the joints were achieved at the condition of ω 2 /υ = 6300. • All the tensile fractures occurred at the interface of the SZ and base metal. - Abstract: In this investigation the effect of friction stir welding pin geometry on the microstructure and mechanical properties of AZ31B magnesium alloy joints is studied. The considered pin geometries are simple cylindrical, screw threaded cylindrical and taper. The joints are friction stir welded at different traverse and rotational speeds. Microstructures of the joints are examined using the optical and scanning electron microscopes. Also, the tensile properties and hardness of the joints are measured. The results show that taper and screw threaded cylindrical pins produce defect free joints. In addition, the taper pin results in finest microstructure and highest mechanical properties. Furthermore, it is found that rotational speed has a more significant role on the final microstructure and mechanical properties of the joints, compared to the traverse speed

  5. Homogeneous weldings of copper

    International Nuclear Information System (INIS)

    Campurri, C.; Lopez, M.; Fernandez, R.; Osorio, V.

    1995-01-01

    This research explored the metallurgical and mechanical properties of arc welding of copper related with influence of Argon, Helium and mixtures of them. Copper plates of 6 mm thickness were welded with different mixtures of the mentioned gases. The radiography of welded specimens with 100% He and 100% Ar does not show show any porosity. On the other hand, the copper plates welded different gas mixtures presented uniform porosity in the welded zone. The metallographies show recrystallized grain in the heat affected zone, while the welding zone showed a dendritic structure. The results of the tensile strength vary between a maximum of 227 MPa for 100% He and a minimum of 174 MOa for the mixture of 60% He and 40% Ar. For the elongation after fracture the best values, about 36%, were obtained for pure gases. As a main conclusion, we can say that arc welding of copper is possible without loosing the mechanical and metallurgical properties of base metal. 6 refs

  6. Mechanical properties and microstructural investigations of TIG welded 40 mm and 60 mm thick SS 316L samples for fusion reactor vacuum vessel applications

    Energy Technology Data Exchange (ETDEWEB)

    Buddu, Ramesh Kumar, E-mail: brkumar75@gmail.com; Chauhan, N.; Raole, P.M.

    2014-12-15

    Highlights: • Austenitic stainless steels (316L) of 40 mm and 60 mm thickness plates were joined by Tungsten Inert Gas welding (TIG) process which are probable materials for advanced fusion reactor vacuum vessel requirements. • Mechanical properties and detailed microstructure studies have been carried out for welded samples. • Fractography analysis of impact test specimens indicated ductile fracture mode in BM, HAZ and WZ samples. • Presence of delta ferrite phase was observed in the welded zone and ferrite number data was measured for the base and weld metal and was found high in welds. - Abstract: The development of advanced fusion reactors like DEMO will have various challenges in materials and fabrication. The vacuum vessel is important part of the fusion reactor. The double walled design for vacuum vessel with thicker stainless steel material (40–60 mm) has been proposed in the advanced fusion reactors like ITER. Different welding techniques will have to be used for such vacuum vessel development. The required mechanical, structural and other properties of stainless steels have to be maintained in these joining processes of components of various shapes and sizes in the form of plates, ribs, shells, etc. The present paper reports characterization of welding joints of SS316L plates with higher thicknesses like 40 mm and 60 mm, prepared using multi-pass Tungsten Inert Gas (TIG) welding process. The weld quality has been evaluated with non-destructive tests by X-ray radiography and ultrasonic methods. The mechanical properties like tensile, bend tests, Vickers hardness and impact fracture tests have been carried out for the weld samples. Tensile property test results indicate sound weld joints with efficiencies over 100%. Hardening was observed in the weld zone in non-uniform manner. Macro and microstructure studies have been carried out for Base Metal (BM), Heat Affected Zone (HAZ) and Weld Zone (WZ). Scanning Electron Microscopy (SEM) analysis carried

  7. Mechanical properties and microstructural investigations of TIG welded 40 mm and 60 mm thick SS 316L samples for fusion reactor vacuum vessel applications

    International Nuclear Information System (INIS)

    Buddu, Ramesh Kumar; Chauhan, N.; Raole, P.M.

    2014-01-01

    Highlights: • Austenitic stainless steels (316L) of 40 mm and 60 mm thickness plates were joined by Tungsten Inert Gas welding (TIG) process which are probable materials for advanced fusion reactor vacuum vessel requirements. • Mechanical properties and detailed microstructure studies have been carried out for welded samples. • Fractography analysis of impact test specimens indicated ductile fracture mode in BM, HAZ and WZ samples. • Presence of delta ferrite phase was observed in the welded zone and ferrite number data was measured for the base and weld metal and was found high in welds. - Abstract: The development of advanced fusion reactors like DEMO will have various challenges in materials and fabrication. The vacuum vessel is important part of the fusion reactor. The double walled design for vacuum vessel with thicker stainless steel material (40–60 mm) has been proposed in the advanced fusion reactors like ITER. Different welding techniques will have to be used for such vacuum vessel development. The required mechanical, structural and other properties of stainless steels have to be maintained in these joining processes of components of various shapes and sizes in the form of plates, ribs, shells, etc. The present paper reports characterization of welding joints of SS316L plates with higher thicknesses like 40 mm and 60 mm, prepared using multi-pass Tungsten Inert Gas (TIG) welding process. The weld quality has been evaluated with non-destructive tests by X-ray radiography and ultrasonic methods. The mechanical properties like tensile, bend tests, Vickers hardness and impact fracture tests have been carried out for the weld samples. Tensile property test results indicate sound weld joints with efficiencies over 100%. Hardening was observed in the weld zone in non-uniform manner. Macro and microstructure studies have been carried out for Base Metal (BM), Heat Affected Zone (HAZ) and Weld Zone (WZ). Scanning Electron Microscopy (SEM) analysis carried

  8. Thermomechanical Modelling of Direct-Drive Friction Welding Applying a Thermal Pseudo Mechanical Model for the Generation of Heat

    DEFF Research Database (Denmark)

    Sonne, Mads Rostgaard; Hattel, Jesper Henri

    2018-01-01

    In the present work a 2D a xisymmetric thermomechanical model of the direct-drive friction welding process is developed, taking the temperature dependent shear yield stress into account in the description of the heat generation, utilizing a recent thermal pseudo mechanical model originally...... developed for the friction stir welding (FSW) process. The model is implemented in ABAQUS/Explicit via a subroutine. The application in this case is joining of austenitic stainless steel rods with an outer diameter of 112 mm, used for manufacturing of exhaust gas valves for large two stroke marine engines....... The material properties in terms of the temperature dependent flowstress curves used both in the thermal and the mechanical constitutive description are extracted from compression tests performed between 20 °C and 1200 °C on a Gleeble 1500 thermomechanical simulator. Comparison between measured and simulated...

  9. Mechanical behavior of 27CD4 and 100C6 steel joints, rapidly welded using dynamic diffusion welding

    International Nuclear Information System (INIS)

    Page, G. le; Hourcade, M.; Criqui, B.

    1993-01-01

    A new process, dynamic-diffusion-bonding (DDB) was improved in our laboratory (1). It offers the advantages of both classical diffusion-bonding and rapidity, which is consistent with mass production. It was proven possible to carry out high strength bonds in a very short time: 60 seconds with specimens of 27CD4 steel (diameter=16mm). After bonding, the specimens were heat treated in order to homogeneize the structure along the piece. With the optimal bonding conditions, namely a few seconds at 1060 C, in a nitrogen with 5% hydrogen gas, with a proper surface preparation (Ra=0,04 μm) and under a modulated pressure during the whole bonding process (2,3): a) deformation of the bonded specimens is limited to about 2% of the heated length, b) tensile and torsion behaviour is very good: failure occurs out of the interface. No defect remains across the weld interface, c) the failure energy of joints measured with impact tests is lower than that of the base metal, because of the flatness of the interface and because of the presence of very fine oxide particles in the bond, d) fatigue behaviour (rotating beam tests) of bonded pieces is very good: their fatigue strength (720 MPa: stair case estimation for 5 .10 6 cycles) is very closed to those of unbonded specimens (780 MPa), and the crack initiates out of the interface near a big inclusion. With the 100C6 steel, bonds of the same quality were obtained, and with higher roughness of specimens (Ra=0,15 μm), high quality joints were achieved with a duration of 60 seconds at 1050 C. (orig.)

  10. Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing

    OpenAIRE

    Górka J.

    2017-01-01

    This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by...

  11. Characterization of microstructure and mechanical properties of friction stir welded AlMg5- Al_2O_3 nanocomposites

    International Nuclear Information System (INIS)

    Babu, N. Kishore; Kallip, Kaspar; Leparoux, Marc; AlOgab, Khaled A.; Reddy, G.M.; Talari, M.K.

    2016-01-01

    In the present study, powder metallurgy processed unmilled AlMg5, milled AlMg5 and milled AlMg5-0.5 vol% Al_2O_3 nanocomposite have been successfully friction stir welded (FSW). The effect of friction stir welding on the evolution of weld microstructures; hardness and tensile properties were studied and discussed in detail. FSW of unmilled AlMg5 resulted in significant grain refinement and strain hardening in the nugget zone induced by the thermo-mechanical processing, thereby increasing the stir zone hardness and tensile strengths to 100 HV and 324 MPa when compared to 80 HV and 300 MPa of base metal, respectively. In contrast, the FSW of milled AlMg5 and milled AlMg5-0.5 vol% Al_2O_3 samples showed a reduction in UTS values to 375 MPa and 401 MPa in the stir zone compared to 401 MPa and 483 MPa of respective base metal values. Transmission electron microscopic (TEM) investigation of weld stir zones revealed the homogenous distribution of Al_4C_3 nanophases in milled AlMg5 and Al_2O_3 nanoparticles in milled AlMg5-0.5 vol% Al_2O_3 samples throughout the aluminium matrix. It was revealed that the pre-stored energy from the prior ball milling and hot pressing processes, higher deformation energy and grain boundary pinning effect due to the presence of reinforcement particles has resulted in a higher recrystallization tendency and retarded grain growth during FSW of milled samples. The welds prepared with milled AlMg5-0.5 vol% Al_2O_3 exhibited higher hardness and tensile strength in the stir zone when compared to all other conditions which was attributed to Hall Petch effect due to fine grain size and Orowan strengthening effect due to Al_2O_3 reinforcements.

  12. Modelling the mechanical behaviour of heterogeneous Ta/TA6V welded joints: behaviour and failure criteria

    International Nuclear Information System (INIS)

    Paris, Th.

    2008-12-01

    As laser welding of two different materials (heterogeneous welding) leads to a joint having a characteristic size close to the millimetre, i.e. much smaller than that of a structure, and as such a junction displays completely different mechanical properties because of the metallurgical transformations induced by intense thermal loading, the aim of this research thesis is to develop a behaviour model, flexible and robust enough, to represent all together the mechanical behaviours of the Ta, the TA6V and the melted zone. This model must be able to take plasticity and visco-plasticity into account, and also to provide a failure criterion through damage mechanics and its coupling with the behaviour. The author first reports the experimental characterization of the base materials (Ta and TA6V) by using tensile tests under different strain rates and different directions, relaxation tests and fatigue shear tests. He also characterizes the melted zone by describing the influence of a thermal treatment (induced by welding) on the formation of the melted zone, and by using different tests: four point bending on notched specimens, nano-indentation test, and longitudinal tensile test. In a second part, the author develops the model within the framework of continuum thermodynamics, and explores the numerical issues. The last part deals with the validation of the model for the concerned materials (Ta and TA6V) and melted zone

  13. Influence of Zn Interlayer on Interfacial Microstructure and Mechanical Properties of TIG Lap-Welded Mg/Al Joints

    Science.gov (United States)

    Gao, Qiong; Wang, Kehong

    2016-03-01

    This study explored 6061 Al alloy and AZ31B Mg alloy joined by TIG lap welding with Zn foils of varying thicknesses, with the additional Zn element being imported into the fusion zone to alloy the weld seam. The microstructures and chemical composition in the fusion zone near the Mg substrate were examined by SEM and EDS, and tensile shear strength tests were conducted to investigate the mechanical properties of the Al/Mg joints, as well as the fracture surfaces, and phase compositions. The results revealed that the introduction of an appropriate amount of Zn transition layer improves the microstructure of Mg/Al joints and effectively reduces the formation of Mg-Al intermetallic compounds (IMCs). The most common IMCs in the fusion zone near the Mg substrate were Mg-Zn and Mg-Al-Zn IMCs. The type and distribution of IMCs generated in the weld zone differed according to Zn additions; Zn interlayer thickness of 0.4 mm improved the sample's mechanical properties considerably compared to thicknesses of less than 0.4 mm; however, any further increase in Zn interlayer thickness of above 0.4 mm caused mechanical properties to deteriorate.

  14. Multi-Track Friction Stir Lap Welding of 2024 Aluminum Alloy: Processing, Microstructure and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Shengke Zou

    2016-12-01

    Full Text Available Friction stir lap welding (FSLW raises the possibility of fabricating high-performance aluminum components at low cost and high efficiency. In this study, we mainly applied FSLW to fabricate multi-track 2024 aluminum alloy without using tool tilt angle, which is important for obtaining defect-free joint but significantly increases equipment cost. Firstly, systematic single-track FSLW experiments were conducted to attain appropriate processing parameters, and we found that defect-free single-track could also be obtained by the application of two-pass processing at a rotation speed of 1000 rpm and a traverse speed of 300 mm/min. Then, multi-track FSLW experiments were conducted and full density multi-track samples were fabricated at an overlapping rate of 20%. Finally, the microstructure and mechanical properties of the full density multi-track samples were investigated. The results indicated that ultrafine equiaxed grains with the grain diameter about 9.4 μm could be obtained in FSLW samples due to the dynamic recrystallization during FSLW, which leads to a yield strength of 117.2 MPa (17.55% higher than the rolled 2024-O alloy substrate and an elongation rate of 31.05% (113.84% higher than the substrate.

  15. Prevention of weld-decay in austenitic stainless steel by using surface mechanical attrition treatment

    Science.gov (United States)

    Laleh, Majid; Kargar, Farzad; Rouhaghdam, Alireza Sabour

    2012-11-01

    Surface mechanical attrition treatment (SMAT) was applied to the samples of a type AISI 304 stainless steel in order to induce grain refinement as well as formation of twins. Transmission electron microscopy and X-ray diffraction analysis results showed that the average grain size at the surface of the SMATed sample was about 10 nm. The untreated and SMATed samples were then welded using a one-pass gas tungsten arc procedure. The heat-affected zone (HAZ) of the samples was examined by optical microscopy and corrosion tests. Results of the double loop electrochemical potentiokinetic reactivation tests showed that the degree of sensitization in the HAZ for the SMATed sample was very low as compared to that of the untreated one. The pre-SMATed sample was resistant to intergranular corrosion. This is mainly due to the formation of high density of twins which are not prone to carbide precipitation because of their regular and coherent atomic structure and extreme low grain boundary energy as compared with those of other grain boundaries.

  16. THE ROLE OF SHIELDING GAS ON MECHANICAL, METALLURGICAL AND CORROSION PROPERTIES OF CORTEN STEEL WELDED JOINTS OF RAILWAY COACHES USING GMAW

    Directory of Open Access Journals (Sweden)

    Byju John

    2016-12-01

    Full Text Available This analysis lays emphasis on finding a suitable combination of shielding gas for welding underframe members such as sole bar of Railway Coaches made of corten steel; for improved mechanical, metallurgical and corrosion properties of welds using copper coated solid MIG/MAG welding filler wire size 1.2 mm conforming to AWS/SFA 5.18 ER 70 S in Semi-automatic GMAW process. Solid filler wire is preferred by welders due to less fumes, practically no slag and easy manipulation of welding torch with smooth wire flow during corrosion repair attention, when compared to Flux cored wire. Three joints using Gas metal arc welding (GMAW with shielding gases viz., Pure CO2, (80% Ar – 20% CO2 and (90% Ar – 10% CO2 were made from test pieces cut from Sole bar material of Railway Coach. Study of Mechanical properties such as tensile strength, hardness and toughness revealed that welded joint made using shielding gas (80% Ar – 20% CO2 has better Mechanical properties compared to the other two shielding gases and comparable to that of Parent metal. Type of Shielding gas used has influence on the chemical composition and macro & micro structures. The Tafel extrapolation study of freshly ground samples in 3.5% NaCl solution revealed that the welded joint made using shielding gas (80% Ar – 20% CO2 has also better corrosion resistance which is comparable to the Parent metal as well as similar commercial steels.

  17. Improved microstructure and mechanical properties in gas tungsten arc welded aluminum joints by using graphene nanosheets/aluminum composite filler wires.

    Science.gov (United States)

    Fattahi, M; Gholami, A R; Eynalvandpour, A; Ahmadi, E; Fattahi, Y; Akhavan, S

    2014-09-01

    In the present study, different amounts of graphene nanosheets (GNSs) were added to the 4043 aluminum alloy powders by using the mechanical alloying method to produce the composite filler wires. With each of the produced composite filler wires, one all-weld metal coupon was welded using the gas tungsten arc (GTA) welding process. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. As the amount of GNSs in the composition of filler wire is increased, the microstructure of weld metal was changed from the dendritic structure to fine equiaxed grains. Furthermore, the tensile strength and microhardness of weld metal was improved, and is attributed to the augmented nucleation and retarded growth. From the results, it was seen that the GNSs/Al composite filler wire can be used to improve the microstructure and mechanical properties of GTA weld metals of aluminum and its alloys. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. An investigation on mechanical properties of steel fibre reinforced for underwater welded joint

    Science.gov (United States)

    Navin, K.; Zakaria, M. S.; Zairi, S.

    2017-09-01

    Underwater pipelines are always exposed to water and have a high tendency to have corrosion especially on the welded joint. This research is about using fiber glass as steel fiber to coat the welded joint to determine the effectiveness in corrosion prevention of the welded joint. Number of coating is varied to determine the better number coating to coat the pipeline. Few samples were left without immersion in salt water and few samples are immersed into salt water with same salinity as sea water. The material sample is prepared in dog bone shape to enable to be used in Universal Tensile Machine (UTM). The material prepared is left immersed for recommended time and tested in Universal Tensile Machine. Upon analyzing the result, the result is used to determine the breakage point whether broken on the welded joint or different place and also the suitable number of coating to be used.

  19. Friction welding of a nickel free high nitrogen steel: influence of forge force on microstructure, mechanical properties and pitting corrosion resistance

    Directory of Open Access Journals (Sweden)

    Mrityunjoy Hazra

    2014-01-01

    Full Text Available In the present work, nickel free high nitrogen austenitic stainless steel specimens were joined by continuous drive friction welding process by varying the amount of forge (upsetting force and keeping other friction welding parameters such as friction force, burn-off, upset time and speed of rotation as constant at appropriate levels. The joint characterization studies include microstructural examination and evaluation of mechanical (micro-hardness, impact toughness and tensile and pitting corrosion behaviour. The integrity of the joint, as determined by the optical microscopy was very high and no crack and area of incomplete bonding were observed. Welds exhibited poor Charpy impact toughness than the parent material. Toughness for friction weld specimens decreased with increase in forge force. The tensile properties of all the welds were almost the same (irrespective of the value of the applied forge force and inferior to those of the parent material. The joints failed in the weld region for all the weld specimens. Weldments exhibited lower pitting corrosion resistance than the parent material and the corrosion resistance of the weld specimens was found to decrease with increase in forge force.

  20. The effect of laser welding process parameters on the mechanical and microstructural properties of V-4Cr-4Ti structural materials

    International Nuclear Information System (INIS)

    Reed, C.; Natesan, K.; Xu, Z.; Smith, D.

    2000-01-01

    This paper reports on a systematic study which was conducted to examine the use of a pulsed Nd:YAG laser to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the resulting joints. Deep penetration and defect-free welds were achieved under an optimal combination of laser parameters including focal length of lens, pulse energy, pulse repetition rate, beam travel speed, and shielding gas arrangement. The key for defect-free welds was found to be the stabilization of the keyhole and providing an escape path for the gas trapped in the weld. An innovative method was developed to obtain deep penetration and oxygen contamination free welds. Oxygen and nitrogen uptake were reduced to levels only a few ppm higher than the base metal by design and development of an environmental control box. Effort directed at developing an acceptable postwelding heat treatment showed that five passes of a diffuse laser beam over the welded region softened the weld material, especially in the root region of the weld

  1. Microstructure Evolution and Mechanical Properties of Underwater Dry and Local Dry Cavity Welded Joints of 690 MPa Grade High Strength Steel.

    Science.gov (United States)

    Shi, Yonghua; Sun, Kun; Cui, Shuwan; Zeng, Min; Yi, Jianglong; Shen, Xiaoqin; Yi, Yaoyong

    2018-01-22

    Q690E high strength low alloy (HSLA) steel plays an important role in offshore structures. In addition, underwater local cavity welding (ULCW) technique was widely used to repair important offshore constructions. However, the high cooling rate of ULCW joints results in bad welding quality compared with underwater dry welding (UDW) joints. Q690E high strength low alloy steels were welded by multi-pass UDW and ULCW techniques, to study the microstructural evolution and mechanical properties of underwater welded joints. The microstructure and fracture morphology of welded joints were observed by scanning electron microscope and optical microscope. The elemental distribution in the microstructure was determined with an Electron Probe Microanalyzer. The results indicated that the microstructure of both two welded joints was similar. However, martensite and martensite-austenite components were significantly different with different underwater welding methods such that the micro-hardness of the HAZ and FZ in the ULCW specimen was higher than that of the corresponding regions in UDW joint. The yield strength and ultimate tensile strength of the ULCW specimen are 109 MPa lower and 77 MPa lower, respectively, than those of the UDW joint. The impact toughness of the UDW joint was superior to those of the ULCW joint.

  2. Microstructure Evolution and Mechanical Properties of Underwater Dry and Local Dry Cavity Welded Joints of 690 MPa Grade High Strength Steel

    Science.gov (United States)

    Sun, Kun; Cui, Shuwan; Zeng, Min; Yi, Jianglong; Shen, Xiaoqin; Yi, Yaoyong

    2018-01-01

    Q690E high strength low alloy (HSLA) steel plays an important role in offshore structures. In addition, underwater local cavity welding (ULCW) technique was widely used to repair important offshore constructions. However, the high cooling rate of ULCW joints results in bad welding quality compared with underwater dry welding (UDW) joints. Q690E high strength low alloy steels were welded by multi-pass UDW and ULCW techniques, to study the microstructural evolution and mechanical properties of underwater welded joints. The microstructure and fracture morphology of welded joints were observed by scanning electron microscope and optical microscope. The elemental distribution in the microstructure was determined with an Electron Probe Microanalyzer. The results indicated that the microstructure of both two welded joints was similar. However, martensite and martensite-austenite components were significantly different with different underwater welding methods such that the micro-hardness of the HAZ and FZ in the ULCW specimen was higher than that of the corresponding regions in UDW joint. The yield strength and ultimate tensile strength of the ULCW specimen are 109 MPa lower and 77 MPa lower, respectively, than those of the UDW joint. The impact toughness of the UDW joint was superior to those of the ULCW joint. PMID:29361743

  3. 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.

  4. The effect of laser welding process parameters on the mechanical and microstructural properties of V-4CR-4TI structural materials

    International Nuclear Information System (INIS)

    Reed, C. B.; Natesan, K.; Xu, Z.; Smith, D. L.

    1999-01-01

    V-Cr-Ti alloys are among the leading candidate materials for the frost wall and other structural materials applications in fusion power reactors because of several important advantages including inherently low irradiation-induced activity, good mechanical properties, good compatibility with lithium, high thermal conductivity and good resistance to irradiation-induced swelling and damage [1]. However, weldability of these alloys in general must be demonstrated, and laser welding, specifically, must be developed. Laser welding is considered to be an attractive process for construction of a reactor due to its high penetrating power and potential flexibility. This paper reports on a systematic study which was conducted to examine the use of a pulsed Nd:YAG laser to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the resulting joints. Deep penetration and defect-free welds were achieved under an optimal combination of laser parameters including focal length of lens, pulse energy, pulse repetition rate, beam travel speed, and shielding gas arrangement. The key for defect-free welds was found to be the stabilization of the keyhole and providing an escape path for the gas trapped in the weld. An innovative method was developed to obtain deep penetration and oxygen contamination free welds. Oxygen and nitrogen uptake were reduced to levels only a few ppm higher than the base metal by design and development of an environmental control box. The effort directed at developing an acceptable postwelding heat treatment showed that five passes of a diffuse laser beam over the welded region softened the weld material, especially in the root region of the weld

  5. Effect of tool rotational speed on force generation, microstructure and mechanical properties of friction stir welded Al–Mg–Cr–Mn (AA 5052-O) alloy

    International Nuclear Information System (INIS)

    Moshwan, Raza; Yusof, Farazila; Hassan, M.A.; Rahmat, S.M.

    2015-01-01

    Highlights: • 3 mm thick AA 5052-O alloy plates were successfully joined by FSW process. • The joint was produced at 1000 rpm yielded a maximum tensile strength of 132 MPa. • The dissolution of β-Mg 2 Al 3 intermetallic phases of FSWed joints were reported. • Different axial forces acted on welding tool during welding were investigated. - Abstract: Friction stir welding (FSW) between 3 mm thick AA 5052-O aluminum alloy plates was investigated in the present study. Different welded specimens were produced by employing a constant tool traverse speed of 120 mm/min and by varying rotating speeds from 800 to 3000 rpm. The welded joints were characterized by its appearances, microstructural and mechanical properties at room temperature. The measurement of different forces acted on the tool during the FSW of AA 5052-O plates provided a significant insight to determine the quality of the welded joints. From the appearances of the welded joints it was evident that, except the tool rotational speed of 3000 rpm all other rotational speeds produced sound welded joints with smooth surface. The joint produced at 1000 rpm yielded a maximum tensile strength of 132 MPa which was 74% of the base material strength. Field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) analyses on the stir zone suggested that, β-Mg 2 Al 3 intermetallic phases of the base material were mechanically fractured, smeared and mixed to different geometries due to tool stirring. The dissolution and redistribution of β-Mg 2 Al 3 second phase particles in the stir zone had a considerable effect on the reduction of the tensile strength of the welded joints. The reduction in hardness at the nugget zone (NZ) of the welded joints under different tool rotational speeds could be attributed to the dislocation of Mg-rich phases and segregation of Mg solute atoms at grain boundaries, which drew solute Mg atoms away from the α-aluminum matrix

  6. Exploring the effects of SiC reinforcement incorporation on mechanical properties of friction stir welded 7075 aluminum alloy: Fatigue life, impact energy, tensile strength

    International Nuclear Information System (INIS)

    Bahrami, Mohsen; Helmi, Nader; Dehghani, Kamran; Givi, Mohammad Kazem Besharati

    2014-01-01

    In the current research, the role of SiC nano-particles in improving the mechanical properties of friction stir welded (FSWed) 7075 aluminum alloy is investigated. To this end, friction stir welding (FSW) was conducted at 1250 rpm and 40 mm/min. The experiment carried out with and without incorporating SiC nano-particles along the joint line. Cross-sectional microstructures of the joints were characterized employing optical and scanning electron microscopy (SEM). Results achieved through X-ray diffraction (XRD) confirmed the presence of SiC powders. Moreover, it was discovered that the volume fraction of the reinforcement particles was 20%. Along with an excellent bonding between SiC nano-particles and aluminum matrix, SEM photograph demonstrated a good dispersion of SiC reinforcements. Atomic force microscopy (AFM) results were also in tight agreement with the recent SEM microstructure. Thanks to the presence of SiC nano-particles, tensile strength, percent elongation, fatigue life, and toughness of the joint improved tremendously. The fracture morphologies were in good agreement with corresponding ductility results

  7. Exploring the effects of SiC reinforcement incorporation on mechanical properties of friction stir welded 7075 aluminum alloy: Fatigue life, impact energy, tensile strength

    Energy Technology Data Exchange (ETDEWEB)

    Bahrami, Mohsen, E-mail: Mohsen.bahrami@aut.ac.ir [Faculty of Mining and Metallurgical Engineering, Amirkabir University of Technology (AUT), Hafez Avenue, Tehran (Iran, Islamic Republic of); Helmi, Nader [Faculty of Mining and Metallurgical Engineering, Amirkabir University of Technology (AUT), Hafez Avenue, Tehran (Iran, Islamic Republic of); Dehghani, Kamran [Faculty of Mining and Metallurgical Engineering, Amirkabir University of Technology (AUT), Hafez Avenue, Tehran (Iran, Islamic Republic of); Centre of Excellence in Smart Structures and Dynamical Systems (Iran, Islamic Republic of); Givi, Mohammad Kazem Besharati [Department of Mechanical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2014-02-10

    In the current research, the role of SiC nano-particles in improving the mechanical properties of friction stir welded (FSWed) 7075 aluminum alloy is investigated. To this end, friction stir welding (FSW) was conducted at 1250 rpm and 40 mm/min. The experiment carried out with and without incorporating SiC nano-particles along the joint line. Cross-sectional microstructures of the joints were characterized employing optical and scanning electron microscopy (SEM). Results achieved through X-ray diffraction (XRD) confirmed the presence of SiC powders. Moreover, it was discovered that the volume fraction of the reinforcement particles was 20%. Along with an excellent bonding between SiC nano-particles and aluminum matrix, SEM photograph demonstrated a good dispersion of SiC reinforcements. Atomic force microscopy (AFM) results were also in tight agreement with the recent SEM microstructure. Thanks to the presence of SiC nano-particles, tensile strength, percent elongation, fatigue life, and toughness of the joint improved tremendously. The fracture morphologies were in good agreement with corresponding ductility results.

  8. Thermo-mechanic and Microstructural Analysis of an Underwater Welding Joint

    Directory of Open Access Journals (Sweden)

    Pedro Hernández Gutiérrez

    Full Text Available Abstract The aim of this research is to present a comparative analysis between theoretical and experimental thermal fields as well as a microstructural behaviour and residual stresses applying multiple weld beads in the joint of two API 5L X52 pipe sections. The thermal field, microstructural and residual stresses were numerically modelled through the finite element method (FEM and compared to experimentally. The simulation conditions used in the FEM analysis were similar considerations to the underwater welding conditions. The finite element analysis was carried out, first by a non-linear transient thermal analysis for obtaining the global temperature history generated during the underwater welding process. Subsequently, a microstructural behaviour was determined using the temperatures distribution obtained in the pipe material by calculating the structural transformations of the material during the welding process, and finally a stress analysis was developed using the temperatures obtained from the thermal analysis. It was found that this simulation method can be used efficiently to determinate with accuracy the optimum welding parameters of this kind of weld applications.

  9. Using contract mechanisms to coordinate product line decisions

    NARCIS (Netherlands)

    Nalla, V.R.; Venugopal, V.; Veen, van der J.A.A.

    2008-01-01

    In this paper we design contract mechanisms to increase the efficiency of product line decisions in a Supply Chain (SC). A two stage SC with a buyer and the supplier is considered. The end consumers are comprised of two segments with different willingness to pay. The final demand and the segments’

  10. On the mechanics of elastic lines in thin shells

    Science.gov (United States)

    Benet, Eduard; Vernerey, Franck

    The deformation of soft shells in nature and engineering is often conditioned by the presence of lines whose mechanical properties are different from the shell. For instance, the deformation of tree leaves is conditioned by the presence of harder stems, and cell mitosis is driven by a stiffening line along its membrane. From an experimental standpoint, many groups have taken advantage of this feature to develop self-actuated shells with prescribed deformations. Examples include the polymerization of gels along certain lines, or the inclusion of stiffer lines via 3D printing. However, there is not yet a general continuum theory that accounts for this type of discontinuity within the membrane. Hence, we extend the general shell theory to account for the inclusion of a line that potentially induces jumps in stresses, couple stresses and moments, across its thickness. This is achieved via coupling the rod and the membrane deformations, and ensuring continuity of displacements. The model is then applied to three important problems: a constriction disc inside a shell of revolution, the induced twisting of a shell via the torsion of an embedded line, and the effect of an helicoidal line on the uni-axial deformation of a cylindrical shell. National Science Foundation CAREER award 1350090.

  11. Modelling and Pareto optimization of mechanical properties of friction stir welded AA7075/AA5083 butt joints using neural network and particle swarm algorithm

    International Nuclear Information System (INIS)

    Shojaeefard, Mohammad Hasan; Behnagh, Reza Abdi; Akbari, Mostafa; Givi, Mohammad Kazem Besharati; Farhani, Foad

    2013-01-01

    Highlights: ► Defect-free friction stir welds have been produced for AA5083-O/AA7075-O. ► Back-propagation was sufficient for predicting hardness and tensile strength. ► A hybrid multi-objective algorithm is proposed to deal with this MOP. ► Multi-objective particle swarm optimization was used to find the Pareto solutions. ► TOPSIS is used to rank the given alternatives of the Pareto solutions. -- Abstract: Friction Stir Welding (FSW) has been successfully used to weld similar and dissimilar cast and wrought aluminium alloys, especially for aircraft aluminium alloys, that generally present with low weldability by the traditional fusion welding process. This paper focuses on the microstructural and mechanical properties of the Friction Stir Welding (FSW) of AA7075-O to AA5083-O aluminium alloys. Weld microstructures, hardness and tensile properties were evaluated in as-welded condition. Tensile tests indicated that mechanical properties of the joint were better than in the base metals. An Artificial Neural Network (ANN) model was developed to simulate the correlation between the Friction Stir Welding parameters and mechanical properties. Performance of the ANN model was excellent and the model was employed to predict the ultimate tensile strength and hardness of butt joint of AA7075–AA5083 as functions of weld and rotational speeds. The multi-objective particle swarm optimization was used to obtain the Pareto-optimal set. Finally, the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS) was applied to determine the best compromised solution.

  12. Microstructure and mechanical properties of friction stir welded Al/Mg2Si metal matrix cast composite

    International Nuclear Information System (INIS)

    Nami, H.; Adgi, H.; Sharifitabar, M.; Shamabadi, H.

    2011-01-01

    In this research, friction stir weldability of 15 wt.% Mg 2 Si particulate aluminum matrix cast composite and effects of tool rotation speed and number of welding passes on microstructure and mechanical properties of the joints were investigated. Microstructural observations were carried out by employing optical and scanning electron microscopy of the cross sections perpendicular to the tool traverse direction. Mechanical properties including microhardness and tensile strength were evaluated in detail. The results showed fragmentation of Mg 2 Si particles and Mg 2 Si needles existing in eutectic structure in stir zone. Also, homogeneous distribution of Mg 2 Si particles was observed in the stir zone as a result of stirring with high plastic strains. Tension test results indicated that tensile strength of the joint had an optimum at 1120 rpm tool rotation speed and decreased with increasing of the number of welding passes. Hardness of the joint increased due to modification of solidification microstructure of the base composite. This research indicates that friction stir welding is a good candidate for joining of 15 wt.% Mg 2 Si aluminum matrix composite castings.

  13. 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.