Supercritical water corrosion of high Cr steels and Ni-base alloys

International Nuclear Information System (INIS)

Jang, Jin Sung; Han, Chang Hee; Hwang, Seong Sik

2004-01-01

High Cr steels (9 to 12% Cr) have been widely used for high temperature high pressure components in fossil power plants. Recently the concept of SCWR (supercritical water-cooled reactor) has aroused a keen interest as one of the next generation (Generation IV) reactors. Consequently Ni-base (or high Ni) alloys as well as high Cr steels that have already many experiences in the field are among the potential candidate alloys for the cladding or reactor internals. Tentative inlet and outlet temperatures of the anticipated SCWR are 280 and 510 .deg. C respectively. Among many candidate alloys there are austenitic stainless steels, Ni base alloys, ODS alloys as well as high Cr steels. In this study the corrosion behavior of the high Cr steels and Ni base (or high Ni) alloys in the supercritical water were investigated. The corrosion behavior of the unirradiated base metals could be used in the near future as a guideline for the out-of-pile or in-pile corrosion evaluation tests

Effect of cloric acid concentration on corrosion behavior of Ni/Cr coated on carbon steel

Science.gov (United States)

Desiati, Resetiana Dwi; Sugiarti, Eni; Thosin, K. A. Zaini

2018-05-01

Corrosion is one of the causes of metal degradation. Carbon steel (Fe) is easy to corrode in the extreme environment. Coating on carbon steel is required to improve corrosion resistance owing to protection or hindrance to extreme environmental conditions. In this present work, carbon steel was coated by electroplating techniques for nickel and pack cementation for chrome. The corrosion rate test was performed by Weight Loss method on FeNiCr, FeNi, FeCr and uncoated Fe as comparator which was dyed in 37% HCl and 25% HCl which had previously been measured dimension and mass. The immersion test result of FeNiCr and FeNi specimen were better than FeCr and uncoated Fe in terms of increasing corrosion resistance. The corrosion rate for 56 hours in 37% HCl for FeNiCr was 1.592 mm/y and FeNi was 3.208 mm/y, FeCr only lasted within 32 hours with corrosion rate was 6.494 mm/y. Surface of the sample after the corrosion test there was pitting, crevice corrosion and alloy cracking caused by chloride. The higher the concentration of HCl the faster the corrosion rate.

The effects of adding molybdenum and niobium on the creep strength of 18Cr-10Ni-20Co austenitic steel

International Nuclear Information System (INIS)

Tomono, Yutaka

1987-01-01

The decrease in the creep strength of structural materials during service at elevated temperatures is a very important problem that affects the security of plants and machinery. The improvement in the creep strength of 18Cr-10Ni-20Co austenitic steel achieved through the addition of molybdenum and niobium was studied in tests carried out at 973K and 1,073K. The creep strengthening mechanism was examined using transmission electron micrographs, X-ray diffraction, etc. The results obtained are summarized as follows: (1) The creep strength of low C-18Cr-10Ni-20Co austenitic steel with molybdenum was greatly improved by the addition of niobium up to 1% by weight. In the case of long-term creep, no trend toward decreasing creep strength was observed. (2) The creep strength of austenitic steel possessing a matrix strengthened with molybdenum can be improved through the addition of niobium combined with precipitation hardening with fine carbides precipitated in the grains. (author)

Observations of copper clustering in a 25Cr-7Ni super duplex stainless steel during low-temperature aging under load

Science.gov (United States)

Thuvander, M.; Zhou, J.; Odqvist, J.; Hertzman, S.; Hedström, P.

2012-07-01

Atom-probe tomography was used to investigate phase separation and copper (Cu) clustering in the ferrite phase of a 25Cr-7Ni super duplex stainless steel. The steel was subjected to a tensile load during aging at 325°C for 5800 h. The degree of phase separation into α (Fe-rich) and α‧ (Cr-rich) was small, but still, it was the highest in the steel subjected to the highest load. Cu was found to cluster, and the number density of clusters increased with increasing load. In the material subjected to the highest load, Cu was enriched in regions that were neither Fe-rich nor Cr-rich. These regions also had the highest number density of Cu clusters.

PLASTIC DEFORMATION ON THE MACHINED SURFACE OF STEEL Cr20Ni10MoTi AT DRILLING

Directory of Open Access Journals (Sweden)

Jozef Jurko

2009-07-01

Full Text Available Information about material machinability is very important for the machining technology. Precise and reliable information on the machinability of a material before it enters the machining process is a necessity, and this brings the verification of technological methods in practice. This article presents the conclusions of machinability tests on austenitic stainless steel according to EN-EU (ISO: steel Cr20Ni10MoTi. This article presents the conclusions of VEGA grant agency at the Ministry of Education SR for supporting research work and co-financing the projects: Grant work #01/3173/2006 with the title „Experimental investigation of cutting zones in drilled and milled stainless steels

Alloying effect on hardening of martensite stainless steels of the Fe-Cr-Ni and Fe-Cr-Co systems

International Nuclear Information System (INIS)

Fel'dgandler, Eh.G.; Savkina, L.Ya.

1975-01-01

The effect of alloying elements is considered on the γ → a-transformation and hardening of certain compositions of the ternary Fe-Cr-Ni- and Fe-Cr-Co alloy systems with the martensite structure. In martensite Fe-(10 to 14)% Cr base steels the elements Co, Cu, W, Ni, Mo, Si, Cr decrease, Mn, Si, Mo, Cu increase, and Cr, Ni, Co decrease the temperature of α → γ-transition. The tempering of martensite steels of the Fe-Cr-Ni- and Fe-Cr-Co-systems containing 10 to 14% Cr, 4 to 9% Ni, and 7 to 12% Co does not lead to hardening. Alloyage of the martensite Fe-Cr-Ni-, Fe-Cr-Co- and Fe-Cr-Ni-Co base separately with Mo, W, Si or Cu leads to a hardening during tempering, the hardening being the higher, the higher is the content of Ni and, especially, of Co. The increase in the content of Mo or Si produces the same effect as the increase in the Co content. In on Fe-Cr-Co or Fe-Cr-Ni-Co based steels alloyed with Mo or Si, two temperature ranges of ageing have been revealed which, evidently, have different hardening natures. The compositions studied could serve as the base material for producing maraging stainless steels having a complex variety of properties

Investigation of Cr-Ni duplex stainless steel

International Nuclear Information System (INIS)

Lu Shiying

1985-01-01

At temperatures of 450 - 750 0 C, a laminate-shaped intermetallic phase Fe3Cr3Mo2Si2 has been observed. Intergranular brittle fracture is due to the precipitation of the Fe3Cr3Mo2SI2 phase, but quasi-cleavage fracture is connected with the precipitation of chi and σ phases. The formation of chi and σ during aging at 750 - 900 0 C results in a drastic decrease of the SCC resistance of Cr18Ni5 steel. In order to avoid a fully ferritic microstructure in Cr18Ni5 duplex steel after heating at high temperature or welding, the K value must be kept to 0.42 for thin wall tube. The decrease in SCC resistance after cold deformation is not due to the formation of strain-induced martensite but is connected with significant reduction in the resistance to pitting corrosion. (author)

The effects of minor alloy modifications and heat treatment on the microstructure and creep rupture behavior of 2.25Cr-1Mo Steel

International Nuclear Information System (INIS)

Todd, J.A.; Chung, D.W.; Parker, E.R.

1983-01-01

The effects of alloy additions on the microstructure of simulated cooled and tempered 2.25Cr-1Mo steels have been studied using transmission electron microscopy. Carbide precipitation sequences have been identified in the modification 3Cr-1Mo-1Mn-1Ni and compared to those in 2.25Cr-1Mo steels modified with Mn and Ni and also with Ti, V and B. The influence of minor compositional changes on the creep rupture behavior of 2.25Cr-1Mo steel has been studied at 500 C, 560 C, and 600 C. The most significant effect of alloy modifications on creep properties resulted from additions of Mn and Cr. Preliminary studies show that 1% Mn and 0.5Mn + 1Ni + 0.75Cr additions significantly reduce creep strength at all three temperatures for tests up to 2000 hours duration. The 3Cr-1Mo-1Mn-1Ni steel showed improvements in rupture ductility at all temperatures when compared with the base 2.25Cr-1Mo steel and the manganese-nickel modifications. Plots of the Larson-Miller parameter for both these modifications lay within the scatter band for commercial 2.25Cr-1Mo steels

characterization and weldability of plasma nitrided P/M martensitic stainless steel X 20 Cr Ni 172

International Nuclear Information System (INIS)

Abdel-Karim, R.A.; El-demellawy, M.A; Waheed, A.F.

2004-01-01

stainless steels are widely used in nuclear applications, as a construction material. in these applications stainless steels suffer from corrosion degradation due severe environment and operating conditions. improving the engineering properties of such material prolong the service life time.in the present study, powder metallurgy technique namely plasma rotating electrode process (PREP) was used to produce martensitic steel DIN X 20 Cr Ni 172 with 0.5 % N. this step was followed by hot isostatic pressing process (HIP) . the effect of N on the weldability of this steel has been investigated . this included microstructure characterization, hardness evaluation and ferrite content measurements. the results showed that the presence of high nitrogen content in this steel resulted in a pore free structure with improved the hardness across the welding area. A single phase with few precipitates was detected on the grain boundaries in the heat affected zone. the results were supplemented by x-ray diffraction patterns and EDAX analysis

Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi2 and CoCrFeNi2Mo0.25 under Sodium Chloride Aqueous Conditions

Directory of Open Access Journals (Sweden)

Alvaro A. Rodriguez

2018-01-01

Full Text Available The corrosion behavior of high-entropy alloys (HEAs CoCrFeNi2 and CoCrFeNi2Mo0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276 and stainless steel 316L (UNS 31600 to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi2Mo0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi2 and stainless steel 316L.

Impact Strength of Austenitic and Ferritic-Austenitic Cr-Ni Stainless Cast Steel in -40 and +20°C Temperature

Directory of Open Access Journals (Sweden)

Kalandyk B.

2014-10-01

Full Text Available Studies described in this paper relate to common grades of cast corrosion resistant Cr-Ni steel with different matrix. The test materials were subjected to heat treatment, which consisted in the solution annealing at 1060°C followed by cooling in water. The conducted investigations, besides the microstructural characteristics of selected cast steel grades, included the evaluation of hardness, toughness (at a temperature of -40 and +20oC and type of fracture obtained after breaking the specimens on a Charpy impact testing machine. Based on the results of the measured volume fraction of ferrite, it has been found that the content of this phase in cast austenitic steel is 1.9%, while in the two-phase ferritic-austenitic grades it ranges from 50 to 58%. It has been demonstrated that within the scope of conducted studies, the cast steel of an austenitic structure is characterised by higher impact strength than the two-phase ferritic-austenitic (F-A grade. The changing appearance of the fractures of the specimens reflected the impact strength values obtained in the tested materials. Fractures of the cast austenitic Cr-Ni steel obtained in these studies were of a ductile character, while fractures of the cast ferritic-austenitic grade were mostly of a mixed character with the predominance of brittle phase and well visible cleavage planes.

The Phase Transformations in Hypoeutectoid Steels Mn-Cr-Ni

Directory of Open Access Journals (Sweden)

RoŻniata E.

2015-04-01

Full Text Available The results of a microstructure and hardness investigations of the hypoeutectoid steels Mn-Cr-Ni, imitating by its chemical composition toughening steels, are presented in the paper. The analysis of the kinetics of phase transformations of undercooled austenite of steels containing different amounts of alloying elements in their chemical composition, constitutes the aim of investigations.

Capture cross sections for Cr, Fe and Ni

International Nuclear Information System (INIS)

Corvi, F.

1990-01-01

Since stainless steel represents about 25% of the volume of a fast power reactor, its constituent elements strongly influence its two main neutronic parameters: critical enrichment and breeding gain. Also, capture in the narrow p and d-wave resonances of Cr, Fe and Ni contributes as much as 10 to 15% of the Doppler coefficient of reactivity. Following sensitivity calculations, typical accuracy requirements in the energy range 0.1-100 keV are 5-10% for capture in Fe and 10-20% for capture in Ni and Cr. 11 refs, 2 tabs

The influence of interstitial impurities on temperature ranges of deuterium retention in austenitic stainless steel 18Cr10NiTi

International Nuclear Information System (INIS)

Neklyudov, I.M.; Morozov, O.M.; Kulish, V.G.; Zhurba, V.I.; Galytsky, A.G.; Piatenko, E.V.

2009-01-01

The influence of nitrogen, oxygen and helium on the temperature range of deuterium retention in 18Cr10NiTi stainless steel (of AISI304L type) has been investigated. It is demonstrated that the introduction of oxygen, nitrogen or helium into 18Cr10NiTi steel extends the upper limit in the high-temperature range of deuterium retention. It has been found that for 18Cr10NiTi stainless steel, pre-irradiated with helium ions, the increase in the temperature range of deuterium retention occurs in steps: on attainment of helium concentration of ∼0.5 at.% He the temperature range increases by ∼100 K, and on attainment of helium concentration of ∼2.5 at.% He the temperature range increases by ∼350 K. The introduction of oxygen into 18Cr10NiTi stainless steel results in the increase of the temperature range of deuterium retention in the direction of rise in temperature. In the deuterium thermodesorption spectrum, this manifests itself by the occurrence of an additional low-amplitude peak with the maximum temperature T m ∼ 560 K. The introduction of nitric impurity into 18Cr10NiTi stainless steel results in the extension of the temperature range of deuterium retention towards higher temperatures.

Microstructural Characterization of Clad Interface in Welds of Ni-Cr-Mo High Strength Low Alloy Steel

Energy Technology Data Exchange (ETDEWEB)

Kim, Hong-Eun; Kim, Min-Chul; Lee, Ho-Jin; Kim, Keong-Ho [KAERI, Daejeon (Korea, Republic of); Lee, Ki-Hyoung [KAIST, Daejeon (Korea, Republic of); Lee, Chang-Hee [Hanyang Univ., Seoul (Korea, Republic of)

2011-08-15

SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at 610°C for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

Microstructural Characterization of Clad Interface in Welds of Ni-Cr-Mo High Strength Low Alloy Steel

International Nuclear Information System (INIS)

Kim, Hong-Eun; Kim, Min-Chul; Lee, Ho-Jin; Kim, Keong-Ho; Lee, Ki-Hyoung; Lee, Chang-Hee

2011-01-01

SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at 610°C for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

Optimizing Heat Treatment Process of Fe-13Cr-3Mo-3Ni Martensitic Stainless of Steel

Science.gov (United States)

Anwar, M. S.; Prifiharni, S.; Mabruri, E.

2017-05-01

The Fe-13Cr-3Mo-3Ni stainless steels are modified into martensitic stainless steels for steam turbine blades application. The working temperature of steam turbine was around 600 - 700 °C. The improvement properties of turbine blade material is necessary to maintain steam turbine work. The previous research revealed that it has corrosion resistance of Fe-13Cr-3Mo-3Ni which is better than 13Cr stainless steels in the chloride environment. In this work, the effect of heat treatment on microstructure and hardness of Fe-13Cr-3Mo-3Ni stainless steels has been studied. The steel was prepared by induction melting followed by hot forging. The steels were austenitized at 1000, 1050, and 1100 °C for 1 hour and were tempered at 600, 650, and 700 °C for 1 hour. The steels were then subjected to metallographic observation and hardness test of Rockwell C. The optimal heat treatment of Fe-13Cr-3Mo-3Ni was carried out austenitized in 1050 °C and tempered in 600 - 700 °C.

Reduced-activation austenitic stainless steels: The Fe--Mn--Cr--C system

International Nuclear Information System (INIS)

Klueh, R.L.; Maziasz, P.J.

1988-01-01

Nickel-free manganese-stabilized steels are being developed for fusion-reactor applications. As the first part of this effort, the austenite-stable region in the Fe--Mn--Cr--C system was determined. Results indicated that the Schaeffler diagram developed for Fe--Ni--Cr--C alloys cannot be used to predict the constituents expected for high-manganese steels. This is true because manganese is not as strong an austenite stabilizer relative to δ-ferrite formation as predicted by the diagram, but it is a stronger austenite stabilizer relative to martensite than predicted. Therefore, the austenite-stable region for Ne--Mn--Cr--C alloys occurs at lower chromium and hugher combinations of manganese and carbon than predicted by the Schaeffler diagram. Development of a manganese-stabilized stainless steel should be possible in the composition range of 20 to 25% Mn, 10 to 15% Cr, and 0.01 to 0.25%C. Tensile behavior of an Fe--20%Mn--12%Cr--0.25%C alloy was determined. The strength and ductility of this possible base composition was comparable to type 316 stainless steel in both the solution-annealed and cold-worked condition

Development of improved HP/IP rotor material 2% CrMoNiWV (23 CrMoNiWV 88)

International Nuclear Information System (INIS)

Wiemann, W.

1989-01-01

The new 2% CrMoNiWV steel has a sufficient strength level, a very good creep (rupture) behaviour and an excellent toughness behaviour for a creep resistant steel. Even after long time high temperature exposure the toughness degradation is so small that it is still better than this of best 1% CrMo(Ni)V steels. The fatigue behaviour is well comparable to this of 1% CrMo(Ni)V. The 2% CrMoNiWV steel has the capability to substitute the traditional 1% CrMo(Ni)V. (orig.) With 26 annexes

Residual stress determination by neutron diffraction in a car gear-shaft made of 20NiCrMo2 alloyed case hardening steel

Czech Academy of Sciences Publication Activity Database

Rogante, M.; Mazzanti, M.; Mikula, Pavol; Vrána, Miroslav

2012-01-01

Roč. 50, č. 4 (2012), s. 213-220 ISSN 0023-432X R&D Projects: GA ČR(CZ) GAP204/12/1360 Institutional support: RVO:61389005 Keywords : 20NiCrMo2 steel * gear-shaft * caser hardening * residual stress * neutron diffraction Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.687, year: 2012

Corrosion resistance of stainless steels and high Ni-Cr alloys to acid fluoride wastes

International Nuclear Information System (INIS)

Smith, H.D.; Mackey, D.B.; Pool, K.H.; Schwenk, E.B.

1992-04-01

TRUEX processing of Hanford Site waste will utilize potentially corrosive acid fluoride processing solutions. Appropriate construction materials for such a processing facility need to be identified. Toward this objective, candidate stainless steels and high Ni-Cr alloys have been corrosion tested in simulated acid fluoride process solutions at 333K. The high Ni-Cr alloys exhibited corrosion rates as low as 0.14 mm/y in a solution with an HF activity of about 1.2 M, much lower than the 19 to 94 mm/y observed for austenitic stainless steels. At a lower HF activity (about 0.008 M), stainless steels display delayed passivation while high Ni-Cr alloys display essentially no reaction

Microstructural evolution in austenitic heat-resistant cast steel 35Cr25Ni12NNbRE during long-term service

International Nuclear Information System (INIS)

Liu Jiangwen; Jiao Dongling; Luo Chengping

2010-01-01

The microstructural evolution of austenitic heat-resistant cast steel 35Cr25Ni12NNbRE during aging and long-term service was investigated using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The microstructure of the as cast steel consists of the dendritic austenite, the block-like eutectic carbide M 7 C 3 spreaded among austenitic dendrite, and a small quantity of M 23 C 6 carbide. The microstructure of the steel aged at 600 deg. C consists of eutectic carbide M 23 C 6 transformed from eutectic carbide M 7 C 3 and dendritic austenite in which fine secondary carbide particles M 23 C 6 precipitated. The precipitated carbide M 23 C 6 kept a cubic-cubic orientation relationship (OR) with austenite matrix. There existed a carbide precipitation free zone (PFZ) around the eutectic carbide. For the long-term serviced samples, the secondary carbide precipitated in the austenite strikingly increased and the PFZ disappeared. Part of the M 23 C 6 transformed into M 6 C, which always kept a twin OR, [114] M 6 C //[110] A //[110] M 23 C 6 , with the austenite and the M 23 C 6 secondary carbide. In addition, a small quantity of σ phase FeCr and ε-Cr 2 N were also identified. The effects of alloy composition and service condition on the microstructural evolution of the steel were discussed.

The Effect of Si and Mn on Microstructure and Selected Properties of Cr-Ni Stainless Steels

Directory of Open Access Journals (Sweden)

Kalandyk B.

2017-03-01

Full Text Available Cast stainless steel of the Cr-Ni duplex type is used, among others, for the cast parts of pumps and valves handling various chemically aggressive media. Therefore, the main problem discussed in this article is the problem of abrasion wear resistance in a mixture of SiC and water and resistance to electrochemical corrosion in a 3% NaCl-H2O solution of selected cast steel grades, i.e. typical duplex cast steel, high silicon and manganese duplex cast steel, and Cr-Ni austenitic cast steel (type AISI 316L. The study shows that the best abrasion wear resistance comparable to Ni-Hart cast iron was obtained in the cast duplex steel, where Ni was partially replaced with Mn and N. This cast steel was also characterized by the highest hardness and matrix microhardness among all the tested cast steel grades. The best resistance to electrochemical corrosion in 3% NaCl-H2O solution showed the cast duplex steel with high content of Cr, Mo and N. The addition of Ni plays rather insignificant role in the improvement of corrosion resistance of the materials tested.

Formability of high-alloy dual-phase Cr-Ni steels

International Nuclear Information System (INIS)

Elfmark, J.

2004-01-01

The formability of dual-phase high-alloy Cr-Ni steel within the temperature range from 900 to 1250 C was studied using laboratory tensile and torsion tests. The dual-phase steels on 24% Cr basis are characterized by poor hot formability due to very low stable deformation values and slow recrystallization. Mathematical description of deformation stability exhaustion was derived, as well as a model of formability control based on analysis of the gradual diffuse deformation stability from the stability limit to the moment when the deformation starts to concentrate in a small volume of the test piece. Rolling simulation of dual-phase steel strip was used as an example demonstrating the draught scheme optimization technique which avoids the danger of crack occurrence during the rolling of dual-phase steel strip. (orig.)

Determination of chemical activities of Fe, Cr, Ni and Mn in stainless steel 316 by Knudsen effusion cell mass spectrometry

International Nuclear Information System (INIS)

Venugopal, V.; Kulkarni, S.G.; Subbanna, C.S.; Sood, D.D.

1995-01-01

Cold-worked austenitic stainless steel of the type AISI 316 is being used as the cladding and wrapper materials in fast reactor fuel pins. Knowledge of the thermodynamic activities of the steel constituents is necessary to predict the possibility of fuel-cladding, coolant-cladding or fission product-cladding chemical reactions. The thermodynamic activities of Fe, Cr, Ni and Mn for stainless steel 316 were determined by measuring their partial pressures in the temperature range 1293-2120 K, using Knudsen effusion cell mass spectrometry. High purity Ag was used as an internal calibrant. The chemical activities of Fe (a Fe ), Cr (a Cr ), Ni (a Ni ) and Mn (a Mn ) were evaluated using literature data for the vapour pressures of pure metals. log a Fe ±0.18=-1.586+2074/T (T=1293-1872 K)log a Cr ±0.30=-2.350+2612/T (T=1293-2120 K)log a Ni ±0.20=-2.140+1794/T (T=1468-1974 K)log a Mn ±0.23=-2.041-5478/T (T=1302-1894 K) ((orig.))

Microstructure of reactive synthesis TiC/Cr18Ni8 stainless steel bonded carbides

Institute of Scientific and Technical Information of China (English)

Jiang Junsheng; Liu Junbo; Wang Limei

2008-01-01

TiC/Cr18Ni8 steel bonded carbides were synthesized by vacuum sintering with mixed powders of iron, ferrotitanium, ferrochromium, colloidal graphite and nickel as raw materials. The microstructure and microhardness of the steel bonded carbides were analyzed by scanning electron microscope (SEM),X-ray diffraction (XRD) and Rockwell hardometer. Results show that the phases of steel bonded carbides mainly consist of TiC and Fe-Cr-Ni solid solution. The synthesized TiC particles are fine. Most of them are not more than 1 μm With the increase of sintering temperature, the porosity of TiC/Cr18Ni8 steel bonded carbides decreases and the density and hardness increase, but the size of TiC panicles slightly increases. Under the same sintering conditions, the density and hardness of steel bonded carbides with C/Ti atomic ratio 0.9 are higher than those with C/Ti atomic ratio 1.0.The TiC particles with C/Ti atomic ratio 0.9 are much finer and more homogeneous.

Effect of niobium on the embrittlement of 2.25 Cr and 2.25 Cr-1Mo steels by phosphous

International Nuclear Information System (INIS)

Antunes, J.L.B.

1985-01-01

The influence of niobium on the temper embrittlement of 2.25Cr and 2.25 Cr-1Mo steels doped with phosphorus is evaluated. The transition temperatures of the samples tempered at 650 0 C and aged at different temperatures for niobium steels. (M.J.C.) [pt

Structure and delayed failure behaviour of 0.25C-Ni-Cr-Mo-V steel

International Nuclear Information System (INIS)

Kang, C.H.; Maeng, S.C.

1980-01-01

Delayed failure behaviour of the different transformation structures of 0.25C-2.5Ni-2.5Cr-0.5Mo-0.1V low alloy steel has been studied. The studied microstructures are martensite, lower bainite, and mixed structure of 50% martensite and 50% lower bainite. All these structures have been tempered at 450 deg C for 40 min to have the same tensile strength level of 143 kg/mm 2 . Delayed failure testing has been carried out with cantilever bend tester, in distilled water at 25 deg C. By comparing K 1 sub(scc) values, lower bainitic structure has shown the highest value, although it is only slightly higher than that of the martensitic structure. Mixed structure has the lowest resistance to delayed failure. The fracture modes of both martensitic and mixed structures have been observed as intergranular. In the martensitic structure, however, it is noticeable that there is a larger amount of ductile tearing between intergranular facets. The fracture mode of lower bainitic structure is the mixed topography of microplastic tearing and microvoid coalescence. The above experimental results are discussed in terms of Oriani's decohesion theory of hydrogen embrittlement. The lowest resistance of the mixed structure to delayed failure may be due to the enhanced decohesion by hydrogen at the phase boundaries of martensite and lower bainite. (author)

A Weakest-Link Approach for Fatigue Limit of 30CrNiMo8 Steels (Preprint)

Science.gov (United States)

2011-03-01

34Application of a Weakest-Link Concept to the Fatigue Limit of the Bearing Steel Sae 52100 in a Bainitic Condition," Fatigue and Fracture of...AFRL-RX-WP-TP-2011-4206 A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) S. Ekwaro-Osire and H.V. Kulkarni Texas...2011 4. TITLE AND SUBTITLE A WEAKEST-LINK APPROACH FOR FATIGUE LIMIT OF 30CrNiMo8 STEELS (PREPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT

Aging behaviour of 25Cr-17Mn high nitrogen duplex stainless steel

OpenAIRE

Machado, I. F.; Padilha, A. F.

2000-01-01

The precipitation behaviour of a nickel free stainless steel containing 25% chromium, 17% manganese and 0.54% nitrogen, with duplex ferritic-austenitic microstructure, was studied using several complementary techniques of microstructural analysis after aging heat treatments between 600 and 1 000 degrees C for periods of lime between 15 and 6 000 min. During aging heat treatments, ferrite was decomposed into sigma phase and austenite by a eutectoid reaction, like in the Fe-Cr-Ni duplex stainle...

The research of axial corrosion fatigue on 10Ni3CrMoV steel

Science.gov (United States)

Xie, Xing; Yi, Hong; Xu, Jian; Xie, Kun

2017-09-01

Fatigue life had been studied with 10CrNi3MoV steel at different load ratios and in different environmental medias. The microstructure and micro-topography had been observed and analyzed by means of SEM, EDS and TEM. Our findings indicated that, the fatigue life of 10Ni3CrMoV steel in seawater was shorter than in air, the difference in longevity was larger with the decreasing of axis stress. Corrosion pits had a great influence on corrosion fatigue life.

Welding and corrosion resistance of the new nitrogen alloyed steel X2 CrNiMnMoN241764

International Nuclear Information System (INIS)

Arit, N.; Henser, H.; GroB, V.

1994-01-01

Remanit 4565 S is a new developed nitrogen alloyed austenitic stainless steel. Characteristic features are: improved strength and toughness, delayed precipitation of carbides and intermetallic phases, improved corrosion resistance. Welding fabrication is possible without the risk of pore formation. TIG-welded joints are as resistant as the base metal, using filler metal SG-NiCr 20 Mo 15 (Thermanit Nimo C) respectively SG-NiCr 28 Mo(Thermanit 30/40 E) according to the area of application. (Author) 8 refs

A New Method to Produce Ni-Cr Ferroalloy Used for Stainless Steel Production

Science.gov (United States)

Chen, Pei-Xian; Chu, Shao-Jun; Zhang, Guo-Hua

2016-08-01

A new electrosilicothermic method has been proposed in the present paper to produce Ni-Cr ferroalloy, which can be used for the production of 300 series stainless steel. Based on this new process, the Ni-Si ferroalloy is first produced as the intermediate alloy, and then the desiliconization process of Ni-Si ferroalloy melt with chromium concentrate is carried out to generate Ni-Cr ferroalloy. The silicon content in the Ni-Si ferroalloy produced in the submerged arc furnace should be more than 15 mass% (for the propose of reducing dephosphorization), in order to make sure the phosphorus content in the subsequently produced Ni-Cr ferroalloy is less than 0.03 mass%. A high utilization ratio of Si and a high recovery ratio of Cr can be obtained after the desiliconization reaction between Ni-Si ferroalloy and chromium concentrate in the electric arc furnace (EAF)-shaking ladle (SL) process.

Welding of heterogeneous 12Kh2MFSR steels with the Mn-Cr-Si-Ni system

International Nuclear Information System (INIS)

Smirnov, A.N.; Belogolov, E.I.

1978-01-01

The process of welding pipes of the 12Kh2MFSR pearlitic steels and austenitic steels of the Mn-Cr-Si-Ni system was studied. The filler materials were selected, and the working capacity of welded joints was examined in ageing and cyclic heatings. The microhardness of steels was measured, and the ultimate strength of welded joints was determined. The following has been established: the composite joints of steels of the Mn-Cr-Si-Ni system and 12Kh2MFSR steel are advisable to be welded on a coating layer welded by the EhA395/9 electrodes on the surface of a pipe of the 12Kh2MFSR pearlitic steel; this guarantees the sufficient working capacity of welded joints

Chemical diffusion of Cr, Ni and Si in welded joints. II

International Nuclear Information System (INIS)

Kucera, J.; Ciha, K.

1987-01-01

The results are given of a study in chemical diffusion in welded joints P2/A and P3/A. P2 stands for the steel (Fe-17.48 Cr-8.15 Ni-0.14 Si), P3 for (Fe-18.52 Cr-8.20 Ni-1.78 Si) and A for the Fe-Arema. Triadic sandwiche-like samples were diffusion heated at temperatures from 920 to 1170 degC. The concentration distributions N(x,t) of the given elements were measured with microprobe JXA-3A. The evaluation of the experimental data was carried out either by Grube's method, or in some cases by the spline-polynomial method. The evaluated diffusivities D-bar satisfy the Arrhenius relation and yield the standard diffusion characteristics D 0 and H. The diffusivities D-bar of Cr, Ni and Si in P1/A, in P2/A and P3/A welded joints vary with Si content in P1, P2 and P3 alloys, similar to the Cr-51 and Ni-63 self-diffusivities in Fe-18 Cr-12 Ni-X Si steels, and tend to increase with increasing Si content. The values D-bar measured in the vicinity of grain boundaries are higher than the bulk diffusion coefficients. The most rapid diffusant is Si and the slowest one Ni. Thus, the relations D-bar Si :D-bar Cr :D-bar Ni ≅ 6:3:1 (P3/A) and D-bar Si :D-bar Cr :D-bar Ni ≅ 1.7:1.4:1 (P3/A) are valid at 1050 degC. Comparing the results with those published if can be noted that the Cr-51 and Ni-63 self-diffusion in Fe-18 Cr-12 Ni-X Si steels is faster than chemical diffusion of these elements in the said steel welded joints P2/A and P3/A; X varies from 0.14 to 1.98. (author). 7 tabs., 7 figs., 20 refs

Comparison of extrapolation methods for creep rupture stresses of 12Cr and 18Cr10NiTi steels

International Nuclear Information System (INIS)

Ivarsson, B.

1979-01-01

As a part of a Soviet-Swedish research programme the creep rupture properties of two heat resisting steels namely a 12% Cr steel and an 18% Cr12% Ni titanium stabilized steel have been studied. One heat from each country of both steels were creep tested. The strength of the 12% Cr steels was similar to earlier reported strength values, the Soviet steel being some-what stronger due to a higher tungsten content. The strength of the Swedish 18/12 Ti steel agreed with earlier results, while the properties of the Soviet steel were inferior to those reported from earlier Soviet creep testings. Three extrapolation methods were compared on creep rupture data collected in both countries. Isothermal extrapolation and an algebraic method of Soviet origin gave in many cases rather similar results, while the parameter method recommended by ISO resulted in higher rupture strength values at longer times. (author)

Characterization on the Microstructure Evolution and Toughness of TIG Weld Metal of 25Cr2Ni2MoV Steel after Post Weld Heat Treatment

Directory of Open Access Journals (Sweden)

Xia Liu

2018-03-01

Full Text Available The microstructure and toughness of tungsten inert gas (TIG backing weld parts in low-pressure steam turbine welded rotors contribute significantly to the total toughness of the weld metal. In this study, the microstructure evolution and toughness of TIG weld metal of 25Cr2Ni2MoV steel low-pressure steam turbine welded rotor under different post-weld heat treatment (PWHT conditions are investigated. The fractography and microstructure of weld metal after PWHT are characterized by optical microscope, SEM, and TEM, respectively. The Charpy impact test is carried out to evaluate the toughness of the weld. The optical microscope and SEM results indicate that the as-welded sample is composed of granular bainite, acicular ferrite and blocky martensite/austenite (M-A constituent. After PWHT at 580 °C, the blocky M-A decomposes into ferrite and carbides. Both the number and size of precipitated carbides increase with holding time. The impact test results show that the toughness decreases dramatically after PWHT and further decreases with holding time at 580 °C. The precipitated carbides are identified as M23C6 carbides by TEM, which leads to the dramatic decrease in the toughness of TIG weld metal of 25Cr2Ni2MoV steel.

Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

NARCIS (Netherlands)

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

2016-01-01

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

High Temperature Behavior of Cr3C2-NiCr Coatings in the Actual Coal-Fired Boiler Environment

Science.gov (United States)

Bhatia, Rakesh; Sidhu, Hazoor Singh; Sidhu, Buta Singh

2015-03-01

Erosion-corrosion is a serious problem observed in steam-powered electricity generation plants, and industrial waste incinerators. In the present study, four compositions of Cr3C2-(Ni-20Cr) alloy coating powder were deposited by high-velocity oxy-fuel spray technique on T-91 boiler tube steel. The cyclic studies were performed in a coal-fired boiler at 1123 K ± 10 K (850 °C ± 10 °C). X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis and elemental mapping analysis techniques were used to analyze the corrosion products. All the coatings deposited on T-91 boiler tube steel imparted hot corrosion resistance. The 65 pctCr3C2 -35 pct (Ni-20Cr)-coated T-91 steel sample performed better than all other coated samples in the given environment.

Characteristics of Ni-Cr-Fe laser clad layers on EA4T steel

Science.gov (United States)

Chen, Wenjing; Chen, Hui; Wang, Yongjing; Li, Congchen; Wang, Xiaoli

2017-07-01

The Ni-Cr-Fe metal powder was deposited on EA4T steel by laser cladding technology. The microstructure and chemical composition of the cladding layer were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bonding ability between the cladding layer and the matrix was measured. The results showed that the bonding between the cladding layer and the EA4T steel was metallurgical bonding. The microstructure of cladding layer was composed of planar crystals, columnar crystals and dendrite, which consisted of Cr2Ni3, γ phase, M23C6 and Ni3B phases. When the powder feeding speed reached 4 g/min, the upper bainite occurred in the heat affected zone (HAZ). Moreover, the tensile strength of the joint increased, while the yield strength and the ductility decreased.

Toughness of 2,25Cr-1Mo steel and weld metal

Science.gov (United States)

Acarer, Mustafa; Arici, Gökhan; Acar, Filiz Kumdali; Keskinkilic, Selcuk; Kabakci, Fikret

2017-09-01

2,25Cr-1Mo steel is extensively used at elevated temperature structural applications in fossil fire power plants for steam pipes, nozzle chambers and petrochemical industry for hydrocracking unit due to its excellent creep resistance and good redundant to oxidation. Also they should have acceptable weldability and toughness. The steels are supplied in quenched and tempered condition and their welded components are subjected to post-weld heat treatment (PWHT). Tempering process is carried out at 690-710°C to improve toughness properties. However they are sensitive to reheat cracking and temper embrittlement. To measure temper embrittlement of the steels and their weld metal, temper embrittlement factor and formula (J factor - Watanabe and X formula- Bruscato) are used. Step cooling heat treatment is also applied to determine temper embrittlement. In this study, toughness properties of Cr Mo (W) steels were reviewed. Also transition temperature curves of 2,25Cr-1Mo steel and its weld metal were constructed before and after step cool heat treatment as experimental study. While 2,25Cr-1Mo steel as base metal was supplied, all weld metal samples were produced in Gedik Welding Company. Hardness measurements and microstructure evaluation were also carried out.

Effect of Solution Annealing on Susceptibility to Intercrystalline Corrosion of Stainless Steel with 20% Cr and 8% Ni

Science.gov (United States)

Taiwade, R. V.; Patil, A. P.; Patre, S. J.; Dayal, R. K.

2013-06-01

In general, as-received (AR) austenitic stainless steels (ASSs) contain complex carbide precipitates due to manufacturing operations, subsequent annealing treatment, or due to the fabrication processes such as welding. The presence of pre-existing carbides leads to cumulative sensitization and make the steel susceptible to intercrystalline corrosion (ICC)/intergranular corrosion (IGC) which causes premature failure during service. Solution annealing (SA) is one of the ways to deal with such situations. In this present investigation, the AR (hot rolled and mill annealed) chromium-nickel (Cr-Ni) ASS is compared with SA Cr-Ni ASS. The extent of ICC/IGC was evaluated qualitatively and quantitatively by various electrochemical tests including ASTM standard A-262 Practice A and Practice E, double loop electrochemical potentiokinetic reactivation and electrochemical impedance spectroscopy. The degree of sensitization for hot rolled mill annealed AR condition is found to be substantially higher (51.55%) than that of SA condition (26.9%) for thermally aged samples (at 700 °C). The chemical composition across the grain boundary was measured using electron probe micro-analyzer for both (AR and SA) conditions and confirms that the pre-sensitization effect was completely removed after SA treatment.

High Temperature Performance Evaluation of As-serviced 25Cr35Ni Type Heat-resistant Steel Based on Stress Relaxation Tests

Directory of Open Access Journals (Sweden)

XU Jun

2017-08-01

Full Text Available Based on an as-serviced 25Cr35Ni type steel, the high temperature property evaluation using stress relaxation test(SRT method and residual life prediction were studied. The results show that creep rupture property decreases because of the formation of network carbides along grain boundaries and coarsening of secondary carbides in the austenitic matrix. Based on the relationship of stress relaxation strain rate curves obtained at different temperatures, and the extrapolation equation of stress relaxation rate-rupture time, it is capable to perform residual life evaluation by combining SRT data and a small amount of creep rupture test(CRT. Good agreement is observed for predicting results performed by current method and traditional method.

Radiation-induced sensitisation of stainless steels

International Nuclear Information System (INIS)

Norris, D.I.R.

1987-01-01

The book contains the proceedings of a symposium on radiation-induced sensitization of stainless steels, which took place at Berkeley, United Kingdom, 1986. The purpose of the symposium was to examine the mechanism leading to inter-granular corrosion of 20%Cr/25% Ni/Nb stainless steel cladding of AGR fuel following irradiation. Nine papers are presented, of which three are theoretical, two papers are based upon corrosion studies of 20%Cr/25%Ni/Nb steel, and the remaining are concerned with compositional redistribution and its measurement. (U.K.)

Nitrogen effect on the tendency of Cr-Ni-MN steels to delayed fracture under stress and hydrogen effects

International Nuclear Information System (INIS)

Suvorova, S.O.; Fillipov, G.A.

1996-01-01

Austenitic steels types 03Kh17N16G10AM5, 03Kh6N12G10AM5 and 07Kh13AG20 with various nitrogen contents were studied for their tendency to delayed fracture using mechanical tests, fractography and X ray diffraction analysis. The steel type 07Kh13G20 exhibited the highest strength in the initial state but showed an increase tendency to delayed fracture after hydrogenation. It is underlined that nitrogen additions essentially intensify the tendency of cold worked steels to delayed fracture. This fact should be taken into account when using nitrogen-containing Cr-Ni-Mn steels under severe operational conditions. 4 refs., 2 tabs

Development of banded microstructure in 34CrNiMo6 steel

Directory of Open Access Journals (Sweden)

A. Nagode

2016-07-01

Full Text Available In this paper the development of a banded microstructure in hot-rolled 34CrNiMo6 steel which consisted of bainitic and martensitic bands is explained. The chemical compositions of the bands were measured with energy dispersive x-ray spectroscopy (EDS, which showed that the martensitic bands contained more alloying elements (Mn, Cr, Mo, Si than bainitic bands. By using Oberhoffer reagent, the segregations of phosphorus were also revealed. These phosphorus segregations coincided with the positive segregations of the alloying elements. The continuous cooling transformation (CCT diagrams of steel were calculated. They confirmed the formation of martensite in positive segregations and the formation of bainite in negative segregations.

Effect of quenching temperature on martensite multi-level microstructures and properties of strength and toughness in 20CrNi2Mo steel

Energy Technology Data Exchange (ETDEWEB)

Long, Shao-lei [College of Materials Science and Metallurgical Engineering, Guizhou University (China); Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials (China); National & Local Joint Engineering Laboratory for High-performance Metal Structure Material and Advanced Manufacturing Technology (China); Liang, Yi-long, E-mail: liangyilong@126.com [College of Materials Science and Metallurgical Engineering, Guizhou University (China); Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials (China); National & Local Joint Engineering Laboratory for High-performance Metal Structure Material and Advanced Manufacturing Technology (China); Jiang, Yun [Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials (China); National & Local Joint Engineering Laboratory for High-performance Metal Structure Material and Advanced Manufacturing Technology (China); Liang, Yu; Yang, Ming; Yi, Yan-liang [College of Materials Science and Metallurgical Engineering, Guizhou University (China); Guizhou Key Laboratory for Mechanical Behavior and Microstructure of Materials (China); National & Local Joint Engineering Laboratory for High-performance Metal Structure Material and Advanced Manufacturing Technology (China)

2016-10-31

The martensite multi-level microstructures of 20CrNi2Mo steel, which were quenched at the different temperatures of 900–1200 °C and tempered at 200 °C, were investigated by optical microscope (OM), scanning electron microscopy (SEM), electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM), and the relationship between the microstructures and properties of strength and toughness was discussed by the classic formula of Hall–Petch. The results show that the size of prior austenite grain (d{sub r}), martensite packet (d{sub p}) and block (d{sub b}) increase with increasing of the quenching temperature, while the martensite lath (d{sub l}) size is opposite. On another hand, the confusion degree of the martensite packets changes from disorder to order. The boundaries of prior austenite grain, packet, block and the martensite lath are high angle boundaries (HBs) and low angle boundaries (LBs), respectively, and the ratio of the low angle boundaries increase with the quenching temperature by calculating to the multi-level microstructure size with the mathematical model established by myself. In addition, the relationship between the packet/block and strength follows the classical formula of Hall–Petch, and the size of d{sub b} is far lower than the size of d{sub p}, d{sub b} is the effective control unit of the strength. Meanwhile, d{sub l} is the effective control unit of toughness because it strongly impacts the crack initiation and propagation and follows also the Hall-Petch with toughness in 20CrNi2Mo steel.

Developing of complex for hot plastic deformation modeling of steel type 20-30CrNiMoV for heavy forging

Directory of Open Access Journals (Sweden)

Dub Vladimir

2017-01-01

Full Text Available Production of heavy forging of bars weighing more then 235 tons for such products as rotors made of steel type 20-30CrNiMoV is a critical independent work, failure to perform which entails high costs related to repeated production (in case of defective product and untimely launch of production plants. One of the frequent causes of a defective product is the impossibility of ultrasonic testing in the barrel-gate zones on the rotor workpiece, which is due to the microstructure of the metal, namely the grain size. Determing the stages of deformation process wich causes such defects in structure is the main goal of this work.

Structure of Fe-Ni-Cr steel welded joints

International Nuclear Information System (INIS)

Bratukhin, A.G.; Maslenkov, S.B.; Logunov, A.V.

1993-01-01

Properties of a welded joint depend on the structure of metal of the joint and near the joint areas subjected to thermal effect in the process of welding. The well-known phenomena, accompanying the welding (grain growth in near the joint area, intergrain slip, stressed state related to crystallization and rapid cooling), as well as certain other processes, which have been insufficiently studied either due to their poor pronouncement or owing to imperfection of the equipment and methods employed, were analyzed, as applied to stainless hihg-strength Fe-Ni-Cr steels

Estimation of the Temperature-Dependent Nitrogen Solubility in Stainless Fe-Cr-Mn-Ni-Si-C Steel Melts During Processing

Science.gov (United States)

Wendler, Marco; Hauser, Michael; Sandig, Eckhard Frank; Volkova, Olena

2018-04-01

The influence of chemical composition, temperature, and pressure on the nitrogen solubility of various high alloy stainless steel grades, namely Fe-14Cr-(0.17-7.77)Mn-6Ni-0.5Si-0.03C [wt pct], Fe-15Cr-3Mn-4Ni-0.5Si-0.1C [wt pct], and Fe-19Cr-3Mn-4Ni-0.5Si-0.15C [wt pct], was studied in the melt. The temperature-dependent N-solubility was determined using an empirical approach proposed by Wada and Pehlke. The thus calculated N-concentrations overestimate the actual N-solubility of all the studied Fe-Cr-Mn-Ni-Si-C steel melts at a given temperature and pressure. Consequently, the calculation model has to be modified by Si and C because both elements are not recognized in the original equation. The addition of the 1st and 2nd order interaction parameters for Si and C to the model by Wada and Pehlke allows a precise estimation of the temperature-dependent nitrogen solubility in the liquid steel bath, and fits very well with the measured nitrogen concentrations during processing of the steels. Moreover, the N-solubility enhancing effect of Cr- and Mn-additions has been demonstrated.

Interface bonding of NiCrAlY coating on laser modified H13 tool steel surface

Science.gov (United States)

Reza, M. S.; Aqida, S. N.; Ismail, I.

2016-06-01

Bonding strength of thermal spray coatings depends on the interfacial adhesion between bond coat and substrate material. In this paper, NiCrAlY (Ni-164/211 Ni22 %Cr10 %Al1.0 %Y) coatings were developed on laser modified H13 tool steel surface using atmospheric plasma spray (APS). Different laser peak power, P p, and duty cycle, DC, were investigated in order to improve the mechanical properties of H13 tool steel surface. The APS spraying parameters setting for coatings were set constant. The coating microstructure near the interface was analyzed using IM7000 inverted optical microscope. Interface bonding of NiCrAlY was investigated by interfacial indentation test (IIT) method using MMT-X7 Matsuzawa Hardness Tester Machine with Vickers indenter. Diffusion of atoms along NiCrAlY coating, laser modified and substrate layers was investigated by energy-dispersive X-ray spectroscopy (EDXS) using Hitachi Tabletop Microscope TM3030 Plus. Based on IIT method results, average interfacial toughness, K avg, for reference sample was 2.15 MPa m1/2 compared to sample L1 range of K avg from 6.02 to 6.96 MPa m1/2 and sample L2 range of K avg from 2.47 to 3.46 MPa m1/2. Hence, according to K avg, sample L1 has the highest interface bonding and is being laser modified at lower laser peak power, P p, and higher duty cycle, DC, prior to coating. The EDXS analysis indicated the presence of Fe in the NiCrAlY coating layer and increased Ni and Cr composition in the laser modified layer. Atomic diffusion occurred in both coating and laser modified layers involved in Fe, Ni and Cr elements. These findings introduce enhancement of coating system by substrate surface modification to allow atomic diffusion.

Effect of Si and Mn additions on ferrite and austenite phase fractions in 25Cr-7Ni-1.5Mo-3W base super duplex stainless steels

International Nuclear Information System (INIS)

Jeong, S.W.; Lee, Z.-H.; Lee, H.M.

2000-01-01

The effect of heat treatment and Si and Mn additions on the ferrite and austenite phase fractions of the super duplex stainless steel (SDSS), Fe-25Cr-7Ni-1.5Mo-3W-Si-Mn-0.25N (numbers are all in wt.% unless specified otherwise), was investigated. The thermodynamic calculations of phase equilibria and phase fractions were performed using the Thermo-Calc program. Based on the calculated results, specific compositions of Si and Mn were selected and alloys with these compositions were analysed by Feritscope, X-ray diffractometry and scanning electron microscopy. The calculated phase fractions and experimentally analysed ones were compared and there was a good agreement between calculations and measurements. The optimum heat treatment condition for Fe-25Cr-7Ni-1.5Mo-3W-0.5Si-0.5Mn-0.25N is to hold at 1050 to 1100 C for 2 h in considering the ferrite to austenite ratio of 50:50 and to avoid second phase precipitation such as the σ phase. It was suggested that an excessive addition of more than 0.8Si and 1.0Mn may induce the σ phase precipitation. (orig.)

Creep Rupture Analysis and Life Estimation of 1.25Cr-0.5Mo, 2.25Cr-1Mo and Modified 9Cr-1Mo Steel: A Comparative Study

Science.gov (United States)

Roy, Prabir Kumar

2018-04-01

This paper highlights a comparative assessment of creep life of 1.25Cr-0.5Mo, 2.25Cr-1Mo and modified 9Cr-1Mo steels based on accelerated creep rupture tests. Creep rupture test data have been analysed and creep life of the above mentioned materials have been assessed using Larson Miller parameter at the stress levels of 60 and 42 MPa for different temperatures. Limiting steam temperatures for minimum design life of 105 h at 42 and 60 MPa for the above mentioned steels have also been calculated. Microstructural studies for the three above mentioned steels are also done.

Electrochemical characterisation of X10CrNi 18-8 steel in artificial plasma

Directory of Open Access Journals (Sweden)

J. Przondziono

2015-01-01

Full Text Available Quality of applied guide wires conditions the course of treatment and its success to a great extent. In order to simulate conditions that can be found in blood vascular system samples were exposed to artificial blood plasma (T = 37 } 1 oC for the time of 8 h. In order to obtain information regarding physical and chemical properties of modified surface of wire made of X10CrNi 18-8 steel, electrochemical impedance spectroscopy (EIS test and tests of chemical composition of the surface layer X-ray photoelectron spectroscopy (XPS were made. On the ground of performed EIS and XPS tests, favourable impact of steam sterilisation process on corrosion resistance of X10CrNi 18-8 steel was observed only for the case when chemical passivation was applied prior to sterilisation.

Effect of iron content on the structure and mechanical properties of Al25Ti25Ni25Cu25 and (AlTi)60-xNi20Cu20Fex (x=15, 20) high-entropy alloys

International Nuclear Information System (INIS)

Fazakas, É.; Zadorozhnyy, V.; Louzguine-Luzgin, D.V.

2015-01-01

Highlights: • Three new refractory alloys namely: Al 25 Ti 25 Ni 25 Cu 25 , Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 , were produced by induction-melting and casting. • This kind of alloys exhibits high resistance to annealing softening. • Most the alloys in the annealed state possess even higher Vickers microhardness than the as-cast alloys. • The Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 alloys annealed at 973 K show the highest compressive stress and ductility values. - Abstract: In this work, we investigated the microstructure and mechanical properties of Al 25 Ti 25 Ni 25 C u25 Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al 25 Ti 25 Ni 25 Cu 25 , Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 alloys are relatively hard and ductile. Being heat treated at 973 K the Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

High Temperature Tensile Properties of Unirradiated and Neutron Irradiated 20 Cr-35 Ni Austenitic Steel

Energy Technology Data Exchange (ETDEWEB)

Roy, R B; Solly, B

1966-12-15

The tensile properties of an unirradiated and neutron irradiated (at 40 deg C) 20 % Cr, 35 % Ni austenitic steel have been studied at 650 deg C, 750 deg C and 820 deg C. The tensile elongation and mode of fracture (transgranular) of unirradiated specimens tested at room temperature and 650 deg C are almost identical. At 750 deg C and 820 deg C the elongation decreases considerably and a large part of the total elongation is non-uniform. Furthermore, the mode of fracture at these temperatures is intergranular and microscopic evidence suggests that fracture is caused by formation and linkup of grain boundary cavities. YS and UTS decrease monotonically with temperature. Irradiated specimens show a further decrease in ductility and an increase in the tendency to grain boundary cracking. Irradiation has no significant effect on the YS, but the UTS are reduced. The embrittlement of the irradiated specimens is attributed to the presence of He and Li atoms produced during irradiation and the possible mechanisms are discussed. Prolonged annealing of irradiated and unirradiated specimens at 650 deg C appears to have no significant effect on tensile properties.

Effect of carbon content on microstructure and mechanical properties of hot-rolled low carbon 12Cr-Ni stainless steel

International Nuclear Information System (INIS)

Zheng, H.; Ye, X.N.; Li, J.D.; Jiang, L.Z.; Liu, Z.Y.; Wang, G.D.; Wang, B.S.

2010-01-01

Research highlights: → Hot-rolled ultra low carbon martensite is characterized by dislocation cells substructure. → The formation of dislocation cells is attributed to high Ms and low interstitial atoms content. → Hot-rolled ultra low carbon 12Cr-Ni stainless steel has excellent impact toughness. → Delta ferrite deteriorates the impact toughness of hot-rolled 12Cr-Ni stainless steel. - Abstract: 12Cr-Ni stainless steels containing different carbon contents from 0.004 wt.% to 0.034 wt.% were hot-rolled and air-cooled. Their corresponding microstructures were observed with optical microscope and transmission electron microscope, and the Vickers hardness, tensile and impact tests were also carried out. It was found that the martensitic morphology was significantly influenced by carbon content. The as-received ultra low carbon martensite in the steel containing 0.004 wt.% C is characterized by dislocation cells substructure. The formation of dislocation cells is attributed to high martensite finishing point (above 400 deg. C) and low interstitial atoms content. On the other hand, the martensite in the steel containing 0.034 wt.% C consists mainly of typical martensite laths because of low martensite finishing point and high interstitial atoms content which hinder dislocation motion. Furthermore, carbon content has an evident effect on the mechanical properties of 12Cr-Ni steels. The hardness and strength of the as-received steels increase with an increase in carbon content, but their elongation and impact toughness decrease with the carbon content. The steel containing 0.004 wt.% C has excellent impact toughness due to the ultra low carbon content in the martensite composed of dislocation cells.

Hydrogen effect on different melts of steel 03Cr10Ni10Mo2(Ti,Al)

International Nuclear Information System (INIS)

Hruby, J.; Novosad, P.; Axamit, R.

1984-01-01

The effect of hydrogen on martensitic 03Cr10Ni10Mo2(Ti,Al) steel was studied following vacuum induction melting and electroslag remelting with and without the effect of radiation. Under the influence of hydrogen and under the same parameters of catodic hydrogen charging of steel after vacuum induction melting shows a 20 - 30% reduction in total ductility. Steels after electroslag remelting show a higher reduction in total ductility - within the range of 26 - 33%, i.e., 33 - 43% for different melts, and contraction Z shows a reduction of 23 - 59%. Electroslag remelted steels show a greater reduction in plasticity owing to hydrogen than steels melted in vacuum induction furnaces. The reduction of the yield point and the breaking strength owing to hydrogen are more explicit than in steel after vacuum melting. In non-irradiated hydrogenated samples a higher yield point was evident. (B.S.)

Effect of ageing on the microstructural stability of cold-worked titanium-modified 15Cr-15Ni-2.5Mo austenitic stainless steel

International Nuclear Information System (INIS)

Venkadesan, S.; Bhaduri, A.K.; Rodriguez, P.; Padmanabhan, K.A.

1992-01-01

A titanium-modified 15Cr-15Ni-2.5Mo austenitic stainless steel conforming to ASTM A 771 (UNS S 38660), commercially called Alloy D9, is being indigenously developed for application as material for the fuel clad and the hexagonal wrapper for fuel subassemblies of the Prototype Fast Breeder Reactor. As this material would be used in the cold-worked condition and would be subjected to prolonged exposure to elevated service temperatures, the effect of ageing on the microstructural stability was studied as a function of the amount of cold work. The material was given 2.5-30% prior cold work and then aged at temperatures in the range 923 to 1173 K for times ranging from 0.25 to 1000 h. Hardness measurements made before and after ageing were correlated with the Larson-Miller parameter to determine the highest stable prior cold-work level. Optical microscopy was used to study the microstructural changes. The influence of prolonged exposure for two and three years at the operating temperatures of clad and wrapper, on the elevated temperature tensile properties of a 20% prior cold-worked Alloy D9 was also studied through accelerated ageing treatments based on the present parametric approach. (orig.)

Effect of long-term aging on microstructural stabilization and mechanical properties of 20Cr32Ni1Nb steel

Energy Technology Data Exchange (ETDEWEB)

Guo, Xiaofeng; Jia, Xiankai [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816 (China); Gong, Jianming, E-mail: gongjm@njtech.edu.cn [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816 (China); Key Lab of Design and Manufacture of Extreme Pressure Equipment, Jiangsu Province (China); Geng, Luyang; Tang, Jianqun; Jiang, Yong [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816 (China); Key Lab of Design and Manufacture of Extreme Pressure Equipment, Jiangsu Province (China); Ni, Yingying; Yang, Xinyu [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing, Jiangsu 211816 (China)

2017-04-06

The centrifugally cast 20Cr32Ni1Nb stainless steel aged at 950 ℃ from 200 h up to 5000 h was investigated on the mechanical properties and microstructural evolution using post-aged tensile tests, post-aged Charpy impact tests, Optical microscopy (OM) observations, and field emission-scanning electron microscopy (FE-SEM) examinations. Experimental results indicate that the as-cast microstructure of the steel typically consists of a supersaturated solid solution of austenite matrix with a network of interdendritic primary carbides (NbC and M{sub 23}C{sub 6}). During aging process, the growth and coarsening of NbC carbides and M{sub 23}C{sub 6} carbides as well as the transformation of NbC carbide into G phase take place. Meanwhile, the transformation of NbC into G phase releases C into the matrix during aging exposure. This released C tends to combine with Cr, and forms M{sub 23}C{sub 6} at the dendrite boundaries. Compared with a continuous reduction of the elongation in the whole aging period, the strength parameters (σ{sub ult} and σ{sub ys}) exhibit an initial increase followed by a continuous decrease with the aging time prolonged from 1000 h to 5000 h. Additionally, the variation of Charpy impact absorbed energy is relatively complex during aging process. The microstructural evolution during long-term aging process is consistent with the variation of mechanical properties.

Effects of Bond Coating on NiCrBSi-Mo Composite Functional Coating Properties in Plasma Spraying NiCrBSi-Mo/Ni Coating

OpenAIRE

DU Ji-yu; LI Fang-yi; LU Hai-yang; SHANG Jian-tong; LI Zhen

2017-01-01

Nickel-based bond coating and composite functional coating were sprayed on leaf blade steel material FV520B successively by using air plasma spraying system. NiCrBSi-Mo powder deposition rate, coating porosity, bonding strength and surface hardness were tested. The results indicate that, for the NiCrBSi-Mo/Ni coating, bond coating with 180-220μm thickness can improve NiCrBSi-Mo powder deposition rate while the surface coating with lower porosity, higher bonding strength and high hardness is p...

Nitrogen-containing superlow-carbon austenitic steel 02Kh25N22AM2

Science.gov (United States)

Fe'ldgandler, É. G.; Svistunova, T. V.; Savkina, L. Ya.; Lapshina, O. B.

1996-02-01

At present the equipment for manufacturing carbamide mineral fertilizers is produced from domestic steel 03Kh17N14M3 having "carbamide quality." Imported equipment also used in the industry is produced from steel of the 25-22-2 (Cr -Ni-Mo) type shipped by various firms, namely, 2RE69 (Sandvik, Sweden), 254SFER (Avesta, Sweden), 2522LCN (VDM, Germany), DM 1.4466 (Germany), and X2CrNiMo 25-22-2 (Dalmine, Italy). The imported steels are used because in some units steel 03Khl7Nl4M3 does not provide the requisite corrosion resistance in an intensified process of carbamide manufacturing. We currently possess domestic high-alloyed steel for producing new and repairing imported equipment operating under the severe conditions of carbamide synthesis. The present paper concerns the structure, mechanical properties, and corrosion resistance of industrially produced steel 02Kh25N22AM2 (ChS-108) and the recommended range of its application.

Improved hardness of laser alloyed X12CrNiMo martensitic stainless steel

CSIR Research Space (South Africa)

Adebiyi, DI

2011-07-01

Full Text Available The improvement in hardness of X12CrNiMo martensitic stainless steel laser alloyed with 99.9% pure titanium carbide, stellite 6 and two cases of premixed ratio of titanium carbide and stellite 6 [TiC (30 wt.%)- stellite 6 (70 wt.%) and TiC (70 wt...

Long-term Stability of 9- to 12 % Cr Steels

DEFF Research Database (Denmark)

Hald, John

2004-01-01

In the recent 25 years creep rupture strength of 9- to 12 %Cr steels for steam pipes and turbines has been doubled by development of new alloys. This development has formed a basis for improved efficiency of fossil fired steam power plants by introduction of advanced steam temperatures...... and pressures. Newly developed steam pipe steels are based on modifications of well-established steels like the X 20CrMoV12 1. Balanced addition of V, Nb and N to a 9Cr 1 Mo steel led to the Modified 9 Cr steel P 91. Addition of 1% W to a 9Cr 1 MoVNbN base composition led to steel E 911 and partial replacement...... of Mo with 1.8 % W combined with a slight amount of Boron led to steel P 92. The creep rupture strength of these new alloys are now secured with long-term tests up to 100,000 hours, which demonstrate improvements of 50% (P 91), 75 % (E 911) and 100 % (P 92) in strength compared to X 20CrMoV12 1....

HIGH TEMPERATURE TENSILE PROPERTIES OF NEW FE-CR-MN DEVELOPED STEEL

Directory of Open Access Journals (Sweden)

M. Mahmoudiniya

2017-03-01

Full Text Available Nowadays, Ni-free austenitic stainless steels are being developed rapidly and high price of nickel is one of the most important motivations for this development. At present research a new FeCrMn steel was designed and produced based on Fe-Cr-Mn-C system. Comparative studies on microstructure and high temperature mechanical properties of  new steel and AISI 316 steel were done. The results showed that new FeCrMn developed steel has single austenite phase microstructure, and its tensile strength and toughness were higher than those of 316 steel at 25, 200,350 and 500°C. In contrast with 316 steel, the new FeCrMn steel did not show strain induced transformation and dynamic strain aging phenomena during tensile tests that represented higher austenite stability of new developed steel. Lower density and higher strength of the new steel caused higher specific strength in comparison with the 316 one that can be considered as an important advantage in structural applications but in less corrosive environment

Investigations on the Behavior of HVOF and Cold Sprayed Ni-20Cr Coating on T22 Boiler Steel in Actual Boiler Environment

Science.gov (United States)

Bala, Niraj; Singh, Harpreet; Prakash, Satya; Karthikeyan, J.

2012-01-01

High temperature corrosion accompanied by erosion is a severe problem, which may result in premature failure of the boiler tubes. One countermeasure to overcome this problem is the use of thermal spray protective coatings. In the current investigation high velocity oxy-fuel (HVOF) and cold spray processes have been used to deposit commercial Ni-20Cr powder on T22 boiler steel. To evaluate the performance of the coatings in actual conditions the bare as well as the coated steels were subjected to cyclic exposures, in the superheater zone of a coal fired boiler for 15 cycles. The weight change and thickness loss data were used to establish kinetics of the erosion-corrosion. X-ray diffraction, surface and cross-sectional field emission scanning electron microscope/energy dispersive spectroscopy (FE-SEM/EDS) and x-ray mapping techniques were used to analyse the as-sprayed and corroded specimens. The HVOF sprayed coating performed better than its cold sprayed counterpart in actual boiler environment.

Effect of heat treatment on workability of Cr-Ni-Mo steels

International Nuclear Information System (INIS)

Barcal, J.; Macek, K.

1988-01-01

The workability was studied of the new development generation of hardenable martensite Cr-Ni-Mo steels of the 10-10-2 and 6-11-3 types whose application is envisaged in future in nuclear engineering. Attention is paid to identification of inclusions and the phase analysis ofthe structure with respect to heat treatment and steel type. Face milling was used in the test of workability. In addition, tensile strength and impact bending strength testing was performed. The results showed that steel of the 6-11-3 type in the quenched condition was best workable. However, this steel showed a significant reduction in workability when in the hardened condition. Reduced workability can also be presumed for type 10-10-2 steel in the hardened condition when life is considered. Microstructure changes leading to softening of steel by aging had a favourable effect on workability, especially in steels of the 10-10-2 type. Hardened steels of the 6-11-3 type are recommended to be re-quenched. (Z.M.). 7 figs., 3 tabs., 9 refs

Transformation and Precipitation Kinetics in 30Cr10Ni Duplex Stainless Steel

Science.gov (United States)

Fazarinc, Matevz; Terčelj, Milan; Bombač, David; Kugler, Goran

2010-09-01

To improve the microstructure during casting, hot forming, and heat treatment of 30Cr10Ni duplex stainless steel, accurate data on the precipitation and transformation processes at high temperatures are needed. In this article, the precipitation and transformation processes at various aging times in the temperature range 873 K to 1573 K (600 °C to 1300 °C) were studied. The 30Cr10Ni ferrous alloy contains a relatively large amount of Cr, Ni, and C, which results in a complex microstructure. In addition to the ferrite, austenite, and sigma phase, the M23C6 and MC carbides were also observed in the microstructure. The precipitation of the sigma phase was observed after just 3 minutes of aging, and after 30 minutes of aging at approximately 1053 K (780 °C), its fraction exceeded 40 pct. An intensive austenite-to-ferrite transformation was observed above 1423 K (1150 °C). Optical microscopy, energy-dispersive X-ray spectroscopy (EDS), electron backscattered diffraction (EBSD), and X-ray diffraction (XRD), as well as micro-indentation hardness, hardness, impact toughness, and tensile tests, were carried out to evaluate the obtained microstructures of aged samples.

High-temperature brazing of X5CrNi18 10 and NiCr20TiAl using the atmospherically plasma-sprayed L-Ni2 filler metal

International Nuclear Information System (INIS)

Wielage, B.; Drozak, J.

1992-01-01

The hybrid-technological combination of the atmospheric plasma spraying for the application of a high-temperature filler metal followed by a brazing process was analyzed in terms of structure and mechanical properties of X5CrNi18 10 and NiCr20TiAl brazing joints. The thickness of the filler metal layer was minimized at [de

Precipitation sequences in austenitic Fe-22Cr-21Ni-6Mo-(N) stainless steels

International Nuclear Information System (INIS)

Kim, S.-J.; Lee, T.-H.

1999-01-01

Precipitation sequence of nitrogen containing Fe-22Cr-21Ni-6Mo-N austenitic stainless steel has been investigated after aging at high temperatures, and compared with nitrogen free steel. The σ phases and M 23 C 6 carbides were observed along the grain boundaries as well as in the matrix in both of the solution treated specimens. The M 6 C carbides and chi phase appeared successively in between 3 hours and 24 hours depending on the nitrogen content. Main difference in aging behavior was the precipitation of fine nitrides. Aging for 24 hours and 168 hours of nitrogen containing steel resulted in the formation of fine Cr 2 N and faceted AlN nitrides. The crystallography, structure and morphology were analyzed with analytical electron microscopy. (orig.)

Hydrogen induced plastic damage in pressure vessel steel of 2.25Cr-1Mo

International Nuclear Information System (INIS)

Han, G.W.; Song, Y.J.

1995-01-01

2.25Cr-1Mo steel is generally employed as a hydrogenation reaction vessel material used at elevated temperature and in a hydrogen containing environment. During service of the reaction vessel, a large number of hydrogen atoms would enter its wall. When the reaction vessel is shutdown and the temperature reduces to about ambient temperature, the hydrogen atoms remaining in the wall would induce plastic damage in the steel. The mechanism of hydrogen induced plastic damage is different for various materials with different microstructures. Investigations have demonstrated that the hydrogen induced plastic damage in carbide annealed carbon steels is caused by hydrogen accelerating the initiating and growing of microvoids from the carbide particles. However, SEM examination on the fracture surface of hydrogen charged tensile specimen of 2.25Cr-1Mo steel show that a large number of fisheyes appear on the fracture surface. This indicates that hydrogen induced plastic damage in 2.25Cr-1Mo steel is related to the occurrence of fisheye cracks during plastic deformation. By means of micro-fracture mechanics to analyze fisheye crack occurrence from the first generation microvoid, the mechanism of hydrogen induced plastic damage in the pressure vessel steel is investigated

Characterization of corrosion resistant on NiCoCr coating layer exposed to 5%NaCl

Science.gov (United States)

Sugiarti, E.; Sundawa, R.; Desiati, R. D.; Zaini, K. A.

2018-03-01

Highly corrosion resistant of carbon steel coated NiCoCr was applied in corrosive of marine environtment. Carbon steel coated NiCoCr was prepared by a two step technique of NiCo electro-deposition and Cr pack cementation. The samples were exposed to 5 wt.% NaCl for 48 and 168 hours. The microstructure and corrosion product were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The corrosion resistance of carbon steel coated NiCoCr was found to be better than that of carbon steel substrate without coating. The results showed the microstructure of 48 h corroded sample has duplex layer composed of inner α-(Ni,Co), α-Cr and outer Cr2O3, while a quite thin and continues protective oxide of Cr2O3 was observed in outer layer of 168 h corroded sample. The formation of oxide scale rich in Cr2O3 has contributed for the better corrosion resistance of carbon steel coated NiCoCr, whereas the formation of non protective oxide of iron might caused low corrosion resistance of carbon steel substrate.

Contamination assessment of heavy metals in the soils around Khouzestan Steel Company (Ni, Mn, Pb, Fe, Zn, Cr)

International Nuclear Information System (INIS)

Hormozi Nejad, F.; Rastmanesh, F.; Zarasvandi, A.

2016-01-01

The highest concentrations were found at soil samples 4 and 12. Comparison of heavy metals concentration with unpolluted soil standard indicated that, concentrations of Cr, Zn, Fe, Ni and Pb is higher than that of unpolluted soil standard. In general, Manganese, Chromium, Zinc and Lead are the most important elements that are found in emissions of steel plants. The soil samples near the steel plant and downwind direction have much higher pollution level. The results showed that Mn, Pb and Zn is related to human activity and Cr have geogenic source and Fe and Ni have both geogenic and anthropogenic source in the study area in the city of Ahwaz.

The influence of Cr and Al pack cementation on low carbon steel to improve oxidation resistance

Science.gov (United States)

Prasetya, Didik; Sugiarti, Eni; Destyorini, Fredina; Thosin, Kemas Ahmad Zaini

2012-06-01

Pack chromizing and aluminizing has been widely used for many years to improve hot temperature oxidation and corrosion resistance of metals. The coating process involves packing the steel in a powder mixture which contain aluminum and chromium source, and inert filler (usually alumina), and halide activator NH4Cl. Al and Cr were deposited onto carbon steel by pack cementation process using elemental Al and Cr powder as Al and Cr source, whereas NiCo alloys codeposited by electrodeposition. The position of Al and Cr could be under or over Ni-Co alloys deposited. Pack cementation was heated on dry inert gas at temperature 800 °C about 5 hours and 20 minute for Cr and Al respectively. Al and Cr was successfully deposited. Laying down effect of Al and Cr onto carbon steel whether up and down toward NiCo alloys coating have affected to oxidation resistance. The pack aluminizing as top layer given best resitance to restrain excessive oxide scale, in contrast pack chromizing reveal bad oxidation resistance, moreover occured spallation on layer.

Slurry Erosion Studies on Surface Modified 13Cr-4Ni Steels: Effect of Angle of Impingement and Particle Size

Science.gov (United States)

Manisekaran, T.; Kamaraj, M.; Sharrif, S. M.; Joshi, S. V.

2007-10-01

Hydroturbine steels, such as 13Cr-4Ni martensitic steels, are generally subjected to heavy-erosive wear and loss of efficiency due to solid particulate entrainment in the water. Surface-modified steels have proven to give better performance in terms of erosive wear resistance. In the present study, an attempt is made to investigate the effect of angle of impingement and particle size on slurry-jet erosion behavior of pulsed plasma nitrided and laser hardened 13Cr-4Ni steels. Laser hardening process has shown good performance at all angles of impingement due to martensitic transformation of retained austenite. Plastic deformation mode of material removal was also an evident feature of all laser-hardened surface damage locations. However, pulsed-plasma nitrided steels have exhibited chip formation and micro-cutting mode of erosive wear. Erosion with 150-300 μm size was twice compared to 150 μm size slurry particulates.

Internal carbonitriding behavior of Ni-V, Ni-Cr, and Ni-3Nb alloys

International Nuclear Information System (INIS)

Allen, A.T.; Douglass, D.L.

1999-01-01

Ni-2V, Ni-5V, Ni-12V, Ni-10Cr, Ni-20Cr, and Ni-3Nb alloys were carbonitrided in C 3 H 6 and NH 3 gas mixtures (bal H 2 ) over the range 700--1,000 C. Carbonitridation of Ni-12V and Ni-20Cr in C 3 H 6 /NH 3 /H 2 (1.5/1.5/97 v/o) and (1.5/10/88.5 v/o) produced duplex subscales consisting of near-surface nitrides with underlying carbides. Growth of each zone obeyed the parabolic rate law under most conditions. The presence of carbon generally did not effect the depth of the nitride zones compared to nitriding the alloys in NH 3 /H 2 (10/90 v/o). However, at 700 C, the nitride zones were deeper in the carbonitrided Ni-V alloys and Ni-20Cr. The presence of nitrogen generally increased the depth of the carbide zones in Ni-12V and Ni-20Cr compared to carburizing these alloys in C 3 H 6 /H 2 (1.5/98.5 v/o). VN, CrN, and NbN formed in Ni-V, Ni-Cr, and Ni-Nb alloys, respectively, whereas the underlying carbide layers contained V 4 C 3 in Ni-12V, Cr 3 C 2 above a zone of Cr 7 C 3 in Ni-20Cr, and NbC in Ni-3Nb. The solubilities and diffusivities of nitrogen and carbon in nickel were determined. Nitrogen and carbon each exhibited retrograde solubility with temperature in pure Ni in both carbonitriding environments. Nitrogen diffusion in nickel was generally lower in each carbonitriding mixture compared to nitrogen diffusion in a nitriding environment, except at 700 C when nitrogen diffusion was higher. Carbon diffusion in nickel was generally higher in the carbonitriding environments compared to carbon diffusion in a carburizing environment

Study of magnetism in Ni-Cr hardface alloy deposit on 316LN stainless steel using magnetic force microscopy

Science.gov (United States)

Kishore, G. V. K.; Kumar, Anish; Chakraborty, Gopa; Albert, S. K.; Rao, B. Purna Chandra; Bhaduri, A. K.; Jayakumar, T.

2015-07-01

Nickel base Ni-Cr alloy variants are extensively used for hardfacing of austenitic stainless steel components in sodium cooled fast reactors (SFRs) to avoid self-welding and galling. Considerable difference in the compositions and melting points of the substrate and the Ni-Cr alloy results in significant dilution of the hardface deposit from the substrate. Even though, both the deposit and the substrate are non-magnetic, the diluted region exhibits ferromagnetic behavior. The present paper reports a systematic study carried out on the variations in microstructures and magnetic behavior of American Welding Society (AWS) Ni Cr-C deposited layers on 316 LN austenitic stainless steels, using atomic force microscopy (AFM) and magnetic force microscopy (MFM). The phase variations of the oscillations of a Co-Cr alloy coated magnetic field sensitive cantilever is used to quantitatively study the magnetic strength of the evolved microstructure in the diluted region as a function of the distance from the deposit/substrate interface, with the spatial resolution of about 100 nm. The acquired AFM/MFM images and the magnetic property profiles have been correlated with the variations in the chemical compositions in the diluted layers obtained by the energy dispersive spectroscopy (EDS). The study indicates that both the volume fraction of the ferromagnetic phase and its ferromagnetic strength decrease with increasing distance from the deposit/substrate interface. A distinct difference is observed in the ferromagnetic strength in the first few layers and the ferromagnetism is observed only near to the precipitates in the fifth layer. The study provides a better insight of the evolution of ferromagnetism in the diluted layers of Ni-Cr alloy deposits on stainless steel.

Creep and creep fatigue crack behavior of 1Cr- and 9Cr-steels

International Nuclear Information System (INIS)

Maile, K.; Klenk, A.; Schellenberg, G.; Granacher, J.; Tramer, M.

2000-01-01

A large database for creep crack initiation and propagation under constant load conditions is available on conventional power plant steels of types 1%Cr and 12%Cr. Modern plants are often used in the medium and peak load regime, thus the dominant loading situation in high temperature components is creep fatigue. For life assessment data about crack initiation and growth under creep fatigue loading are required. These characteristics can not be substituted by pure fatigue or creep crack data. Therefore, a comprehensive test programme was started to investigate the creep fatigue crack behaviour of a 1%CrMoNiV turbine rotor steel (30CrMoNiV 4 11) at 550 C and a new 9%CrMoVNb pipe steel (type P 9 1) at 600 C. DENT-specimen with 15 and 60 mm thickness as well as side grooved CT-specimen with 25 and 50 mm thickness have been tested to determine possible influences of geometry and thus to check the transferability of the data to components. The creep fatigue crack growth results of tests with dwell times between t H = 0,32h and 10 h lie in the scatterbands given by creep crack growth results. Nevertheless a higher crack growth rate under creep fatigue conditions can be stated. An increase in crack growth rate due to creep fatigue is clearly visible. Loading situations with frequencies higher than 1.10 -4 Hz should be not assessed with pure creep crack results or sufficient safety margins have to be applied. (orig.)

Structural evolution of Fe-18Ni-16Cr-4Al steel during aging at 950 .deg. C

Energy Technology Data Exchange (ETDEWEB)

Wang, Man; Jang, Jinsung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Zhou, Zhangjian [School of Materials Science and Engineering, USTB, Beijing (China)

2015-05-15

Austenitic stainless steels are also among important structural materials for in-core components of nuclear reactors, and the performance, the oxidation resistance as well as the mechanical strength at high temperature are further expected after Fukushima accident. Alumina-forming austenitic (AFA) steel was first developed by Y. Yamamoto et al. , which showed a good combination of oxidation resistance and creep resistance. The strengthening is achieved through nano-sized MX and Laves. Microstructural evolution of Fe-18Ni-16Cr-4Al during aging at 950 .deg. C was studied. This steel consists of two phases of austenite and ferrite. During aging, needle-shaped NiAl precipitates in austenite, while round shaped NiAl form in ferrite, which is supposed to be due to different crystal structural parameters.

Establishment of Wear Resistant HVOF Coatings for 50CrMo4 Chromium Molybdenum Alloy Steel as an Alternative for Hard Chrome Plating

Science.gov (United States)

Karuppasamy, S.; Sivan, V.; Natarajan, S.; Kumaresh Babu, S. P.; Duraiselvam, M.; Dhanuskodi, R.

2018-05-01

High cost imported components of seamless steel tube manufacturing plants wear frequently and need replacement to ensure the quality of the product. Hard chrome plating, which is time consuming and hazardous, is conventionally used to restore the original dimension of the worn-out surface of the machine components. High Velocity Oxy-Fuel (HVOF) thermal spray coatings with NiCrBSi super alloy powder and Cr3C2 NiCr75/25 alloy powder applied on a 50CrMo4 (DIN-1.7228) chromium molybdenum alloy steel, the material of the wear prone machine component, were evaluated for use as an alternative for hard chrome plating in this present work. The coating characteristics are evaluated using abrasive wear test, sliding wear test and microscopic analysis, hardness test, etc. The study results revealed that the HVOF based NiCrBSi and Cr3C2NiCr75/25 coatings have hardness in the range of 800-900 HV0.3, sliding wear rate in the range of 50-60 µm and surface finish around 5 microns. Cr3C2 NiCr75/25 coating is observed to be a better option out of the two coatings evaluated for the selected application.

Experimental study on kinematic hardening of 1Cr18Ni9Ti stainless steel under low cycle fatigue

International Nuclear Information System (INIS)

Shao Er; Yang Xianjie; Mao Jianghui; Sun Yafang

2006-01-01

To study the effect of the monotonic loading on subsequent cyclic plastic hardening and flow properties of 1Cr18Ni9Ti steel, an experimental study of the low cycle fatigue tests with mean strains for 1Cr18Ni9Ti stainless steel was carried out. An analysis on the evolutions of the yield surface radius and the back stresses under symmetric and asymmetric cyclic strain loading with different strain amplitudes was made. The dependence of the evolutions of the material kinematic hardening and isotropic hardening on the strain amplitude and mean strain was observed. These results provide the experimental foundation for the constitutive model of the material under combined monotonic and cyclic complicated loads. (authors)

Investigation of intergranular corrosion resistance of Cr16Ni25NMo6 steel

International Nuclear Information System (INIS)

Kamenev, Yu.B.; Nazarov, A.A.; Kuusk, L.V.; Majdeburova, T.F.

1990-01-01

The effect of 08Kh16N25AM6 steel susceptibility to intergranular corrosion on its intergranular cracking resistance in high-temperature water is investigated. In addition, the performed tests point to the susceptibility of sensibilized Kh16N25AM6 steel to intergranular corrosion in media simulating an agressive environment of power generation equipment; the latter requires a strict control over the resistance of weld joints of the above steel to intergranular corrosion. It is shown that Kh16N25AM6 type steel in sensibilized state is susceptible to intercrystalline corrosion cracking in high-temperature water which correlates with its susceptibility to intergranular corrosion established by AM GOST 6032-84 and potentiodynamic reactivation methods

Slurry Erosion Behavior of AlxCoCrFeNiTi0.5 High-Entropy Alloy Coatings Fabricated by Laser Cladding

Directory of Open Access Journals (Sweden)

Jianhua Zhao

2018-02-01

Full Text Available High-entropy alloys (HEAs have gained extensive attention due to their excellent properties and the related scientific value in the last decade. In this work, AlxCoCrFeNiTi0.5 HEA coatings (x: molar ratio, x = 1.0, 1.5, 2.0, and 2.5 were fabricated on Q345 steel substrate by laser-cladding process to develop a practical protection technology for fluid machines. The effect of Al content on their phase evolution, microstructure, and slurry erosion performance of the HEA coatings was studied. The AlxCoCrFeNiTi0.5 HEA coatings are composed of simple face-centered cubic (FCC, body-centered cubic (BCC and their mixture phase. Slurry erosion tests were conducted on the HEA coatings with a constant velocity of 10.08 m/s and 16–40 meshs and particles at impingement angles of 15, 30, 45, 60 and 90 degrees. The effect of three parameters, namely impingement angle, sand concentration and erosion time, on the slurry erosion behavior of AlxCoCrFeNiTi0.5 HEA coatings was investigated. Experimental results show AlCoCrFeNiTi0.5 HEA coating follows a ductile erosion mode and a mixed mode (neither ductile nor brittle for Al1.5CoCrFeNiTi0.5 HEA coating, while Al2.0CoCrFeNiTi0.5 and Al2.5CoCrFeNiTi0.5 HEA coatings mainly exhibit brittle erosion mode. AlCoCrFeNiTi0.5 HEA coating has good erosion resistance at all investigated impingement angles due to its high hardness, good plasticity, and low stacking fault energy (SFE.

Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

Science.gov (United States)

Zhao, Zichun; Li, Hui; Yang, Tianlong; Zhu, Hongbin

2018-04-01

Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

Tribological Properties of HVOF-Sprayed TiB2-NiCr Coatings with Agglomerated Feedstocks

Science.gov (United States)

Zhao, Zichun; Li, Hui; Yang, Tianlong; Zhu, Hongbin

2018-03-01

Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball.

Determination of Cr, Mn, Si, and Ni in carbon steels by optical emission spectrometry with spark source

International Nuclear Information System (INIS)

Garcia Gonzalez, M.A.; Pomares Alfonso, M.; Mora Lopez, L.

1995-01-01

Elemental composition of steels determines some important of his characteristic moreover it is necessary to obtain their quality certification. Analytical procedure has performed for determination of Cr, Mn, Si and Ni in carbon steels by optical emission spectrometry with spark source. reproducibility of results is 5-11 %. Exactitude has tested with results that have obtained by internationally recognised methods-

The characteristics of precipitates in 18% Cr/30% Ni cast steel with additions of Nb and Ti

International Nuclear Information System (INIS)

Piekarski, B.

1995-01-01

The microstructure of austenitic cast steel with approx. 0.3%C, 4.37%Si, 0.69%Mn, 17.8%Cr, 29.3%Ni, 1.47%Nb and 1.07%Ti have been examined after ageing at 900 C for 300 h. There was found five precipitates: M 23 C 6 , MnS, Ni 3 Fe, (Ti,Nb)C and an intermetallic Ni-Nb-S phase. Ni, Nb, Si-rich precipitate could have been formed in as cast condition. (author)

Precipitation kinetics in austenitic 18Cr-30Ni-Nb cast steel

Directory of Open Access Journals (Sweden)

M. Garbiak

2008-08-01

Full Text Available The study presents the results of investigations on the precipitation kinetics in austenitic 18%Cr-30%Ni cast steel stabilised with an addition of 1.84 wt% niobium. Phase analysis of isolates extracted from the alloy subjected to annealing within the temperature range of 600–1000oC during 10–1000 h was made. The phase constitution of the isolates mainly comprised niobium carbides of the NbC type and complex chromium carbides of the Cr23C6 type. In specimens annealed within the temperature range of 700–900oC, a high-silicon G phase was additionally identified. The highest kinetics of the precipitation process was recorded after annealing at the temperatures of 800 and 900oC.

Changes in mechanical properties and structure of electrolytic plasma treated X 12 CrNi 18 10 Ti stainless steel

Energy Technology Data Exchange (ETDEWEB)

Kurbanbekov, Sherzod; Baklanov, Viktor; Karakozov, Batyrzhan [Republican State Enterprise National Nuclear Center of Kazakhstan, Kurchatov (Kazakhstan). Inst. of Atomic Energy Branch; Skakov, Mazhyn [Republican State Enterprise National Nuclear Center of Kazakhstan, Kurchatov (Kazakhstan)

2017-05-01

The paper addresses findings regarding the influence of electrolytic plasma treatment on the mechanical properties as well as structural and phase states of X 12 CrNi 18 10 Ti steel. Electrolytic plasma treatment is based on carburizing of stainless steel heated in electrolytes. Treatment of steel samples has been performed as follows: the samples were heated up to a temperature between 850 and 950 C and then they were cured for 7 minutes in an electrolyte of an aqueous solution containing 10 % glycerol (C{sub 3}H{sub 8}O{sub 3}) and 15 % sodium carbonate (Na{sub 2}CO{sub 3}). It is found that, after plasma electrolytic treatment, the surface of X 12 CrNi 18 10 Ti steel had a modified structure and high hardness. Increasing wear resistance of X 12 CrNi 18 10 Ti steel has been observed after carburizing and the coefficient of friction has been reduced. X-ray analysis showed that retained austenite γ-Fe is a main phase, and there are some diffraction lines of orthorhombic Fe{sub 3}C phase as well as Fe{sub 3}O{sub 4} cubic phase. It has been determined, that, after plasma electrolytic treatment, a carbide phase in the modified surface layer, irrespective of the location in the steel structure has the chemical composition Fe{sub 3}C. High concentration of carbon atoms in a solid solution based on γ- and α-iron, a large dislocation density, presence of particles of carbide phase and retained austenite layers have been found.

Production and characterization of stainless steel based Fe-Cr-Ni-Mn-Si(-Co) shape memory alloys

International Nuclear Information System (INIS)

Otubo, J.

1995-01-01

It is well known that the Fe based alloys can exhibit shape memory effect due to the γ to ε martensitic transformation. The effect may not be as striking as observed in the NiTi alloy but it might become attractive from the practical point of view. In this work, two compositions of Fe-Cr-Ni-Mn-Si(-Co) stainless steel based shape memory alloy, prepared by the VIM technique, will be presented. The results are good with shape recovery of 95% for a pre-strain of 4% after some training cycles. In terms of workability the alloys produced are worse than the usual AISI304. However, adjusting the thermo-mechanical processing, it is perfectly possible to produce wire as thin as 1,20mm in dia. or down. (orig.)

Influence of Mn contents in 0Cr18Ni10Ti thin wall stainless steel tube on TIG girth weld quality

Science.gov (United States)

Liu, Bo

2017-03-01

Three kinds of cold worked 0Cr18Ni10Ti thin wall stainless steel tubes with the manganese contents of 1.27%, 1.35% and 1.44% and the cold worked 0Cr18Ni10Ti stainless steel end plug with manganese content of 1.35% were used for TIG girth welding in the present investigation. The effect of different manganese contents in stainless steel tube on weld quality was studied. The results showed that under the same welding conditions, the metallographic performance of the girth weld for the thin wall stainless steel tube with the manganese element content 1.44% welded with end plug was the best. Under the appropriate welding conditions, the quality of the girth weld increased with the increase of the manganese content till 1.44%. It was found that in the case of the Mn content of 1.44%, and under the proper welding condition the welding defects, such as welding cracks were effectively avoided, and the qualified weld penetration can be obtained.. It is concluded that the appropriate increase of the manganese content can significantly improve the TIG girth weld quality of the cold worked 0Cr18Ni10Ti stainless steel tube.

Low-Cycle Fatigue Behavior of 10CrNi3MoV High Strength Steel and Its Undermatched Welds.

Science.gov (United States)

Song, Wei; Liu, Xuesong; Berto, Filippo; Razavi, S M J

2018-04-24

The use of high strength steel allows the design of lighter, more slender and simpler structures due to high strength and favorable ductility. Nevertheless, the increase of yield strength does not guarantee the corresponding improvement of fatigue resistance, which becomes a major concern for engineering structure design, especially for the welded joints. The paper presents a comparison of the low cycle fatigue behaviors between 10CrNi3MoV high strength steel and its undermatched weldments. Uniaxial tension tests, Push-pull, strain-controlled fatigue tests were conducted on base metal and weldments in the strain range of 0.2⁻1.2%. The monotonic and cyclic stress-strain curves, stress-life, strain-life and energy-life in terms of these materials were analyzed for fatigue assessment of materials discrepancy. The stress-life results of base metal and undermatched weld metal exhibit cyclic softening behaviors. Furthermore, the shapes of 10CrNi3MoV steel hysteresis loops show a satisfactory Masing-type behavior, while the weld metal shows a non-Masing type behavior. Strain, plastic and total strain energy density amplitudes against the number of reversals to failure results demonstrate that the undermatched weld metal presents a higher resistance to fatigue crack initiation than 10CrNi3MoV high strength steel. Finally, fatigue fracture surfaces of specimens were compared by scanning electron microscopy to identify the differences of crack initiation and the propagation between them.

Low-Cycle Fatigue Behavior of 10CrNi3MoV High Strength Steel and Its Undermatched Welds

Directory of Open Access Journals (Sweden)

Wei Song

2018-04-01

Full Text Available The use of high strength steel allows the design of lighter, more slender and simpler structures due to high strength and favorable ductility. Nevertheless, the increase of yield strength does not guarantee the corresponding improvement of fatigue resistance, which becomes a major concern for engineering structure design, especially for the welded joints. The paper presents a comparison of the low cycle fatigue behaviors between 10CrNi3MoV high strength steel and its undermatched weldments. Uniaxial tension tests, Push-pull, strain-controlled fatigue tests were conducted on base metal and weldments in the strain range of 0.2–1.2%. The monotonic and cyclic stress-strain curves, stress-life, strain-life and energy-life in terms of these materials were analyzed for fatigue assessment of materials discrepancy. The stress-life results of base metal and undermatched weld metal exhibit cyclic softening behaviors. Furthermore, the shapes of 10CrNi3MoV steel hysteresis loops show a satisfactory Masing-type behavior, while the weld metal shows a non-Masing type behavior. Strain, plastic and total strain energy density amplitudes against the number of reversals to failure results demonstrate that the undermatched weld metal presents a higher resistance to fatigue crack initiation than 10CrNi3MoV high strength steel. Finally, fatigue fracture surfaces of specimens were compared by scanning electron microscopy to identify the differences of crack initiation and the propagation between them.

Effects of the Microstructure on Segregation behavior of Ni-Cr-Mo High Strength Low Alloy RPV Steel

Energy Technology Data Exchange (ETDEWEB)

Park, Sang Gyu; Wee, Dang Moon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Min Chul; Lee, Bong Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-10-15

SA508 Gr.4N Ni-Cr-Mo low alloy steel has an improved fracture toughness and strength, compared to commercial Mn-Mo-Ni low alloy RPV steel SA508 Gr.3. Higher strength and fracture toughness of low alloy steels could be achieved by adding Ni and Cr. So there are several researches on SA508 Gr.4N low alloy steel for a RPV application. The operation temperature and time of a reactor pressure vessel is more than 300 .deg. C and over 40 years. Therefore, in order to apply the SA508 Gr.4N low alloy steel for a reactor pressure vessel, it requires a resistance of thermal embrittlement in the high temperature range including temper embrittlement resistance. S. Raoul reported that the susceptibility to temper embrittlement was increasing a function of the cooling rate in SA533 steel, which suggests the martensitic microstructures resulting from increased cooling rates are more susceptible to temper embrittlement. However, this result has not been proved yet. So the comparison of temper embrittlement behavior was made between martensitic microstructure and bainitic microstructure with a viewpoint of boundary features in SA508 Gr.4N, which have mixture of tempered bainite/martensite. In this study, we have compared temper embrittlement behaviors of SA508 Gr.4N low alloy steel with changing volume fraction of martensite. The mechanical properties of these low alloy steels) were evaluated after a long-term heat treatment(450 .deg. C, 2000hr. Then, the images of the segregated boundaries were observed and segregation behavior was analyzed by AES. In order to compare the misorientation distributions of model alloys, grain boundary structures were measured with EBSD

Attempts to improve the fatigue characteristics of the austenitic steel X5CrNi18-10 in the temperature range of 25-600 C by mechanical boundary layer hardening; Zur Verbesserung des Ermuedungsverhaltens des austenitischen Stahls X5CrNi18-10 im Temperaturbereich 25-600 C durch mechanische Randschichtverfestigungsverfahren

Energy Technology Data Exchange (ETDEWEB)

Nikitin, Ivan

2007-01-31

Pieces of the austenitic steel X5CrNi18-10 whose boundary layers had been hardened by different methods were investigated with a view to their fatigue deformation characteristics in the temperature range of 25-600 degC. Parallel to this, microstructural and X-ray analyses provided deeper understanding of fatigue deformation. The microstructure was characterized, among others, by TEM. Boundary layers were solidified by rolling, by a combination of mechanical and thermal processes, by high-temperature rolling, and by laser shock solidification. The analyses focused on microstructural processes and on the intrinsic stress stability and provided important information on the fabrication of structural components with optimised life. (orig.)

Evaluation of rolling contact fatigue of induction heated 13Cr-2Ni-2Mo Stainless steel bar with Si3N4-ball

Science.gov (United States)

Yadoiwa, Ariyasu; Mizobe, Koshiro; Kida, Katsuyuki

2018-03-01

13Cr % martensitic stainless steels were used in various industry, because they have excellent corrosion resistance and high hardness among other stainless steels. They are also expected as a bearing material, however, the research on rolling contact fatigue (RCF) is not enough. In this study, 13Cr-2Ni-2Mo stainless steels were quenched by induction heating and their RCF lives were evaluated. A Si3N4-ball was used in order to apply higher stress (Pmax = 5.6 GPa) than our previous tests (Pmax=5.3 GPa), in a single-ball RCF testing machine. It was found that the basic life (L10) was 2.20×106 cycles and Median life (L50) was 6.04×106 cycles. In addition, Weibull modulus became higher than the previous tests.

Effect of χ Phase Formation on the Mechanical Properties of 25Cr-7Ni-4Mo-0.2N Super Duplex Stainless Steel

International Nuclear Information System (INIS)

Kang, Chang Yong; Kim, Jae Hwan

2011-01-01

This study was carried out to investigate the precipitation behavior of χ phase and effect of χ-phase which precipitated at the initial stage of aging on mechanical properties of 25%Cr-7%Ni-4%Mo-0.2%N super duplex stainless steel. χ-phase was precipitated mainly at the interface of ferrite / austenite phases and inside of the ferrite phase at the initial stage of aging, and it was transformed into σ-phase with an increase of aging time. The ferrite phase was decomposed into new austenite(γ 2 )phase and σ-phase by aging treatment. The hardness and tensile strength of the initial stage of aging when χ-phase was precipitated did not changed considerably, while elongation rapidly decreased. Accordingly, it is considered that χ-phase didn't affect the hardness and strength significantly, but it affected the elongation.

Short Communication on “Self-welding susceptibility of NiCr-B hardfaced coating with and without NiCr-B coating on 316LN stainless steel in flowing sodium at elevated temperature”

Energy Technology Data Exchange (ETDEWEB)

Kumar, Hemant, E-mail: hemant@igcar.gov.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721 302 (India); Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Ramakrishnan, V.; Albert, S.K.; Bhaduri, A.K. [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Ray, K.K. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, Kharagpur, 721 302 (India)

2017-02-15

The self-welding susceptibility between NiCr-B coated 316LN stainless steel and the base metal, and that between NiCr-B hardfaced coatings has been evaluated in flowing sodium at 823 K for 90 and 135 days under contact stress of 8.0 and 11.0 MPa using a fabricated set-up. Neither any self-welding could be observed nor could any damage be detected on the specimen surfaces of the selected materials under the imposed experimental conditions, which indicate their satisfactory potential for applications in Fast Breeder Reactors.

Dimensional stability of some Fe-Ni-Cr alloys used in nuclear power generation

International Nuclear Information System (INIS)

Marucco, A.; Nath, B.

1983-01-01

The dimensional stability of four materials used in the nuclear power industry, viz Nimonic PE16, 20Cr-25Ni steel, Alloy 600 and Inconel 690, have been studied using X-ray diffractometry, electrical resistivity and thin foil microscopic techniques. Appreciable reductions in lattice parameters of these alloys occur on exposure to temperatures of 823 deg K and below. An order-disorder transformation has been found to be responsible for the observed behaviour. The transformation kinetics, associated microstructural changes and the implications for the usage of these materials are discussed. (author)

Effect of load ratio and saltwater corrosive environment on the initiation life of fatigue of 10Ni5CrMoV steel

Science.gov (United States)

Xie, Xing; Yi, Hong; Xu, Jian; Gen, Liming; Chen, Luyun

2017-09-01

Fatigue initiation life has been studied with 10CrNi5MoV steel for use in ocean engineering at different load ratios and in different environmental media. The microstructure and micro-topography have been observed and analyzed by means of SEM, EDS and EBSD. Our findings indicate that, the initiation life of 10Ni5CrMoV steel in seawater is shorter than that in air, and the difference in longevity is larger with the increasing of load ratio. Corrosion pits had a great influence on initial corrosion fatigue life.

Neutron irradiation embrittlement of reactor pressure vessel steel 20 MnMoNi55 weld

International Nuclear Information System (INIS)

Ghoneim, M.M.

1987-05-01

The effect of neutron irradiation on the mechanical and fracture properties of an 'improved' 20 MnMoNi 55 Pressure Vessel Steel (PVS) weld was investigated. In addition to very low residual element content, especially Cu (0.035 wt.%), and relatively higher Ni content (0.9 wt.%), this steel has higher strength (30% more) than the steels used currently in nuclear reactor pressure vessels. The material was irradiated to 3.5x10 19 and 7x10 19 n/cm 2 (E > 1 Mev) at 290 0 C and 2.5x10 19 n/cm 2 (E > 1 MeV) at 160 0 C in FRJ-1 and FRJ-2 research reactors at KFA, Juelich, F.R.G. Test methods used in the evaluation included instrumented impact testing of standard and precracked Charpy specimens, tensile, and fracture toughness testing. Instrumented impact testing provided load and energy vs. time (deflection) data in addition to energy absorption data. The results indicated that the investigated high strength improved steel is more resistant to irradiation induced embrittlement than conventional PVSs. (orig./IHOE)

Cr-Ni ALLOY ELECTRODEPOSITION AND COMPARISON WITH CONVENTIONAL PURE Cr COATING TECHNIQUE

Directory of Open Access Journals (Sweden)

M. Moniruzzaman

2012-12-01

Full Text Available Cr coating is widely used as the outer surface of precision parts due to its attractive appearance and superior corrosion resistance properties. It is obtained by electrodeposition via a conventional bath with hexavalent Cr ions. This manufacturing technique has many drawbacks, such as very low efficiency and high operating temperature and it is hazardous to health. In this work, we studied a Cr-Ni alloy deposition technique and compared the alloy coating properties to those with conventional Cr coating. Sequential two-step alloy electrodeposition was also compared. We took varying concentrations of Cr, Ni and complexing agents for the electrodeposition of Cr-Ni alloy and sequential Cr-Ni alloy coating on mild steel. Operating parameters, i.e. current density and temperature, were varied to examine their effects on the coating properties. The coatings thus obtained were characterized by visual observation, corrosion test, microhardness measurement, morphology and chemical analysis. The Cr-Ni alloy coating was found to be more corrosion resistant in 5% NaCl solution and harder than the pure Cr coating obtained by conventional electrodeposition. Toxic gas was produced in a much lower extent in the alloy coating than the conventional Cr coating technique. Again, the two-step Cr-Ni alloy coating was found better in terms of corrosion resistance as well as hardness compared to the Cr-Ni alloy coating. The process was also found to be much more environmentally friendly.

Tensile properties of the modified 13Cr martensitic stainless steels

Energy Technology Data Exchange (ETDEWEB)

Mabruri, Efendi, E-mail: effe004@lipi.go.id; Anwar, Moch Syaiful, E-mail: moch.syaiful.anwar@lipi.go.id; Prifiharni, Siska, E-mail: siska.prifiharni@lipi.go.id; Romijarso, Toni B.; Adjiantoro, Bintang [Research Center for Metallurgy and Materials, Indonesian Institute of Sciences (LIPI) Kawasan Puspiptek Gd. 470 Serpong, Tangerang Selatan 15314 (Indonesia)

2016-04-19

This paper reports the influence of Mo and Ni on the tensile properties of the modified 13Cr martensitic stainless steels in tempered condition. Four steels with different content of Mo and Ni were prepared by induction melting followed by hot forging, quenching and tempering. The experimental results showed that the addition of about 1% and 3% Mo has a beneficial effect to increase both the tensile strength and the elongation of the steels. On the contrary, the addition of about 3% Ni into the martensitic stainless steel results in decreasing of both the tensile strength and the elongation. Among the alloys investigated the 13Cr3Mo type steel exhibited largest tensile strength of 1348 MPa and largest elongation of 12%. The observation on the tensile fractured surfaces by using scanning electron microscope supported these findings.

Tensile properties of the modified 13Cr martensitic stainless steels

International Nuclear Information System (INIS)

Mabruri, Efendi; Anwar, Moch Syaiful; Prifiharni, Siska; Romijarso, Toni B.; Adjiantoro, Bintang

2016-01-01

This paper reports the influence of Mo and Ni on the tensile properties of the modified 13Cr martensitic stainless steels in tempered condition. Four steels with different content of Mo and Ni were prepared by induction melting followed by hot forging, quenching and tempering. The experimental results showed that the addition of about 1% and 3% Mo has a beneficial effect to increase both the tensile strength and the elongation of the steels. On the contrary, the addition of about 3% Ni into the martensitic stainless steel results in decreasing of both the tensile strength and the elongation. Among the alloys investigated the 13Cr3Mo type steel exhibited largest tensile strength of 1348 MPa and largest elongation of 12%. The observation on the tensile fractured surfaces by using scanning electron microscope supported these findings.

Effect of iron content on the structure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25} and (AlTi){sub 60-x}Ni{sub 20}Cu{sub 20}Fe{sub x} (x=15, 20) high-entropy alloys

Energy Technology Data Exchange (ETDEWEB)

Fazakas, É., E-mail: eva.fazakas@bayzoltan.hu [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Wigner Research Center for Physics, Hungarian Academy of Sciences, H-1525, P.O.B. 49 (Hungary); Bay Zoltán Nonprofit Ltd., For Applied Research H-1116 Budapest, Fehérvári út 130 (Hungary); Zadorozhnyy, V. [National University of Science and Technology «MISIS», Leninsky prosp., 4, Moscow 119049 (Russian Federation); Louzguine-Luzgin, D.V. [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

2015-12-15

Highlights: • Three new refractory alloys namely: Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20}, were produced by induction-melting and casting. • This kind of alloys exhibits high resistance to annealing softening. • Most the alloys in the annealed state possess even higher Vickers microhardness than the as-cast alloys. • The Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys annealed at 973 K show the highest compressive stress and ductility values. - Abstract: In this work, we investigated the microstructure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}C{sub u25} Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys are relatively hard and ductile. Being heat treated at 973 K the Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

Influence of Copper on the Hot Ductility of 20CrMnTi Steel

Science.gov (United States)

Peng, Hong-bing; Chen, Wei-qing; Chen, Lie; Guo, Dong

2015-02-01

The hot ductility of 20CrMnTi steel with x% copper (x = 0, 0.34) was investigated. Results show that copper can reduce its hot ductility, but there is no significant copper-segregation at the boundary tested by EPMA. The average copper content at grain boundaries and substrate is 0.352% and 0.318% respectively in steel containing 0.34% copper tensile-tested at 950 °C. The fracture morphology was examined with SEM and many small and shallow dimples were found on the fracture of steel with copper, and fine copper sulfide was found from carbon extraction replicas using TEM. Additionally, adding 0.34% copper caused an increase in the dynamic recrystallization temperature from 950 °C to 1000 °C, which indicates that copper can retard the dynamic recrystallization (DRX) of austenite. The detrimental influence of copper on hot ductility of 20CrMnTi steel is due mainly to the fine copper sulfide in the steel and its retarding the DRX.

On the corrosion testing of weldments of high alloyed CrNiMo-stainless steels and NiCrMo-alloys

International Nuclear Information System (INIS)

Riedel, G.; Voigt, C.; Werner, H.

1997-01-01

Weldments of high-alloyed CrNiMo stainless steels and NiCrMo alloys can be more susceptible to localized corrosion than the solution annealed basic material owing to segregations and precipitations in the heat affected zone, the high temperature zone and/or in the weld. To investigate these differences the FeCl 3 -test (10% FeCl 3 . 6aq), the test ''green death'' (11.5% H 2 SO 4 , 1.2% HCl, 1% CuCl 2 , 1% FeCl 3 ) as well as chronopotentiostatic tests in artificial sea water or in 3% NaCl-solution are used. In particular for testing the highest alloyed materials a CaCl 2 -test was developed (4.5 M CaCl 2 , chronopotentiostatic test in duration of 8 to 10 hours at + 200 mV (SCE)), which can be carried out to a temperature of 115 C at atmospheric pressure. The aggressivity increases in the range FeCl 3 -test, ''green death''-test, CaCl 2 -test. Matching and graduated over-alloyed weldments (TIG, heat input of 7 and 15.5 kJ/cm) of materials 1.4529, 1.4562, 2.4856, 2.4819 (german materials No.) are comparingly examined in various tests, of materials 1.4406, 1.4539, 1.4439 and 1.4563 (german materials No.) only matching weldments in the FeCl 3 -test. In strongly oxidizing media only a highly over-alloyed performed weldment (filler material 2.4607, german material No.) produces the best corrosion behaviour, measured as the critical temperatures of localized corrosion. Measurements of critical current densities of passivation can be used for investigations of corrosion behaviour of weldments, too. Critical current densities of passivation are showing a tendency to inverse proportion to the critical temperatures of localized corrosion. Suitable electrolytes are among others 0.2 M H 2 SO 4 + 1 M NaCl + 10 -3 % KSCN, N 2 -bubbled, 25 to 60 C and xM H 2 SO 4 + 4 M NaCl + 10 -3 % KSCN (x = 0.05 to 1), 25 C, in contact with air. An influence of heat input at the welding is indicated in the test of localized corrosion, but it is only small. It is sometimes more clearly shown at

Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

International Nuclear Information System (INIS)

Lopez B, I.; Trapaga M, L. G.; Martinez F, E.; Zoz, H.

2011-01-01

The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

Energy Technology Data Exchange (ETDEWEB)

Lopez B, I.; Trapaga M, L. G. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico); Martinez F, E. [Centro de Investigacion e Innovacion Tecnologica, Cerrada de Cecati s/n, Col. Santa Catarina Azcapotzalco, 02250 Mexico D. F. (Mexico); Zoz, H., E-mail: israelbaez@gmail.co [Zoz GmbH, D-57482, Wenden (Germany)

2011-07-01

The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

The permeation behavior of deuterium through 1Cr18Ni9Ti stainless steel with TiN+TiC-TiN multiple films

International Nuclear Information System (INIS)

Xiong, Y.; Song, J.; Luo, D.; Lei, Q.; Chen, C.

2015-01-01

The prevention of tritium losses via permeation through structure components is an important issue in fusion technology. The production of thin layers on materials with low diffusivity and/or low surface recombination constants (so-called permeation barriers) seems to be the most practical method to reduce or hinder the permeation of tritium through materials. TiN+TiC+TiN multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel by ion-beam assisted deposition technology. The characteristics of films are tested by XPS ASEM and XRD, which shows that the film are compact and uniform with a thickness of about 15 μm, and have a good adherence with the substrate below 773 K. The diffraction peaks in the XRD patterns for TiC and TiN are broadened, implying that the multiple films are deposited on the surface of 1Cr18Ni9Ti stainless steel. Meanwhile, the C-H bonded CH 4 -appears in the infrared spectra of multiple films, suggesting that the CH 4 - is in a static state, so hydrogen atom cannot migrate from the site bonded with carbon to a neighboring site. The measured deuterium permeability in 1Cr18Ni9Ti stainless steel coated with multiple films is 2-3 orders of magnitude lower than that of pure 1Cr18Ni9Ti stainless steel substrate from 473 K to 773 K. However, this barrier is partly destroyed above 773 K

The effect of cobalt and molybdenum on the creep strength of low C-18Cr-10Ni steel

International Nuclear Information System (INIS)

Tomono, Yutaka; Ueda, Jitsuhiko

1982-01-01

The improvement of creep strength through the addition of cobalt and molybdenum to low C-18Cr-10Ni steel was studied at a temperature range of between 700 and 800 0 C. Changes in mechanical and physical properties such as lattice parameter and stacking fault energy, related to the additional elements were investigated to estimate the strengthening effect. Dislocation structures corresponding to the various creep stages were observed through a transmission electron microscope to distinguish the solution hardening effect of the added elements from the precipitation hardening effects of carbide. The results obtained are summarized as follows: (1) Addition of cobalt of up to 20% by weight improved the creep strength of austenitic steel. Addition of molybdenum of up to 5% by weight remarkably improved the creep strength of austenitic steel having a cobalt content of 20% by weight. (2) The trend for creep strength to improve with the addition of these elements was closely coincident with increases in lattice parameter and did not necessarily coincide with changes in the stacking fault energy. (author)

HIGH TEMPERATURE TENSILE PROPERTIES OF NEW FE-CR-MN DEVELOPED STEEL

OpenAIRE

M. Mahmoudiniya; Sh. Kheirandish; M. Asadi Asadabad

2017-01-01

Nowadays, Ni-free austenitic stainless steels are being developed rapidly and high price of nickel is one of the most important motivations for this development. At present research a new FeCrMn steel was designed and produced based on Fe-Cr-Mn-C system. Comparative studies on microstructure and high temperature mechanical properties of  new steel and AISI 316 steel were done. The results showed that new FeCrMn developed steel has single austenite phase microstructure, and its tensile st...

Creep and time to rupture of a 16/16 Cr Ni Steel

International Nuclear Information System (INIS)

Solano, R.; Garcia, R.; Bohm, H.; Schirra, M.

1972-01-01

The influence of different thermal-mechanical treatments on the creep and time to rupture of a 16/16 Cr.Ni steel is studied. The solution treated material after annealing at 700-800 degree centigree did not affect time to rupture. At the contrary a 12% cold-working and annealing at 800 degree centigree improve the time to rupture. This treatment is preserved up to 700 degree centigree 10 4 hours. The ductility is not strongly affected. A metallographic study of the fracture was carried out. (Author) 23 refs

Trace element control in binary Ni-25Cr and ternary Ni-30Co-30Cr master alloy castings

Energy Technology Data Exchange (ETDEWEB)

Detrois, Martin [National Energy Technology Lab. (NETL), Albany, OR (United States); Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); Jablonski, Paul D. [National Energy Technology Lab. (NETL), Albany, OR (United States);

2017-10-23

Electro-slag remelting (ESR) is used for control of unwanted elements in commercial alloys. This study focuses on master alloys of Ni-25Cr and Ni-30Co-30Cr, processed through a combination of vacuum induction melting (VIM) and electro-slag remelting (ESR). Minor additions were made to control tramp element levels and modify the melting characteristics. Nitrogen and sulfur levels below 10 ppm and oxygen levels below 100 ppm were obtained in the final products. The role of the alloy additions in lowering the tramp element content, the resulting residual inclusions and the melting characteristics were determined computationally and confirmed experimentally. Additions of titanium were beneficial to the control of oxygen levels during VIM and nitrogen levels during ESR. Aluminum additions helped to control oxygen levels during remelting, however, aluminum pickup occurred when excess titanium was present during ESR. The usefulness of these master alloys for use as experimental remelt stock will also be discussed.

Effect of titanium on the creep deformation behaviour of 14Cr-15Ni-Ti stainless steel

Science.gov (United States)

Latha, S.; Mathew, M. D.; Parameswaran, P.; Nandagopal, M.; Mannan, S. L.

2011-02-01

14Cr-15Ni-Ti modified stainless steel alloyed with additions of phosphorus and silicon is a potential candidate material for the future cores of Prototype Fast Breeder Reactor. In order to optimise the titanium content in this steel, creep tests have been conducted on the heats with different titanium contents of 0.18, 0.23, 0.25 and 0.36 wt.% at 973 K at various stress levels. The stress exponents indicated that the rate controlling deformation mechanism was dislocation creep. A peak in the variation of rupture life with titanium content was observed around 0.23 wt.% titanium and the peak was more pronounced at lower stresses. The variation in creep strength with titanium content was correlated with transmission electron microscopic investigations. The peak in creep strength exhibited by the material with 0.23 wt.% titanium is attributed to the higher volume fraction of fine secondary titanium carbide (TiC) precipitates.

Effect of titanium on the creep deformation behaviour of 14Cr-15Ni-Ti stainless steel

Energy Technology Data Exchange (ETDEWEB)

Latha, S. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102 (India); Mathew, M.D., E-mail: mathew@igcar.gov.in [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102 (India); Parameswaran, P.; Nandagopal, M. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102 (India); Mannan, S.L. [National Engineering College, Kovilpatti, Tamil Nadu 628 503 (India)

2011-02-28

14Cr-15Ni-Ti modified stainless steel alloyed with additions of phosphorus and silicon is a potential candidate material for the future cores of Prototype Fast Breeder Reactor. In order to optimise the titanium content in this steel, creep tests have been conducted on the heats with different titanium contents of 0.18, 0.23, 0.25 and 0.36 wt.% at 973 K at various stress levels. The stress exponents indicated that the rate controlling deformation mechanism was dislocation creep. A peak in the variation of rupture life with titanium content was observed around 0.23 wt.% titanium and the peak was more pronounced at lower stresses. The variation in creep strength with titanium content was correlated with transmission electron microscopic investigations. The peak in creep strength exhibited by the material with 0.23 wt.% titanium is attributed to the higher volume fraction of fine secondary titanium carbide (TiC) precipitates.

Effect of titanium on the creep deformation behaviour of 14Cr-15Ni-Ti stainless steel

International Nuclear Information System (INIS)

Latha, S.; Mathew, M.D.; Parameswaran, P.; Nandagopal, M.; Mannan, S.L.

2011-01-01

14Cr-15Ni-Ti modified stainless steel alloyed with additions of phosphorus and silicon is a potential candidate material for the future cores of Prototype Fast Breeder Reactor. In order to optimise the titanium content in this steel, creep tests have been conducted on the heats with different titanium contents of 0.18, 0.23, 0.25 and 0.36 wt.% at 973 K at various stress levels. The stress exponents indicated that the rate controlling deformation mechanism was dislocation creep. A peak in the variation of rupture life with titanium content was observed around 0.23 wt.% titanium and the peak was more pronounced at lower stresses. The variation in creep strength with titanium content was correlated with transmission electron microscopic investigations. The peak in creep strength exhibited by the material with 0.23 wt.% titanium is attributed to the higher volume fraction of fine secondary titanium carbide (TiC) precipitates.

Electrochemical Behavior and Hydrophobic Properties of CrN and CrNiN Coatings in Simulated Proton Exchange Membrane Fuel Cell Environment

Directory of Open Access Journals (Sweden)

JIN Jie

2016-10-01

Full Text Available The CrN and CrNiN coatings were prepared on the surface of 304 stainless steel by closed field unbalanced magnetron sputtering.X ray diffraction and field emission scanning electron microscopy were used to characterize the structure and morphology of the coatings.The electrochemical corrosion properties under the simulated proton exchange membrane fuel cell(PEMFC environment, interfacial contact resistance and hydrophobic properties of the two kinds of different coatings were investigated by electrochemical methods,contact resistance test and hydrophobic test,respectively.The results indicate that CrN coating mainly consists of CrN and Cr2N phase,CrN and Cr2N phases in the CrNiN coating are less compared to CrN film, and Ni exist as element in CrNiN coating; dynamic polarization tests show the coating is of better corrosion resistance,whereas the corrosion resistance of CrNiN coating is worse than that of CrN coating,constant potential polarization test shows the corrosion current density of CrN and CrNiN coatings are equivalent; CrN and CrNiN coatings significantly reduce the interfacial contact resistance of the 304 stainless steel,among which CrN coating has the smallest contact resistance; and CrNiN coating which has better hydrophobicity than that of CrN coating is more beneficial for the water management in proton exchange membrane fuel cell.

TEM Studies of Boron-Modified 17Cr-7Ni Precipitation-Hardenable Stainless Steel via Rapid Solidification Route

Science.gov (United States)

Gupta, Ankur; Bhargava, A. K.; Tewari, R.; Tiwari, A. N.

2013-09-01

Commercial grade 17Cr-7Ni precipitation-hardenable stainless steel has been modified by adding boron in the range 0.45 to 1.8 wt pct and using the chill block melt-spinning technique of rapid solidification (RS). Application of RS has been found to increase the solid solubility of boron and hardness of 17Cr-7Ni precipitation-hardenable stainless steel. The hardness of the boron-modified rapidly solidified alloys has been found to increase up to ~280 pct after isochronal aging to peak hardness. A TEM study has been carried out to understand the aging behavior. The presence of M23(B,C)6 and M2(B,C) borocarbides and epsilon-carbide in the matrix of austenite and ferrite with a change in heat treatment temperature has been observed. A new equation for Creq is also developed which includes the boron factor on ferrite phase stability. The study also emphasizes that aluminum only takes part in ferrite phase stabilization and remains in the solution.

Precipitation sensitivity to alloy composition in Fe-Cr-Mn austenitic steels developed for reduced activation for fusion application

International Nuclear Information System (INIS)

Maziasz, P.J.; Klueh, R.L.

1988-01-01

Special austenitic steels are being designed in which alloying elements like Mo, Nb, and Ni are replaced with Mn, W, V, Ti, and/or Ta to reduce the long-term radioactivity induced by fusion reactor irradiation. However, the new steels still need to have properties otherwise similar to commercial steels like type 316. Precipitation strongly affects strength and radiation-resistance in austenitic steels during irradiation at 400--600/degree/C, and precipitation is also usually quite sensitive to alloy composition. The initial stage of development was to define a base Fe-Cr-Mn-C composition that formed stable austenite after annealing and cold-working, and resisted recovery or excessive formation of coarse carbide and intermetallic phases during elevated temperature annealing. These studies produced a Fe-12Cr-20Mn-0.25C base alloy. The next stage was to add the minor alloying elements W, Ti, V, P, and B for more strength and radiation-resistance. One of the goals was to produce fine MC precipitation behavior similar to the Ti-modified Fe-Cr-Ni prime candidate alloy (PCA). Additions of Ti+V+P+B produced fine MC precipitation along network dislocations and recovery/recrystallization resistance in 20% cold worked material aged at 800/degree/C for 166h, whereas W, Ti, W+Ti, or Ti+P+B additions did not. Addition of W+Ti+V+P+B also produced fine MC, but caused some σ phase formation and more recrystallization as well. 29 refs., 14 figs., 9 tabs

Effect of heat treatment on pitting corrosion of austenitic Cr-Ni-Mo steels in sodium chloride solution

International Nuclear Information System (INIS)

Stefec, R.; Franz, F.; Holecek, A.

1979-01-01

The pitting corrosion resistance of Cr17Ni12Mo2,5 type steel under potentiostatic polarization in a sodium chloride solution is adversely affected by previous annealing. The data obtained were systematically dependent on annealing temperature, time and surface roughness. The corrosion current, the number of pits or the mean area of pit opening and the corrosion rate within the pits were increased by previous annealing at 550 to 750 0 C for 1-100 hrs. The highest corrosion rate estimated corresponded to heat treatments provoking severe sensitization to intergranular corrosion. The paercentage area of corrosion pit openings and the estimated pit penetration rates were several times higher for as-machined than for polished surfaces. It can be assumed that pitting corrosion is little affected by the carbon content and that molybdenum depletion of grain-boundary zones is responsible for the reduced pitting resistance of annealed steels. (orig./HP) [de

Hot Deformation Behavior of 1Cr12Ni3Mo2VN Martensitic Stainless Steel

Science.gov (United States)

He, Xiaomao; Jiang, Peng; Zhou, Leyu; Chen, Chao; Deng, Xiaochun

2017-08-01

1Cr12Ni3Mo2VN is a new type of martensitic stainless steel for the last-stage blades of large-capacity nuclear and thermal power turbines. The deformation behavior of this steel was studied by thermal compression experiments that performed on a Gleeble-3500 thermal simulator at a temperature range of 850°C to 1200°C and a strain rate of 0.01s-1 to 20s-1. When the deformation was performed at high temperature and low strain rate, a necklace type of microstructures was observed, the plastic deformation mechanism is grain boundary slip and migration, when at low temperature and lower strain rate, the slip bands were observed, the mechanism is intracrystalline slips, and when at strain rate of 20s-1, twins were observed, the mechanism are slips and twins. The Arrhenius equation was applied to describe the constitutive equation of the flow stress. The accuracy of the equation was verified by using the experimental data and the correlation coefficient R2 = 0.9786, and the equation can provide reasonable data for the design and numerical simulation of the forging process.

Dissolution and oxidation behaviour of various austenitic steels and Ni rich alloys in lead-bismuth eutectic at 520 °C

Energy Technology Data Exchange (ETDEWEB)

Roy, Marion, E-mail: marion.roy@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Martinelli, Laure, E-mail: laure.martinelli@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Ginestar, Kevin, E-mail: kevin.ginestar@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, F-91191 Gif-sur-Yvette (France); Favergeon, Jérôme, E-mail: jerome.favergeon@utc.fr [Laboratoire Roberval, UMR 7337, Université de Technologie de Compiègne, Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex (France); Moulin, Gérard [Laboratoire Roberval, UMR 7337, Université de Technologie de Compiègne, Centre de Recherche de Royallieu, CS 60319, 60203 Compiègne Cedex (France)

2016-01-15

Ten austenitic steels and Ni rich alloys were tested in static lead-bismuth eutectic (LBE) at 520 °C in order to obtain a selection of austenitic steels having promising corrosion behaviour in LBE. A test of 1850 h was carried out with a dissolved oxygen concentration between 10{sup −9} and 5 10{sup −4} g kg{sup −1}. The combination of thermodynamic of the studied system and literature results leads to the determination of an expression of the dissolved oxygen content in LBE as a function of temperature: RT(K)ln[O](wt%) = −57584/T(K) −55.876T(K) + 254546 (R is the gas constant in J mol{sup −1} K{sup −1}). This relation can be considered as a threshold of oxygen content above which only oxidation is observed on the AISI 316L and AISI 304L austenitic alloys in static LBE between 400 °C and 600 °C. The oxygen content during the test leads to both dissolution and oxidation of the samples during the first 190 h and leads to pure oxidation for the rest of the test. Results of mixed oxidation and dissolution test showed that only four types of corrosion behaviour were observed: usual austenitic steels and Ni rich alloys behaviour including the reference alloy 17Cr-12Ni-2.5Mo (AISI 316LN), the 20Cr-31Ni alloy one, the Si containing alloy one and the Al containing alloy one. According to the proposed criteria of oxidation and dissolution kinetics, silicon rich alloys and aluminum rich alloy presented a promising corrosion behaviour. - Highlights: • 10 austenitic steels and Ni rich alloys were tested in LBE at 520 °C with dissolved oxygen content between 10{sup -9} and 5 10{sup -4} wt%. • It is shown that only thermodynamics cannot explain the Ni rich alloys corrosion behaviour in LBE. • The role of oxygen on corrosion behaviour in LBE was highlighted. • An equilibrium line was defined above which only oxidation has occurred on 316L: RTln[O](wt%) = -57584/T(K)-55.876T(K)+254546. • 18Cr-15Ni-3.7Si, 21Cr-11Ni-1.6Si and 14Cr-25Ni-3.5Al

Reformed austenite transformation during fatigue crack propagation of 13%Cr-4%Ni stainless steel

Energy Technology Data Exchange (ETDEWEB)

Thibault, Denis, E-mail: thibault.denis@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Bocher, Philippe, E-mail: philippe.bocher@etsmtl.ca [Ecole de technologie superieure, 1100, rue Notre-Dame Ouest, Montreal, Quebec, H3C 1K3 (Canada); Thomas, Marc, E-mail: marc.thomas@etsmtl.ca [Ecole de technologie superieure, 1100, rue Notre-Dame Ouest, Montreal, Quebec, H3C 1K3 (Canada); Lanteigne, Jacques, E-mail: lanteigne.jacques@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Hovington, Pierre, E-mail: hovington.pierre@ireq.ca [Institut de recherche d' Hydro-Quebec (IREQ), 1800, boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1 (Canada); Robichaud, Patrice, E-mail: patrice.robichaud@riotinto.com [Centre de recherche et de developpement Arvida (CRDA), 1955, boul. Mellon, Jonquiere, Quebec, G7S 4K8 (Canada)

2011-08-15

Highlights: {yields} Reformed austenite in 13%Cr-4%Ni stainless steel transforms during fatigue crack growth. {yields} Low cycle fatigue tests showed that this transformation to martensite is gradual. {yields} XRD spectrums obtained on the fracture surface and have been correlated to LCF results. - Abstract: In the as-quenched state, 13%Cr-4%Ni martensitic stainless steels are essentially 100% martensitic. However, a certain amount of austenite is formed during the tempering of this alloy. This reformed austenite is thermally stable at room temperature but can transform to martensite under stress. This transformation is known to happen during impact testing but it has never been established if it occurs during fatigue crack propagation. This study presents the results of X-ray diffraction measurements of reformed austenite before and after crack growth testing. It has been found that reformed austenite does transform to martensite at the crack tip and that this transformation occurs even at a low stress intensity factor. Low-cycle fatigue tests were conducted to verify austenite transformation under cyclic straining. It was found that reformed austenite transforms only partially during the first strain reversal but that essentially all austenite has disappeared after 100 cycles. The relation between austenite transformation under low-cycle fatigue and its transformation during crack growth is also discussed.

Reformed austenite transformation during fatigue crack propagation of 13%Cr-4%Ni stainless steel

International Nuclear Information System (INIS)

Thibault, Denis; Bocher, Philippe; Thomas, Marc; Lanteigne, Jacques; Hovington, Pierre; Robichaud, Patrice

2011-01-01

Highlights: → Reformed austenite in 13%Cr-4%Ni stainless steel transforms during fatigue crack growth. → Low cycle fatigue tests showed that this transformation to martensite is gradual. → XRD spectrums obtained on the fracture surface and have been correlated to LCF results. - Abstract: In the as-quenched state, 13%Cr-4%Ni martensitic stainless steels are essentially 100% martensitic. However, a certain amount of austenite is formed during the tempering of this alloy. This reformed austenite is thermally stable at room temperature but can transform to martensite under stress. This transformation is known to happen during impact testing but it has never been established if it occurs during fatigue crack propagation. This study presents the results of X-ray diffraction measurements of reformed austenite before and after crack growth testing. It has been found that reformed austenite does transform to martensite at the crack tip and that this transformation occurs even at a low stress intensity factor. Low-cycle fatigue tests were conducted to verify austenite transformation under cyclic straining. It was found that reformed austenite transforms only partially during the first strain reversal but that essentially all austenite has disappeared after 100 cycles. The relation between austenite transformation under low-cycle fatigue and its transformation during crack growth is also discussed.

Numerical simulation on temperature field of TIG welding for 0Cr18Ni10Ti steel cladding and experimental verification

International Nuclear Information System (INIS)

Luo Hongyi; Tang Xian; Luo Zhifu

2015-01-01

Aiming at tungsten inert gas (TIG) for 0Cr18Ni10Ti stainless steel cladding for radioactive source, the numerical calculation of welding pool temperature field was carried out through adopting ANSYS software. The numerical model of non-steady TIG welding pool shape was established, the heat enthalpy and Gaussian electric arc heat source model of surface distribution were introduced, and the effects of welding current and welding speed to temperature field distribution were calculated. Comparing the experimental data and the calculation results under different welding currents and speeds, the reliability and correctness of the model were proved. The welding technological parameters of 0Cr18Ni10Ti stainless steel were optimized based on the calculation results and the welding procedure was established. (authors)

Quasicrystalline and crystalline precipitation during isothermal tempering in a 12Cr-9Ni-4Mo maraging stainless steel

International Nuclear Information System (INIS)

Liu, P.; Stigenberg, A.H.; Nilsson, J.O.

1995-01-01

A thorough microstructural investigation has been performed on a high strength maraging steel of the type 12%Cr-9%Ni-4%Mo-2%Cu-1%Ti. The major precipitate formed during isothermal aging at 475 C is a quasicrystalline phase possessing icosahedral symmetry termed R'-phase with a typical chemical composition of 48%Mo-33%Fe-13%Cr-2%Ni-4%Si. At 550 C the major precipitate is trigonal R-phase with a typical composition of 45%Mo-31%Fe-18%Cr-4%Ni-2%Si. At 550 C also Laves phase with a composition of 48%Mo-35%Fe-13%Cr-2%Ni-2%Si could be observed. At both 475 and 550 C an ordered phase termed L-phase precipitated. This minority phase has an ordered face centered cubic (f.c.c.) structure of type L1 0 . Its composition is typically 9%Fe-4%Cr-52%Ni-15%Mo.-16%Ti-4%Al. R'-phase formed at 475 C transformed to R-phase and Laves phase during aging at 550 C. In an analogous manner, R-phase and Laves phase formed at 550 C transformed to R'-phase during subsequent aging at 475 C. This transformation was rationalized by a strong similarity in crystal structure between quasicrystalline R'-phase of icosahedral symmetry and Frank-Kasper phases such as R-phase and Laves phase

Mitigating Localized Corrosion Using Thermally Sprayed Aluminum (TSA) Coatings on Welded 25% Cr Superduplex Stainless Steel

Science.gov (United States)

Paul, S.; Lu, Q.; Harvey, M. D. F.

2015-04-01

Thermally sprayed aluminum (TSA) coating has been increasingly used for the protection of carbon steel offshore structures, topside equipment, and flowlines/pipelines exposed to both marine atmospheres and seawater immersion conditions. In this paper, the effectiveness of TSA coatings in preventing localized corrosion, such as pitting and crevice corrosion of 25% Cr superduplex stainless steel (SDSS) in subsea applications, has been investigated. Welded 25% Cr SDSS (coated and uncoated) with and without defects, and surfaces coated with epoxy paint were also examined. Pitting and crevice corrosion tests, on welded 25% Cr SDSS specimens with and without TSA/epoxy coatings, were conducted in recirculated, aerated, and synthetic seawater at 90 °C for 90 days. The tests were carried out at both the free corrosion potentials and an applied cathodic potential of -1100 mV saturated calomel electrode. The acidity (pH) of the test solution was monitored daily and adjusted to between pH 7.5 and 8.1, using dilute HCl solution or dilute NaOH, depending on the pH of the solution measured during the test. The test results demonstrated that TSA prevented pitting and crevice corrosion of 25% Cr SDSS in artificial seawater at 90 °C, even when 10-mm-diameter coating defect exposing the underlying steel was present.

Comparative studies on ultrasonic, friction, laser and resistance pressure welding of NiTi shape memory alloys with high-alloy steels. Final report; Vergleichende Untersuchungen zum Ultraschall-, Reib-, Laserstrahl- und Widerstandspressschweissen von NiTi-Shape-Memory-Metall mit hochlegierten Staehlen. Abschlussbericht

Energy Technology Data Exchange (ETDEWEB)

Zuckschwerdt, K.

2000-04-01

The suitability of different welding techniques for welding of NiTi shape memory alloys with high-alloy steel (C12CrNi17-7, X5CrNiNb19-9, X20Cr13) was investigated. The quality of the welds was analyzed using mechanical-technological, fractographic, metallographic and electron microscopy analysis. [German] Ziel dieses Forschungsvorhabens ist es, die Eignung der einzelnen Schweissverfahren fuer das Fuegen von NiTi-Formgedaechtnislegierungen mit hochlegiertem Stahl (X12CrNi17-7, X5CrNiNb19-9, X20Cr13) darzustellen und zu beurteilen. Die Qualitaet der Fuegeverbindungen wird mit Hilfe mechanisch-technologischer, fraktographischer, metallographischer und elektronenmikroskopischer Untersuchungen bewertet.

Reversed austenite in 0Cr13Ni4Mo martensitic stainless steels

Energy Technology Data Exchange (ETDEWEB)

Song, Y.Y., E-mail: songyuanyuan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Li, X.Y.; Rong, L.J.; Li, Y.Y. [Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Nagai, T. [National Institute for Materials Science, Sengen 1-2-1, Tsukuba 305-0047 (Japan)

2014-01-15

The austenite reversion process and the distribution of carbon and other alloying elements during tempering in 0Cr13Ni4Mo martensitic stainless steel have been investigated by in-situ high temperature X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The microstructure of the reversed austenite was characterized using transmission electron microscopy (TEM). The results revealed that the amount of the reversed austenite formed at high temperature increased with the holding time. Direct experimental evidence supported carbon partitioning to carbides and Ni to the reversed austenite. The reversed austenite almost always nucleated in contact with lath boundary M{sub 23}C{sub 6} carbides during tempering and the diffusion of Ni promoted its growth. The Ni enrichment and the ultrafine size of the reversed austenite were considered to be the main factors that accounted for the stability of the reversed austenite. - Highlights: • The amount of the reversed austenite formed at high temperature increases with the holding time. • STEM results directly show that carbon is mainly partitioned into the carbides and Ni into the reversed austenite. • The Ni enrichment and the ultrafine size are the main factors leading to the stabilization of the reversed austenite.

Effect of shot peening on the residual stress and mechanical behaviour of low-temperature and high-temperature annealed martensitic gear steel 18CrNiMo7-6

DEFF Research Database (Denmark)

Yang, R.; Zhang, X.; Mallipeddi, D.

2017-01-01

A martensitic gear steel (18CrNiMo7-6) was annealed at 180 degrees C for 2h and at similar to 750 degrees C for 1h to design two different starting microstructures for shot peening. One maintains the original as-transformed martensite while the other contains irregular-shaped sorbite together...... with ferrite. These two materials were shot peened using two different peening conditions. The softer sorbite + ferrite microstructure was shot peened using 0.6 mm conditioned cut steel shots at an average speed of 25 m/s in a conventional shot peening machine, while the harder tempered martensite steel...

Solidification Segregation and Homogenization Behavior of 1Cr-1.25Mo-0.25V Steel Ingot

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Bae [Dae-gu Mechatronics and Materials Institute, Daegu (Korea, Republic of); Na, Young-Sang; Seo, Seong-Moon [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lee, Je-Hyun [Changwon National University, Changwon (Korea, Republic of)

2016-09-15

As a first step to optimizing the homogenization heat treatment following high temperature upset forging, the solidification segregation and the homogenization behaviors of solute elements were quantitatively analyzed for 1Cr-1.25Mo-0.25V steel ingot by electron probe micro-analysis (EPMA). The random sampling approach, which was designed to generate continuous compositional profiles of each solute element, was employed to clarify the segregation and homogenization behaviors. In addition, ingot castings of lab-scale and a 16-ton-sized 1Cr-1.25Mo-0.25V steel were simulated using the finite element method in three dimensions to understand the size effect of the ingot on the microsegregation and its reduction during the homogenization heat treatment. It was found that the microsegregation in a large-sized ingot was significantly reduced by the promotion of solid state diffusion due to the extremely low cooling rate. On the other hand, from the homogenization point of view, increasing the ingot size causes a dramatic increase in the dendrite arm spacing, and hence the homogenization of microsegregation in a large-sized ingot appears to be practically difficult.

Cyclic oxidation behavior of plasma sprayed NiCrAlY/WC-Co/cenosphere coating

Science.gov (United States)

Mathapati, Mahantayya; Ramesh M., R.; Doddamani, Mrityunjay

2018-04-01

Components working at elevated temperature like boiler tubes of coal and gas fired power generation plants, blades of gas and steam turbines etc. experience degradation owing to oxidation. Oxidation resistance of such components can be increased by developing protective coatings. In the present investigation NiCrAlY-WC-Co/Cenosphere coating is deposited on MDN 321 steel substrate using plasma spray coating. Thermo cyclic oxidation behavior of coating and substrate is studied in static air at 600 °C for 20 cycles. The thermo gravimetric technique is used to approximate the kinetics of oxidation. X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray mapping techniques are used to characterize the oxidized samples. NiCrAlY-WC-Co/Cenosphere coating exhibited lower oxidation rate in comparison to MDN 321 steel substrate. The lower oxidation rate of coating is attributed to formation of Al2O3, Cr2O3, NiO and CoWO4 oxides on the outermost surface.

Soft-martensitic stainless Cr-Ni-Mo steel for turbine rotors in geothermic power stations

International Nuclear Information System (INIS)

Schonfeld, K.; Potthast, E.

1986-01-01

Steel Grade X5 Cr-Ni-Mo 12 6 containing 0.05% carbon, 12% chromium, 6% nickel, and 1.50% molybdenum is an advantageous material for turbine rotors in geothermic power stations because of its excellent strength and toughness properties in combination with good erosion and corrosion resistance. In terms of the phase diagram, this soft-martensitic steel has its place at the martensite/austenite/ferrite interface. Therefore, its chemical composition must be chosen so as to have a completely martensitic structure after hardening. The manufacture of and the mechanical properties of a turbine rotor 1200 mm in diameter by 5600 mm in length with a finished weight of approximately 21.5 tons are described in detail

Determination of susceptibility to intergranular corrosion of stainless steels type X5CrNi18-10 in field

Directory of Open Access Journals (Sweden)

Bore V. Jegdic

2016-12-01

Full Text Available In this paper, the DL EPR method (electrochemical potentiokinetic reactivation with double loop was modified and used to study the susceptibility to intergranular corrosion and stress corrosion cracking of a stainless steel type X5CrNi18-10. The tests were performed in a special electrochemical cell, with the electrolyte in the gel form. Modified DL EPR method is characterized by simple and high accuracy measurements as well as repeatability of the test results. The indicator of susceptibility to intergranular corrosion (Qr/QpGBA obtained by modified DL EPR method is in a very good agreement with the same indicator obtained by standard DL EPR method. The modified DL EPR method is quantitative and highly selective method. Small differences in the susceptibility of the stainless steel type CrNi18-10 to intergranular corrosion and stress corrosion cracking can be determined. Test results can be obtained in a short time. The cost of tests performed by modified DL EPR method is much lower than the cost of tests by conventional chemical methods. Modified DL EPR method can be applied in the field on the stainless steels constructions.

Impact behavior of 9-Cr and 12-Cr ferritic steels after low-temperature irradiation

International Nuclear Information System (INIS)

Klueh, R.L.; Vitek, J.M.; Corwin, W.R.; Alexander, D.J.

1987-01-01

Miniature Charpy impact specimens of 9Cr-1MoVNb and 12Cr-1MoVW steels and these steels with 1 and 2% Ni were irradiated in the High-Flux Isotope Reactor (HFIR) at 50 0 C to displacement damage levels of up to 9 dpa. Nickel was added to study the effect of transmutation helium. Irradiation caused an increase in the ductile-brittle transition temperature (DBTT). The 9Cr-1MoVNb steels, with and without nickel, showed a larger shift than the 12Cr-1MoVW steels, with and without nickel. The results indicated that helium also increased the DBTT. The same steels were previously irradiated at higher temperatures. From the present and past tests, the effect of irradiation temperature on the DBTT behavior can be evaluated. For the 9Cr-1MoVNb steel, there is a continuous decrease in the magnitude of the DBTT increase up to an irradiation temperature of about 400 0 C, after which the shift drops rapidly to zero at about 450 0 C. The DBTT of the 12Cr-1MoVW steel shows a maximum increase at an irradiation temperature of about 400 0 C and less of an increase at either higher or lower irradiation temperatures

Comparison of the corrosion resistance of DIN W. Nr. 1.4970 (15%Cr-15%Ni-1.2%Mo-Ti and ASTM F-138 (17%Cr-13%Ni-2.5%Mo austenitic stainless steels for biomedical applications

Directory of Open Access Journals (Sweden)

Maysa Terada

2006-09-01

Full Text Available The resistance to localised corrosion of the full austenitic 15%Cr-15%Ni-1.2%Mo titanium stabilized stainless steel (DIN W. Nr. 1.4970 was investigated by electrochemical methods including electrochemical impedance spectroscopy (EIS, potentiodynamic polarization and potentiostatic polarization measurements in a phosphate-buffered solution (PBS. The low carbon and non-stabilized austenitic stainless steel, AISI 316L (ASTM F-138, widely used for surgical implants, was also tested for comparison. The tests were conducted at room temperature after a stable potential had been reached. After the electrochemical measurements, the surfaces of the specimens were observed using SEM to evaluate the presence of pits. Potentiodynamic polarization results showed that both steels are prone to localized corrosion. Larger pits were found on the surface of AISI 316L specimens after the electrochemical tests. EIS response has indicated the duplex structure of the passive oxides. The results showed that the electrochemical behaviour of the DIN W. Nr. 1.4970 is better than of AISI 316L steel. Therefore, their application as an implant material may be considered.

The influence of heat treatment and process parameters optimization on hardness and corrosion properties of laser alloyed X12CrNiMo steel

CSIR Research Space (South Africa)

Popoola, API

2016-10-01

Full Text Available Martensitic stainless steels are used in the production of steam turbine blades but their application is limited due to low hardness and poor corrosion resistance. Laser surface alloying and heat treatment of X12CrNiMo Martensitic stainless steel...

Creep Strength of Dissimilar Welded Joints Using High B-9Cr Steel for Advanced USC Boiler

Science.gov (United States)

Tabuchi, Masaaki; Hongo, Hiromichi; Abe, Fujio

2014-10-01

The commercialization of a 973 K (700 °C) class pulverized coal power system, advanced ultra-supercritical (A-USC) pressure power generation, is the target of an ongoing research project initiated in Japan in 2008. In the A-USC boiler, Ni or Ni-Fe base alloys are used for high-temperature parts at 923 K to 973 K (650 °C to 700 °C), and advanced high-Cr ferritic steels are planned to be used at temperatures lower than 923 K (650 °C). In the dissimilar welds between Ni base alloys and high-Cr ferritic steels, Type IV failure in the heat-affected zone (HAZ) is a concern. Thus, the high B-9Cr steel developed at the National Institute for Materials Science, which has improved creep strength in weldments, is a candidate material for the Japanese A-USC boiler. In the present study, creep tests were conducted on the dissimilar welded joints between Ni base alloys and high B-9Cr steels. Microstructures and creep damage in the dissimilar welded joints were investigated. In the HAZ of the high B-9Cr steels, fine-grained microstructures were not formed and the grain size of the base metal was retained. Consequently, the creep rupture life of the dissimilar welded joints using high B-9Cr steel was 5 to 10 times longer than that of the conventional 9Cr steel welded joints at 923 K (650 °C).

Fatigue damage evolution of cold-worked austenitic nickel-free high-nitrogen steel X13CrMnMoN18-14-3 (1.4452)

Energy Technology Data Exchange (ETDEWEB)

Tikhovskiy, I.; Weiss, S.; Fischer, A. [Univ. of Duisburg-Essen, Materials Science and Engineering II, Duisburg (Germany)

2004-07-01

Due to the fact that the risk of Ni-allergies becomes more and more important for modern therapies, the necessity of Ni-free implant materials becomes increasingly important. Beside Co- and Ti-base alloys Ni-free high-nitrogen steels may offer an attractive alternative. The present work presents the austenitic high-nitrogen and nickel-free steel X13CrMnMoN18-14-3, (Material No.: 1.4452) after 20% cold-working. In addition this material was deformed under axial cyclic total strain controlled fatigue tests at room temperature. The development of dislocation structure due to different loading amplitudes was compared to none cyclically deformed material. The good mechanical und fatigue properties of these austenitic high-nitrogen steels as well as the better tribological, chemical and biological properties compared to CrNiMo-steels qualify these steels as a promising alternative in medical applications. (orig.)

Formed electroslag welded joint from austenitic steel 18/10 CrNi

International Nuclear Information System (INIS)

Jilek, L.; Kusak, L.; Martinak, A.

1987-01-01

The electroslag welded joint from titanium stabilized steel 18/10 CrNi of 150 mm in thickness showed positive results for both nondestructive and destructive testing. Czechoslovak flux VUZ-4F and the optimized welding mode were completely proven. The weldment was subject to deformation by forging with a removal of 20 to 50% and to bending deformation. A 40% to 50% deformation was necessary for breaking the coarse-grain casting structure. The bending deformation resulted in breaking the coarse-grain casting structure in the entire cross-section, it was, however, only acting in a narrow band corresponding to the largest curvature. At the same time, the heat affected zone decayed. Following heat treatment, especially forming, the delta ferrite content in the weld metal decreased, the mechanical properties of the weld metal and the welded joint following welding and heat treatment showed a relatively large scatter. Forming reduced the scatter and improved plastic properties. Machining within 40 and 50% resulted in good echogenicity of the welded joint in ultrasound testing. The welded joint showed equal properties as the base material of the weldment. (author). 15 figs., 2 tabs., 16 refs

Comparative study of creep behaviour in three Cr Ni 15/15 steel stabilized with Ti and with different contents in W, Mn, Mo and Bor

International Nuclear Information System (INIS)

Solano, R.R.; Rivas, M. de las; Schirra, M.; Seith, B.

1975-01-01

The main difference between the three steels which are tested at temperature range from 650 0 C to 750 0 C is due to the hardening elements pf the matrix and the Boron content: 1. 12R72HV (X10NiCrMoTiB 1515) 2% Mn 1,5% Mo 80 ppmB 2. Vaccutherm (X12CrNiWTi 1613) 3% W 2,5 ppmB 3. RGT 21 (X12CrNiWTi 1613) 3% W 50 ppm B. The investigations of all casts are carried out in two different heat treatments which are suitable for the conditions required for the operation of the reactor. Cond. I: 1150 0 C 30 min, water quenced; 800 0 32 hour, air; 10% cold work. Cond. II: 1150 0 C 30 min, water quenched; 10% cold work. In connection with creep test the condition I irrespective of 3 steels show no remarkable difference. The observation at 750 0 C test temperature and also at condition II above 650 0 C on Boron-free Vaccutherm cast shows an unfavourable behaviour. There is no significant difference in the stress dependence of secondary creep rate and also absolute creep rate. A definite superiority is to be found for 12R72HV when considering the values for time-yield-limit-ratio and ductility compared to the W-steels. The test results shows different fracture behaviour. Transcrystalline fracture is found on cast 12R72HV, whereas RGT 21 and Vaccutherm show transition from transcrystalline to intercrystalline fracture, depending on the rupture time and test temperature. The long term rupture specimens show intercrystalline fracture. (author)

Interfacial microstructure and performance of brazed diamond grits with Ni-Cr-P alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, C.Y. [Faculty of Mechanical and Electronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)], E-mail: cywang@gdut.edu.cn; Zhou, Y.M.; Zhang, F.L.; Xu, Z.C. [Faculty of Mechanical and Electronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

2009-05-12

The reaction mechanism of the interface among diamond, commercial Ni-Cr-P alloy and steel substrate has been studied by optical microscopy, scanning electron microscope, X-ray diffraction and Raman spectroscopy. The reaction layers formed among diamond, brazing alloy and steel substrate produced good wettability of diamond grits for achieving better quality tools. The reaction layer between diamond and brazing alloy comprised a reaction layer of brazing alloy and a reaction layer of diamond. Cr{sub 7}C{sub 3} and Cr{sub 3}C{sub 2} formed in the reaction layer of brazing alloy was the main reason for improving the bonding strength of Ni-Cr alloy to the diamond grits. A reaction layer of diamond may be a graphitization layer formed on the surface of diamond under high temperature brazing. The reaction layer of brazing alloy and steel substrate was the co-diffusion of Ni, Cr and Fe between the brazing alloy and the steel substrate. The life and sharpness of brazed diamond boring drill bits fabricated in this study were superior to the electroplated one in the market owing to its high protrusion and bonding strength.

Shot Peening Effects on Subsurface Layer Properties and Fatigue Performance of Case-Hardened 18CrNiMo7-6 Steel

Directory of Open Access Journals (Sweden)

H. S. Ho

2018-01-01

Full Text Available The present study is conducted with a dual-aim: firstly, to examine the effect of several single shot peening conditions on the subsurface layer properties and fatigue performance of the case-hardened 18CrNiMo7-6 steel, and secondly, to propose an optimized peening condition for improved fatigue performance. By carrying out the subsurface integrity analysis and fatigue testing, the underlying relationships among the peening process, subsurface layer property and fatigue performance are investigated, the way peening conditions affect the fatigue life and its associated scatter for the case-hardened 18CrNiMo7-6 steel is quantitatively assessed. The in-depth study shows that dual peening can be an optimized solution, for it is able to produce a subsurface layer with enhanced properties and eventually gain a significant improvement in fatigue performance.

Comparison of the segregation behavior between tempered martensite and tempered bainite in Ni-Cr-Mo high strength low alloy RPV steel

Energy Technology Data Exchange (ETDEWEB)

Park, Sang Gyu; Kim, Min Chul; Kim, Hyung Jun; Lee, Bong Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

SA508 Gr.4N Ni-Cr-Mo low alloy steel has an superior fracture toughness and strength, compared to commercial Mn-Mo-Ni low alloy RPV steel SA508 Gr.3. Higher strength and fracture toughness of low alloy steels could be obtained by adding Ni and Cr. So several were performed on researches on SA508 Gr.4N low alloy steel for a RPV application. The operation temperature and term of a reactor pressure vessel is more than 300 .deg. C and over 40 years. Therefore, in order to apply the SA508 Gr.4N low alloy steel for a reactor pressure vessel, the resistance of thermal embrittlement in the high temperature range including temper embrittlement is required. S. Raoul reported that the susceptibility to temper embrittlement was increasing a function of the cooling rate in SA533 steel, which suggests the martensitic microstructures resulting from increased cooling rates are more susceptible to temper embrittlement. However, this result has not been proved yet. So the comparison of temper embrittlement behavior was made between martensitic microstructure and bainitic microstructure with a viewpoint of boundary features in SA508 Gr.4N, which have mixture of tempered bainite/martensite. We have compared temper embrittlement behaviors of SA508 Gr.4N low alloy steel with changing volume fraction of martensite. The mechanical properties of these low alloy steels were evaluated after a long-term heat treatment. Then, the the segregated boundaries were observed and segregation behavior was analyzed by AES. In order to compare the misorientation distributions of model alloys, grain boundary structures were measured with EBSD

Electrochemical impedance spectrometry using 316L steel, hastelloy, maraging, Inconel 600, Elgiloy, carbon steel, TiN and NiCr. Simulation in tritiated water. 2 volumes

International Nuclear Information System (INIS)

Bellanger, G.

1994-03-01

Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the slow and fast kinetics (voltammetry) of different stainless steel alloys. These corrosion kinetics, the actual or simulated tritiated water redox potentials, and the corrosion potentials provide a classification of the steels studied here: 316L, Hastelloy, Maraging, Inconel 600, Elgiloy, carbon steel and TiN and NiCr deposits. From the results it can be concluded that Hastelloy and Elgiloy have the best corrosion resistance. (author). 49 refs., 695 figs., tabs

Multiaxial creep of fine grained 0.5Cr-0.5Mo-0.25V and coarse grained 1Cr-0.5Mo steels

International Nuclear Information System (INIS)

Browne, R.J.; Flewitt, P.E.J.; Lonsdale, D.

1991-01-01

To explore the multiaxial creep response of materials used for electrical power generating plant, two steels, a fine grained 0.5Cr-0.5Mo-0.25V steel in a normalised and tempered condition with high creep ductility and a coarse grained 1Cr-0.5Mo steel in a quenched and tempered condition with low uniaxial creep ductility, have been selected. A range of multiaxial stress testing techniques which span the stress states that would allow identification of any technique dependent variables has been used. The deformation and failure of the normalised and tempered 0.5Cr-0.5Mo-0.25V steel for a range of multiaxial test techniques and, therefore, stress states may be described by an equivalent stress criterion. The results from the multiaxial tests carried out on the fully bainitic 1Cr-0.5Mo steel show that the multiaxial stress rupture criterion (MSRC) varies with stress state; at high triaxiality (notch), it is controlled by the maximum principal stress, whereas at low triaxiality (shear) it is dependent on both maximum principal stress and equivalent stress. Furthermore, a simple description of stress state based on maximum principal and equivalent stress does not define this uniquely, since the MSRC derived from uniaxial and torsion testing does not describe the failure of notch, tube, or double shear tests. (author)

Corrosion behavior of steels in liquid lead bismuth with low oxygen concentrations

Science.gov (United States)

Kurata, Yuji; Futakawa, Masatoshi; Saito, Shigeru

2008-02-01

Corrosion tests in pots were conducted to elucidate corrosion behavior of various steels in liquid lead-bismuth for 3000 h under the condition of an oxygen concentration of 5 × 10 -8 wt% at 450 °C and an oxygen concentration of 3 × 10 -9 wt% at 550 °C, respectively. Significant corrosion was not observed at 450 °C for ferritic/martensitic steels, F82H, Mod.9Cr-1Mo steel, 410SS, 430SS except 2.25Cr-1Mo steel. Pb-Bi penetration into steels and dissolution of elements into Pb-Bi were severe at 550 °C even for ferritic/martensitic steels. Typical dissolution attack occurred for pure iron both at 550 °C without surface Fe 3O 4 and at 450 °C with a thin Fe 3O 4 film. Ferritization due to dissolution of Ni and Cr, and Pb-Bi penetration were recognized for austenitic stainless steels, 316SS and 14Cr-16Ni-2Mo steel at both temperatures of 450 °C and 550 °C. The phenomena were mitigated for 18Cr-20Ni-5Si steel. In some cases oxide films could not be a corrosion barrier in liquid lead-bismuth.

Effect of nitrogen alloying of stainless steels on their corrosion stability

International Nuclear Information System (INIS)

Chigal, V.; Knyazheva, V.M.; Pitter, Ya.; Babich, S.G.; Bogolyubskij, S.D.

1986-01-01

Results of corrosion tests and structural investigations of 03Cr18Ni10 and 03Cr18Ni10Mo3 steels without nitrogen and with nitrogen content of 0.15-0.3% are presented. Corrosion-electrochemical behaviour of Cr20Ni20 steel with ultralow carbon content (0.004-0.006%) and nitrogen content with 0-0.5% as well as Cr 2 N nitride behaviour are investigated. A conclusion is made on nitrogen and excessive nitride phase effect on corrosion stability of steel in corrosive media with different reduction-oxidation properties

Heterogeneity of structure and properties of 12Cr18Ni10Ti and 08Cr16Ni11Mo3 stainless steels irradiated up to high damaging doses in reactor Bn-350

International Nuclear Information System (INIS)

Maksimkin, O.P.; Tivanova, O.V.; Turubarova, L.G.; Silnyagina, N.S.; Doronina, T.A.

2006-01-01

Full text: Earlier, during investigation of post-operating properties and structure of responsible units of fast neutron reactors there was shown /1, 2/ that depending on character of preliminary treatment of austenite stainless steel (austenization, cold deformation, mechanical and thermal treatment) radiation effects could be different. In /2/ one could observe heterogeneity at swelling of cold- worked hexahedral ducts along perimeter, in particular, the swelling of corners was less than plates'. At the same time after mechanical-thermal treatment the corners swell in 3-5 times of magnitude higher than plates. By the present there are several assumptions about nature of this phenomenon. One of them is a difference of deformation degree of material in corners and plates of the duct. It is known that /3/ external effects (including deformation) induce martensitic γ→α transformation in austenitic steels, due to which the structure and properties of steel are changed. In particular, paramagnetic FCC matrix reveals sites with ferromagnetic BCC structure. Steel heating, containing martensitic α-phase higher than ∼ 450-800 deg C, results in reverse γ→α transformation in material, which in its turn leads to formation of phase phase-hardened austenite. We can expect that only peculiarities of processes of direct and reverse martensitic transformations, which took place during preliminary austenitic steel treatment, will predetermine its behavior under irradiation. Taking into account the above mentioned there have been carried out complex material-scientific investigations of 12Cr18Ni10Ti and 08Cr16Ni11Mo3 steel samples cut off from different sites (both adjacent to corners and far from them) of hexagonal ducts of spent fuel assemblies of BN-350 reactor. There were used samples in the form of plates of different sizes: 5x10x2 mm - for metallographic investigations (microscope Neophot-2) and determination of microhardness (PMT-3); 2x20x0,3 mm - for mechanical

Effect of rare earth element yttrium addition on microstructures and properties of a 21Cr-11Ni austenitic heat-resistant stainless steel

International Nuclear Information System (INIS)

Chen, Lei; Ma, Xiaocong; Wang, Longmei; Ye, Xiaoning

2011-01-01

Research highlights: → Applications of Y in 21Cr-11Ni austenitic heat-resistant stainless steel. → Sensible characteristics of microstructure and properties have been observed. → Y has been found be effective in improving hot ductility of 21Cr-11Ni steel. → Inhibitory effect of Y on S segregation to the grain boundary has been observed. -- Abstract: In this comparative study, the microstructure and the mechanical properties of a 21Cr-11Ni austenitic heat-resistant stainless steel with and without addition of rare earth (RE) element yttrium have been investigated. The results show that a number of fine spherical yttrium-rich oxide particles are not uniformly distributed in the matrix of steel with yttrium; instead, they are aligned along the rolling direction. The grains surrounding the alignment are nearly one order of magnitude smaller than those farther away from the alignment. The approximate calculation results indirectly show that the grain refinement may be mainly attributed to the stimulation for nucleation of recrystallization rather than to pinning by particles. Furthermore, the alignment has resulted in significant loss in transverse impact toughness and tensile elongation at room temperature. There is a trough in the hot ductility-temperature curve, which is located between 973 and 1173 K. The ductility trough of steel with yttrium becomes shallow within a certain temperature range, especially around 1073 K, indicating that improvement on hot ductility is achieved by yttrium addition. The results may be attributed to the increase of grain boundary cohesion indicated by the effective improvement on intergranular failure tendency, and the inhibitory effect of yttrium on sulfur segregation to grain boundaries is believed to be an important cause.

Microstructure and Corrosion Behavior of Ni-Alloy/CrN Nanolayered Coatings

Directory of Open Access Journals (Sweden)

Hao-Hsiang Huang

2011-01-01

Full Text Available The Ni-alloy/CrN nanolayered coatings, Ni-Al/CrN and Ni-P/CrN, were deposited on (100 silicon wafer and AISI 420 stainless steel substrates by dual-gun sputtering technique. The influences of the layer microstructure on corrosion behavior of the nanolayered thin films were investigated. The bilayer thickness was controlled approximately 10 nm with a total coating thickness of 1m. The single-layer Ni-alloy and CrN coatings deposited at 350∘C were also evaluated for comparison. Through phase identification, phases of Ni-P and Ni-Al compounds were observed in the single Ni-alloy layers. On the other hand, the nanolayered Ni-P/CrN and Ni-Al/CrN coatings showed an amorphous/nanocrystalline microstructure. The precipitation of Ni-Al and Ni-P intermetallic compounds was suppressed by the nanolayered configuration of Ni-alloy/CrN coatings. Through Tafel analysis, the corr and corr values ranged from –0.64 to –0.33 V and 1.42×10−5 to 1.14×10−6 A/cm2, respectively, were deduced for various coating assemblies. The corrosion mechanisms and related behaviors of the coatings were compared. The coatings with a nanolayered Ni-alloy/CrN configuration exhibited a superior corrosion resistance to single-layer alloy or nitride coatings.

Monotonic and Cyclic Behavior of DIN 34CrNiMo6 Tempered Alloy Steel

Directory of Open Access Journals (Sweden)

Ricardo Branco

2016-04-01

Full Text Available This paper aims at studying the monotonic and cyclic plastic deformation behavior of DIN 34CrNiMo6 high strength steel. Monotonic and low-cycle fatigue tests are conducted in ambient air, at room temperature, using standard 8-mm diameter specimens. The former tests are carried out under position control with constant displacement rate. The latter are performed under fully-reversed strain-controlled conditions, using the single-step test method, with strain amplitudes lying between ±0.4% and ±2.0%. After the tests, the fracture surfaces are examined by scanning electron microscopy in order to characterize the surface morphologies and identify the main failure mechanisms. Regardless of the strain amplitude, a softening behavior was observed throughout the entire life. Total strain energy density, defined as the sum of both tensile elastic and plastic strain energies, was revealed to be an adequate fatigue damage parameter for short and long lives.

Combating Wear of ASTM A36 Steel by Surface Modification Using Thermally Sprayed Cermet Coatings

Directory of Open Access Journals (Sweden)

Vineet Shibe

2016-01-01

Full Text Available Thermal spray coatings can be applied economically on machine parts to enhance their requisite surface properties like wear, corrosion, erosion resistance, and so forth. Detonation gun (D-Gun thermal spray coatings can be applied on the surface of carbon steels to improve their wear resistance. In the present study, alloy powder cermet coatings WC-12% Co and Cr3C2-25% NiCr have been deposited on ASTM A36 steel with D-Gun thermal spray technique. Sliding wear behavior of uncoated ASTM A36 steel and D-Gun sprayed WC-12% Co and Cr3C2-25% NiCr coatings on base material is observed on a Pin-On-Disc Wear Tester. Sliding wear performance of WC-12% Co coating is found to be better than the Cr3C2-25% NiCr coating. Wear performance of both these cermet coatings is found to be better than uncoated ASTM A36 steel. Thermally sprayed WC-12% Co and Cr3C2-25% NiCr cermet coatings using D-Gun thermal spray technique is found to be very useful in improving the sliding wear resistance of ASTM A36 steel.

The causes of relaxation- and hot cracking in the heat-affected zone of 22 NiMoCr 37 and 20 MnMoNi 55

International Nuclear Information System (INIS)

Schellhammer, W.

1977-01-01

Non-destructive and metallographic investigations with a view to relaxation cracking and hot cracking were carried out in 53 component-specific welds with wall thicknesses of 40 to 360 mm and 21 experimental welds with wall thicknesses of 140 to 275 mm of high-temperature, fine-grained structural steel 22 NiMoCr 37 as well as in 27 component-specific welds of high-strength, fine-grained structural steel 20 MnMoNi 55. Non-destructive tests and conventional metallographic analyses by means of transverse structure micrography were unable to give a sufficiently accurate picture of the two types of cracks in the micro- and millimeter range, a 'volumetric' method was employed (tangential structure micrography with stepwise abrasion) which permitted semi-automatic and fast evaluation. The experimental results showed the selective influence of several elements and led to the development of a method to evaluate the cumulative effect of the chemical elements on relaxation cracking and hot cracking by addition of the selective influence. The method gives quantitative data on material optimisation with regard to the reduction of brittle and crack-prone states and confirms the findings of welding simulation tests. (orig./IHOE) 891 IHOE/orig.- 892 HIS [de

Effect of cold work on decarburization of 2.25Cr-1Mo steel in high temperature sodium

International Nuclear Information System (INIS)

Aoki, Norichika; Yoshida, Eiichi; Wada, Yusaku.

1994-01-01

It is known that the mechanical properties of a 2.25Cr-1Mo steel deteriorated due to the decarburization during immersion in the melt sodium at high temperatures. In low-alloy steel as well as a 2.25Cr-1Mo steel, precipitation reactions of carbides are known to be accelerated by cold working and aging. Thus, it may be expected that cold working and aging effectively suppress the decarburization of the mechanical properties of a 2.25Cr-1Mo steel because the decarburization will be restrained owing to fixation of carbon as precipitates of the carbides. In the present article, effects of cold-working and heat treatments on the kinetics of the decarburization of a 2.25Cr-1Mo steel has been studied experimentally. The annealed, cold-rolled, and normalized and tempered specimens were immersed in the melt of sodium at 500, 600 and 700degC for 425, 437 and 432h, respectively. On the basis of the observations obtained from these specimens, the experiment was also carried out at 450, 500 and 550degC for 2270 and 5465h. The microstructures before and after the immersion were observed with optical and scanning electron microscopes. An average concentration of carbon in each specimen was analyzed by an inert gas fusion method. The carbides extracted from the specimens were identified by X-ray diffraction. At immersion temperatures of 450 and 500degC, a 10% reduction of the decarburization in thickness by cold-working is sufficiently effective for retardation of the decarburization at both 2270 and 5465h. Whereas, at 550degC, more than 30% reduction in thickness by cold-working is needed for it at 2270h but even 80% reduction in thickness by cold-working causes merely slight retardation of the decarburization at 5465h. (author)

Atomistic study of the hardening of ferritic iron by Ni-Cr decorated dislocation loops

Science.gov (United States)

Bonny, G.; Bakaev, A.; Terentyev, D.; Zhurkin, E.; Posselt, M.

2018-01-01

The exact nature of the radiation defects causing hardening in reactor structural steels consists of several components that are not yet clearly determined. While generally, the hardening is attributed to dislocation loops, voids and secondary phases (radiation-induced precipitates), recent advanced experimental and computational studies point to the importance of solute-rich clusters (SRCs). Depending on the exact composition of the steel, SRCs may contain Mn, Ni and Cu (e.g. in reactor pressure vessel steels) or Ni, Cr, Si, Mn (e.g. in high-chromium steels for generation IV and fusion applications). One of the hypotheses currently implied to explain their formation is the process of radiation-induced diffusion and segregation of these elements to small dislocation loops (heterogeneous nucleation), so that the distinction between SRCs and loops becomes somewhat blurred. In this work, we perform an atomistic study to investigate the enrichment of loops by Ni and Cr solutes and their interaction with an edge dislocation. The dislocation loops decorated with Ni and Cr solutes are obtained by Monte Carlo simulations, while the effect of solute segregation on the loop's strength and interaction mechanism is then addressed by large scale molecular dynamics simulations. The synergy of the Cr-Ni interaction and their competition to occupy positions in the dislocation loop core are specifically clarified.

Corrosion resistance of Ultra-Low-Carbon 19% Cr-11% Ni stainless steel for nuclear fuel reprocessing plants in nitric acid

International Nuclear Information System (INIS)

Ariga, Tamako; Takagi, Yoshio; Inazumi, Toru; Masamura, Katsumi; Sukekawa, M.

1995-01-01

An Ultra-Low-Carbon 19% Cr-11% Ni Stainless Steels used in nuclear fuel reprocessing plants where highly corrosion resistance in nitric acid is required has been developed. This steel has optimized the chemistry composition to decrease inclusions and deformation-induced martensitic transformation. The formation of deformation-induced martensite has the potential danger of accelerating corrosion in nitric acid. In this paper, effects of cold reduction and martensitic transformation on corrosion resistance of Ultra-Low-Carbon Stainless Steels in nitric acid are discussed. The developed steel showed excellent corrosion resistance during long-term exposure to nitric acid. (author)

Effect of chemical composition on irradiation embrittlement and annealing in Ni-Cr-Mo-V reactor pressure vessel steel

Energy Technology Data Exchange (ETDEWEB)

Novosad, P [Czech Nuclear Society, Prague (Czech Republic)

1994-12-31

Results concerning copper and phosphorus influence on radiation-induced changes in the Ni-Cr-Mo-V steel mechanical properties, are presented. Correlations between different mechanical properties for steels with different chemical composition, are presented. A comparison of transition temperature shifts obtained for static and dynamic fracture toughness tests and Charpy impact tests, is discussed. Recovery of radiation hardening, measured by hardness test after isochronal annealing of steels with different compositions, is also shown. Copper content strongly affects irradiation-induced changes of mechanical properties, but phosphorus content in connection with variable copper content has only a small effect. (author). 4 refs., 4 figs., 4 tabs.

Gradient microstructure and microhardness in a nitrided 18CrNiMo7-6 gear steel

Science.gov (United States)

Yang, R.; Wu, G. L.; Zhang, X.; Fu, W. T.; Huang, X.

2017-07-01

A commercial gear steel (18CrNiMo7-6) containing a tempered martensite structure was nitrided using a pressurized gas nitriding process under a pressure of 5 atm at 530 °C for 5 hours. The mechanical properties and microstructure of the nitrided sample were characterized by Vickers hardness measurements, X-ray diffraction, and backscatter electron imaging in a scanning electron microscope. A micro-hardness gradient was identified over a distance of 500 μm with hardness values of 900 HV at the top surface and 300 HV in the core. This micro-hardness gradient corresponds to a gradient in the microstructure that changes from a nitride compound layer at the top surface (∼ 20 μm thick) to a diffusion zone with a decreasing nitrogen concentration and precipitate density with distance from the surface, finally reaching the core matrix layer with a recovered martensite structure.

The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

International Nuclear Information System (INIS)

Schuon, S.R.

1982-01-01

The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life

Mechanical properties of steel 8 CrMoNiNb 9 10 in dependence on the microstructural condition

International Nuclear Information System (INIS)

Fabritius, H.; Schnabel, E.

1976-01-01

Tension tests at room temperature to 600 0 C and creep-rupture tests at 500 to 600 0 C lasting up to about 75,000 h on two casts of steel 8 CrMoNiNb 9 10 with about 0.08% C, 0.3% Si, 0.7% Mn, 0.012% N, 0.005% Al, 2.34% Cr, 0.95% Mo, 0.8% Nb and 0.64% Ni in bainitic and ferritic microstructural condition. Influence of annealing at 650 to 800 0 C on the properties in the tension test. Influence of aging at 500 to 600 0 C lasting up to 30,000 h with and without mechanical stress on the properties in the tension test at aging temperature and on the toughness behaviour in the notched bar impact bend test at room temperature. (orig.) [de

Microstructure and elevated temperature stability of 9-12% Cr steels

Energy Technology Data Exchange (ETDEWEB)

Dogan, Omer N.; Hawk, Jeffrey A.

2005-02-01

Medium Cr steels have been used in fossil fired power plants for many years because of their excellent high temperature stability and mechanical properties. As the desire to increase the efficiency of power plants continues, the operating temperature (>650C) continues to go up. Currently available low and medium Cr containing steels will not withstand the new operating temperature and must be reassessed in terms of their solid-solution and precipitation strengthening schemes. Three medium Cr steels were developed to investigate high temperature alloy strengthening strategies: 0.08C-(9-12)Cr-1.2Ni-0.7Mo-3.0Cu-3.0Co-0.5Ti. The microstructure of the alloy will be described in the as-cast and thermo-mechanically worked states. In addition, the effect on microstructure from long-term high temperature exposure will also be discussed. Finally, the overall stability of these steels will be compared against currently available power plant steels.

Hardness and Wear Resistance of TiC-Fe-Cr Locally Reinforcement Produced in Cast Steel

Directory of Open Access Journals (Sweden)

Olejnik E.

2016-06-01

Full Text Available In order to increase wear resistance cast steel casting the TiC-Fe-Cr type composite zones were fabricated. These zones were obtained by means of in situ synthesis of substrates of the reaction TiC with a moderator of a chemical composition of white cast iron with nickel of the Ni-Hard type 4. The synthesis was carried out directly in the mould cavity. The moderator was applied to control the reactive infiltration occurring during the TiC synthesis. The microstructure of composite zones was investigated by electron scanning microscopy, using the backscattered electron mode. The structure of composite zones was verified by the X-ray diffraction method. The hardness of composite zones, cast steel base alloy and the reference samples such as white chromium cast iron with 14 % Cr and 20 % Cr, manganese cast steel 18 % Mn was measured by Vickers test. The wear resistance of the composite zone and the reference samples examined by ball-on-disc wear test. Dimensionally stable composite zones were obtained containing submicron sizes TiC particles uniformly distributed in the matrix. The macro and microstructure of the composite zone ensured three times hardness increase in comparison to the cast steel base alloy and one and a half times increase in comparison to the white chromium cast iron 20 % Cr. Finally ball-on-disc wear rate of the composite zone was five times lower than chromium white cast iron containing 20 % Cr.

The change of NiCrBSi alloys’ phase composition after plasma spraying

Directory of Open Access Journals (Sweden)

A. Dudek

2008-08-01

Full Text Available Material for investigations was NiCrBSi powder for components’ coatings which improve their corrosion resistance as well as resistance to friction wear and erosion. Plasma spraying method was used to produce a coating with thickness of 300 μm on low-alloy steel which was then remelted with the base material. Using X-ray quality analysis, phase composition was determined for: NiCrBSi powder, obtained coating and the alloyed surface layer. Crystallinity degree was also calculated for NiCrBSi layer sprayed on the base material.

TiC reinforced cast Cr steels

Energy Technology Data Exchange (ETDEWEB)

Dogan, O.N.; Hawk, J.A.; Schrems, K.K.

2006-06-01

A new class of materials, namely TiC-reinforced cast chromium (Cr) steels, was developed for applications requiring high abrasion resistance and good fracture toughness. The research approach was to modify the carbide structure of commercial AISI 440C steel for better fracture resistance while maintaining the already high abrasion resistance. The new alloys contained 12Cr, 2.5–4.5Ti, and 1–1.5C (wt.%) and were melted in a vacuum induction furnace. Their microstructure was composed primarily of a martensitic matrix with a dispersion of TiC precipitates. Modification of TiC morphology was accomplished through changing the cooling rate during solidification. Wear rates of the TiC-reinforced Cr steels were comparable to that of AISI 440C steel, but the impact resistance was much improved.

Thermal fatigue strength estimation of 2.25Cr-1Mo steel under creep-fatigue interaction

International Nuclear Information System (INIS)

Kuwahara, Kazuo; Nitta, Akihito; Kitamura, Takayuki

1980-01-01

A 2-1/4Cr-1Mo steel is one of principal materials for high temperature equipments in nuclear and thermal power plants. The authors experimentally analyzed the high temperature fatigue strength and creep strength of a 2-1/4 Cr-1Mo steel main steam pipe which had been used in a thermal plant for operation up to 130,000 hours, and pointed out that the strain-range vs. life curves crossed each other due to the difference of temperature-strain phase in thermal fatigue. This suggests that it is difficult to estimate thermal fatigue life of steel materials having been subjected to different temperature-strain phase on the basis of isothermal low-cycle fatigue life at the upper limit temperature of thermal fatigue, and that it is urgently required to establish an appropriate method of evaluating thermal fatigue life. The authors attempted to prove that the strain range partitioning method used for the evaluation of thermal fatigue life in SUS 304 steels is applicable to this 2-1/4Cr-1Mo steel. Consequently, it was found that the thermal fatigue life could be estimated within a factor of 2.5 by the application of this method. (author)

Microstructure-strength relations in a hardenable stainless steel with 16 pct Cr, 1.5 pct Mo, and 5 pct Ni

Science.gov (United States)

Grobner, P. J.; Blšs, V.

1984-07-01

Metallographic studies have been conducted on a 0.024 pct C-16 pct Cr-1.5 pct Mo-5 pct Ni stainless steel to study the phase reactions associated with heat treatments and investigate the strengthening mechanisms of the steel. In the normalized condition, air cooled from 1010 °C, the microstructure consists of 20 pct ferrite and 80 pct martensite. Tempering in a temperature range between 500 and 600 °C results in a gradual transformation of martensite to a fine mixture of ferrite and austenite. At higher tempering temperatures, between 600 and 800 °C, progressively larger quantities of austenite form and are converted during cooling to proportionally increasing amounts of fresh martensite. The amount of retained austenite in the microstructure is reduced to zero at 800 °C, and the microstructure contains 65 pct re-formed martensite and 35 pct total ferrite. Chromium rich M23C6 carbides precipitate in the single tempered microstructures. The principal strengthening is produced by the presence of martensite in the microstructure. Additional strengthening is provided by a second tempering treatment at 400 °C due to the precipitation of ultrafine (Cr, Mo) (C,N) particles in the ferrite.

Development of small punch tests for ductile-brittle transition temperature measurement of temper embrittled Ni-Cr steels

International Nuclear Information System (INIS)

Baik, J.M.; Kameda, J.; Buck, O.

1983-01-01

Small punch tests were developed to determine the ductile-brittle transition temperature of nickel-chromium (Ni-Cr) steels having various degrees of temper embrittlement and various microstructures. It was found that the small punch test clearly shows the ductile-brittle transition behavior of the temper-embrittled steels. The measured values were compared with those obtained from Charpy impact and uniaxial tensile tests. The effects of punch tip shape, a notch, and the strain rate on the ductile-brittle transition behavior were examined. It was found that the combined use of a notch, high strain rates, and a small punch tip strongly affects the ductile-brittle transition behavior. Considerable variations in the data were observed when the small punch tests were performed on coarse-grained steels. Several factors controlling embrittlement measurements of steels are discussed in terms of brittle fracture mechanisms

Mechanical properties of irradiated 9Cr-2WVTa steel

International Nuclear Information System (INIS)

Klueh, R.L.; Alexander, D.J.; Rieth, M.

1998-01-01

An Fe-9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa) steel has excellent strength and impact toughness before and after irradiation in the Fast Flux Test Facility and the High Flux Reactor (HFR). The ductile-brittle transition temperature (DBTT) increased only 32 C after 28 dpa at 365 C in FFTF, compared to a shift of ∼60 C for a 9Cr-2WV steel--the same as the 9Cr-2WVTa steel but without tantalum. This difference occurred despite the two steels having similar tensile but without tantalum. This difference occurred despite the two steels having similar tensile properties before and after irradiation. The 9Cr-2WVTa steel has a smaller prior-austenite grain size, but otherwise microstructures are similar before irradiation and show similar changes during irradiation. The irradiation behavior of the 9Cr-2WVTa steel differs from the 9Cr-2WV steel and other similar steels in two ways: (1) the shift in DBTT of the 9Cr-2WVTa steel irradiated in FFTF does not saturate with fluence by ∼28 dpa, whereas for the 9Cr-2WV steel and most similar steels, saturation occurs at <10 dpa, and (2) the shift in DBTT for 9Cr-2WVTa steel irradiated in FFTF and HFR increased with irradiation temperature, whereas it decreased for the 9Cr-2WV steel, as it does for most similar steels. The improved properties of the 9Cr-2WVTa steel and the differences with other steels were attributed to tantalum in solution

Microstructure of Vacuum-Brazed Joints of Super-Ni/NiCr Laminated Composite Using Nickel-Based Amorphous Filler Metal

Science.gov (United States)

Ma, Qunshuang; Li, Yajiang; Wu, Na; Wang, Juan

2013-06-01

Vacuum brazing of super-Ni/NiCr laminated composite and Cr18-Ni8 stainless steel was carried out using Ni-Cr-Si-B amorphous filler metal at 1060, 1080, and 1100 °C, respectively. Microstructure and phase constitution were investigated by means of optical and scanning electron microscopy, energy-dispersive spectroscopy, x-ray diffraction, and micro-hardness tester. When brazed at 1060-1080 °C, the brazed region can be divided into two distinct zones: isothermally solidified zone (ISZ) consisting of γ-Ni solid solution and athermally solidified zone (ASZ) consisting of Cr-rich borides. Micro-hardness of the Cr-rich borides formed in the ASZ was as high as 809 HV50 g. ASZ decreased with increase of the brazing temperature. Isothermal solidification occurred sufficiently at 1100 °C and an excellent joint composed of γ-Ni solid solution formed. The segregation of boron from ISZ to residual liquid phase is the reason of Cr-rich borides formed in ASZ. The formation of secondary precipitates in diffusion-affected zone is mainly controlled by diffusion of B.

Study of the 1.25Cr-1Mo-0.25V steel microstructure after a carburization phenomenon

Energy Technology Data Exchange (ETDEWEB)

Simonetti, S., E-mail: ssimonet@uns.edu.ar [Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Departamentos de Ciencias Basicas e Ingenieria Mecanica, Universidad Tecnologica Nacional, 11 de Abril 461, 8000 Bahia Blanca (Argentina); Lanz, C. [Departamento de Ingenieria, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina); Brizuela, G.; Juan, A. [Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina)

2010-08-20

We studied the changes in the structure and carbide particle size in 1.25Cr-1Mo-0.25V steel under 600 deg. C and 168 MPa, after 4000 h service. We used microscopy and microanalysis techniques to analyze the carbide particles. We performed a complementary theoretical study on the chemical bonding and electronic structure of the carbide-Fe matrix interaction. The results contribute to the understanding of the changes in the alloy microstructure caused by the carburization phenomenon.

Low-activation Mn-Cr austenitic stainless steel with further reduced content of long-lived radioactive elements

Energy Technology Data Exchange (ETDEWEB)

Onozuka, M.; Saida, T.; Hirai, S. [Mitsubishi Heavy Ind. Ltd., Yokohama (Japan); Kusuhashi, M.; Sato, I.; Hatakeyama, T. [The Japan Steel Works Ltd., Chatsu-machi 4, Muroran 051-8505 (Japan)

1998-06-01

Low-activation austenitic stainless steel based on Mn-Cr non-magnetic steels has been developed. The alloying elements of long-life activation, such as Ni, Mo and Co, were eliminated and substituted with Mn along with an addition of N. A Mn-Cr austenitic stainless steel, 24.5Mn-13.5Cr-0.02C-0.2N, has been developed successfully. Examined material properties, including mechanical, thermal and magnetic properties, as well as weldability and characteristics of corrosion resistance, are presented. It was found that the alloy has excellent material properties virtually equivalent to those of 316SS. In this study, the applicability of the Schaeffler, DeLong and Hull constitution diagrams for the stainless steels with low Ni and high Mn contents was also examined. The boundary conditions distinguishing the single austenite phase from the others have been identified for the Mn-Cr steels. (orig.) 22 refs.

Low-activation Mn Cr austenitic stainless steel with further reduced content of long-lived radioactive elements

Science.gov (United States)

Onozuka, Masanori; Saida, Tomikane; Hirai, Shouzou; Kusuhashi, Mikio; Sato, Ikuo; Hatakeyama, Tsuyoshi

1998-06-01

Low-activation austenitic stainless steel based on Mn-Cr non-magnetic steels has been developed. The alloying elements of long-life activation, such as Ni, Mo and Co, were eliminated and substituted with Mn along with an addition of N. A Mn-Cr austenitic stainless steel, 24.5Mn-13.5Cr-0.02C-0.2N, has been developed successfully. Examined material properties, including mechanical, thermal and magnetic properties, as well as weldability and characteristics of corrosion resistance, are presented. It was found that the alloy has excellent material properties virtually equivalent to those of 316SS. In this study, the applicability of the Schaeffler, DeLong and Hull constitution diagrams for the stainless steels with low Ni and high Mn contents was also examined. The boundary conditions distinguishing the single austenite phase from the others have been identified for the Mn-Cr steels.

Microstructural, mechanical and tribological investigation of 30CrMnSiNi2A ultra-high strength steel under various tempering temperatures

Science.gov (United States)

Arslan Hafeez, Muhammad; Farooq, Ameeq

2018-01-01

The aim of the research was to investigate the variation in microstructural, mechanical and tribological characteristics of 30CrMnSiNi2A ultra-high strength steel as a function of tempering temperatures. Steel was quenched at 880 °C and tempered at five different tempering temperatures ranging from 250 °C to 650 °C. Optical microscopy and pin on disc tribometer was used to evaluate the microstructural and wear properties. Results show that characteristics of 30CrMnSiNi2A are highly sensitive to tempering temperatures. Lathe and plate shaped martensite obtained by quenching transform first into ε-carbide, second cementite, third coarsened and spheroidized cementite and finally into recovered ferrite and austenite. Hardness, tensile and yield strengths decreased while elongation increased with tempering temperatures. On the other hand, wear rate first markedly decreased and then increased. Optimum amalgamation of characteristics was achieved at 350 °C.

Corrosion testing of NiCrAl(Y) coating alloys in high-temperature and supercritical water

International Nuclear Information System (INIS)

Biljan, S.; Huang, X.; Qian, Y.; Guzonas, D.

2011-01-01

With the development of Generation IV (Gen IV) nuclear power reactors, materials capable of operating in high-temperature and supercritical water environment are essential. This study focuses on the corrosion behavior of five alloys with compositions of Ni20Cr, Ni5Al, Ni50Cr, Ni20Cr5Al and Ni20Cr10AlY above and below the critical point of water. Corrosion tests were conducted at three different pressures, while the temperature was maintained at 460 o C, in order to examine the effects of water density on the corrosion. From the preliminary test results, it was found that the binary alloys Ni20Cr and Ni50Cr showed weight loss above the critical point (23.7 MPa and 460 o C). The higher Cr content alloy Ni50Cr suffered more weight loss than Ni-20Cr under the same conditions. Accelerated weight gain was observed above the critical point for the binary alloy Ni5Al. The combination of Cr, Al and Y in Ni20Cr10AlY provides stable scale formation under all testing conditions employed in this study. (author)

Low-field spin dynamics of Cr7Ni and Cr7Ni-Cu -Cr 7Ni molecular rings as detected by μ SR

Science.gov (United States)

Sanna, S.; Arosio, P.; Bordonali, L.; Adelnia, F.; Mariani, M.; Garlatti, E.; Baines, C.; Amato, A.; Sabareesh, K. P. V.; Timco, G.; Winpenny, R. E. P.; Blundell, S. J.; Lascialfari, A.

2017-11-01

Muon spin rotation measurements were used to investigate the spin dynamics of heterometallic Cr7Ni and Cr7Ni -Cu-Cr7Ni molecular clusters. In Cr7Ni the magnetic ions are arranged in a quasiplanar ring and interact via an antiferromagnetic exchange coupling constant J , while Cr7Ni -Cu-Cr7Ni is composed of two Cr7Ni linked by a bridging moiety containing one Cu ion, that induces an inter-ring ferromagnetic interaction J'≪J . The longitudinal muon relaxation rate λ collected at low magnetic fields μ0H BPP)-like heuristic fitting model that takes into account of a distribution of electronic spin characteristic times for T >5 K, while the shoulder presented by Cr7Ni can be reproduced by a BPP function that incorporates a single electronic characteristic time theoretically predicted to dominate for T <5 K. The flattening of λ (T ) in Cr7Ni -Cu-Cr7Ni occurring at very low temperature can be tentatively attributed to field-dependent quantum effects and/or to an inelastic term in the spectral density of the electronic spin fluctuations.

Room and elevated temperature Mechanical Behavior of 9-12% Cr Steels

Energy Technology Data Exchange (ETDEWEB)

Dogan, Omer N.; Hawk, Jeffrey A.; Schrems, Karol K.

2005-02-01

The mechanical properties of medium Cr steels used in fossil fired power plants are very good because of their excellent high temperature microstructural stability. However, as the desire to increase the operating temperature (>650C) of the plant goes up, the need for steels that maintain their strength at these temperatures also increases. The mechanical properties of three medium Cr steels (0.08C-(9-12)Cr-1.2Ni-0.7Mo-3.0Cu-3.0Co-0.5Ti) were investigated through hardness, hot hardness and tensile measurements. The strength of the 9-12%Cr steels at room temperature after long-term isothermal aging (750C; 1000 hours) compares favorably with that of other power plant steels (e.g., P91). In addition, the elevated temperature strength and hot hardness also behave similarly. The mechanical behavior will be discussed in terms of the strength, elongation and tensile fracture characteristics.

Microstructure of steel X 20 Cr 13 in the electron microscopical picture

International Nuclear Information System (INIS)

Gesatzke, W.

1982-01-01

The tempered microstructure of the steel X 20 Cr 13 is described by an electron microscopical overall picture and additional information is gained which would not be possible with the optical microscope. The large transmission area permits one to quantitatively evaluate a microstructure component which due to its small size can only be measured with electron microscope pictures. (orig.) [de

Soft zone formation in dissimilar welds between two Cr-Mo steels

International Nuclear Information System (INIS)

Albert, S.K.; Gill, T.P.S.; Tyagi, A.K.; Mannan, S.L.; Rodriguez, P.; Kulkarni, S.D.

1997-01-01

Two dissimilar weldments between 9Cr-1Mo and 2.25Cr-1Mo ferritic steels have been characterized for their microstructural stability during various postweld heat treatments (PWHTs). The samples for the investigation were extracted from bead-on-plate weldments made by depositing 2.25Cr-1Mo weld metal on 9Cr-1Mo base plate and vice versa. Subsequent application of PWHT resulted in the formation of a soft zone in the low Cr ferritic steel weld or base plate. A carbide-rich hard zone, adjoining the soft zone, was also detected in the high Cr side of the weldment. Unmixed zones in the weld metal provided additional soft and hard zones in the weld metals. The migration of carbon from low-Cr steel to high-Cr steel, driven by the carbon activity gradient, has been shown to be responsible for the formation of soft and hard zones. A carbon activity diagram for 2.25Cr-1Mo/9Cr-1Mo weldments has been proposed to aid in the selection of welding consumables for reducing or preventing the soft zone formation

Standard and applied material testing methods of austenitic CrNi stainless steels in different nitric acid media - procedures and results

International Nuclear Information System (INIS)

Leistikow, S.; Kraft, R.; Schanz, G.

1989-07-01

Extended ASTM Standard Huey Testing has been performed in at 120 0 C boiling 14.4 molar (65%) nitric acid during 15 periods (15x48 = 720 h duration) for quality control of numerous commercial nitric acid resistant austenitic CrNi steels. It was shown how sensitively the chosen testing conditions could differentiate between CrNi steels of the same nominal composition as specified for DIN W.Nr. 1.4306 (AISI Type 304 L), but with varying residual element contents. Within an attempt to differentiate within this group of steels by application of electrochemical methods, potentiostatic tests at 1250 mV in nitric acid of equal concentration and temperature were able to detect remarkable differences in corrosion behaviour already after one hour. Another approach, more typical for the electrochemical potentials during materials application in reprocessing plants of nuclear fuel, gave preference to long-term immersion tests, which were performed in nitric acid of lower concentration and temperature. Reference tests in pure 7 molar, 90 0 C nitric acid could only reveal by surface attack small differences in steel quality by exposures of 720 h duration. To shorten the test time by an increase of the redox potential chromium (VI) ions were added to the nitric acid. In a solution of 0,5 g Gr (VI)/l at 90 0 C remarkable differences in corrosion behavior of the steels - similar to the Huey test results - became measurable by means of gravimetry and metallography already during a short-term exposure of 24-71 h. (orig./MM) [de

Effect of Tin, Copper and Boron on the Hot Ductility of 20CrMnTi Steel between 650 °C and 1100 °C

Science.gov (United States)

Peng, Hong-bing; Chen, Wei-qing; Chen, Lie; Guo, Dong

2015-02-01

The hot ductility of 20CrMnTi steel with x% tin, y% copper and z ppm boron (x = 0, 0.02; y = 0, 0.2; z = 0, 60) was investigated. The results show that tin and copper in 20CrMnTi steel are detrimental to its hot ductility while adding boron can eliminate the adverse effect and enhance hot ductility greatly. Tin is found to segregate to the boundaries tested by EPMA in 20CrMnTi steel containing tin and copper and tin-segregation is suppressed by adding boron, moreover, copper was found not to segregate to boundaries, however, fine copper sulfide was found from carbon extraction replicas using TEM. The adverse effect of tin and copper on the hot ductility was due mainly to tin segregation and fine copper sulfide in the steel. The proeutectoid ferrite film precipitating along the austenite grain boundary causes the ductility trough of the three examined steels. Tin and copper in 20CrMnTi steel can retard the occurrence of dynamic recrystallization (DRX) while boron-addition can compensate for that change. The beneficial effect of boron on 20CrMnTi steel containing tin and copper might be ascribed to the fact that boron segregates to grain boundaries, accelerates onset of DRX, retards austenite/ferrite transformation and promotes intragranular nucleation of ferrite.

Measurement of high temperature elastic moduli of an 18Cr-9Ni-2.95 Cu-0.58 Nb-0.1C (Wt %) austenitic stainless steel

Science.gov (United States)

Tripathy, Haraprasanna; Hajra, Raj Narayan; Sudha, C.; Raju, S.; Saibaba, Saroja

2018-04-01

The Young's modulus (E) and Shear modulus (G) of an indigenously developed 18Cr-9Ni-0.1C-2.95 Cu-0.58Nb (wt %) austenitic stainless steel has been evaluated in the temperature range 298 K to 1273 K (25 °C to 1000 °C), using Impulse excitation technique (IET). The Bulk modulus (K) and the poison's ratio have been estimated from the measured values of E and G. It is observed that the elastic constants (E, G and K) are found to decrease in a nonlinear fashion with increase in temperature. The Cu precipitation is found to influence the elastic moduli of the steel in the cooling cycle. The observed elastic moduli are fitted to 3rd order polynomial equations in order to describe the temperature dependence of E, G, K moduli in the temperature range 298-1273 K (25 °C to 1000 °C). The room temperature values of E,G and K moduli is found to be 207, 82 and 145 GPa respectively for the present steel.

Refinement of grain structure in 20 MnNiMo (SA508C) steel

International Nuclear Information System (INIS)

Sheng Zhongqi; Xiao Hong; Peng Feng; Zou Min

1997-04-01

The size of prior austenite grains and bainitic colonies of 20 MnNiMo (SA508C) steel (a reactor pressure vessel steel) after normal heat treatment is measured and its controlling factors are discussed. Results show that low aluminium content can induce serious mixed structure with fine and coarse grains in prior austenite. Fast cooling rate can promote refinement of bainitic colonies. Further refinement of grains can be obtained by inter-critical quenching. (5 figs., 1 tab.)

Preliminary Microstructural and Microscratch Results of Ni-Cr-Fe and Cr3C2-NiCr Coatings on Magnesium Substrate

Science.gov (United States)

Istrate, B.; Munteanu, C.; Lupescu, S.; Benchea, M.; Vizureanu, P.

2017-06-01

Thermal coatings have a large scale application in aerospace and automotive field, as barriers improving wear mechanical characteristics and corrosion resistance. In present research, there have been used two types of coatings, Ni-Cr-Fe, respectively Cr3C2-NiCr which were deposited on magnesium based alloys (pure magnesium and Mg-30Y master alloy). There have been investigated the microstructural aspects through scanning electronic microscopy and XRD analysis and also a series of mechanical characteristics through microscratch and indentation determinations. The results revealed the formation of some adherent layers resistant to the penetration of the metallic indenter, the coatings did not suffer major damages. Microstructural analysis highlighted the formation of Cr3C2, Cr7C3, Cr3Ni2, Cr7Ni3, FeNi3, Cr-Ni phases. Also, the apparent coefficient of friction for Ni-Cr-Fe coatings presents superior values than Cr3C2-NiCr coatings.

Difference between Cr and Ni K-edge XANES spectra of rust layers formed on Fe-based binary alloys exposed to Cl-rich environment

International Nuclear Information System (INIS)

Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

2005-01-01

The rust layer formed on weathering steel possesses a strong protective ability against corrosives in an atmospheres. This ability is related to the structure of the rust layer. The difference in the protective ability of a rust layer. The difference in the protective ability of a rust layer in a Cl-rich environment between conventional weathering steel containing Cr and advanced weathering steel containing Ni is believed to be caused by the differences in local structural and chemical properties between alloying elements. Cr and Ni, in the rust layer. In order to examine the effect of these alloying elements on the structure of the rust layer formed on steel in a Cl-rich environment, we have performed Cr and Ni K-edge X-ray absorption near-edge structure (XANES) measurements for the rust layer of Fe-Cr and Fe-Ni binary alloys exposed to a Cl-rich atmosphere using synchrotron radiation. The results of the Cr K-edge XANES measurements for the rust layer of Fe-Cr binary alloys show that the atomic geometry around Cr depends on the concentration of Cr. Therefore, it is expected that the local structure around Cr in the rust layer is unstable. On the other hand, from the results of the Ni K-edge XANES measurements for the rust layer of Fe-Ni binary alloys. Ni is considered to be positioned at a specific site in the crystal structure of a constituent of the rust layer, such as akaganeite or magnetite. As a consequence, Ni negligibly interacts with Cl - ions in the rust layer. (author)

Electrochemical impedance spectrometry using 316L steel, hastelloy, maraging, Inconel 600, Elgiloy, carbon steel, TiN and NiCr. Simulation in tritiated water. 2 volumes; Spectrometrie d`impedance electrochimique sur acier 316L, hastelloy, maraging inconel 600, elgiloy, acier au carbone, TiN, NiCr. Simulations en eau tritiee. 2 volumes

Energy Technology Data Exchange (ETDEWEB)

Bellanger, G.

1994-03-01

Polarization and electrochemical impedance spectrometry curves are presented and discussed. These curves make it possible to ascertain the corrosion domains and to compare the slow and fast kinetics (voltammetry) of different stainless steel alloys. These corrosion kinetics, the actual or simulated tritiated water redox potentials, and the corrosion potentials provide a classification of the steels studied here: 316L, Hastelloy, Maraging, Inconel 600, Elgiloy, carbon steel and TiN and NiCr deposits. From the results it can be concluded that Hastelloy and Elgiloy have the best corrosion resistance. (author). 49 refs., 695 figs., tabs.

Physical properties of molten core materials: Zr-Ni and Zr-Cr alloys measured by electrostatic levitation

Energy Technology Data Exchange (ETDEWEB)

Ohishi, Yuji, E-mail: ohishi@see.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University (Japan); Kondo, Toshiki [Graduate School of Engineering, Osaka University (Japan); Ishikawa, Takehiko [Japan Aerospace Exploration Agency (Japan); SOKEN-DAI (Graduate University for Advanced Studies) (Japan); Okada, Junpei T. [Institute for Materials Research, Tohoku University (Japan); Watanabe, Yuki [Advanced Engineering Services Co. Ltd. (Japan); Muta, Hiroaki; Kurosaki, Ken [Graduate School of Engineering, Osaka University (Japan); Yamanaka, Shinsuke [Graduate School of Engineering, Osaka University (Japan); Research Institute of Nuclear Engineering, University of Fukui (Japan)

2017-03-15

It is important to understand the behaviors of molten core materials to investigate the progression of a core meltdown accident. In the early stages of bundle degradation, low-melting-temperature liquid phases are expected to form via the eutectic reaction between Zircaloy and stainless steel. The main component of Zircaloy is Zr and those of stainless steel are Fe, Ni, and Cr. Our group has previously reported physical property data such as viscosity, density, and surface tension for Zr-Fe liquid alloys using an electrostatic levitation technique. In this study, we report the viscosity, density, and surface tension of Zr-Ni and Zr-Cr liquid alloys (Zr{sub 1-x}Ni{sub x} (x = 0.12 and 0.24) and Zr{sub 0.77}Cr{sub 0.23}) using the electrostatic levitation technique. - Highlights: • The physical properties of Zr-Ni and Zr-Cr liquid alloys have been measured Zr{sub 1-x}Ni{sub x} (x = 0.12 and 0.24) and Zr{sub 77}Cr{sub 23}. • The measurement was conducted using the electrostatic levitation technique. • The density, viscosity, and surface tension of each liquid alloy were measured.

Physical properties of molten core materials: Zr-Ni and Zr-Cr alloys measured by electrostatic levitation

International Nuclear Information System (INIS)

Ohishi, Yuji; Kondo, Toshiki; Ishikawa, Takehiko; Okada, Junpei T.; Watanabe, Yuki; Muta, Hiroaki; Kurosaki, Ken; Yamanaka, Shinsuke

2017-01-01

It is important to understand the behaviors of molten core materials to investigate the progression of a core meltdown accident. In the early stages of bundle degradation, low-melting-temperature liquid phases are expected to form via the eutectic reaction between Zircaloy and stainless steel. The main component of Zircaloy is Zr and those of stainless steel are Fe, Ni, and Cr. Our group has previously reported physical property data such as viscosity, density, and surface tension for Zr-Fe liquid alloys using an electrostatic levitation technique. In this study, we report the viscosity, density, and surface tension of Zr-Ni and Zr-Cr liquid alloys (Zr 1-x Ni x (x = 0.12 and 0.24) and Zr 0.77 Cr 0.23 ) using the electrostatic levitation technique. - Highlights: • The physical properties of Zr-Ni and Zr-Cr liquid alloys have been measured Zr 1-x Ni x (x = 0.12 and 0.24) and Zr 77 Cr 23 . • The measurement was conducted using the electrostatic levitation technique. • The density, viscosity, and surface tension of each liquid alloy were measured.

Effect of boron on the hot ductility of 2.25Cr1Mo steel

International Nuclear Information System (INIS)

Song, S.-H.; Guo, A.-M.; Shen, D.-D.; Yuan, Z.-X.; Liu, J.; Xu, T.-D.

2003-01-01

The effect of boron on the hot ductility of 2.25Cr1Mo steel is investigated by means of a Gleeble 2000 thermomechanical simulator. There is a trough in the hot ductility-temperature curve, which is located between 1000 and 700 deg. C. The ductility trough shifts to lower temperatures with increasing boron content and the hot brittle range becomes shallow and narrow. In general, boron may improve the steel hot ductility in that it may retard the formation of pro-eutectoid ferrite and increase grain boundary cohesion. These effects may be related to the segregation of boron to austenite grain boundaries

Structure of steel 8 CrMoNiNb 9 10 and its variations in long-term thermal stress

International Nuclear Information System (INIS)

Fabritius, H.; Schnabel, E.

1976-01-01

On four casts of steel 8 CrMoNiNb 9 10 with about 0.06% C, 0.25; Si, 0.7% Mn, 0.012% N, 0.002 to 0.020% Al, 2.25% Cr, 0.94% Mo, 0.63 to 0.91% Nb and 0.67% Ni, transformation behaviour and structural changes during long-time annealing at 500 to 750 degC lasting up to 30,000 h were studied in unformed condition and after previous cold forming. The carbon content was largely bound in form of primary niobium carbonitrides so that during quenching and tempering low-carbon bainite was formed, or at very slow cooling a ferritic structure without pearlite. Martensite occurred only after fast cooling from temperatures above 1200 degC. Bainite exhibited a very high dislocation density and a large number of coherent niobium carbonitrides. During tempering, the precipitates overaged, and the dislocations started to arrange themselves to subgrain boundaries. Hardness and strength in quenched and tempered condition were essentially governed by dislocation density and size of subgrains. In the whole range of bainite transformation, they are only slightly dependent upon the cooling rate and hence upon the dimensions of the products. The structural changes which occurred in bainitic material during long-time aging and led to a ferritic structure in the final state were interpreted as recovery and recrystallization. In unformed and slightly formed material recrystallization led to a very coarse-grained structure. In highly formed material a very fine-grained structure was achieved by recrystallization. By a high degree of cold forming the recrystallization process was considerably promoted. With an annealing time of 10 5 h, no recrystallization is to be expected for unformed specimens of the studied cast up to 580 degC, but above 650 degC complete recrystallization. (author)

Random cyclic constitutive models of 0Cr18Ni10Ti pipe steel

International Nuclear Information System (INIS)

Zhao Yongxiang; Yang Bing

2004-01-01

Experimental study is performed on the random cyclic constitutive relations of a new pipe stainless steel, 0Cr18Ni10Ti, by an incremental strain-controlled fatigue test. In the test, it is verified that the random cyclic constitutive relations, like the wide recognized random cyclic strain-life relations, is an intrinsic fatigue phenomenon of engineering materials. Extrapolating the previous work by Zhao et al, probability-based constitutive models are constructed, respectively, on the bases of Ramberg-Osgood equation and its modified form. Scattering regularity and amount of the test data are taken into account. The models consist of the survival probability-strain-life curves, the confidence strain-life curves, and the survival probability-confidence-strain-life curves. Availability and feasibility of the models have been indicated by analysis of the present test data

Grain boundary segregation in FeCrNi model alloys; Korngrenzensegregation in FeCrNi-Modellegierungen

Energy Technology Data Exchange (ETDEWEB)

Schlueter, B.; Schneider, F.; Mummert, K. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Muraleedharan, P. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Div. of Metallurgy

1998-12-31

P and S segregate at the grain boundaries and thus increase susceptibility to intergranular corrosion at those sites. This could be proven by means of nitric acid-chromate tests and potentiostatic etching tests. There is a direct connection between loss in mass, mean depth of intergranular corrosion attacks, dissolution current density, and level of segregation-induced concentration of P and S at the grain boundaries. The segregation effect at these sites was found to be most evident in specimens of the examined Fe-Cr-Ni steel which had been heat-treated for 1000 hours at 550 C. However, segregation occurs also in materials that received a heat treatment of 400 C/5000 hours, while intergranular corrosion is observed only after heat treatment of 500 C/1000 hours. Apart from segregation of P, formation of Cr-rich phosphides is observed, which leads to depletion of Cr at the precipitates. (orig./CB) [Deutsch] P und S segregieren an die KG und erhoehen dort die IK-Anfaelligkeit. Dies konnte mit Hilfe von Salpetersaeure-Chromat- und Potentiostatischem Aetztest nachgewiesen werden. Es besteht ein direkter Zusammenhang zwischen Masseverlust, mittlerer IK-Angriffstiefe, Aufloesungsstromdichte und Hoehe der segregationsbedingten Anreicherungen von P und S an den KG. Der KG-Segregationseffekt am untersuchten Fe-Cr-Ni-Stahl ist im Waermebehandlungszustand 550 C/1000 h am deutlichsten ausgepraegt. Aber auch bereits bei 400 C/5000 h findet Segregation statt. IKSpRK tritt nur im Waermebehandlungszustand 550 C/1000 h auf. Neben der P-Segregation wird die Bildung Cr-reicher Phosphide beobachtet, die zur Abreicherung von Cr an den Ausscheidungen fuehrt. (orig.)

Numerical simulation of Cr2N age-precipitation in high nitrogen stainless steels

International Nuclear Information System (INIS)

Dai, Q.X.; Yuan, Z.Z.; Luo, X.M.; Cheng, X.N.

2004-01-01

At the temperature raging from 700 to 950 deg. C, the Cr 2 N age-precipitation in high nitrogen austenitic stainless steels Fe24Mn18Cr3Ni0.62N was investigated in this paper. A qualitative mathematical model of Cr 2 N age-precipitation, ln t S = f (Me,1/T), was established based on the thermodynamics and kinetics and phase transformation theories. Satisfactory results were obtained by means of the test of artificial neural network. This mathematical model can be applied to the calculation design and predication of Cr 2 N age-precipitation in high nitrogen stainless steels

Highly corrosive and high strength Cr-Mn series austenite sintered steel, method of manufacturing the same and the usage

International Nuclear Information System (INIS)

Arai, Masahiko; Hirano, Tatsumi; Aono, Yasuhisa; Kato, Takahiko; Kondo, Yasuo; Inagaki, Masatoshi

1998-01-01

The steel of the present invention comprises a highly corrosive and high strength Cr-Mn series austenite sintered steel containing up to 0.1% of C, up to 1% of Si, up to 0.4% of N, from 9 to 25% of (Mn + Ni) within a range of more than 2% and up to 15% of Mn and from 14 to 20% of Cr, and it has an average crystal grain size of 1μm or less and comprises at least 90 vol% of an austenite phase. In addition, the alloy is incorporated with one or more elements of up to 3% of Mo, 1.0% of Ti, up to 2.0% of Zr and up to 1.0% of Nb in an amount of up to 2.0% in total of Ti, Zr and Nb. When these materials are used under the circumstance where materials are generally deteriorated in grain boundaries, since they are excellent in corrosion resistance and strength, remarkable effects can be attained in the improvement of the safety and the reliability of products. In addition, they are applied not only to a reactor core but also to a water-cooled circumstance and a circumstance where hydrogen exists, thereby capable of exhibiting remarkable effects. (T.M.)

Ab initio and Atomic kinetic Monte Carlo modelling of segregation in concentrated FeCrNi alloys

Science.gov (United States)

Piochaud, J. B.; Becquart, C. S.; Domain, C.

2014-06-01

Internal structure of pressurised water reactors are made of austenitic materials. Under irradiation, the microstructure of these concentrated alloys evolves and solute segregation on grain boundaries or irradiation defects such as dislocation loops are observed to take place. In order to model and predict the microstructure evolution, a multiscale modelling approach needs to be developed, which starts at the atomic scale. Atomic Kinetic Monte Carlo (AKMC) modelling is the method we chose to provide an insight on defect mediated diffusion under irradiation. In that approach, we model the concentrated commercial steel as a FeCrNi alloy (γ-Fe70Cr20Ni10). As no reliable empirical potential exists at the moment to reproduce faithfully the phase diagram and the interactions of the elements and point defects, we have adjusted a pair interaction model on large amount of DFT calculations. The point defect properties in the Fe70Cr20Ni10, and more precisely, how their formation energy depends on the local environment will be presented and some AKMC results on thermal non equilibrium segregation and radiation induce segregation will be presented. The effect of Si on the segregation will also be discussed.

The kinetics of phase transformations of undercooled austenite of the 38MnCrNi6-4-4 hypoeutectoid steel

OpenAIRE

R. Dąbrowski; R. Dziurka; E. Rożniata

2012-01-01

Purpose: Present work corresponds to the research on the kinetic of phase transformation of undercooled austenite of 38MnCrNi6-4-4 hypoeutctoid steel. The kinetic of phase transformation of under cooled austenite of investigated alloy was presented on CCT diagram (continuous cooling transformation). Also the methodology of a dilatometric samples preparation and the method of the critical points determination were described.Design/methodology/approach: The austenitising temperature was defined...

Development of the dentistry alloy Ni-Cr-Nb; Desenvolvimento de ligas odontologicas Ni-Cr-Nb

Energy Technology Data Exchange (ETDEWEB)

Souza, M.A.; Ramos, A.S.; Hashimoto, T.M., E-mail: mari_sou@hotmail.co [UNESP/FEG, Guaratingueta, SP (Brazil). Fac. de Engenharia. Dept. de Materiais e Tecnologia

2010-07-01

This work reports on the structural characterization of Ni-Cr-Mo and Ni-Cr-Nb alloys produced by arc melting. Samples were characterized by means of optical microscopy, X-ray diffraction, scanning electron microscopy, and EDS analysis. Results indicated that the arc melting process was efficient to produce homogeneous structures in Ni-Cr-Mo and Ni-Cr-Nb alloys. The nickel dissolved large amounts of Cr, Mo and Nb, which was detected by EDS analysis and X-ray diffraction. The alloy containing molybdenum indicated the presence of structure based on Ni{sub SS}, while that the alloys containing niobium presented primary grains of Ni{sub SS} and precipitates formed by the simultaneous transformation of the Ni and Ni{sub 3}Nb phases. (author)

Microstructure and wear behaviors of laser clad NiCr/Cr3C2-WS2 high temperature self-lubricating wear-resistant composite coating

Science.gov (United States)

Yang, Mao-Sheng; Liu, Xiu-Bo; Fan, Ji-Wei; He, Xiang-Ming; Shi, Shi-Hong; Fu, Ge-Yan; Wang, Ming-Di; Chen, Shu-Fa

2012-02-01

The high temperature self-lubricating wear-resistant NiCr/Cr3C2-30%WS2 coating and wear-resistant NiCr/Cr3C2 coating were fabricated on 0Cr18Ni9 austenitic stainless steel by laser cladding. Phase constitutions and microstructures were investigated, and the tribological properties were evaluated using a ball-on-disc wear tester under dry sliding condition at room-temperature (17 °C), 300 °C and 600 °C, respectively. Results indicated that the laser clad NiCr/Cr3C2 coating consisted of Cr7C3 primary phase and γ-(Fe,Ni)/Cr7C3 eutectic colony, while the coating added with WS2 was mainly composed of Cr7C3 and (Cr,W)C carbides, with the lubricating WS2 and CrS sulfides as the minor phases. The wear tests showed that the friction coefficients of two coatings both decrease with the increasing temperature, while the both wear rates increase. The friction coefficient of laser clad NiCr/Cr3C2-30%WS2 is lower than the coating without WS2 whatever at room-temperature, 300 °C, 600 °C, but its wear rate is only lower at 300 °C. It is considered that the laser clad NiCr/Cr3C2-30%WS2 composite coating has good combination of anti-wear and friction-reducing capabilities at room-temperature up to 300 °C.

Investigations on avoidance of hot cracks during laser welding of austenitic Cr-Ni steels and nickel-based alloys using temperature field tailoring. Final report; Untersuchungen zur Vermeidung von Heissrissen beim Laserstrahlschweissen von austenitischen Cr-Ni-Staehlen und Nickelbasislegierungen mittels Temperaturfeld-Tailoring. Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-08-08

The aim of the project was to transfer the developed method of laser beam welding of heat treated machining steels of temperature field tailoring on hot crack endangered austenitic Cr-Ni steels and nickel-based alloys. With this method, transient thermal stresses adjacent to the weld are produced by an travelling induction heating so that the hot cracking is prevented during welding. As test materials the austenitic Cr-Ni steel with sulfur additive 1.4305, the Cr-Ni steels 1.4404 and 1.4435 and the nickel-based alloy Udimet 720 were selected. As a result of the research it was shown that a hot crack-free laser welding in the investigated materials using at least three different welding and material-technical approaches is possible. [German] Das Ziel des Forschungsvorhabens bestand darin, das fuer das Laserstrahlschweissen verguetbarer Automatenstaehle entwickelte Verfahren des Temperaturfeld-Tailorings auf heissrissgefaehrdete austenitische Cr-Ni-Staehle und Nickelbasislegierungen zu uebertragen. Mit diesem Verfahren werden waehrend des Schweissens transiente thermische Spannungen neben der Schweissnaht durch eine mitlaufende induktive Erwaermung so erzeugt, dass die Heissrissbildung verhindert wird. Als Versuchswerkstoffe wurden der austenitische Cr-Ni-Stahl mit Schwefelzusatz 1.4305, die Cr-Ni-Staehle 1.4404 und 1.4435 sowie die Nickelbasislegierung Udimet 720 ausgewaehlt. Im Ergebnis des Forschungsvorhabens konnte gezeigt werden, dass ein heissrissfreies Laserstrahlschweissen bei den untersuchten Werkstoffen unter Nutzung von mindestens drei verschiedenen schweiss- und werkstofftechnischen Ansaetzen moeglich ist: Erstens koennen mit einem Temperaturfeld-Tailoring bei im Stumpfstoss zu verschweissenden Blechen aus austenitischen Staehlen bis mindestens 6 mm Dicke senkrecht zur Naht und parallel zur Blechoberflaeche wirkende transiente Druckspannungen erzeugt werden, die der Bildung von Mittelrippenrissen oder dazu parallel liegenden Heissrissen entgegenwirken

Microstructure of laser cladded martensitic stainless steel

CSIR Research Space (South Africa)

Van Rooyen, C

2006-08-01

Full Text Available and martensite with 10% ferrite for Material B. Table 7 - Proposed martensitic stainless steel alloys for laser cladding Material C* Cr Ni Mn Si Mo Co Ms (ºC)* Cr eq Ni eq Material A 0.4 13 - 1 0.5 2.5 5.5 120 16.5 12.5 Material B 0.2 15 2 1 0.7 2.5 5.5 117... dilution, low heat input, less distortion, increased mechanical and corrosion properties excellent repeatability and control of process parameters. Solidification of laser cladded martensitic stainless steel is primarily austenitic. Microstructures...

Creep and time to rupture of a 16/16 Cr Ni Steel; Comportamiento a la fluencia lenta de la aleacion X 8 Cr Ni Mo Nb 1616 con distintos tratamientos termicos

Energy Technology Data Exchange (ETDEWEB)

Solano, R; Garcia, R; Bohm, H; Schirra, M

1972-07-01

The influence of different thermal-mechanical treatments on the creep and time to rupture of a 16/16 Cr.Ni steel is studied. The solution treated material after annealing at 700-800 degree centigree did not affect time to rupture. At the contrary a 12% cold-working and annealing at 800 degree centigree improve the time to rupture. This treatment is preserved up to 700 degree centigree 10{sup 4} hours. The ductility is not strongly affected. A metallographic study of the fracture was carried out. (Author) 23 refs.

Microstructure and Wear Resistance of TIG Remelted NiCrBSi Thick Coatings

Directory of Open Access Journals (Sweden)

Guo-lu Li

2018-01-01

Full Text Available The self-fluxing NiCrBSi coatings with 800 μm thickness were prepared on the surface of AISI1045 steel substrate by plasma spraying. And the remelted coating was obtained using by the tungsten inert gas (TIG arc process. The microstructure, surface roughness, hardness, phase composition, and wear resistance of the sprayed coating and remelted coating were systematically investigated. The results demonstrate that TIG remelted treatment can significantly eliminate the microscopic defects in thick coating and improve its density. The surface roughness (Ra of the remelted coating is only 18.9% of the sprayed coating. The hardness of the remelted coating is 26.8% higher than that of the sprayed coating. The main phases in the sprayed coating are changed from γ-Ni, Cr7C3, and Cr2B to γ-Ni, Cr23C6, CrB, Ni3B, and Fe3C. The wear mass loss of the remelted coating is only 17.1% of the sprayed coating. Therefore, a Ni-based thick coating with good wear resistance can be obtained by plasma spraying and remelted technique.

Development of ferritic steels for fusion reactor applications

Energy Technology Data Exchange (ETDEWEB)

Klueh, R.L.; Maziasz, P.J.; Corwin, W.R.

1988-08-01

Chromium-molybdenum ferritic (martensitic) steels are leading candidates for the structural components for future fusion reactors. However, irradiation of such steels in a fusion environment will produce long-lived radioactive isotopes that will lead to difficult waste-disposal problems. Such problems could be reduced by replacing the elements in the steels (i.e., Mo, Nb, Ni, N, and Cu) that lead to long-lived radioactive isotopes. We have proposed the development of ferritic steels analogous to conventional Cr-Mo steels, which contain molybdenum and niobium. It is proposed that molybdenum be replaced by tungsten and niobium be replaced by tantalum. Eight experimental steels were produced. Chromium concentrations of 2.25, 5, 9, and 12% were used (all concentrations are in wt %). Steels with these chromium compositions, each containing 2% W and 0.25% V, were produced. To determine the effect of tungsten and vanadium, 2.25 Cr steels were produced with 2% W and no vanadium and with 0.25% V and O and 1% W. A 9Cr steel containing 2% W, 0.25 V, and 0.07% Ta was also studied. For all alloys, carbon was maintained at 0.1%. Tempering studies on the normalized steels indicated that the tempering behavior of the new Cr-W steels was similar to that of the analogous Cr-Mo steels. Microscopy studies indicated that 2% tungsten was required in the 2.25 Cr steels to produce 100% bainite in 15.9-mm-thick plate during normalization. The 5Cr and 9Cr steels were 100% martensite, but the 12 Cr steel contained about 75% martensite with the balance delta-ferrite. 33 refs., 35 figs., 5 tabs.

Development of ferritic steels for fusion reactor applications

International Nuclear Information System (INIS)

Klueh, R.L.; Maziasz, P.J.; Corwin, W.R.

1988-08-01

Chromium-molybdenum ferritic (martensitic) steels are leading candidates for the structural components for future fusion reactors. However, irradiation of such steels in a fusion environment will produce long-lived radioactive isotopes that will lead to difficult waste-disposal problems. Such problems could be reduced by replacing the elements in the steels (i.e., Mo, Nb, Ni, N, and Cu) that lead to long-lived radioactive isotopes. We have proposed the development of ferritic steels analogous to conventional Cr-Mo steels, which contain molybdenum and niobium. It is proposed that molybdenum be replaced by tungsten and niobium be replaced by tantalum. Eight experimental steels were produced. Chromium concentrations of 2.25, 5, 9, and 12% were used (all concentrations are in wt %). Steels with these chromium compositions, each containing 2% W and 0.25% V, were produced. To determine the effect of tungsten and vanadium, 2.25 Cr steels were produced with 2% W and no vanadium and with 0.25% V and O and 1% W. A 9Cr steel containing 2% W, 0.25 V, and 0.07% Ta was also studied. For all alloys, carbon was maintained at 0.1%. Tempering studies on the normalized steels indicated that the tempering behavior of the new Cr-W steels was similar to that of the analogous Cr-Mo steels. Microscopy studies indicated that 2% tungsten was required in the 2.25 Cr steels to produce 100% bainite in 15.9-mm-thick plate during normalization. The 5Cr and 9Cr steels were 100% martensite, but the 12 Cr steel contained about 75% martensite with the balance delta-ferrite. 33 refs., 35 figs., 5 tabs

The study of tribological and corrosion behavior of plasma nitrided 34CrNiMo6 steel under hot and cold wall conditions

International Nuclear Information System (INIS)

Maniee, A.; Mahboubi, F.; Soleimani, R.

2014-01-01

Highlights: • 34CrNiMo6 steel was plasma nitrided under hot and cold wall conditions. • The amount of ε phase in hot wall condition was more than that of cold wall condition. • Wear resistance of hot wall nitrided samples was more than cold wall treated ones. • Hot wall nitriding provides better corrosion behavior than cold wall nitriding. - Abstract: This paper reports on a comparative study of tribological and corrosion behavior of plasma nitrided 34CrNiMo6 low alloy steel under modern hot wall condition and conventional cold wall condition. Plasma nitriding was carried out at 500 °C and 550 °C with a 25% N 2 + 75% H 2 gas mixture for 8 h. The wall temperature of the chamber in hot wall condition was set to 400 °C. The treated specimens were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), microhardness and surface roughness techniques. The wear test was performed by pin-on-disc method. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were also used to evaluate the corrosion resistance of the samples. The results demonstrated that in both nitriding conditions, wear and corrosion resistance of the treated samples decrease with increasing temperature from 500 °C to 550 °C. Moreover, nitriding under hot wall condition at the same temperature provided slightly better tribological and corrosion behavior in comparison with cold wall condition. In consequence, the lowest friction coefficient, and highest wear and corrosion resistance were found on the sample treated under hot wall condition at 500 °C, which had the maximum surface hardness and ε-Fe 2–3 N phase

Microchemistry of neutron irradiated 12%CrMoVNb martensitic steel

International Nuclear Information System (INIS)

Little, E.A.; Morgan, T.S.; Faulkner, R.G.

1992-01-01

Non-equilibrium solute segregation has been studied in a 12%CrMoVNb martensitic steel following fast reactor irradiation at 465 C and correlated with the development of M 6 X η-phase. Cr, Ni, Si, Mo, P and Mn are all shown to exhibit positive segregation to lath boundaries and are subsequently incorporated into M 6 X precipitates. The co-segregation of a combination of these elements which include P and Si, and possibly Cr or Mo, appears to promote M 6 X formation

Wear of Flame-Sprayed Ni-Cr-B-Si Powder Coating on Journal for Seal Contact

Directory of Open Access Journals (Sweden)

Hu Sheng-Yen

2016-01-01

Full Text Available Flame-sprayed techniques is used in this paper to coat Ni-Cr-B-Si powder on low-carbon steel or bearing steel materials of the journal surface. The wear tester is used to explore material properties of the binding capability, surface hardness, wear and friction within each layer depth. The normal force is applied in addition to the cladding layer by not only using bearing ball but also oil seal pieces, to explore rubber material of oil seal contact journal. In experiments to explore the material and processing conditions affect the microstructure and hardness of the cladding layer, and at the same hardness, surface roughness to affect the performance of the mill run.The results showed that spraying Ni-Cr-B-Si alloy powder in mild steel sheet to melt and run, cladding layer and the substrate has a uniform distribution of fine abrasive particles and binding effect, causing the substrate surface hardness (HRC about promotion 10 times. While, if sprayed Ni-Cr-B-Si alloy powder to steel panels bearing surface because the surface coated compact structure, can reduce the surface roughness and the coefficient of friction, and more improve the wear resistance of the cladding layer.

Creep and Oxidation Behavior of Modified CF8C-Plus with W, Cu, Ni, and Cr

Science.gov (United States)

Unocic, Kinga A.; Dryepondt, Sebastien; Yamamoto, Yukinori; Maziasz, Philip J.

2016-04-01

The microstructures of modified CF8C-Plus (Fe-19Cr-12Ni-0.4W-3.8Mn-0.2Mo-0.6Nb-0.5Si-0.9C) with W and Cu (CF8CPWCu) and CF8CPWCu enhanced with 21Cr + 15Ni or 22Cr + 17.5Ni were characterized in the as-cast condition and after creep testing. When imaged at lower magnifications, the as-cast microstructure was similar among all three alloys as they all contained a Nb-rich interdendritic phase and Mn-based inclusions. Transmission electron microscopy (TEM) analysis showed the presence of nanoscale Cu-rich nanoprecipitates distributed uniformly throughout the matrix of CF8CPWCu, whereas in CF8CPWCu22/17, Cu precipitates were found primarily at the grain boundaries. The presence of these nanoscale Cu-rich particles, in addition to W-rich Cr23C6, nanoscale Nb carbides, and Z-phase (Nb2Cr2N2), improved the creep strength of the CF8CPWCu steel. Modification of CF8CPWCu with Cr and Ni contents slightly decreased the creep strength but significantly improved the oxidation behavior at 1073 K (800 °C). In particular, the addition of 22Cr and 17.5Ni strongly enhanced the oxidation resistance of the stainless steel resulting in a 100 degrees or greater temperature improvement, and this composition provided the best balance between improving both mechanical properties and oxidation resistance.

Stress corrosion of very high purity stainless steels in alkaline media

International Nuclear Information System (INIS)

Hechmat-Dehcordi, Ebrahim

1981-01-01

This research thesis reports the study of stress corrosion resistance of stainless steels in caustic environments. It notably concerns the electronuclear industrial sector, the production of soda by electrolysis, and the preparation of hydrogen as energy vector. After a presentation of the experimental conditions, the author highlights the influence of purity on stress corrosion cracking of 20Cr-25Ni-type austenitic alloys. The specific action of a high number of addition metallic and non-metallic elements has been studied. Stress corrosion tests have been also performed in autoclave on austeno-ferritic (21 to 25 pc Cr - 6 to 10 pc Ni) as well as ferritic (26 pc Cr) grades. The author reports the study of electrochemical properties of stainless steel in soda by means of potentiostatic techniques with an application of Pourbaix thermodynamic equilibrium diagrams, and the study of the chemical composition of passivation thin layers by Auger spectroscopy. He more particularly studies the influence of electrode potential and of some addition elements on the chemical characteristics of oxides developed at the surface of austenite. Then, the author tries to establish correlations between strain hardening microstructure of the various steels and their sensitivity to stress corrosion [fr

Density of Liquid Ni-Cr Alloy

Institute of Scientific and Technical Information of China (English)

无

2003-01-01

The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

Boron Steel: An Alternative for Costlier Nickel and Molybdenum Alloyed Steel for Transmission Gears

Directory of Open Access Journals (Sweden)

A. Verma

2010-06-01

Full Text Available Case Carburized (CC low carbon steels containing Ni, Cr and Mo alloying elements are widely used for transmission gears in automobile, as it possesses desired mechanical properties. In order to cut cost and save scarce materials like Ni and Mo for strategic applications, steel alloyed with Boron has been developed, which gives properties comparable to Ni-Cr-Mo alloyed steel. In the process of steel development, care was taken to ensure precipitation of boron which results in precipitation hardening. The characterization of the developed boron steel had exhibited properties comparable to Ni-Cr-Mo alloyed steel and superior to conventional boron steel.

The thermal fatigue behaviour of creep-resistant Ni-Cr cast steel

Directory of Open Access Journals (Sweden)

B. Piekarski

2007-12-01

Full Text Available The study gives a summary of the results of industrial and laboratory investigations regarding an assessment of the thermal fatigue behaviour of creep-resistant austenitic cast steel. The first part of the study was devoted to the problem of textural stresses forming in castings during service, indicating them as a cause of crack formation and propagation. Stresses are forming in carbides and in matrix surrounding these carbides due to considerable differences in the values of the coefficients of thermal expansion of these phases. The second part of the study shows the results of investigations carried out to assess the effect of carbon, chromium and nickel on crack resistance of austenitic cast steel. As a criterion of assessment the amount and propagation rate of cracks forming in the specimens as a result of rapid heating followed by cooling in running water was adopted. Tests were carried out on specimens made from 11 alloys. The chemical composition of these alloys was comprised in a range of the following values: (wt-%: 18-40 %Ni, 17-30 %Cr, 1.2-1.6%Si and 0.05-0.6 %C. The specimens were subjected to 75 cycles of heating to a temperature of 900oC followed by cooling in running water. After every 15 cycles the number of the cracks was counted and their length was measured. The results of the measurements were mathematically processed. It has been proved that the main factor responsible for an increase in the number of cracks is carbon content in the alloy. In general assessment of the results of investigations, the predominant role of carbon and of chromium in the next place in shaping the crack behaviour of creep-resistant austenitic cast steel should be stressed. Attention was also drawn to the effect of high-temperature corrosion as a factor definitely deteriorating the cast steel resistance to thermal fatigue.

Low-field spin dynamics of Cr₇Ni and Cr₇Ni-Cu-Cr₇Ni molecular rings as detected by μsR

OpenAIRE

Sanna, S.; Arosio, P.; Bordonali, L.; Adelnia, F.; Mariani, M.; Garlatti, E.; Baines, C.; Amato, A.; Sabareesh, K. P.V.; Timco, G.; Winpenny, R. E.P.; Blundell, S. J.; Lascialfari, A.

2017-01-01

Muon spin rotation measurements were used to investigate the spin dynamics of heterometallic Cr7Ni and Cr7Ni-Cu-Cr7Ni molecular clusters. In Cr7Ni the magnetic ions are arranged in a quasiplanar ring and interact via an antiferromagnetic exchange coupling constant J, while Cr7Ni-Cu-Cr7Ni is composed of two Cr7Ni linked by a bridging moiety containing one Cu ion, that induces an inter-ring ferromagnetic interaction J ≪ J. The longitudinal muon relaxation rate λ collected at low magnetic fields...

On phase equilibria in duplex stainless steels

Energy Technology Data Exchange (ETDEWEB)

Wessman, S. [Swerea KIMAB AB, Stockholm (Sweden); Pettersson, R. [Outokumpu Stainless AB, Avesta Research Centre, Avesta (Sweden); Hertzman, S. [Outokumpu Stainless Research Foundation, Stockholm (Sweden)

2010-05-15

The equilibrium conditions of four duplex stainless steels; Fe-23Cr-4.5Ni-0.1N, Fe-22Cr-5.5Ni-3Mo-0.17N, Fe-25Cr-7Ni-4Mo-0.27N and Fe-25Cr-7Ni-4Mo-1W-1.5Cu-0.27N were studied in the temperature region from 700 to 1000 C. Phase compositions were determined with SEM EDS and the phase fractions using image analysis on backscattered SEM images. The results showed that below 1000 C the steels develop an inverse duplex structure with austenite and sigma phase, of which the former is the matrix phase. With decreasing temperature, the microstructure will be more and more complex and finely dispersed. The ferrite is, for the higher alloyed steels, only stable above 1000 C and at lower temperatures disappears in favour of intermetallic phases. The major intermetallic phase is sigma phase with small amounts of chi phase, the latter primarily in high Mo and W grades. Nitrides, not a focus in this investigation, were present as rounded particles and acicular precipitates at lower temperatures. The results were compared to theoretical predictions using the TCFE5 and TCFE6 databases. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Point defect properties of ternary fcc Fe-Cr-Ni alloys

Energy Technology Data Exchange (ETDEWEB)

Wróbel, J.S., E-mail: jan.wrobel@inmat.pw.edu.pl [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland); Nguyen-Manh, D.; Dudarev, S.L. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kurzydłowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland)

2017-02-15

Highlights: • Properties of point defects depend on the local atomic environment. • As the degree of chemical order increases, the formation energies increase, too. • Relaxation volumes are larger for the more ordered structures. - Abstract: The properties of point defects in Fe-Cr-Ni alloys are investigated, using density functional theory (DFT), for two alloy compositions, Fe{sub 50}Cr{sub 25}Ni{sub 25} and Fe{sub 55}Cr{sub 15}Ni{sub 30}, assuming various degrees of short-range order. DFT-based Monte Carlo simulations are applied to explore short-range order parameters and generate representative structures of alloys. Chemical potentials for the relevant structures are estimated from the minimum of the substitutional energy at representative atoms sites. Vacancies and 〈1 0 0〉 dumbbells are introduced in the Fe{sub 2}CrNi intermetallic phase as well as in two Fe{sub 55}Cr{sub 15}Ni{sub 30} alloy structures: the disordered and short range-ordered structures, generated using Monte Carlo simulations at 2000 K and 300 K, respectively. Formation energies and relaxation volumes of defects as well as changes of magnetic moments caused by the presence of defects are investigated as functions of the local environment of a defect.

Thermodynamic investigation on the formation of inclusions containing MgAl2O4 spinel during 16Cr-14Ni austenitic stainless steel manufacturing processes

International Nuclear Information System (INIS)

Park, J.H.

2008-01-01

The formation mechanism of the inclusions containing the spinel crystals has been developed based on the experimental results for the equilibrium between the Fe-16%Cr-14%Ni stainless steel melts and the inclusions as well as the compositions of the inclusions in the plant samples. In the laboratory experiments, the molar content of alumina in the inclusions linearly increases with increasing content of aluminum according to the theoretical expectation and the composition of the inclusions could be described as a function of the activity of aluminum and silicon. From the analysis of the plant samples, the content of MgO and Al 2 O 3 in the calcium silicate type inclusions continuously increases as the steel melts transfer from AOD converter to LT processes and thus, the spinel phase could be crystallized and grown in the calcium silicate matrix during cooling through tundish to cast slabs. On the other hand, the manganese silicate type inclusions were observed after tapping molten steel to the ladle, and then the MnO and Cr 2 O 3 (and SiO 2 ) in the inclusions were reduced by silicon and aluminum through LT to CC mold. The fraction of the inclusions containing spinel crystals at cast slabs was null at (Al 2 O 3 ) 2 O 3 ) > 20 mass%

Quantitative evaluation of safety use limit for crevice corrosion in Ni-Cr-Mo alloys

International Nuclear Information System (INIS)

Fukaya, Yuichi; Akashi, Masatsune; Sasaki, Hidetsugu; Tsujikawa, Shigeo

2007-01-01

The most important problem with corrosion-resistant alloys such as stainless steels is localized corrosion. Crevice corrosion, which is a typical localized corrosion, occurs under the mildest environmental conditions. Consequently, whether crevice corrosion occurs or not is an important issue in structural material selection. This study investigated highly corrosion-resistant Ni-Cr-Mo alloys whose resistance for crevice corrosion is difficult to evaluate with the JIS G 0592 standard for common strainless steels. The optimized procedures for determining the critical potential and temperature for crevice corrosion of the alloys were developed based on the JIS method. The limits of safety usage of various Ni-Cr-Mo alloys were evaluated quantitatively in chloride solution environments. (author)

Study of the microstructure and of microhardness variation of a Ni-Fe-Cr austenitic alloy by niobium

International Nuclear Information System (INIS)

Carvalho e Camargo, M.U. de; Lucki, G.

1979-01-01

The mechanisms of hardening and corrosion resistance increase in Ni-Fe-Cr austenitic stainless steels by Nb additions are of interest to nuclear technology Niobium additions to a 321 type stainless steel were made in order to study the microhardness, electrical resistivity and metallography. Experimental measurements results are shown. The effect of Nb additions as a micro-alloying element and the thermal and mechanical processes (cold working in particular) in the microstructure and microhardness properties of the 11% Ni - 70%Fe - 17% Cr austenitic alloys were studied. (Author) [pt

Ab initio and atomic kinetic Monte Carlo modelling of segregation in concentrated FeCrNi alloys

International Nuclear Information System (INIS)

Piochaud, J.B.; Becquart, C.S.; Domain, C.

2013-01-01

Internal structure of pressurised water reactors are made of austenitic materials. Under irradiation, the microstructure of these concentrated alloys evolves and solute segregation on grain boundaries or irradiation defects such as dislocation loops are observed to take place. In order to model and predict the microstructure evolution, a multi-scale modelling approach needs to be developed, which starts at the atomic scale. Atomic Kinetic Monte Carlo (AKMC) modelling is the method we chose to provide an insight on defect mediated diffusion under irradiation. In that approach, we model the concentrated commercial steel as a FeCrNi alloy (γ-Fe 70 Cr 20 Ni 10 ). As no reliable empirical potential exists at the moment to reproduce faithfully the phase diagram and the interactions of the elements and point defects, we have adjusted a pair interaction model on large amount of DFT (Density Functional Theory) calculations. The point defect properties in the Fe 70 Cr 20 Ni 10 , and more precisely, how their formation energy depends on the local environment will be presented and some AKMC results on thermal non equilibrium segregation (TNES) and radiation induce segregation will be presented. The effect of Si on the segregation will also be discussed. Preliminary results show that it is the solute- grain boundaries interactions which drive TNES

Dry sliding wear behavior and corrosion resistance of NiCrBSi coating deposited by activated combustion-high velocity air fuel spray process

International Nuclear Information System (INIS)

Liu, Shenglin; Zheng, Xueping; Geng, Gangqiang

2010-01-01

NiCrBSi is a Ni-based superalloy widely used to obtain high wear and corrosion resistant coatings. This Ni-based alloy coating has been deposited onto 0Cr13Ni5Mo stainless steel using the AC-HVAF technique. The structure and morphologies of the Ni-based coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The wear resistance and corrosion resistance were studied. The tribological behaviors were evaluated using a HT-600 wear test rig. The wear resistance of the Ni-based coating was shown to be higher than that of the 0Cr13Ni5Mo stainless steel because Fe 3 B, with high hardness, was distributed in the coating so the dispersion strengthening in the Ni-based coating was obvious and this increased the wear resistance of the Ni-based coating in a dry sliding wear test. Under the same conditions, the worn volume of 0Cr13Ni5Mo stainless steel was 4.1 times greater than that of the Ni-based coating. The wear mechanism is mainly fatigue wear. A series of the electrochemical tests was carried out in a 3.5 wt.% NaCl solution in order to examine the corrosion behavior. The mechanisms for corrosion resistance are discussed.

Electron-beam welding of 21-6-9 (Cr--Ni--Mn) stainless steel: effect of machine parameters on weldability

International Nuclear Information System (INIS)

Casey, H.

1975-04-01

The high-manganese, nitrogen-strengthened 21-6-9 (Cr--Ni--Mn) austenitic stainless steel has a weldability rating similar to that of more common austenitic stainless steels in terms of cracking, porosity, etc. However, weld pool disruption problems may occur with this alloy that can be related to instability within the molten weld pool. Selection of machine parameters is critical to achieving weld pool quiescence as this report confirms from recent tests. Test samples came from heats of air-melted, vacuum-arc remelted, and electroslag remelted material. Low- and high-voltage machine parameters are discussed, and effects of parameter variation on weld pool behavior are given. Data relate weld pool behavior to weld fusion-zone geometry. Various weld parameters are recommended for the 21-6-9 alloy, regardless of its source or chemistry. (auth)

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

DEFF Research Database (Denmark)

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

2015-01-01

Ferritic stainless steel interconnect plates are widely used in planar solid oxide fuel cell (SOFC) or electrolysis cell (SOEC) stacks. During stack production and operation, nickel from the Ni/YSZ fuel electrode or from the Ni contact component diffuses into the IC plate, causing transformation...... of the ferritic phase into an austenitic phase in the interface region. This is accompanied with changes in volume and in mechanical and corrosion properties of the IC plates. In this work, kinetic modeling of the inter-diffusion between Ni and FeCr based ferritic stainless steel was conducted, using the CALPHAD...

Hot Corrosion Behavior of Bare, Cr3C2-(NiCr) and Cr3C2-(NiCr) + 0.2wt.%Zr Coated SuperNi 718 at 900 °C

Science.gov (United States)

Mudgal, Deepa; Singh, Surendra; Prakash, Satya

2015-01-01

Corrosion in incinerators, power plants, and chemical industries are frequently encountered due to the presence of salts containing sodium, sulphur, and chlorine. To obviate this problem, bare and coated alloys were tested under environments simulating the conditions present inside incinerators and power plants. 0.2 wt.% zirconium powder was incorporated in the Cr3C2-(NiCr) coating powder. The original powder and Zr containing powder was sprayed on Superni 718 alloy by D-gun technique. The bare and coated alloys were tested under Na2SO4 + K2SO4 + NaCl + KCl and Na2SO4 + NaCl environment. The corrosion rate of specimens was monitored using weight change measurements. Characterization of the corrosion products has been done using FE-SEM/EDS and XRD techniques. Bare and coated alloys showed very good corrosion resistance under given molten salt environments. Addition of 0.2wt.%Zr in Cr3C2-25%(NiCr) coating further greatly reduced the oxidation rate as well as improved the adherence of oxide scale to the coating surface during the time of corrosion.

Study and characterization of FeNi and NiCr(80-20) % w alloys, during and after neutron irradiation, using the resistivity method

International Nuclear Information System (INIS)

Otero, Mauro Pereira

1978-01-01

We have used the resistivity method with and without neutron irradiation to study the parameters that appear in the Order-Disorder Transitions of Fe Ni(50-50)% at. and Ni Cr( 80 - 20) % w. alloys. The results obtained with Fe Ni are in agreement with those obtained by Marchand at the University of Grenoble. Several isothermal annealings were made in the range 400 - 302 deg C in which T c (Order-Disorder Transition Critical Temperature) was determined between 327 and 310 deg C. The activation energy obtained was E a = 0,49 eV and is in agreement with works of Marchand, Dienes and Damask. As for Ni Cr(80-20)% the following has been done: a) Electrical Properties characterizations, having in mind the technological applications; b) Linear and isothermal annealings were performed to determine the Order-Disorder Transition Critical Temperature (I ) supported by hypothesis made, taking into account the Yano's and Taylor's marks. The-result is T c = (536 +- 4) deg C; c) determination of activation energy E a = (1,36 +- 0.14) eV. The resistivity measurements mere performed by means of the classical 4-wire method. An anisotropy of electrical resistivity was found to exist depending on the sense of the applied electrical field. (author)

Alloying and heat treatment optimization of Fe/Cr/C steels for improved mechanical properties

International Nuclear Information System (INIS)

Sarikaya, M.

1979-06-01

The effects of alloying elements and heat treatments on the microstructural changes and strength-toughness properties were investigated in optimization of vacuum melted Fe/Cr/C base steels. The structure of the steels in the as-quenched conditions consisted of highly dislocated autotempered lath martensite (strong phase) and thin continuous interlath films of retained austenite (tough phase). It has been emphasized again that the mechanical properties of the steels are sensitive to the amount and the stability of retained austenite. To increase the stability of retained austenite in the as-quenched condition 2 w/o Mn or 2 w/o Ni was added to the base steel, viz., Fe/3Cr/0.3C. Partial replacement of Cr by about 0.5 w/o Mo did not alter the beneficial microstructure

Corrosion behavior of high purity Fe-Cr-Ni alloys in trans-passive condition

International Nuclear Information System (INIS)

Mayuzumi, Masami; Ohta, Jyoji; Kako, Kenji

1998-01-01

The corrosion behavior of high-purity (99.99%) Fe-Cr-Ni alloys was investigated in 13 N nitric acid with/without Ce 4+ ions to clarify the effect of impurities on the trans-passive corrosion of stainless steel. The following results were obtained. (1) Almost no intergranular corrosion was observed in the high-purity alloys, although the corrosion rate of the matrix region was nearly the same as that of a commercial stainless steel with the same Cr and Ni content. (2) Due to the improved intergranular corrosion resistance, the effect of the purification became significant in the corrosion condition with the grain-separation being predominant. (3) The high-purity alloys showed higher susceptivility to intergranular corrosion with aging treatment between 873 K and 1073 K. Although the sulfuric acid/copper sulfate test suggested the formation of Cr-depleted zones, a grain boundary micro-analysis using a FETEM with an EDX did not reveal any change in Cr content or impurity segregain along the grain boundaries. The mechanism of corrosion enhancement resulting from the aging treatment remains nuclear. (author)

Hot Corrosion Behavior of Stainless Steel with Al-Si/Al-Si-Cr Coating

Science.gov (United States)

Fu, Guangyan; Wu, Yongzhao; Liu, Qun; Li, Rongguang; Su, Yong

2017-03-01

The 1Cr18Ni9Ti stainless steel with Al-Si/Al-Si-Cr coatings is prepared by slurry process and vacuum diffusion, and the hot corrosion behavior of the stainless steel with/without the coatings is studied under the condition of Na2SO4 film at 950 °C in air. Results show that the corrosion kinetics of stainless steel, the stainless steel with Al-Si coating and the stainless steel with Al-Si-Cr coating follow parabolic laws in several segments. After 24 h corrosion, the sequence of the mass gain for the three alloys is the stainless steel with Al-Si-Cr coating coating coating. The corrosion products of the three alloys are layered. Thereinto, the corrosion products of stainless steel without coating are divided into two layers, where the outside layer contains a composite of Fe2O3 and FeO, and the inner layer is Cr2O3. The corrosion products of the stainless steel with Al-Si coating are also divided into two layers, of which the outside layer mainly consists of Cr2O3, and the inner layer is mainly SiO2. The corrosion film of the stainless steel with Al-Si-Cr coating is thin and dense, which combines well with substrate. Thereinto, the outside layer is mainly Cr2O3, and the inside layer is Al2O3. In the matrix of all of the three alloys, there exist small amount of sulfides. Continuous and protective films of Cr2O3, SiO2 and Al2O3 form on the surface of the stainless steel with Al-Si and Al-Si-Cr coatings, which prevent further oxidation or sulfide corrosion of matrix metals, and this is the main reason for the much smaller mass gain of the two alloys than that of the stainless steel without any coatings in the 24 h hot corrosion process.

Effect of cold deformation on latent energy value and high-temperature mechanical properties of 12Cr18Ni10Ti steel

International Nuclear Information System (INIS)

Maksimkin, O.P.; Shiganakov, Sh.B.; Gusev, M.N.

1997-01-01

Energetic and magnetic characteristics and also the high-temperature mechanical properties depending on the preliminary cold deformation of 12Cr18Ni10Ti steel are presented. It is shown that the value of storage energy in the steel has being grown with increase of the deformation. The rate of its growth has been increased after beginning of martensitic γ→α'- transformation when value of comparative storage energy at first decreased and then has been stay practically constant. Level of mechanical properties of the steel at 1073 K has been determined not only by value of cold deformation but and structural reconstruction corresponding to deformations 35-45% and accompanying with α'-phase martensite formation and change of energy accumulating rate. Preliminary cold deformation (40-60 %) does not improve high- temperature plasticity of steel samples implanted by helium. refs. 7, figs. 2

Effect of Cavitation on Surface Damage of 16.7Cr-10Ni-2Mo Stainless Steel in Marine Environment

Energy Technology Data Exchange (ETDEWEB)

Chong, Sang-Ok; Han, Min-Su; Kim, Seong-Jong [Mokpo National Maritime University, Mokpo (Korea, Republic of)

2015-10-15

Stainless steel is generally known to have characteristics of excellent corrosion resistance and durability, but in a marine environment it can suffer from localized corrosion due to the breakdown of passivity film due to chloride ion in seawater. Furthermore, the damage behaviors are sped up under a cavitation environment because of complex damage from electrochemical corrosion and cavitation-erosion. In this study the characteristics of electrochemical corrosion and cavitation erosion behavior were evaluated on 16.7Cr-10Ni-2Mo stainless steel under a cavitation environment in natural seawater. The electrochemical experiments have been conducted at both static conditions and dynamic conditions inducing cavitation with different current density parameters. The surface morphology and damage behaviors were compared after the experiment. After the cavitation test with time variables morphological examinations on damaged specimens were analyzed by using a scanning electron microscope and a 3D microscope. the galvanostatic experiment gave a cleaner surface morphology presented with less damage depth at high current density regions. It is due to the effect of water cavitation peening under the cavitation condition. In the cavitation experiment, with amplitude of 30 μm and seawater temperature of 25 ℃, weight loss and cavitation-erosion damage depth were dramatically increased after 5 hours inducing cavitation.

Effect of various heat treatments on microstructure and mechanical properties of 34CrNiMo6 steel

International Nuclear Information System (INIS)

Abd El-Azim, M.E.; Ghoneim, M.M.; Nasreldin, A.M.; Soliman, S.

1997-01-01

Three different austenitization treatments were applied to high strength 34CrNiMo6 steel: conventional austenitization (CAT), high temperature austenitization (HTA) and duplex treatment (DT). It was found that DT structure has finer prior austenite grain size (30 μm) than those of HTA (200 μm) and CAT (70 μm) structures. DT and HTA structures have coarser lath size for martensite than CAT structure. DT results in higher room temperature impact toughness than HTA and CAT structures and shifts the ductile-brittle transition to lower temperatures by 14 K and 32 K in comparison with HTA and CAT structures, respectively. However, DT structure has intermediate values of room temperature yield stress and ultimate tensile strength between those of CAT and HTA structures. When this steel was tempered at 300 and 400 C it underwent tempered martensite embrittlement associated with intergranular fracture. (orig.)

Precipitation hardening in a 12%Cr-9%Ni-4%Mo-2%Cu stainless steel

International Nuclear Information System (INIS)

Haettestrand, Mats; Nilsson, Jan-Olof; Stiller, Krystyna; Liu Ping; Andersson, Marcus

2004-01-01

A combination of complementary techniques including one-dimensional and three-dimensional atom probe, energy-filtered transmission electron microscopy and conventional transmission electron microscopy has been used to assess the precipitation reactions at 475 deg. C in a 12%Cr-9%Ni-4%Mo-2%Cu precipitation hardening stainless steel. The continuous hardening up to at least 1000 h of ageing was attributed to a sequence of precipitation reactions involving nickel-rich precipitates nucleating at copper clusters followed by molybdenum-rich quasicrystalline precipitates and nickel-rich precipitates of type L1 0 . An estimate of the relative contributions to the strength increment during tempering based on measurements of particle densities was performed. Nickel-rich precipitates were found to play the most important role up to about 40 h of ageing after which the effect of quasicrystalline particles became increasingly important

Helium accumulation and bubble formation in FeCoNiCr alloy under high fluence He+ implantation

Science.gov (United States)

Chen, Da; Tong, Y.; Li, H.; Wang, J.; Zhao, Y. L.; Hu, Alice; Kai, J. J.

2018-04-01

Face-centered cubic (FCC) high-entropy alloys (HEA), as emerging alloys with equal-molar or near equal-molar constituents, show a promising radiation damage resistance under heavy ion bombardment, making them potential for structural material application in next-generation nuclear reactors, but the accumulation of light helium ions, a product of nuclear fission reaction, has not been studied. The present work experimentally studied the helium accumulation and bubble formation at implantation temperatures of 523 K, 573 K and 673 K in a homogenized FCC FeCoNiCr HEA, a HEA showing excellent radiation damage resistance under heavy ion irradiation. The size and population density of helium bubbles in FeCoNiCr samples were quantitatively analyzed through transmission electron microscopy (TEM), and the helium content existing in bubbles were estimated from a high-pressure Equation of State (EOS). We found that the helium diffusion in such condition was dominated by the self-interstitial/He replacement mechanism, and the corresponding activation energy in FeCoNiCr is comparable with the vacancy migration energy in Ni and austenitic stainless steel but only 14.3%, 31.4% and 51.4% of the accumulated helium precipitated into helium bubbles at 523 K, 573 K and 673 K, respectively, smaller than the pure Ni case. Importantly, the small bubble size suggested that FeCoNiCr HEA has a high resistance of helium bubble formation compared with Ni and steels.

Modelling and characterization of chi-phase grain boundary precipitation during aging of Fe-Cr-Ni-Mo stainless steel

International Nuclear Information System (INIS)

Xu, W.; San Martin, D.; Rivera Diaz del Castillo, P.E.J.; Zwaag, S. van der

2007-01-01

High molybdenum stainless steels may contain the chi-phase precipitate (χ, Fe 36 Cr 12 Mo 10 ) which may lead to undesirable effects on strength, toughness and corrosion resistance. In the present work, specimens of a 12Cr-9Ni-4Mo wt% steel are heat treated at different temperatures and times, and the average particle size and particle size distribution of chi-phase precipitate are studied quantitatively. A computer model based on the KWN framework has been developed to describe the evolution of chi-phase precipitation. The kinetic model takes advantage of the KWN model to describe the precipitate particle size distribution, and is coupled with the thermodynamic software ThermoCalc for calculating the instantaneous local thermodynamic equilibrium condition at the interface and the driving force for nucleation. A modified version of Zener's theory accounting for capillarity effects at early growth stages is implemented in this model. The prediction of the model for chi-phase precipitation at a grain boundary is compared to experimental results and both the average particle size and the particle size distribution are found to be in good agreement with experimental observations at late precipitation stages

Observations of defect structure evolution in proton and Ni ion irradiated Ni-Cr binary alloys

Energy Technology Data Exchange (ETDEWEB)

Briggs, Samuel A., E-mail: sabriggs2@wisc.edu [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Barr, Christopher M. [Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Pakarinen, Janne [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); SKC-CEN Belgian Nuclear Research Centre, Boeretang 200, B-2400 Mol (Belgium); Mamivand, Mahmood [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Hattar, Khalid [Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185 (United States); Morgan, Dane D. [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Taheri, Mitra [Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Sridharan, Kumar [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States)

2016-10-15

Two binary Ni-Cr model alloys with 5 wt% Cr and 18 wt% Cr were irradiated using 2 MeV protons at 400 and 500 °C and 20 MeV Ni{sup 4+} ions at 500 °C to investigate microstructural evolution as a function of composition, irradiation temperature, and irradiating ion species. Transmission electron microscopy (TEM) was applied to study irradiation-induced void and faulted Frank loops microstructures. Irradiations at 500 °C were shown to generate decreased densities of larger defects, likely due to increased barriers to defect nucleation as compared to 400 °C irradiations. Heavy ion irradiation resulted in a larger density of smaller voids when compared to proton irradiations, indicating in-cascade clustering of point defects. Cluster dynamics simulations were in good agreement with the experimental findings, suggesting that increases in Cr content lead to an increase in interstitial binding energy, leading to higher densities of smaller dislocation loops in the Ni-18Cr alloy as compared to the Ni-5Cr alloy. - Highlights: • Binary Ni-Cr alloys were irradiated with protons or Ni ions at 400 and 500 °C. • Higher irradiation temperatures yield increased size, decreased density of defects. • Hypothesize that varying Cr content affects interstitial binding energy. • Fitting CD models for loop nucleation to data supports this hypothesis.

A comparison of low-chromium and high-chromium reduced-activation steels for fusion applications

International Nuclear Information System (INIS)

Klueh, R.L.; Maziasz, P.J.; Alexander, D.J.

1996-01-01

Ferritic steels have been considered candidate structural materials for first wall and blanket structures for fusion power plants since the late 1970s. The first steels considered in the United States were the conventional Cr-Mo steels Sandvik HT9 (nominally 12Cr-1Mo-0.25V-0.5W-0.5Ni-0.2C, here designated l2Cr-1MoVW), modified 9Cr-1Mo steel (9Cr-1Mo-0.2V-0.06Nb-0. IC, designated 9Cr-1MoVNb) and, to a lesser extent, 2 1/4Cr-1Mo steel (2.25Cr-Mo-0.1C). All compositions are in wt. %. The normalized-and-tempered 9 and 12Cr steels had a tempered martensite microstructure, and the normalized-and-tempered 2 1/4 Cr steel had a tempered bainite microstructure. This report describes chromium steels tested in normalized and tempered conditions. Miniature tensile and Charpy specimens were tested

Phase transformation in a Ni-Mo-Cr alloy

International Nuclear Information System (INIS)

Dymek, S.; Wrobel, M.; Blicharski, M.; Dollar, M.

2001-01-01

The paper gives a characteristic of a nickel-based superalloy containing 25 wt.% Mo and 8 wt.% Cr with particular attention to the influence of a thermochemical and heat treatment on phase transformations. The applied heat treatments are comprised of soaking temperature 1100 o C followed by aging at 650 o C at three conditions: conventional aging for 72 hours, prolonged aging for 4000 hours and prolonged aging for 4000 hours followed by cold working and subsequent aging for 1000 hours. The conventional aging led to the formation of lenticular precipitates of the dispersed metastable Ni 2 (Mo,Cr) phase. The aging for 4000 hours brought about coarsening of the ordered domains without changing their crystallographic and ordering characteristics. The plastic deformation preceded the further aging for 1000 hours accelerated the decomposition of the Ni 2 (Mo,Cr) phase on the mixture of the Ni 3 Mo and Ni 4 Mo-based phases. (author)

Heat treatment for improvement in lower temperature mechanical properties of 0.40 pct C-Cr-Mo ultrahigh strength steel

Science.gov (United States)

Tomita, Yoshiyuki; Okabayashi, Kunio

1983-11-01

In the previous paper, it was reported that isothermal heat treatment of a commercial Japanese 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel (AISI 4340 type) at 593 K for a short time followed by water quenching, in which a mixed structure of 25 vol pct lower bainite and 75 vol pct martensite is produced, results in the improvement of low temperature mechanical properties (287 to 123 K). The purpose of this paper is to study whether above new heat treatment will still be effective in commercial practice for improving low temperature mechanical properties of the ultrahigh strength steel when applied to a commercial Japanese 0.40 pct C-Cr-Mo ultrahigh strength steel which is economical because it lacks the expensive nickel component (AISI 4140 type). At and above 203 K this new heat treatment, as compared with the conventional 1133 K direct water quenching treatment, significantly improved the strength, tensile ductility, and notch toughness of the 0.40 pct C-Cr-Mo ultrahigh strength steel. At and above 203 K the new heat treatment also produced superior fracture ductility and notch toughness results at similar strength levels as compared to those obtained by using γ α' repetitive heat treatment for the same steel. However, the new heat treatment remarkably decreased fracture ductility and notch toughness of the 0.40 pct C-Cr-Mo ultrahigh strength steel below 203 K, and thus no significant improvement in the mechanical properties was noticeable as compared with the properties produced by the conventional 1133 K direct water quenching treatment and the γ α' repetitive heat treatment. This contrasts with the fact that the new heat treatment, as compared with the conventional 1133 K direct water quenching treatment and the γ α' repetitive heat treatment, dramatically improved the notch toughness of the 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel, providing a better combination of strength and ductility throughout the 287 to 123 K temperature range. The difference

Role of oxides and porosity on high temperature oxidation of liquid fuelled HVOF thermal sprayed Ni50Cr coatings

OpenAIRE

Song, B.; Bai, M.; Voisey, K.T.; Hussain, Tanvir

2017-01-01

High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid fuelled high velocity oxy-fuel (HVOF) thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using...

Effects of Cr2N Precipitation on the Antibacterial Properties of AISI 430 Stainless Steel

OpenAIRE

Je-Kang Du; Chih-Yeh Chao; Yu-Ting Jhong; Chung-Hao Wu; Ju-Hui Wu

2016-01-01

Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainless steels have been widely applied as biomaterials, including the austenitic 304 stainless steel, the austenitic 316 stainless steel, the duplex 2205 stainless steel, and the ferritic 430 stainless steel. In order to reduce the occurrence of infections resulting from biomaterial implants, instruments, and medical devices, Cu2+ and Ag2+ ions have been added onto biomaterials for increasing the anti...

Comparison of SA508 Gr.3 and SA508 Gr.4N Low Alloy Steels for Reactor Pressure Vessel Steel

Energy Technology Data Exchange (ETDEWEB)

Kim, Min Chul; Lee, B. S

2009-12-15

The microstructural characteristics and mechanical properties of SA508 Gr.3 Mn-Mo-Ni low alloy steel and SA508 Gr.4N Ni-Mo-Cr low alloy steel were investigated. The differences in the stable phases between these two low alloy steels were evaluated by means of a thermodynamic calculation using ThermoCalc. They were then compared to microstructural features and correlated with mechanical properties. Mn-Mo-Ni low alloy steel shows the upper bainite structure which has the coarse cementite in the lath boundaries. However, Ni-Mo-Cr low alloy steel shows the mixture of lower bainite and tempered martensite structure that homogeneously precipitates the small carbides such as M{sub 23}C{sub 6} and M{sub 7}C{sub 3} due to an increase of hardenability and Cr addition. In the mechanical properties, Ni-Mo-Cr low alloy steel has higher strength and toughness than Mn-Mo-Ni low alloy steel. Ni and Cr additions increase the strength by solid solution hardening. Besides, microstructural changes from upper bainite to tempered martensite improve the strength of the low alloy steel by grain refining effect. And the changes in the precipitation behavior by Cr addition improve the ductile-brittle transition behavior along with a toughening effect of Ni addition.

Hydrogen embrittlement of the 22 Cr5 Ni austeno-ferritic stainless steel. Role of the microstructure

International Nuclear Information System (INIS)

Iacoviello, Francesco

1997-01-01

Austenitic-ferritic stainless steels are characterised by very good mechanical properties and by a high corrosion resistance, especially to stress-corrosion and to pitting. However, their duplex structure shows a sensitivity to hydrogen embrittlement. Among duplex stainless steels, the 22 Cr 5 Ni grade has gradually became the most used. In this work the tensile properties and the resistance to fatigue crack propagation of 22 Cr5 Ni duplex stainless steel have been analysed, with and without hydrogen charging, after it had been treated at temperatures ranging between 200-1050 deg. C for varying times. The heat treatment times and temperatures were chosen to characterise completely the effects of the different intermetallic and the carbide and nitride phases and to compare these results with those from the tensile tests and those in the literature. A technique for obtaining the hydrogen diffusion coefficient in the steel was optimised and was shown to be alternative to the permeation technique. Thermal analysis was used to determine the activation energy of the hydrogen traps in the steel. From the results the following conclusions were established: - Grain boundaries and dislocations have very little influence on the process of hydrogen diffusion. - The quantity of hydrogen absorbed depends in that any type of precipitate decrease the absorption. This decrease was probably due to changes in the diffusivity and solubility of hydrogen caused by the precipitation. - The charging with hydrogen caused a large decrease in ε m pc for the steel for all heat treatments temperature, except 1050 deg. C. At this temperature the effect was much less as the dislocation density was very low and the precipitates were now in solution. - Hydrogen charging of the steel did not affect the YS and the decrease in UTS produced depended on the microstructure. Use of the embrittlement index 'F' showed that spinodal decomposition and precipitation of G phase decrease hydrogen embrittlement

Relationship of bainitic microstructure to impact toughness in Cr-Mo and Cr-W steels

International Nuclear Information System (INIS)

Klueh, R.L.; Alexander, D.J.

1992-01-01

Non-classical bainite microstructures can develop during continuous cooling of low-carbon alloy steels. These differ from classical upper and lower bainite developed by isothermal transformation. Two non-classical bainite microstructures were produced in a 3Cr-1.5Mo0.25V-0.lC steel using different cooling rates after austenitizing--water quenching and air cooling. The carbide-free acicular bainite formed in the quenched steel had a lower ductile-brittle transition temperature (DBTT) than the granular bainite formed in the air-cooled steel. With increasing tempering parameter (defined bv tempering time and temperature), the DBTT of both decreased and approached a common value, although the final value occurred at a much lower tempering parameter for the quenched steel than for the air-cooled steel. The upper-shelf enery was similarly affected by microstructure. These observations along with similar observations in two Cr-W steels indicate that control of the bainite microstructure can be used to optimize strength and toughness

Effect of ETA treatment on corrosion fatigue in rotors and blades and stress corrosion cracking in 3.5 NiCrMoV steel low-pressure turbine discs

International Nuclear Information System (INIS)

Hitomi, Itoh; Takashi, Momoo; Takayuki, Shiomi

2001-01-01

In recent years, to increase the reliability and reduce the amount of feed water iron to prevent of fouling of steam generator tubes, ethanolamine (ETA) treatment has been adopted into the secondary system. In this investigation, the authors verified that ethanolamine treatment does not adversely affect the susceptibility of either stress corrosion cracking (SCC) in the turbine discs that are the principal units in the secondary system or corrosion fatigue (CF) in rotors and blades. In the first stage, a laboratory investigation was made of (1) SCC initiation and propagation in 3,5 NiCrMoV steel and (2) CF in 3,5 NiCrMoV steel and blade steels, in both cases using deaerated water to which had been added ethanolamine with few organic acids that is 10 times the estimated concentration. It was confirmed that the ethanolamine treatment had almost no effect. In the second stage, test pieces (removed from the disc steel inserted into the turbine extraction chamber before the ethanolamine treatment was started) were used to observe the initiation and propagation of SCC. Even after long-term observation, ethanolamine treatment into the secondary system was found to have almost no effect on the susceptibility of SCC in discs. (author)

Two feasible approaches to enhance the wear behaviors of NiCrBSi coating in atmosphere and aqueous environments

Science.gov (United States)

Ye, Yuwei; Wang, Chunting; Zheng, Wenru; Xiong, Wei; Wang, Yongxin; Li, Xiaogang

2017-09-01

NiCrBSi coating was deposited successfully on the surface of 316 stainless steel substrate by means of plasma spraying. The microstructures and mechanical property were analyzed by scanning electron microscopy, x-ray diffraction, and a Vickers hardness tester. The wear performances of the coatings sliding against the GCr15 ball under ambient air and water conditions were investigated, and two feasible approaches (tungsten carbide (WC)-doping and heat treatment) were used to improve the tribological performance. Results showed that the hardness of the NiCrBSi coating increased by 12.5% and 28.5% and the porosity decreased by 26.1% and 47.8%, respectively, after WC-doping and heat treatment. During dry friction, the friction coefficient and wear rate of the NiCrBSi coating were about 0.47 and 1.4  ×  10-5 mm3 N-1 m-1, respectively. These values were higher than those obtained on other coatings. In water conditions, all coatings showed a lower friction and wear rate than that in ambient air, which was as a result of the lubrication effect of water. Significantly, with WC-doping and heat treatment, the friction coefficients of both coatings were about 18.5% and 36.7%, respectively, lower than that of the NiCrBSi coating. Furthermore, the wear rates of both coatings were about 20% and 70%, respectively, lower than that of the NiCrBSi coating.

Mechanical properties and microstructure changes of low-activation 3Cr-2W-V-Ti ferritic steels developed for nuclear applications

International Nuclear Information System (INIS)

Asakura, Kentaro; Kohyama, Akira; Yamada, Takemi.

1990-01-01

The effects of alloying elements such as Cr, W, V and Mn on tensile strength at elevated temperatures, creep-rupture properties and toughness of low activation (2.25-3)Cr-(2-2.5)W-V-Ti steels were investigated together with their microstructure change during high temperature exposure. These steels were normalized to produce bainitic structures in the same manner as that for a conventional 2.25Cr-1Mo steel. They presented superior tensile strength at elevated temperatures and creep-rupture strength in comparison with a conventional 2.25Cr-1Mo steel. The creep-rupture strength of the steels at 500degC for 100 000 h demonstrated about twice that of the conventional 2.25Cr-1Mo steel. The 3Cr-2.5W-0.2V-0.01Ti steel is recommended as a potential low activation ferritic steel for nuclear applications with well optimized mechanical properties, such as tensile strength at elevated temperatures, creep-rupture strength and toughness. The effects of alloying elements were discussed with correlating microstructural and mechanical aspects. (author)

Effect of Boron Addition on Microstructural Evolution and Room-Temperature Mechanical Properties of Novel Fe66- x CrNiB x Si ( x = 0, 0.25, 0.50 and 0.75 Wt Pct) Advanced High-Strength Steels

Science.gov (United States)

Askari-Paykani, Mohsen; Shahverdi, Hamid Reza; Miresmaeili, Reza

2016-11-01

In this study, the Vickers hardnesses and room-temperature uniaxial tensile behaviors of four Fe66- x CrNiB x Si ( x = 0 (0B), 0.25 (25B), 0.50 (50B), and 0.75 (75B) wt pct) advanced high-strength steels (AHSSs) in the as-hot-rolled and heat-treated (1373 K (1100 °C)/2 h + 973 K (700 °C)/20 min) conditions were investigated. Microstructural evolution after solidification, hot rolling, heat treatment, and uniaxial tensile tests of 0B, 25B, 50B, and 75B AHSSs was also characterized using field emission gun scanning electron microscopy and X-ray diffraction. The tensile behaviors of the 0B, 25B, 50B, and 75B AHSSs were manifested by an excellent combination of strength and ductility over 34.7 and 47.1 GPa pct, 36.9 and 42.3 GPa pct, 45.9 and 46.4 GPa pct, and 11.9 and 47.8 GPa pct, respectively, arising from microband-induced plasticity in the 0B, 50B, and 75B AHSSs and transformation-induced plasticity in the 25B specimens. All specimens in the as-hot-rolled and heat-treated states showed an austenitic matrix grain. Adding boron to the base alloy (0B) resulted in grain refinement, M2B dispersion, precipitation hardening, and solid solution strengthening, which led to an increase in strength. The results of the present work show promise for automotive applications that require excellent properties and reduced specific weight.

The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy under Xe26+ ion irradiation

Science.gov (United States)

Chen, Huaican; Hai, Yang; Liu, Renduo; Jiang, Li; Ye, Xiang-xi; Li, Jianjian; Xue, Wandong; Wang, Wanxia; Tang, Ming; Yan, Long; Yin, Wen; Zhou, Xingtai

2018-04-01

The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy was investigated. 7 MeV Xe26+ ion irradiation was performed at room temperature and 650 °C with peak damage dose from 0.05 to 10 dpa. With the increase of damage dose, the hardness of Ni-Mo-Cr and Ni-W-Cr alloy increases, and reaches saturation at damage dose ≥1 dpa. Moreover, the damage dose dependence of hardness in both alloys can be described by the Makin and Minter's equation, where the effective critical volume of obstacles can be used to represent irradiation hardening resistance of the alloys. Our results also show that Ni-W-Cr alloy has better irradiation hardening resistance than Ni-Mo-Cr alloy. This is ascribed to the fact that the W, instead of Mo in the alloy, can suppress the formation of defects under ion irradiation.

Cyclic and isothermal oxidation behavior of 2.25Cr-1Mo steel

International Nuclear Information System (INIS)

Proy, M.; Utrilla, M. v.; Otero, E.

2014-01-01

Cyclic and isothermal oxidation of chromium-molybdenum steel 2.25Cr-1Mo were analyzed at 550 degree centigrade and 650 degree centigrade during 360 hours in air atmospheres. The cycles were performed with two stages; one of heating in furnace during 90 minutes and then the sample were cooled to 50 degree centigrade by air flow. Thermogravimetric analyses were performed to obtain high temperature corrosion kinetics. Several characterization techniques have been used to identify the corrosion mechanism, as X-Ray Diffraction (XRD), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). Thermal cycling tests can changes the corrosion mechanism, due cracks propagation in oxide scale, that witch can favors the access of oxidant agent to the substrate. (Author)

Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

Energy Technology Data Exchange (ETDEWEB)

Ye, Qingfeng [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Feng, Kai, E-mail: fengkai@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Lu, Fenggui [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Ruifeng [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212003 (China); Huang, Jian; Wu, Yixiong [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China)

2017-02-28

Highlights: • Equimolar CrMnFeCoNi high entropy alloy coating are prepared by laser cladding. • The cladding layer forms a simple FCC phase solid solution with identical dendritic structure. • The cladding layer exhibits a noble corrosion resistance in both 3.5 wt.% NaCl and 0.5 M sulfuric acid. • Element segregation makes Cr-depleted interdendrites the starting point of corrosion reaction. - Abstract: Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower i{sub corr} than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted R{sub t} value reaches its maximum at 24 h during a 48 h’ immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H{sub 2}SO{sub 4} reveals that corrosion starts from Cr-depleted interdendrites.

Microstructure evolution and shear strength of vacuum brazed joint for super-Ni/NiCr laminated composite with Ni–Cr–Si–B amorphous interlayer

International Nuclear Information System (INIS)

Wu, Na; Li, Yajiang; Ma, Qunshuang

2014-01-01

Highlights: • Divorced eutectic of γ-Ni and Ni 3 B formed in the brazed region. • The detailed isothermal solidification mechanism was proposed. • Borides formed at the interfaces at different temperatures were identified. • Effect of brazing temperatures on microstructure and shear strength was investigated. • Excellent joint with shear strength of 191 MPa was obtained at 1100 °C for 20 min. - Abstract: Vacuum brazing of super-Ni/NiCr laminated composite and Cr18–Ni8 steel was carried out with Ni–Cr–Si–B amorphous interlayer at different temperatures (1060–1150 °C). The effects of brazing temperature on the microstructure evolution and shear strength of the joints were investigated. Microstructure, chemical composition and microhardness of the joints were studied using field emission scanning electron microscope, energy dispersive spectroscopy, X-ray diffraction and microsclerometer. Shear strength of the joints were measured by the electromechanical universal testing machine. Diffusion of B was the controlling factor for microstructure evolution. The detailed isothermal solidification mechanism was proposed in this study. The fracture morphology of the joint made at 1100 °C exhibited plastic feature and the shear strength reached 191 MPa. Bulky Ni 3 B formed in super-Ni cover layer near the brazed region when performed at 1060–1100 °C while Ni–B eutectic formed instead at 1150 °C

Solubility of sulfur in Fe-Cr-Ni alloys

International Nuclear Information System (INIS)

Bogolyubskij, S.D.; Petrova, E.F.; Rogov, A.I.; Shvartsman, L.A.

1979-01-01

The solubility of 35 S was determined in Fe-Cr-Ni alloys in the range of temperatures between 910 and 1050 deg C by the method of radiometric analysis. It was found that the solubility of sulfur increases with the concentration of chromium in alloys with 20% Ni

Microstructure investigation of NiAl-Cr(Mo) interface in a directionally solidified NiAl-Cr(Mo) eutectic alloyed with refractory metal

International Nuclear Information System (INIS)

Chen, Y.X.; Cui, C.Y.; Guo, J.T.; Li, D.X.

2004-01-01

The microstructure of a directionally solidified NiAl-Cr(Mo) eutectic alloyed with refractory metal in as-processed and heat-treated states has been studied by means of scanning electron microscopy and high resolution electron microscopy (HREM). The microstructure of the NiAl-Cr(Mo) eutectic was characterized by lamellar Cr(Mo) phases embedded within NiAl matrix with common growth direction of . The interface between NiAl and lamellar Cr(Mo) did not have any transition layers. Misfit dislocations were observed at the NiAl-Cr(Mo) interface. In addition to lamellar Cr(Mo) phases, coherent Cr(Mo, Ni, Al) precipitates and NiAl precipitates were also observed in the NiAl matrix and lamellar Cr(Mo) phases, respectively. After hot isostatic pressing and heat treatment, the NiAl-Cr(Mo) interfaces became smooth and straight. Square array of misfit dislocations was directly observed at the (0 0 1) interface between NiAl and Cr(Mo, Ni, Al) precipitate. The configuration of misfit dislocation network showed a generally good agreement with prediction based on the geometric O-lattice model

High Ni austenite stainless steel resistant to neutron irradiation degradation

International Nuclear Information System (INIS)

Yonezawa, Toshio; Iwamura, Toshihiko; Kanasaki, Hiroshi; Fujimoto, Koji; Nakata, Shizuo; Ajiki, Kazuhide; Nakamura, Mitsuhiro.

1997-01-01

The composition of the stainless steel of the present invention comprises from 0.005 to 0.08% of C, up to 3% of Mn, up to 0.2% of Si+P+S, from 25 to 40% of Ni, from 25 to 40% of Cr, up to 3% of Mo, up to 0.3% of Nb+Ta, up to 0.3% of Ti, up to 0.001% of B and the balance of Fe. A solid solubilization treatment at a temperature of from 1,000 to 1,150degC is applied to the stainless steel having the composition. The stainless steel is excellent in stress corrosion cracking-resistance at a working circumstance of a LWR type reactor (high temperature and high pressure water at from 270 to 350degC/from 70 to 160 atm even after undergoing neutron irradiation of about 1 x 10 22 n/cm 2 (E>1 MeV) which is a maximum neutron irradiation amount undergone till the final stage of the working life of the LWR-type reactor. In addition, the average thermal expansion coefficient at from room temperature to 400degC ranges from 15x10 -6 - 19x10 -6 /K. (I.N.)

Effect of Ti content on structure and properties of Al2CrFeNiCoCuTix high-entropy alloy coatings

International Nuclear Information System (INIS)

Qiu, X.W.; Zhang, Y.P.; Liu, C.G.

2014-01-01

Highlights: • Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. • Al 2 CrFeNiCoCuTi x coatings show excellent corrosion resistance and wear resistance. • Al 2 CrFeNiCoCuTi x coatings play a good protective effect on Q235 steel. • Ti element promotes the formation of a BCC structure in a certain extent. -- Abstract: The Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. The structure, hardness, corrosion resistance, wear resistance and magnetic property were studied by metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation tribometer and multi-physical tester. The result shows that, Al 2 CrFeNiCoCuTi x high-entropy alloy samples consist of the cladding zone, bounding zone, heat affected zone and substrate zone. The bonding between the cladding layer and the substrate of a good combination; the cladding zone is composed mainly of equiaxed grains and columnar crystal; the phase structure of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings simple for FCC, BCC and Laves phase due to high-entropy affect. Ti element promotes the formation of a BCC structure in a certain extent. Compared with Q235 steel, the free-corrosion current density of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings is reduced by 1–2 orders of magnitude, the free-corrosion potential is more “positive”. With the increasing of Ti content, the corrosion resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings enhanced in 0.5 mol/L HNO 3 solution. Compared with Q235 steel, the relative wear resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings has improved greatly; both the hardness and plasticity are affecting wear resistance. Magnetization loop shows that, Ti 0.0 high-entropy alloy is a kind of soft magnetic materials

Spectroscopic characterisation of iodine deposits on 18%Cr/8%Ni and mild steel surfaces oxidised in CO2/CH3I gas mixtures

International Nuclear Information System (INIS)

Tyler, J.W.

1987-08-01

An understanding and quantification of iodine-131 attenuation within the gas circuit of a Commercial Advanced Gas-cooled Reactor is required for reactor safety assessments. To this end it is desirable to identify the chemical state of iodine in the gas phase or when deposited on reactor surfaces. Samples of 18%Cr/8%Ni and mild steel pipe, with iodine deposited on their surfaces following oxidation in CO 2 /CH 3 I gas mixtures, have been characterised in the present work using a variety of different spectroscopic techniques including X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, scanning Auger microscopy and X-ray diffraction. The chemical nature of the deposited iodine has been determined by X-ray photoelectron spectroscopy to be a metal iodide by correlating I 3d binding energies with those obtained from well characterised standards; the binding energies of the ejected I 3d photoelectrons being sensitive to the chemical environment experienced by the iodine atoms. The distribution of iodine throughout the oxide layers formed on these steels was determined by repeated cycles of argon-ion bombardment and analysis to build up an elemental depth profile whilst at the same time determining the chemical state of the elements present. Differences in oxide composition and morphology are discussed in relation to the deposition behaviour observed on 18%Cr/8%Ni and mild steel and it is suggested that gradual incorporation of the iodine occurs throughout the oxidation/deposition period. (U.K.)

Mechanical properties of Fe-Ni-Cr-Si-B bulk glassy alloy

International Nuclear Information System (INIS)

Lee, Kee Ahn; Kim, Yong Chan; Kim, Jung Han; Lee, Chong Soo; Namkung, Jung; Kim, Moon Chul

2007-01-01

The mechanical properties and crystallization behavior of new Fe-Ni-Cr-Si-B-based bulk glassy alloys were investigated. The suitability of the continuous roll casting method for the production of bulk metallic glass (BMG) sheets in such alloy systems was also examined. BMG samples (Fe-Ni-Cr-Si-B, Fe-Ni-Zr-Cr-Si-B, Fe-Ni-Zr-Cr-W-Si-B) in amorphous strip, cylindrical, and sheet forms were prepared through melt spinning, copper mold casting, and twin roll strip casting, respectively. Fe-Ni-Cr-Si-B alloy exhibited compressive strength of up to 2.93 GPa and plastic strain of about 1.51%. On the other hand, the Fe-Ni-Zr-Cr-Si-B, composite-type bulk sample with diameter of 2.0 mm showed remarkable compressive plastic strain of about 4.03%. The addition of zirconium was found to enhance the homogeneous precipitation of nanocrystalline less than 7 nm and to develop a hybrid-composite microstructure with increasing sample thickness. Twin roll strip casting was successfully applied to the fabrication of sheets in Fe-Ni-Cr-Si-B-based BMGs. The combined characteristics of high mechanical properties and ease of microstructure control proved to be promising in terms of the future progress of structural bulk amorphous alloys

Mechanical properties of Fe-Ni-Cr-Si-B bulk glassy alloy

Energy Technology Data Exchange (ETDEWEB)

Lee, Kee Ahn [School of Advanced Materials Engineering, Andong National University, Andong 760-749 (Korea, Republic of)]. E-mail: keeahn@andong.ac.kr; Kim, Yong Chan [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of); Kim, Jung Han [Center for Advanced Aerospace materials, POSTECH, Pohang 790-784 (Korea, Republic of); Lee, Chong Soo [Center for Advanced Aerospace materials, POSTECH, Pohang 790-784 (Korea, Republic of); Namkung, Jung [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of); Kim, Moon Chul [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of)

2007-03-25

The mechanical properties and crystallization behavior of new Fe-Ni-Cr-Si-B-based bulk glassy alloys were investigated. The suitability of the continuous roll casting method for the production of bulk metallic glass (BMG) sheets in such alloy systems was also examined. BMG samples (Fe-Ni-Cr-Si-B, Fe-Ni-Zr-Cr-Si-B, Fe-Ni-Zr-Cr-W-Si-B) in amorphous strip, cylindrical, and sheet forms were prepared through melt spinning, copper mold casting, and twin roll strip casting, respectively. Fe-Ni-Cr-Si-B alloy exhibited compressive strength of up to 2.93 GPa and plastic strain of about 1.51%. On the other hand, the Fe-Ni-Zr-Cr-Si-B, composite-type bulk sample with diameter of 2.0 mm showed remarkable compressive plastic strain of about 4.03%. The addition of zirconium was found to enhance the homogeneous precipitation of nanocrystalline less than 7 nm and to develop a hybrid-composite microstructure with increasing sample thickness. Twin roll strip casting was successfully applied to the fabrication of sheets in Fe-Ni-Cr-Si-B-based BMGs. The combined characteristics of high mechanical properties and ease of microstructure control proved to be promising in terms of the future progress of structural bulk amorphous alloys.

Achievement report on research and development in the Sunshine Project in fiscal 1980. Research on a hydrogen manufacturing technology by using thermo-chemical method. (Research on equipment materials for iodine system cycle); 1980 nendo netsukagakuho ni yoru suiso seizo gijutsu no kenkyu seika hokokusho. Yosokei cycle no sochi zairyo no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1981-03-01

This paper describes research on materials of equipment for the second stage reaction in relation with development on a hydrogen manufacturing technology by using the iodine system cycle in the thermo-chemical method. The second stage reaction produces MgO, I{sub 2} and O{sub 2} by decomposition of Mg(IO{sub 3}){sub 2} at 600 to 650 degrees C. Corrosion tests were carried out by using 25Cr-20Ni steel and Ni-50Cr alloy having shown relatively high corrosion resistance in the researches to date, which were added with trace amount of different alloy elements. The tests were performed in gas mixture of I{sub 2}, O{sub 2} and H{sub 2}O at 600 to 700 degrees C for 48 to 192 hours. The average corrosion rate of 25Cr-20Ni steel was reduced by adding Y(0.2%), Ca (0.2%) or Si+Al (1%Si+1%Al), by which relatively uniform corrosion pattern was shown, and the corrosion resistance was improved remarkably. The average corrosion rate of 25Cr-20Ni steel showed a trend of increasing by adding Si and Nb, and non-uniform corrosion like pitting has occurred, revealing that it is not preferable from the aspect of corrosion resistance. The average corrosion rates of the tested materials tended to become somewhat greater under heat insulated condition than under continuously heating condition. Effect of Mg(IO{sub 3}){sub 2} deposition is very small. (NEDO)

X-ray study of rapidly cooled ribbons of Al-Cr-Zr and Al-Ni-Y-Cr-Zr alloys

International Nuclear Information System (INIS)

Betsofen, S.Ya.; Osintsev, O.E.; Lutsenko, A.N.; Konkevich, V.Yu.

2002-01-01

One investigated into phase composition, lattice spacing and structure of rapidly cooled 25-200 μm gauge strips made of Al-4,1Cr-3,2Zr and Al-1,5Cr-1,5Zr-4Ni-3Y alloys, wt. %, produced by melt spinning to a water-cooled copper disk. In Al-4,1Cr-3,2Zr alloy one detected intermetallic phases: Al 3 Zr and two Al 86 Cr 14 composition icosahedral phases apart from aluminium solid solution with 4.040-4.043 A lattice spacing. In Al-1,5Cr-1,5Zr-4Ni-3Y alloy one identified two Al 86 Cr 14 icosahedral phases and two AlNiY and Al 3 Y yttrium-containing ones, lattice spacing of aluminium solid solution was equal to 4.052-4.053 A [ru

Ab initio investigation of the surface properties of austenitic Fe-Ni-Cr alloys in aqueous environments

Energy Technology Data Exchange (ETDEWEB)

Rák, Zs., E-mail: zrak@ncsu.edu; Brenner, D.W.

2017-04-30

Highlights: • The trend in the surface energies of austenitic stainless steels is: (111) < (100) < (110). • On the (111) orientation Ni segregates to the surface and Cr segregates into the bulk. • The surface stability of the alloys in contact with water decrease with temperature and pH. - Abstract: The surface energetics of two austenitic stainless steel alloys (Type 304 and 316) and three Ni-based alloys (Alloy 600, 690, and 800) are investigated using theoretical methods within the density functional theory. The relative stability of the low index surfaces display the same trend for all alloys; the most closely packed orientation and the most stable is the (111), followed by the (100) and the (110) surfaces. Calculations on the (111) surfaces using various surface chemical and magnetic configurations reveal that Ni has the tendency to segregate toward the surface and Cr has the tendency to segregate toward the bulk. The magnetic frustration present on the (111) surfaces plays an important role in the observed segregation tendencies of Ni and Cr. The stability of the (111) surfaces in contact with aqueous solution are evaluated as a function of temperature, pH, and concentration of aqueous species. The results indicate that the surface stability of the alloys decrease with temperature and pH, and increase slightly with concentration. Under conditions characteristic to an operating pressurized water reactor, the Ni-based alloy series appears to be of better quality than the stainless steel series with respect to corrosion resistance and release of aqueous species when in contact with aqueous solutions.

Properties of welded joints of 2,25Cr-1Mo steel with various carbon content

International Nuclear Information System (INIS)

Vornovitskij, I.N.; Brodetskaya, E.Z.; Pozdnyakova, A.S.

1980-01-01

Properties of welded joints of 2,25 Cr - 1 Mo steel pipelines with different carbon content are considered. It is shown that application of electrodes developed in some countries for welding permits in many cases to exclude heat treatment of welded joints owing to high ductility of weld deposited metal. To improve the ductility, it is necessary to limit both carbon content down to 0,03-0,06% and detrimental elements (sulfur, phosphorus). Heat affected zone hardness may be increased at the expense of carbon. Weld deposited metal possesses the highest long-term strength at the given test temperature; in this case long-term strength of welded joints and base metal is practically the same. The long-term strength of high-carbon steel is higher at the test temperature of 565 deg C as compared to mean-carbon and low-carbon steels, whose long-term strength is practically equal at this temperature. The long-term strength of high-carbon and mean-carbon steels is practically the same and higher as compared with low-carbon one at the test temperature of 510 deg C

Cladding nuclear steels - the application of plasma-arc hot wire surfacing

International Nuclear Information System (INIS)

Trarbach, K.O.

1981-01-01

The effect of one and two layer plasma-arc hot wire cladding on the HAZ microstructure of the fine grained structural steel 22 NiMoCr 3 7, which is similar to ASTM A 508, class 2, and steel 20 MnMoNi 5 5, similar to ASTM A 533, grade B, class 1 is determined. Attention is directed particularly to the behaviour of the susceptible region, and the consumables considered are cladding materials X 2 CrNiNb 19 9, similar to ER 347 Elc, and S-NiCr 20 Nb, similar to ER NiCr-3 (Inconel 82). Results of corrosion resistance tests show that this cladding technique can be recommended for manufacture of equipment for the chemical industry to avoid corrosion failure. Plasma-arc hot wire surfacing is also shown to be capable of depositing single or double clad layers to meet the highest safety requirements and could be applied to nuclear power plants for the special manufacture of wear resistant parts and for protection of equipment subject to a variety of corrosive environments. (U.K.)

Low-temperature cyclic cracking resistance of Fe-Cr-Ni and Fe-Cr-Mn steels welded joints

International Nuclear Information System (INIS)

Ostash, O.P.; Zhmur-Klimenko, V.T.; Yarema, S.Ya.; Yushchenko, K.A.; Strok, L.P.; Belotserkovets, V.I.

1983-01-01

Results of further investigations into regularities of development of low-temperature fatigue fracture of welded oints in 07Kh13G20AN4 steel are presented, they are compared with analogous data traditional cryogenic 0Kh18N10T and 03Kh13AG19 steels. Welded joints have been prepared by means of automatic V-like level arc Welding of plates; 0Kh18N10T and 07Kh13G20AN4 steels have been welded by means of sv-04Kh19N9 wire, 03Kh13AG19 steel-by means of sv-07Kh13AG19 wire. Tests at almost zero (asymmetry coefficient R=0.05) cycle of extension at 15-20 Hz frequency have been conducted on 5 mm thick disk samples at 20 deg C and - 160 deg C according to the given methods. It is shown that by cyclic crack resistance of welded joint zones of 0Kh18N10T steel and chromium-manganese steels at normal temperature the 07Kh13G20AN4 steel exceeds 0Kh18N10T steel, at low temperature it yields to 0Kh18N10T only by fracture toughness of heat affected zones HAZ and weld metal (ne). 07Kh13G20AN4 steel and its welded joints as most hardened and cheap may be a good substituent for 0Kh18N10T steel. Optimization of WM alloying for increase of its cyclic fracture toughness at cryogenic temperatures is necessary

Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys

International Nuclear Information System (INIS)

Novakovic, R

2011-01-01

The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi 2 composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al 8 Cr 5 and CrNi 2 chemical complexes, respectively, as energetically favoured.

Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys.

Science.gov (United States)

Novakovic, R

2011-06-15

The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi(2) composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al(8)Cr(5) and CrNi(2) chemical complexes, respectively, as energetically favoured.

Effect of Cr, Ni, and Mo additions on the susceptibility of the 0Kh6n7m7c steel to hot cracking

International Nuclear Information System (INIS)

Tolstykh, L.G.; Pryakhin, A.V.; Popov, A.N.; Usynin, V.F.

1977-01-01

The effect of chromium, molybdenum, and nickel on the tendency of surfacing materials to form hot cracks (Vsub(kp) was studied using the mathematical statistics method. The St3 steel and 38KhN3MFA steel were used in the study. A device facilitating the hot cracking tendency test procedure was developed. It was found that, in the concentration range involved, Ni and Mo produce no effect on Vsub(kp), and Cr enhances it. A new powder wire, PP-OKh7N8M6S, capable of increasing surface material resistance by 1.5-2 times, has been developed

Friction and wear behaviour of Ni-Cr-B hardface coating on 316LN stainless steel in liquid sodium at elevated temperature

Science.gov (United States)

Kumar, Hemant; Ramakrishnan, V.; Albert, S. K.; Bhaduri, A. K.; Ray, K. K.

2017-11-01

The sliding friction and wear behaviour of Ni-Cr-B hardface coating made on 316LN stainless steel were evaluated in liquid sodium at 823 K by using a fabricated reciprocating-type tribometer. The test parameters have been selected based on operational conditions prevailing in the Indian sodium cooled fast breeder reactors (FBRs). Accordingly, the tests were carried out at sliding speeds of 2 and 16 mm/s under contact stresses of 10 and 40 MPa respectively using Ni-Cr-B coated pin and disc specimens. The static and dynamic friction coefficients are found to be in the ranges of 0.03-0.07 and 0.01-0.02 respectively under the imposed test conditions. The estimated wear rates (WR) are found to be in the range of 0.62 × 10-12 - 3.07 × 10-12 m3/m; the magnitude of WR increases with increase in the contact stress. The examination of the worn disc specimens by confocal laser scanning microscopy indicated higher damage in specimens tested at 40 MPa compared to that in specimens tested at 10 MPa; the quantitative estimation of damage was made by the number of scars and their depth. These observations corroborate well with the morphological features of the worn surfaces of the pin specimens examined by scanning electron microscopy. The results unambiguously indicate superior friction coefficients and wear resistance of Ni-Cr-B coatings in liquid sodium compared to that in air under identical test conditions.

Stainless steel leaches nickel and chromium into foods during cooking.

Science.gov (United States)

Kamerud, Kristin L; Hobbie, Kevin A; Anderson, Kim A

2013-10-02

Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel saucepan, cooking times of 2-20 h, 10 consecutive cooking cycles, and four commercial tomato sauces. After a simulated cooking process, samples were analyzed by ICP-MS for Ni and Cr. After 6 h of cooking, Ni and Cr concentrations in tomato sauce increased up to 26- and 7-fold, respectively, depending on the grade of stainless steel. Longer cooking durations resulted in additional increases in metal leaching, where Ni concentrations increased 34-fold and Cr increased approximately 35-fold from sauces cooked without stainless steel. Cooking with new stainless steel resulted in the largest increases. Metal leaching decreases with sequential cooking cycles and stabilized after the sixth cooking cycle, although significant metal contributions to foods were still observed. The tenth cooking cycle resulted in an average of 88 μg of Ni and 86 μg of Cr leached per 126 g serving of tomato sauce. Stainless steel cookware can be an overlooked source of nickel and chromium, where the contribution is dependent on stainless steel grade, cooking time, and cookware usage.

Stainless Steel Leaches Nickel and Chromium into Foods During Cooking

Science.gov (United States)

Kamerud, Kristin L.; Hobbie, Kevin A.; Anderson, Kim A.

2014-01-01

Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel saucepan; cooking times of 2 to 20 hours, ten consecutive cooking cycles, and four commercial tomato sauces. After a simulated cooking process, samples were analyzed by ICP-MS for Ni and Cr. After six hours of cooking, Ni and Cr concentrations in tomato sauce increased up to 26- and 7-fold respectively, depending on the grade of stainless steel. Longer cooking durations resulted in additional increases in metal leaching, where Ni concentrations increased 34 fold and Cr increased approximately 35 fold from sauces cooked without stainless steel. Cooking with new stainless steel resulted in the largest increases. Metal leaching decreases with sequential cooking cycles and stabilized after the sixth cooking cycle, though significant metal contributions to foods were still observed. The tenth cooking cycle, resulted in an average of 88 μg of Ni and 86 μg of Cr leached per 126 g serving of tomato sauce. Stainless steel cookware can be an overlooked source of nickel and chromium, where the contribution is dependent on stainless steel grade, cooking time, and cookware usage. PMID:23984718

Martensite shear phase reversion-induced nanograined/ultrafine-grained Fe-16Cr-10Ni alloy: The effect of interstitial alloying elements and degree of austenite stability on phase reversion

Energy Technology Data Exchange (ETDEWEB)

Misra, R.D.K., E-mail: dmisra@louisiana.edu [Center for Structural and Functional Materials, University of Louisiana at Lafayette, Madison Hall Room 217, P.O. Box 44130, Lafayette, LA 70504-1430 (United States); Zhang, Z.; Venkatasurya, P.K.C. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, Madison Hall Room 217, P.O. Box 44130, Lafayette, LA 70504-1430 (United States); Somani, M.C.; Karjalainen, L.P. [Department of Mechanical Engineering, University of Oulu, P.O. Box 4200, Oulu 90014 (Finland)

2010-11-15

Research highlights: {yields} Development of a novel process involving phase-reversion annealing process. {yields} Austensite stability strongly influences development of nanograined structure. {yields} Interstitial elements influence microstructural evolution during annealing. - Abstract: We describe here an electron microscopy study of microstructural evolution associated with martensitic shear phase reversion-induced nanograined/ultrafine-grained (NG/UFG) structure in an experimental Fe-16Cr-10Ni alloy with very low interstitial content. The primary objective is to understand and obtain fundamental insights on the influence of degree of austenite stability (Fe-16Cr-10Ni, 301LN, and 301 have different austenite stability index) and interstitial elements (carbon and nitrogen) in terms of phase reversion process, microstructural evolution during reversion annealing, and temperature-time annealing sequence. A relative comparison of Fe-16Cr-10Ni alloy with 301LN and 301 austenitic stainless steels indicated that phase reversion in Fe-16Cr-10Ni occurred by shear mechanism, which is similar to that observed for 301, but is different from the diffusional mechanism in 301LN steel. While the phase reversion in the experimental Fe-16Cr-10Ni alloy and 301 austenitic stainless steel occurred by shear mechanism, there were fundamental differences between these two alloys. The reversed strain-free austenite grains in Fe-16Cr-10Ni alloy were characterized by nearly same crystallographic orientation, where as in 301 steel there was evidence of break-up of martensite laths during reversion annealing resulting in several regions of misoriented austenite grains in 301 steel. Furthermore, a higher phase reversion annealing temperature range (800-900 deg. C) was required to obtain a fully NG/UFG structure of grain size 200-600 nm. The difference in the phase reversion and the temperature-time sequence in the three stages is explained in terms of Gibbs free energy change that

The influence of cold work on the oxidation behaviour of stainless steel

International Nuclear Information System (INIS)

Langevoort, J.C.

1985-01-01

In this thesis the study of the interaction of oxygen gas with stainless steel surfaces is described. Thermogravimetry, microscopy and ellipsometry have been used to follow the oxidation in situ, while EDX, AES and XPS have been used to determine the oxide compositions. The aim of this thesis is to reveal the influence on the oxidation behaviour of stainless steel of i) cold work (rolling, drawing, milling, polishing and Ar ion bombardment) ii) the initially formed oxide and iii) the experimental conditions. Two types of stainless steels have been used (AISI 304 (a 18/8 Cr/Ni steel) and Incoloy 800 H (a 20/30 Cr/Ni steel)). (Auth.)

Tantalum-containing Z-phase in 12%Cr martensitic steels

DEFF Research Database (Denmark)

Danielsen, Hilmar Kjartansson; Hald, John

2009-01-01

Z-phases in tantalum-containing 12%Cr steels have been investigated. In 12%Cr steel without any Nb or V, the formation of CrTaN Z-phases was observed. In 12%Cr steel which also contained V, the Ta entered Z-phase as a minor element, Cr(V,Ta)N. The crystal structure of Cr(V,Ta)N seems to be identi......Z-phases in tantalum-containing 12%Cr steels have been investigated. In 12%Cr steel without any Nb or V, the formation of CrTaN Z-phases was observed. In 12%Cr steel which also contained V, the Ta entered Z-phase as a minor element, Cr(V,Ta)N. The crystal structure of Cr(V,Ta)N seems...

Effects of Cr2N Precipitation on the Antibacterial Properties of AISI 430 Stainless Steel

Directory of Open Access Journals (Sweden)

Je-Kang Du

2016-03-01

Full Text Available Based on their mechanical properties and good corrosion resistance, some commercial Ni-Cr stainless steels have been widely applied as biomaterials, including the austenitic 304 stainless steel, the austenitic 316 stainless steel, the duplex 2205 stainless steel, and the ferritic 430 stainless steel. In order to reduce the occurrence of infections resulting from biomaterial implants, instruments, and medical devices, Cu2+ and Ag2+ ions have been added onto biomaterials for increasing the antibacterial properties, but they are known to damage biofilm. The occurrence of nanoparticles can also improve the antibacterial properties of biomaterials through various methods. In this study, we used Escherichia coli and analyzed the microstructures of American Iron and Steel Institute (AISI 430 stainless steel with a 0.18 mass % N alloy element. During a lower temperature aging, the microstructure of the as-quenched specimen is essentially a ferrite and martensite duplex matrix with some Cr2N precipitates formed. Additionally, the antibacterial properties of the alloy for E. coli ranged from 3% to 60%, consistent with the presence of Cr2N precipitates. When aged at a lower temperature, which resulted in nano-Cr2N precipitation, the specimen possessed the highest antibacterial activity.

Testing of Ni-plated ferritic steel interconnect in SOFC stacks

DEFF Research Database (Denmark)

Nielsen, K.A.; Dinesen, A.R.; Korcakova, L.

2006-01-01

heating to 1,030 °C. During this time, 20–70 μm thick surface layers of austenitic steel were formed, which were covered by a 1–4 μm chromia layer on the anode side and by a layer of mixed Cr-Fe-Ni-spinels over a 1–4 μm chromia layer on the cathode side. The microstructure and composition...... of the protective scale on the cathode side was susceptible to pitting-type corrosion patterns, which may limit the life expectancy to less than 2,000 hours for the 200 μm thick interconnect tested. The initial area-specific resistances (ASR) at the interconnect/cathode current collector interface...

Weldability of Stainless Steels

International Nuclear Information System (INIS)

Saida, Kazuyoshi

2010-01-01

It gives an outline of metallographic properties of welding zone of stainless steels, generation and mechanisms of welding crack and decreasing of corrosion resistance of welding zone. It consists of seven chapters such as introduction, some kinds of stainless steels and properties, metallographic properties of welding zone, weld crack, toughness of welding zone, corrosion resistance and summary. The solidification modes of stainless steels, each solidification mode on the cross section of Fe-Cr-Ni alloy phase diagram, each solidification mode of weld stainless steels metal by electron beam welding, segregation state of alloy elements at each solidification mode, Schaeffler diagram, Delong diagram, effects of (P + S) mass content in % and Cr/Ni equivalent on solidification cracking of weld stainless steels metal, solidification crack susceptibility of weld high purity stainless steels metal, effects of trace impurity elements on solidification crack susceptibility of weld high purity stainless steels metal, ductile fracture susceptibility of weld austenitic stainless steels metal, effects of H2 and ferrite content on generation of crack of weld 25Cr-5N duplex stainless steels, effects of O and N content on toughness of weld SUS 447J1 metals, effect of ferrite content on aging toughness of weld austenitic stainless steel metal, corrosion morphology of welding zone of stainless steels, generation mechanism of knife line attack phenomenon, and corrosion potential of some kinds of metals in seawater at room temperature are illustrated. (S.Y.)

Characterization and Evaluation of Aged Chromium Nickel Niobium Stainless Steels

Science.gov (United States)

Dewar, Matthew

20Cr-32Ni-1Nb stainless steel alloys are commonly used in hydrogen reformer manifolds for transporting hot hydrogen by-products at 750-950°C. After long periods of exposure, embrittling secondary carbides and intermetallic phases can precipitate at the grain boundaries which can drastically reduce the ductility, and the repair weldability of the alloy. The intermetallic silicide, G-phase, is commonly observed in 20Cr-32Ni-1Nb stainless steels, and is prone to liquation cracking during welding operations. G-phase is deleterious to the material, where a high degree of G-phase coarsening will render the material unweldable. The present work will investigate various methods in mitigating G-phase precipitation. Variations in casting methods, wall thickness, homogenization treatments, and alloy chemistry will be examined by evaluating their microstructure after periodically aging the samples. Thermodynamic equilibrium modeling using computational thermodynamic tools will be used to optimize the 20Cr-32Ni-1Nb chemistry following ASTM specifications.

Densities of molten Ni-(Cr, Co, W) superalloys

Institute of Scientific and Technical Information of China (English)

XIAO Feng; YANG Ren-hui; FANG Liang; LIU Lan-xiao; ZHAO Hong-kai

2008-01-01

In order to obtain more accurate density for molten Ni-(Cr, Co, W) binary alloy, the densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys were measured with a sessile drop method. It is found that the measured densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys decrease with increasing temperature in the experimental temperature range. The density of alloys increases with increasing W and Co concentrations while it decreases with increasing Cr concentration in the alloy at 1 773-1 873 K. The molar volume of Ni-based alloys increases with increasing W concentration while it decreases with increasing Co concentration. The effect of Cr concentration on the molar volume of the alloy is little in the studied concentration range. The accommodation among atomic species was analyzed. The deviation of molar volume from ideal mixing shows an ideal mixing of Ni-(Cr, Co, W) binary alloys.

Metallographical investigations on cavitation erosion of the steel X 2 CrNiMoN 22 5 3

International Nuclear Information System (INIS)

Pohl, M.; Goecke, A.

1989-01-01

The development of erosion-resistant material, however, presupposes a precise knowledge of the mechanism and progress of the destruction. For this reason, cavitation erosion was studied in this investigation using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and ultra-microhardness tests (UMHT) - as well as gravimetry. A Cr-Ni-Mo steel with a ferritic-austenitic structure was investigated. This material was selected to provide information about the possible interaction between the phases within such a structure and about the damage mechanism of the individual phases. The experimental material was modified by a heat treatment to precipitate the σ-phase so that a three-phase model material could be obtained as well as the two-phase alloy. (orig./MM) [de

Combined equilibrium and non-equilibrium phosphorus segregation to grain boundaries in a 2.25Cr1Mo steel

International Nuclear Information System (INIS)

Song, S.-H.; Shen, D.-D.; Yuan, Z.-X.; Liu, J.; Xu, T.-D.; Weng, L.-Q.

2003-01-01

Grain boundary segregation of phosphorus in a P-doped 2.25Cr1Mo steel during ageing at 540 deg. C after quenching from 980 deg. C is examined by Auger electron spectroscopy. The segregation is a combined effect of equilibrium segregation and non-equilibrium segregation. The effect of phosphorus non-equilibrium segregation is to enhance the kinetics of its equilibrium segregation

Stress corrosion cracking in repair-welded 3.5 NiCrMoV steel in an actual turbine environment

International Nuclear Information System (INIS)

Hitomi, Itoh; Takashi, Shige; Takashi, Momoo

2001-01-01

Temporary welding repairs are sometimes needed when damage occurs at the teeth of blade grooves in a low-pressure turbine rotor operated at the dry/wet boundary region. When repair welding has been performed for the 3,5 NiCrMoV steel used in low-pressure turbines, the soundness of the weld must be confirmed. For this reason, a laboratory investigation of susceptibility for stress corrosion cracking (SCC) was conducted for test specimens taken from simulated welds, and then an exposure test was conducted in an actual turbine environment for approximately 7,000 hours. As no SCC initiation was detected and also the propagation was extremely small, repair welding is deemed to be applicable. (author)

Characterization of oxide scales grown on alloy 310S stainless steel after long term exposure to supercritical water at 500 °C

Energy Technology Data Exchange (ETDEWEB)

Behnamian, Yashar, E-mail: behnamia@ualberta.ca [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada); Mostafaei, Amir [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Kohandehghan, Alireza [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada); Amirkhiz, Babak Shalchi [Canmet MATERIALS, Natural Resources Canada, Hamilton, Ontario L8P 0A5 (Canada); Serate, Daniel [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada); Zheng, Wenyue [Canmet MATERIALS, Natural Resources Canada, Hamilton, Ontario L8P 0A5 (Canada); Guzonas, David [Canadian Nuclear Laboratories, Chalk River Laboratories, Chalk River, Ontario K0J 1J0 (Canada); Chmielus, Markus [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Chen, Weixing, E-mail: Weixing@ualberta.ca [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada); Luo, Jing Li, E-mail: Jingli.luo@ualberta.ca [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 1H9 (Canada)

2016-10-15

The oxide scale grown of static capsules made of alloy 310S stainless steel was investigated by exposure to the supercritical water at 500 °C 25 MPa for various exposure times up to 20,000 h. Characterization techniques such as X-ray diffraction, scanning/transmission electron microscopy, energy dispersive spectroscopy, and fast Fourier transformation were employed on the oxide scales. The elemental and phase analyses indicated that long term exposure to the SCW resulted in the formation of scales identified as Fe{sub 3}O{sub 4} (outer layer), Fe-Cr spinel (inner layer), Cr{sub 2}O{sub 3} (transition layer) on the substrate, and Ni-enrichment (chrome depleted region) in the alloy 310S. It was found that the layer thickness and weight gain vs. exposure time followed parabolic law. The oxidation mechanism and scales grown on the alloy 310S stainless steel exposed to SCW are discussed. - Highlights: •Oxidation of alloy 310S stainless steel exposed to SCW (500 °C/25 MPa) •The layer thickness and weight gain vs. exposure time followed parabolic law. •Oxide layers including Fe{sub 3}O{sub 4} (outer), Fe-Cr spinel (inner) and Cr{sub 2}O{sub 3} (transition) •Ni element is segregated by the selective oxidation of Cr.

Effect of composition on the electrochemical behavior of austenitic stainless steel in Ringer's solution

International Nuclear Information System (INIS)

Bandy, R.; Cahoon, J.R.

1977-01-01

Potentiodynamic cyclic polarization tests on Type 316L stainless steel, a common orthopedic implant alloy, in Ringer's solution show considerable hysteresis and a protection potential more active than the open circuit corrosion potential. This implies that chances of repassivation of actively growing pits in this alloy are limited. Tests in Ringer's solution containing hydrochloric acid show that the open circuit potential of Type 316L steel in this solution may exceed in the noble direction the critical pitting potential in the same solution. This signifies that spontaneous breakdown of passivity may occur in a bulk environment which grossly simulates the electrochemical environment within a crevice. Alloying elements such as Mo, Ni, Cr, all improve the corrosion resistance of Type 316L stainless steel in that the critical pitting potential shifts in the noble direction in the alloys having any of the three alloying elements in a higher proportion than in Type 316L steel. Polarization tests in Ringer's solution on a 20% Cr, 25% Ni, 4.5% Mo, 1.5% Cu austenitic stainless steel, having Mo, Cr, and Ni--all in higher proportions than in Type 316L steel, does not show any critical pitting potential or hysteresis at potentials below that for dissociation of water. However, test in 4% NaCl solution at 60 C, a more aggressive chloride environment than Ringer'ssolution, reveals considerable hysteresis and a very active protection potential, indicating that this behavior is a common feature of austenitic stainless steel in sufficiently aggressive, chloride media

Use of microstructure control to toughen ferritic steels for cryogenic use. I. Fe--Ni steels

International Nuclear Information System (INIS)

Syn, C.K.; Jin, S.; Morris, J.W. Jr.

1976-12-01

Alternation of austenitization and austenite + ferrite two-phase decomposition treatment in a cyclic thermal treatment allows the achievement of ultra-fine grain size in steels containing 8-12% Ni. The grain refinement leads to a substantial improvement in cryogenic mechanical properties. The ductile-brittle transition temperature of a ferritic Fe-12Ni-0.25Ti alloy was suppressed to below liquid helium temperature by this grain refinement procedure; the transition temperature of commercial ''9Ni'' cryogenic steel was similarly reduced by combining the grain refinement with a final temper which introduces a small admixture of retained austenite

Void formation and helium effects in 9Cr-1MoVNb and 12Cr-1MoVW steels irradiated in HFIR and FFTF at 400/degree/C

International Nuclear Information System (INIS)

Maziasz, P.J.; Klueh, R.L.

1988-01-01

Martensitic/ferritic 9Cr-1MoVNb and 12Cr-1MoVW steels doped with up to 2 wt% Ni have up to 450 appm He after HFIR irradiation to /approximately/38 dpa, but only 5 appm He after 47 dpa in FFTF. No fine He bubbles and few or no larger voids were observable in any of these steels after FFTF irradiation at 407/degree/C. By contrast, many voids were found in the undoped steels (30-90 appm He) irradiated in HFIR at 400/degree/C, while voids plus many more fine He bubbles were found in the Ni-doped steels (400-450 appm He). Irradiation in both reactors at /approximately/400/degree/C produced significant changes in the as-tempered lath/subgrain boundary, dislocation, and precipitation structures that were sensitive to alloy composition, including doping with Ni. However, for each specific alloy the irradiation-produced changes were exactly the same comparing samples irradiated in FFTF and HFIR, particularly the Ni-doped steels. Therefore, the increased void formation appears solely due to the increased helium generation found in HFIR. While the levels of void swelling are relatively low after 37-39 dpa in HFIR (0.1-0.4%), details of the microstructural evolution suggest that void nucleation is still progressing, and swelling could increase with dose. The effect of helium on void swelling remains a valid concern for fusion application that requires higher dose experiments. 15 refs., 14 figs., 8 tabs

Investigation on the parameter optimization and performance of laser cladding a gradient composite coating by a mixed powder of Co50 and Ni/WC on 20CrMnTi low carbon alloy steel

Science.gov (United States)

Shi, Yan; Li, Yunfeng; Liu, Jia; Yuan, Zhenyu

2018-02-01

In this study, a gradient composite coating was manufactured on 20CrMnTi alloy steel by laser cladding. The laser power, cladding scan velocity and powder flow rate were selected as influencing factors of the orthogonal cladding experiments. The influencing factors were optimized by the comprehensive analysis of Taguchi OA and TOPSIS method. The high significant parameters and the predicted results were confirmed by the ANOVA method. The macromorphology and microstructures are characterized by using laser microscope, SEM, XRD and microhardness tester. Comparison tests of wear resistance of gradient composite coating, 20CrMnTi cemented quenching sample and the 20CrMnTi sample were conducted on the friction-wear tester. The results show that the phases are γ-Co solid solution, Co3B, M23C6 and etc. The interlayers and wear-resisting layer also contain new hard phases as WC, W2C. The microhardness of the gradient coating was increased to 3 times as compared with that of the 20CrMnTi substrate. The wear resistance of the gradient composite coating and 20CrMnTi cemented quenching sample was enhanced to 36.4 and 15.9 times as compared with that of the 20CrMnTi.

The corrosion of austenitic steel in flowing high-temperature water

International Nuclear Information System (INIS)

Asmundis, C. de; Weisgerber, P.; Mazzocchi, N.; Plog, C.

1981-01-01

This work represents an attempt to obtain data on the corrosion product formation, including corrosion products which are released to the water, of austenitic steel. AISI 316 or DIN Werkstoff No. 14401. The oxidation experiments were carried out in a small laboratory test loop, which was designed for this study. In the stainless water system considered during an oxidation time of 1800 h at 300 0 C, five zones of differing composition developed. 1. The base metal (for comparison) Fe/Cr/Ni = 67/20/13. 2. The metal at the metal/oxide interface nickel enriched, chromium and iron decreased Fe/Cr/Ni = 64/19/17. 3. The inner oxide chromium enriched and iron and nickel decreased Fe/Cr/Ni = 53/32/14. 4. The outer oxide iron enriched, chromium decreased Fe/Cr/Ni = 70/17/13. 5. The corrosion products released to the water, in total, i.e. particulate and dispersed matter, a Fe/Cr/Ni ratio rather close to that base metal: Fe/Cr/Ni = 68/19/13. (80% particulate: Fe/Cr/Ni = 72/23/5, 20% dispersed: Fe/Cr/Ni = 55/1/44)

Thermodynamic Modelling of Fe-Cr-Ni-Spinel Formation at the Light-Water Reactor Conditions

International Nuclear Information System (INIS)

Kurepin, V. A.; Kulik, D. A.; Hitpold, A.; Nicolet, M.

2002-03-01

In the light water reactors (LWR), the neutron activation and transport of corrosion products is of concern in the context of minimizing the radiation doses received by the personnel during maintenance works. A practically useful model for transport and deposition of the stainless steel corrosion products in LWR can only be based on an improved understanding of chemical processes, in particular, on the attainment of equilibrium in this hydrothermal system, which can be described by means of a thermodynamic solid-solution -aqueous-solution (SSAS) model. In this contribution, a new thermodynamic model for a Fe-Cr-Ni multi-component spinel solid solutions was developed that considers thermodynamic consequences of cation interactions in both spinel sub-Iattices. The obtained standard thermodynamic properties of two ferrite and two chromite end-members and their mixing parameters at 90 bar pressure and 290 *c temperature predict a large miscibility gap between (Fe,Ni) chromite and (Fe,Ni) ferrite phases. Together with the SUPCRT92-98 thermo- dynamic database for aqueous species, the 'spinel' thermodynamic dataset was applied to modeling oxidation of austenitic stainless steel in hydrothermal water at 290*C and 90 bar using the Gibbs energy minimization (GEM) algorithm, implemented in the GEMS-PSI code. Firstly, the equilibrium compositions of steel oxidation products were modelIed as function of oxygen fugacity .fO 2 by incremental additions of O 2 in H 2 O-free system Cr-Fe- Ni-O. Secondly, oxidation of corrosion products in the Fe-Cr-Ni-O-H aquatic system was modelIed at different initial solid/water ratios. It is demonstrated that in the transition region from hydrogen regime to oxygen regime, the most significant changes in composition of two spinel-oxide phases (chromite and ferrite) and hematite must take place. Under more reduced conditions, the Fe-rich ferrite (magnetite) and Ni-poor chromite phases co-exist at equilibrium with a metal Ni phase, maintaining

Thermodynamic Modelling of Fe-Cr-Ni-Spinel Formation at the Light-Water Reactor Conditions

Energy Technology Data Exchange (ETDEWEB)

Kurepin, V.A.; Kulik, D.A.; Hitpold, A.; Nicolet, M

2002-03-01

In the light water reactors (LWR), the neutron activation and transport of corrosion products is of concern in the context of minimizing the radiation doses received by the personnel during maintenance works. A practically useful model for transport and deposition of the stainless steel corrosion products in LWR can only be based on an improved understanding of chemical processes, in particular, on the attainment of equilibrium in this hydrothermal system, which can be described by means of a thermodynamic solid-solution -aqueous-solution (SSAS) model. In this contribution, a new thermodynamic model for a Fe-Cr-Ni multi-component spinel solid solutions was developed that considers thermodynamic consequences of cation interactions in both spinel sub-Iattices. The obtained standard thermodynamic properties of two ferrite and two chromite end-members and their mixing parameters at 90 bar pressure and 290 *c temperature predict a large miscibility gap between (Fe,Ni) chromite and (Fe,Ni) ferrite phases. Together with the SUPCRT92-98 thermo- dynamic database for aqueous species, the 'spinel' thermodynamic dataset was applied to modeling oxidation of austenitic stainless steel in hydrothermal water at 290*C and 90 bar using the Gibbs energy minimization (GEM) algorithm, implemented in the GEMS-PSI code. Firstly, the equilibrium compositions of steel oxidation products were modelIed as function of oxygen fugacity .fO{sub 2} by incremental additions of O{sub 2} in H{sub 2}O-free system Cr-Fe- Ni-O. Secondly, oxidation of corrosion products in the Fe-Cr-Ni-O-H aquatic system was modelIed at different initial solid/water ratios. It is demonstrated that in the transition region from hydrogen regime to oxygen regime, the most significant changes in composition of two spinel-oxide phases (chromite and ferrite) and hematite must take place. Under more reduced conditions, the Fe-rich ferrite (magnetite) and Ni-poor chromite phases co-exist at equilibrium with a metal Ni

High temperature aging structures of Ni-20Cr-20W alloys

International Nuclear Information System (INIS)

Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

1977-01-01

High temperature aging structures and age hardening of Ni-20Cr-20W alloys developed as the superalloys for the nuclear energy steelmaking, and effects of C and Zr additions to the alloys and the effect of preheat treatment on these properties were studied. M 6 C, α-W and two kinds of M 23 C 6 having different lattice parameters were found as precipitates in the alloys. M 23 C 6 whose lattice parameter was around 10.7A precipitated in the early stage of aging at 700 0 C-1,150 0 C, and the carbide changed to M 6 C at higher temperature than 1,000 0 C, but it remained as a stable carbide at lower temperature than 900 0 C. α-W precipitated at 800 0 C-1,100 0 C after precipitation of M 23 C 6 and it disappeared with increase of M 6 C. M 23 C 6 having the larger lattice parameter (10.9A) precipitated transitionally in aging stage of 26 x 10 3 in Larson Miller parameter at 900 0 C and 1,000 0 C. Age hardening corresponded to the precipitation of M 23 C 6 and it was reduced by the double pre-heat-treatment. Zr addition and amount of C influenced on the aging structure and age hardening. Zr seemed to be a favorable element to stabilize the carbide. (auth.)

Contamination assessment of heavy metals in the soils around Khouzestan Steel Company (KSC (Ni, Mn, Pb, Fe, Zn, Cr

Directory of Open Access Journals (Sweden)

Fatemeh hormozi Nejad

2017-02-01

Full Text Available Introduction Soil plays a vital role in human life as the very survival of mankind is tied to the preservation of soil productivity (Kabata- Pendies and Mukherjee, 2007. The purpose of this study is the assessment of heavy metal contamination (Zn, Mn, Pb, Fe, Ni, Cr of the soil around the Khuzestan Steel Complex. Materials and methods For this purpose, 13 surface soil samples (0-10 cm were taken. Also a control sample was taken from an area away from the steel complex. The coordinates of each point were recorded by Global Positioning System (GPS. The samples were transferred to the laboratory and then were air dried at room temperature for 72 hours. Then they were sieved through a 2mm sieve for determining physical and chemical parameters (soil texture, pH, OC, and a 63-micron sieve for measurement of heavy metal concentration. pH was measured using a calibrated pH meter at a 2: 1 mixture (soil: water, and soil texture was determined using a hydrometer. The amount of organic matter was measured using the Valkey black method (Chopin and Alloway, 2007. After preparation of the samples in the laboratory, the samples were analyzed using the ICP-OES method to assess concentration of heavy metals. Measurement of heavy metals concentration was carried out at the Zar azma laboratory in Tehran. To ensure the accuracy of the analysis of soil samples, replicate samples were also sent to the laboratory. In order to assess the heavy metal pollution in the soil samples, different indices including contamination factor (CF, contamination degree (Cd, anthropogenic enrichment percent (An%, and saturation degree of metals (SDM were calculated. Discussion In addition, the mean concentrations of heavy metals in soil samples were compared to the concentration of these metals in Control Sample and unpolluted soil standard. Measurement of soil pH showed that the soil has a tendency to alkalinity. Also, soil texture is sandy loam (Moyes, 2011. The results showed that

Application of newly developed heat resistant materials for USC boilers

International Nuclear Information System (INIS)

Sato, T.; Tamura, K.; Fukuda, Y.; Matsuda, J.

2004-01-01

This paper describes the research on the development and improvement of new high strength heat resistant steels such as SUPER304H (18Cr-9Ni-3Cu-Nb-N), NF709 (20Cr-25Ni-1.5Mo-Nb-Ti-N) and HR3C (25Cr-20Ni-Nb-N) as boiler tube, and NF616 (9Cr-0.5Mo-1.8W-Nb-V) and HCM12A (11Cr-0.4Mo-2W-Nb-V-Cu) as thick section pipe. The latest manufacturing techniques applied for these steels are introduced. In addition the high temperature strength of Alloy617 (52Ni-22Cr-13Co-9Mo-Ti-Al) that is one of the candidate materials for the next generation 700 □ USC boilers is described. (orig.)

[Studies on the tolerance of the organism to X 5 CrNiMo 18.10 steel (Königsee). II. Light microscopic studies of the surrounding tissue of metal implants (X 5 CrNiMo 18.10 steel) in guinea pigs].

Science.gov (United States)

Höhndorf, H; Drössler, K; Stiehl, P

1977-06-01

The tissue around X 5 CrNiMo 18.10-steel implantates with different surfaces was examined in 72 guinea-pigs. Aside from controls, these animals were preoperatively sensibilized against chromium and nickel. The results can be summarized since the histologic findings showed no different peculiarities. The authors describe an intussusception of the implantate in connective tissue which evidently depends on time and surface. Further the spreading of alien material in the surrounding of the implantate, and morphologic findings are reported. The morphologic evidences are described and discussed in detail, since they are interpreted as signs of cell-mediated immune reactions. The presence of lymphocytes, lymphoblasts, histiocytes (mostly carrying alien material), and granulocytes, as well as proliferations at the arterioles suggest an overlapping of immune reactions.

Effects of air melting on Fe/0.3/3Cr/0.5Mo/2Mn and Fe/0.3C/3Cr/0.5Mo/2Ni structural alloy steels

International Nuclear Information System (INIS)

Steinberg, B.

1979-06-01

Changing production methods of a steel from vacuum melting to air melting can cause an increase in secondary particles, such as oxides and nitrides, which may have detrimental effects on the mechanical properties and microstructure of the alloy. In the present study a base alloy of Fe/0.3C/3Cr/0.5Mo with either 2Mn or 2Ni added was produced by air melting and its mechanical properties and microstructure were compared to an identical vacuum melted steel. Significant differences in mechanical behavior, morphology, and volume fraction of undissolved inclusions have been observed as a function of composition following air melting. For the alloy containing manganese, all properties remained very close to vacuum melted values but the 2Ni alloy displayed a marked loss in Charpy impact toughness and plane strain fracture toughness. This loss is attributed to an increase in volume fraction of secondary particles in the nickel alloy, as opposed to both the Mn alloy and vacuum melted alloys, as well as to substaintially increased incidence of linear coalescence of voids. Microstructural features are discussed

Role of Oxides and Porosity on High-Temperature Oxidation of Liquid-Fueled HVOF Thermal-Sprayed Ni50Cr Coatings

Science.gov (United States)

Song, B.; Bai, M.; Voisey, K. T.; Hussain, T.

2017-02-01

High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high-temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid-fueled high velocity oxy-fuel thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using oxygen content analysis, mercury intrusion porosimetry, scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Short-term air oxidation tests (4 h) of freestanding coatings (without boiler steel substrate) in a thermogravimetric analyzer at 700 °C were performed to obtain the kinetics of oxidation of the as-sprayed coating. Long-term air oxidation tests (100 h) of the coated substrates were performed at same temperature to obtain the oxidation products for further characterization in detail using SEM/EDX and XRD. In all samples, oxides of various morphologies developed on top of the Ni50Cr coatings. Cr2O3 was the main oxidation product on the surface of all three coatings. The coating with medium porosity and medium oxygen content has the best high-temperature oxidation performance in this study.

Ultrafine particles of Ni and FeCr studied by positron annihilation

DEFF Research Database (Denmark)

Eldrup, Morten Mostgaard; Pedersen, N.J.; Sethi, S.A.

1995-01-01

Ultrafine particles of Ni and Fe80Cr20 have been produced by the gas condensation technique. After surface oxidation the paticles were heated in a reducing H2 atmosphere and positron lifetime and Doppler broadening measurements were carried out. Reduction of the oxide on the Ni powder takes place...... at about 350K and at about 650K for the FeCr powder. Electron microscopy shows sintering of the Ni particles above 450K, and the present results show that defects develop in the growing particles....

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

DEFF Research Database (Denmark)

Chen, Ming; Alimadadi, Hossein; Molin, Sebastian

2017-01-01

Ferritic stainless steel interconnect plates are widely used in planar solid oxide fuel cell and electrolysis cell stacks. During stack production and operation, nickel from the Ni/yttria stabilized zirconia fuel electrode or from the Ni contact component layer diffuses into the interconnect plate......, causing transformation of the ferritic phase into an austenitic phase in the interface region. This is accompanied with changes in volume, and in mechanical and corrosion properties of the interconnect plates. In this work, kinetic modeling of the inter-diffusion between Ni and FeCr based ferritic...

Metallurgical aspects of the weldability of Cr-Mo stabilised ferritic steels

International Nuclear Information System (INIS)

Colombe, Gerard; Petrequin, Pierre; Donati, J.R.; Zacharie, C.

1977-01-01

Results of tests performed to compare the tendency of 2.25 Cr-Mo and 9 Cr-2 Mo steels stabilised with niobium and niobium + vanadium, to different cracking phenomena susceptible to occur during welding, stress-relieving and service in the conditions of fast breeder reactors are presented

Microstructure and Tribological Performance of TiB2-NiCr Composite Coating Deposited by APS

Directory of Open Access Journals (Sweden)

Ning Zhang

2017-12-01

Full Text Available Nickel chromium (NiCr powders with different titanium diboride (TiB2 additions (20, 40 and 60 wt % were prepared with a mechanical alloying method and then sprayed using an air plasma spraying technology. The microstructure and phase composite of the powders and the cross-sections of deposited coatings were analyzed with a scanning electronic microscope and X-ray diffraction. The tribological performance of the coatings was studied using a pin-on-disk tribometer at room temperature. The weight loss of the as-sprayed coating was measured by using a high accuracy weighing balance. Cr3C2-25NiCr coating was produced and tested for comparison. The morphologies of the worn surface were then investigated. Parts of debris with some scratches were found, presenting typical signs of abrasive wear and showing slight adhesive wear on the surface. The 20 wt % additive TiB2 coating demonstrated the highest microhardness and the lowest coefficient of friction. The wear resistance of the metal-ceramic composites coatings was enhanced with the addition of TiB2.

Development of oxide dispersion strengthened 9Cr ferritic-martensitic steel clad tube for fast reactor

International Nuclear Information System (INIS)

Laha, K.; Saroja, S.; Mathew, M.D.; Jayakumar, T.; Vijay, R.; Venugopal Reddy, A.; Lakshminarayana, B.; Kapoor, Komal; Jha, S.K.; Tonpe, S.S.

2012-01-01

One of the key issues in the economical operation of FBR is to achieve high burn-up of fuel (200-250 GWd/t) which considerably reduces the fuel cycle cost. This imposes stringent requirements of void swelling resistance upto 200 dpa for the core structural materials. Presently used alloy 09 (a modified austenitic stainless steel, 15Cr-15Ni-Ti) for PFBR has void swelling limit less than 150 dpa. Because of the inherent void swelling resistance, 9-12Cr steels ferritic/martensitic steels are qualified for irradiation upto 200 dpa but their low creep strength at temperatures above 600 deg C restricts their application as a clad material. Oxide dispersion strengthening is found to be promising means of extending the creep resistance of ferritic/martensitic steels beyond 650 deg C without sacrificing the inherent advantages of high thermal conductivity and low swelling of ferritic steels

Investigation of austenitic alloys for advanced heat recovery and hot-gas cleanup systems

Energy Technology Data Exchange (ETDEWEB)

Swindeman, R.W. [Oak Ridge National Lab., TN (United States)

1997-12-01

Materials properties were collected for the design and construction of structural components for use in advanced heat recovery and hot gas cleanup systems. Alloys systems included 9Cr-1Mo-V steel, modified 316 stainless steel, modified type 310 stainless steel, modified 20Cr-25Ni-Nb stainless steel, and modified alloy 800. Experimental work was undertaken to expand the databases for potentially useful alloys. Types of testing included creep, stress-rupture, creep-crack growth, fatigue, and post-exposure short-time tensile tests. Because of the interest in relatively inexpensive alloys for service at 700 C and higher, research emphasis was placed on a modified type 310 stainless steel and a modified 20Cr-25Ni-Nb stainless steel. Both steels were found to have useful strength to 925 C with good weldability and ductility.

Behaviour of Z phase in 9–12%Cr steels

DEFF Research Database (Denmark)

Danielsen, Hilmar Kjartansson; Hald, John

2006-01-01

The literature on the behaviour of modified Z phase Cr(V,Nb)N in creep resistant martensitic 9–12%Cr steels is briefly reviewed. Ten different 9–12%Cr steels were investigated after prolonged exposure at 600–660uC; the modified Z phase was found in all of them. In steels with high Cr content (11......–12%), Z phase precipitates much faster than in 9%Cr steels. Precipitation of Z phase is associated with dissolution of MX carbonitrides, and causes a breakdown in long term creep strength in 9–12%Cr steels. High Cr steels show creep instabilities accompanied with Z phase precipitation, whereas low Cr...... steels show good long term creep stability. A niobium free CrVN variant of the modified Z phase was observed for the first time during the course of this work. The solution temperature of the Cr(V,Nb)N and CrVN modified Z phases was found to be close to 800uC for 11–12%Cr steels, much lower than the 1200...

Mehanička svojstva i mikrostruktura vakuum plazma naprskane Cr3C2 - 25(Ni20Cr prevlake / Mechanical properties and microstructure of vacuum plasma sprayed Cr3C2 – 25(Ni20Cr coatings / Механические свойства и микроструктура покрытия Cr3C2 - 25(Ni20Cr нанесенного методом вакуумного плазменного напыления

Directory of Open Access Journals (Sweden)

Mihailo R. Mrdak

2015-04-01

Full Text Available U radu je analizirana vakuum plazma sprej prevlaka VPS – Cr3C2 - 25(Ni20Cr. Upotrebljen je komercijalni prah oznake Sulzer Metco Woka 7205. Prah je deponovan sa plazma pištoljem F4 na odstojanju substrata od 340 mm. Glavni cilj rada bio je da se na smanjenom pritisku inertnog gasa Ar eliminiše razgradnja primarnog karbida Cr3C2 u karbid Cr23C6 koji bitno umanjuje mikrotvrdoću i mehaničke karakteristike prevlake. Prevlaka je deponovana debljine od 100 do 120 µm na čeličnom substratu. Mikrotvrdoća prevlake ispitana je metodom HV0.3. Vrednosti mikrotvrdoće bile su u rasponu od 1248 do 1342 HV0.3. Čvrstoća spoja prevlake ispitana je metodom na zatezanje. Utvrđeno je da čvrstoća spoja između substrata i prevlake ima vrednost 89 MPa. Mikrostruktura prevlake ispitana je tehnikom svetlosne mikroskopije. Struktura prevlake sastoji se od osnove NiCr legure sa dominantnom primarnom karbidnom fazom Cr3C2. Pored Cr3C2 faze prisutna je i faza Cr7C3. Nagrizanje prevlake urađeno je reagensom 1HNO3: 4HCl: 4H2O koji prvenstveno rastvara Ni da bi se videla raspodela karbidne faze u prevlaci. Nagrizanjem prevlake reagensom utvrđeno je da je u slojevima prevlake u velikom udelu prisutna primarna nerazgrađena karbidna faza Cr3C2 koja prevlaci daje visoke vrednosti mikrotvrdoće. / This paper analyzes vacuum plasma spray VPS - Cr3C2 - 25(Ni20Cr coatings. Commercial powder marked Sulzer Metco Woka 7205 is used. The powder is deposited with a plasma gun F4 at a distance of 340 mm from the substrate. The main objective of the study was to eliminate, at the reduced pressure of inert gas Ar, the degradation of primary Cr3C2 carbide into Cr23C6 carbide which significantly reduces the microhardness and mechanical properties of the coating. The coating is deposited with a thickness of 100 - 120 µm on a steel substrate. The microhardness of the coating was tested by HV0.3. The microhardness values were in the range of 1248 - 1342 HV0.3. The bond strength

The effect of silicon content on high temperature oxidation of 80Ni-20Cr alloys

International Nuclear Information System (INIS)

Takei, Atsushi; Nii, Kazuyoshi

1981-01-01

The effect of Si content on the oxidation behavior of 80Ni-20Cr alloys has been studied in the cyclic oxidation in an air stream at 1373K. The addition of 1% and 5%Si to the alloy lowered the mass gain in oxidation, whereas the amount of spalling of oxide scale was increased with the addition of Si. The structure of oxide layers observed by microphotography, X-ray diffraction and electron probe microanalysis (EPMA) were different with the Si content of alloys. The oxide layer of the alloy with 1%Si consists of multi-layers, that is Ni oxide, Cr 2 O 3 and SiO 2 as the external oxide layer. The oxide layer remaining on the alloy with 5%Si, however, was made of a single oxide layer of Cr 2 O 3 containing small amounts of Si and Ni. In spite of the fact that the amount of Si in this alloy is larger than that of the alloy with 1%Si, the SiO 2 oxide layer was not observed at the oxide-alloy interface. It was found by EPMA that the concentration of Si in the oxidized 5%Si alloy substrate was increased in the vicinity of the surface, although Si in the 1%Si alloy was depleted. From the above results the internal oxidation of Si is assumed in the near-surface region of the 5%Si alloy. The internal oxidation of the 5%Si alloy was confirmed by an increase in hardness in the near-surface region. The difference in oxidation behavior between the 1%Si and 5%Si alloys can be understood under the assumption that the oxide layer formed of the 5%Si alloy contained much larger amounts of Ni and Si than that on the 1%Si alloy, and that this oxide layer tends to crack more easily, thus being less protective for the penetration of oxygen. (author)

Room-temperature ferromagnetic transitions and the temperature dependence of magnetic behaviors in FeCoNiCr-based high-entropy alloys

Science.gov (United States)

Na, Suok-Min; Yoo, Jin-Hyeong; Lambert, Paul K.; Jones, Nicholas J.

2018-05-01

High-entropy alloys (HEAs) containing multiple principle alloying elements exhibit unique properties so they are currently receiving great attention for developing innovative alloy designs. In FeCoNi-based HEAs, magnetic behaviors strongly depend on the addition of alloying elements, usually accompanied by structural changes. In this work, the effect of non-magnetic components on the ferromagnetic transition and magnetic behaviors in equiatomic FeCoNiCrX (X=Al, Ga, Mn and Sn) HEAs was investigated. Alloy ingots of nominal compositions of HEAs were prepared by arc melting and the button ingots were cut into discs for magnetic measurements as functions of magnetic field and temperature. The HEAs of FeCoNiCrMn and FeCoNiCrSn show typical paramagnetic behaviors, composed of solid solution FCC matrix, while the additions of Ga and Al in FeCoNiCr exhibit ferromagnetic behaviors, along with the coexistence of FCC and BCC phases due to spinodal decomposition. The partial phase transition in both HEAs with the additions of Ga and Al would enhance ferromagnetic properties due to the addition of the BCC phase. The saturation magnetization for the base alloy FeCoNiCr is 0.5 emu/g at the applied field of 20 kOe (TC = 104 K). For the HEAs of FeCoNiCrGa and FeCoNiCrAl, the saturation magnetization significantly increased to 38 emu/g (TC = 703 K) and 25 emu/g (TC = 277 K), respectively. To evaluate the possibility of solid solution FCC and BCC phases in FeCoNiCr-type HEAs, we introduced a parameter of valence electron concentration (VEC). The proposed rule for solid solution formation by the VEC was matched with FeCoNiCr-type HEAs.

Microstructure of the Transitional Area of the Connection of a High-temperature Ni-based Brazing Alloy and Stainless Steel AISI 321 (X6CrNiTi 18–10

Directory of Open Access Journals (Sweden)

R. Augustin

2010-01-01

Full Text Available This paper presents a detailed examination of the structure of the transitional area between a brazing alloy and the parent material, the dimensions of the diffusion zones that are created, and the influence on them of a change in the brazing parameters. Connections between Ni-based brazing alloys (NI 102 with a small content of B and AISI 321 stainless steel (X6CrNiTi 18–10 were created in a vacuum (10−2 Pa at various brazing temperatures and for various holding times at the brazing temperature. Various specimens were tested. First, the brazing alloys were wetted and the dependence of the wetting on the brazing parameters was assessed. Then a chemical microanalysis was made of the interface between the brazing alloy and the parent material. The individual diffusion zones were identified on pictures from a light microscope and REM, and their dimensions, together with their dependence on the brazing parameters, were determined.

Age-hardening susceptibility of high-Cr ODS ferritic steels and SUS430 ferritic steel

Energy Technology Data Exchange (ETDEWEB)

Chen, Dongsheng, E-mail: chen.dongsheng85@gmail.com [Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Kimura, Akihiko; Han, Wentuo; Je, Hwanil [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

2015-10-15

Highlights: • The role of oxide particles in α/α′ phase decomposition behavior; microstructure of phase decomposition observed by TEM. • The characteristics of ductility loss caused by age-hardening. • Correlation of phase decomposition and age-hardening explained by dispersion strengthened models. • Age-hardening susceptibility of ODS steels and SUS430 steel. - Abstract: The effect of aging on high-Cr ferritic steels was investigated with focusing on the role of oxide particles in α/α′ phase decomposition behavior. 12Cr-oxide dispersion strengthened (ODS) steel, 15Cr-ODS steel and commercial SUS430 steel were isothermally aged at 475 °C for up to 10,000 h. Thermal aging caused a larger hardening in SUS430 than 15Cr-ODS, while 12Cr-ODS showed almost no hardening. A characteristic of the ODS steels is that the hardening was not accompanied by the significant loss of ductility that was observed in SUS430 steel. After aging for 2000 h, SUS430 steel shows a larger ductile–brittle transition temperature (DBTT) shift than 15Cr-ODS steel, which suggests that the age-hardening susceptibility is lower in 15Cr-ODS steel than in conventional SUS430 steel. Thermal aging leaded to a large number of Cr-rich α′ precipitates, which were confirmed by transmission electron microscopy (TEM). Correlation of age-hardening and phase decomposition was interpreted by Orowan type strengthening model. Results indicate that oxide particles cannot only suppress ductility loss, but also may influence α/α′ phase decomposition kinetics.

Effect of free Cr content on corrosion behavior of 3Cr steels in a CO2 environment

Science.gov (United States)

Li, Wei; Xu, Lining; Qiao, Lijie; Li, Jinxu

2017-12-01

The corrosion behavior of 3Cr steels with three microstructures (martensite, bainite, combined ferrite and pearlite) in simulated oil field formation water with a CO2 partial pressure of 0.8 MPa was investigated. The relationships between Cr concentrations in corrosion scales and corrosion rates were studied. The precipitated phases that contained Cr were observed in steels of different microstructures, and free Cr content levels were compared. The results showed that steel with the martensite microstructure had the highest free Cr content, and thus had the highest corrosion resistance. The free Cr content of bainite steel was lower than that of martensite steel, and the corrosion rate of bainite steel was higher than that of martensite steel. Because large masses of Cr were combined in ferrite and pearlite steel, the corrosion rates of ferrite and pearlite steel were the highest. Free Cr content in steel affects its corrosion behavior greatly.

Removal of Cr(VI) and Ni(II) from aqueous solution by fused yeast: Study of cations release and biosorption mechanism

International Nuclear Information System (INIS)

Yin Hua; He Baoyan; Peng Hui; Ye Jinshao; Yang Feng; Zhang Na

2008-01-01

Biosorption of Cr(VI) and Ni(II) by a fused yeast from Candida tropicalis and Candida lipolytica under varying range of pH, initial metal concentration and reaction time was investigated. Net cation release and Cr removal reached 2.000 mmol/l and 81.37% when treating 20 mg/l Cr(VI) at pH 2 with 25 mg/l biomass for 30 min, while for Ni were 0.351 mmol/l and 64.60%, respectively. Trace metal elements such as Co, Cu, Mn, Mo, Se and Zn played active role in biosorption as important ingredients of functional enzymes. Cr(VI) was reduced to less toxic Cr(III) and chelated with extracellular secretions, and further accumulated inside the cells. For Ni biosorption, however, largely a passive uptake process influenced by ion gradient led to lower adsorption capacity and cations release. Fourier transform infrared (FTIR) spectrum analysis indicated that amide and pyridine on cells were involved in binding with Cr, but for Ni, bound-OH and nitro-compounds were the main related functional groups. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis confirmed that considerable amounts of metals precipitated on cell surface when dealing with high concentration metals

A Study of Thin Film Resistors Prepared Using Ni-Cr-Si-Al-Ta High Entropy Alloy

Directory of Open Access Journals (Sweden)

Ruei-Cheng Lin

2015-01-01

Full Text Available Ni-Cr-Si-Al-Ta resistive thin films were prepared on glass and Al2O3 substrates by DC magnetron cosputtering from targets of Ni0.35-Cr0.25-Si0.2-Al0.2 casting alloy and Ta metal. Electrical properties and microstructures of Ni-Cr-Si-Al-Ta films under different sputtering powers and annealing temperatures were investigated. The phase evolution, microstructure, and composition of Ni-Cr-Si-Al-Ta films were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and Auger electron spectroscopy (AES. When the annealing temperature was set to 300°C, the Ni-Cr-Si-Al-Ta films with an amorphous structure were observed. When the annealing temperature was at 500°C, the Ni-Cr-Si-Al-Ta films crystallized into Al0.9Ni4.22, Cr2Ta, and Ta5Si3 phases. The Ni-Cr-Si-Al-Ta films deposited at 100 W and annealed at 300°C which exhibited the higher resistivity 2215 μΩ-cm with −10 ppm/°C of temperature coefficient of resistance (TCR.

Tribología de recubrimientos Cermet/NiCrBSi depositados mediante HVOF

Directory of Open Access Journals (Sweden)

Guilemany, J. M.

2004-04-01

Full Text Available This work consists on a deep tribological study of the WX system composed by a mechanical blend in different compositions of NiCrBSi and WC-12Co powders: 20% NiCrBSi (W2, 40% NiCrBSi (W4 y 60% NiCrBSi (W6. The coatings have been obtained by high velocity oxy-fuel process (HVOF. The measurements made by Ball-On-Disk test are: the friction coefficient is lower than 0.5 and the exchanged energy between the counterparts is under 10 KJ. To quantify the friction wear rate, the volume loss and the track depth, Scanning White Light Interferometry and SEM have been used. The track depth is proportional to the amount of NiCrBSi. A higher percentage of WC-12Co increases the friction wear resistance and decreases the abrasion wear rate (Rubber Wheel test. In all the coatings studied, no diffusion processes are found between the mixed phases, the adhesion between the coatings and the substrate is excellent, the porosity level is below 2% and an increase of microhardness of the coating due to a strengthening of the matrix produced by impacts of solid particles, takes place.

El trabajo consta de un completo estudio tribológico del sistema WX que consiste en la mezcla mecánica de WC-12Co y NiCrBSi en diferentes proporciones: 20% NiCrBSi (W2, 40% NiCrBSi (W4 y 60% NiCrBSi (W6. Los recubrimientos se han obtenido por proyección térmica de alta velocidad (HVOF. Para todos los sistemas, el coeficiente de fricción es menor que 0.5 y la energía intercambiada entre el par friccionante y el recubrimiento es inferior a 10 KJ. Para cuantificar el desgaste por fricción se han utilizado la profundidad de la huella y el volumen perdido durante el ensayo, obtenidos mediante Interferometría de Barrido de Luz Blanca (SLWI y SEM. La profundidad de la huella sigue una evolución directamente proporcional al contenido en NiCrBSi. Un mayor contenido en WC-12Co aumenta la resistencia al desgaste por fricción y disminuye la velocidad de desgaste por abrasión (ensayo

Ring head recording on perpendicular media: Output spectra for CoCr and CoCr/NiFe media

Science.gov (United States)

Stubbs, D. P.; Whisler, J. W.; Moe, C. D.; Skorjanec, J.

1985-04-01

The recording density response for sputtered CoCr (thickness=0.5 μm) and CoCr/NiFe (t=0.25 μm/0.5 μm) as well as evaporated CoNi (t=0.12 μm) and Co surface-doped iron oxide particulate media has been measured by reading and writing with Mn-Zn ferrite heads (gap length=0.375 μm, track width=37 μm) in contact with the media. Measurements to 200 kfc/i (thousand flux changes per inch) show a gap null around 115 kfc/i. The data have been normalized by dividing out the head sensitivity to obtain the value of spacing plus transition width (d+a) for the various media. For the CoCr media this value varied from 0.075-0.088 μm; for CoNi, 0.100 μm, and for the particulate medium, 0.163 μm. In addition, testing with a larger gapped Mn-Zn ferrite head (g=2.43 μm) shows that the head fields are distorted by the soft magnetic underlayer in dual layer CoCr/NiFe samples when the gap length is large compared to the distance to the underlayer.

Ni-Flash-Coated Galvannealed Steel Sheet with Improved Properties

Science.gov (United States)

Pradhan, D.; Dutta, M.; Venugopalan, T.

2016-11-01

In the last several years, automobile industries have increasingly focused on galvannealed (GA) steel sheet due to their superior properties such as weldability, paintability and corrosion protection. To improve the properties further, different coatings on GA have been reported. In this context, an electroplating process (flash coating) of bright and adherent Ni plating was developed on GA steel sheet for covering the GA defects and enhancing the performances such as weldability, frictional behavior, corrosion resistance and phosphatability. For better illustration, a comparative study with bare GA steel sheet has also been carried out. The maximum electroplating current density of 700 A/m2 yielded higher cathode current efficiency of 95-98%. The performances showed that Ni-coated (coating time 5-7 s) GA steel sheet has better spot weldability, lower dynamic coefficient of friction (0.07 in lubrication) and three times more corrosion resistance compared to bare GA steel sheet. Plate-like crystal of phosphate coating with size of 10-25 µm was obtained on the Ni-coated GA. The main phase in the phosphate compound was identified as hopeite (63.4 wt.%) along with other phases such as spencerite (28.3 wt.%) and phosphophyllite (8.3 wt.%).

Microstructure and mechanical properties of Al-20Si-5Fe-2X (X = Cu, Ni, Cr) alloys produced by melt-spinning

International Nuclear Information System (INIS)

Rajabi, M.; Simchi, A.; Davami, P.

2008-01-01

Al-20Si-5Fe-2X (X = Cu, Ni and Cr) ribbons were produced by melt-spinning and consolidated by hot pressing at 400 deg. C for 60 min. The microstructure of the ribbons and the consolidated alloys was investigated using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD) method, and transmission electron microscopy (TEM). The hardness and compressive strength of the specimens at ambient and elevated temperatures were examined. The microstructure of the ribbons exhibited featureless and dendritic zones. Results of XRD and TEM showed formation of spherically shaped Si particles with an average diameter of 20 nm. Ultrafine Si (110-150 nm) and iron-containing intermetallic particles were noticed in the microstructure of the consolidated ribbons. An improved strength was achieved by alloying of Al-20Si-5Fe with Cu, Ni, and Cr. Nickel was found to be the most effective element in increasing the maximum stress, particularly at elevated temperatures

Improving the corrosion wear resistance of AISI 316L stainless steel by particulate reinforced Ni matrix composite alloying layer

Science.gov (United States)

Xu, Jiang; Zhuo, Chengzhi; Tao, Jie; Jiang, Shuyun; Liu, Linlin

2009-01-01

In order to overcome the problem of corrosion wear of AISI 316L stainless steel (SS), two kinds of composite alloying layers were prepared by a duplex treatment, consisting of Ni/nano-SiC and Ni/nano-SiO2 predeposited by brush plating, respectively, and subsequent surface alloying with Ni-Cr-Mo-Cu by a double glow process. The microstructure of the two kinds of nanoparticle reinforced Ni-based composite alloying layers was investigated by means of SEM and TEM. The electrochemical corrosion behaviour of composite alloying layers compared with the Ni-based alloying layer and 316L SS under different conditions was characterized by potentiodynamic polarization test and electrochemical impedance spectroscopy. Results showed that under alloying temperature (1000 °C) conditions, amorphous nano-SiO2 particles still retained the amorphous structure, whereas nano-SiC particles were decomposed and Ni, Cr reacted with SiC to form Cr6.5Ni2.5Si and Cr23C6. In static acidic solution, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is lower than that of the Ni-based alloying layer. However, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is prominently superior to that of the Ni-based alloying layer under acidic flow medium condition and acidic slurry flow condition. The corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiC particles interlayer is evidently lower than that of the Ni-based alloying layer, but higher than that of 316L SS under all test conditions. The results show that the highly dispersive nano-SiO2 particles are helpful in improving the corrosion wear resistance of the Ni-based alloying layer, whereas carbides and silicide phase are deleterious to that of the Ni-based alloying layer due to the fact that the preferential removal of the matrix around the precipitated phase takes place by the chemical

Fe-Cr-Ni system alloys

International Nuclear Information System (INIS)

Levin, F.L.

1986-01-01

Phase diagram of Fe-Cr-Ni system, which is the basic one for production of corrosion resistant alloys, is considered. Data on corrosion resistance of such alloys are correlated depending on a number of factors: quality and composition of modifying elements, corrosion medium, temperature, alloy structure, mechanical and thermal treatment. Grades of Fe-Ni-Cr alloys are presented, and fields of their application are pointed out

TiC-reinforced cast Cr steels

Science.gov (United States)

Doğan, Ö. N.; Hawk, J. A.; Schrems, K. K.

2006-06-01

A new class of materials, namely TiC-reinforced cast chromium (Cr) steels, was developed for applications requiring high abrasion resistance and good fracture toughness. The research approach was to modify the carbide structure of commercial AISI 440C steel for better fracture resistance while maintaining the already high abrasion resistance. The new alloys contained 12Cr, 2.5-4.5Ti, and 1-1.5C (wt.%) and were melted in a vacuum induction furnace. Their microstructure was composed primarily of a martensitic matrix with a dispersion of TiC precipitates. Modification of TiC morphology was accomplished through changing the cooling rate during solidification. Wear rates of the TiC-reinforced Cr steels were comparable to that of AISI 440C steel, but the impact resistance was much improved.

Diffusion of 51Cr along high-diffusivity paths in Ni-Fe alloys

International Nuclear Information System (INIS)

Cermak, J.

1990-01-01

Penetration profiles of 51 Cr in polycrystalline alloys Ni-xFe (x = 0, 20, 40, and 60 wt.% Fe) after diffusion anneals at temperatures between 693 and 1473 K are studied. Sectioning of diffusion zones of samples annealed above 858 K is carried out by grinding, at lower temperatures by DC glow discharge sputtering. The concentration of 51 Cr in depth x is assumed to be proportional to relative radioactivity of individual sections. With help of volume and pipe self-diffusion data taken from literature, the temperature dependence of product P = δD g (δ and D g are grain boundary width and grain boundary diffusion coefficient, respectively) is obtained: P = (2.68 - 0.88 +1.3 ) x 10 -11 exp [-(221.3 ± 3.0) kJ/mol/RT]m 3 /s. This result agrees well with the previous measurements of 51 Cr diffusivity in Fe-18 Cr-12 Ni and Fe-21 Cr-31 Ni. It indicates that the mean chemical composition of Fe-Cr-Ni ternary alloys is not a dominant factor affecting the grain boundary diffusivity of Cr in these alloys. (author)

Effect of Ni Addition on the Wear and Corrosion Resistance of Fe-20Cr-1.7C-1Si Hardfacing Alloy

International Nuclear Information System (INIS)

Lee, Sung Hoon; Kim, Ki Nam; Kim, Seon Jin

2011-01-01

In order to improve the corrosion resistance of Fe-20Cr-1.7C-1Si hardfacing alloy without a loss of wear resistance, the effect of Ni addition was investigated. As expected, the corrosion resistance of the alloy increased with increasing Ni concentration. The wear resistance of the alloy did not decrease, even though the hardness decreased, up to Ni concentration of 5 wt.%. This was attributed to the fact that the decrease in hardness was counterbalanced by the strain-induced martensitic transformation. The wear resistance of the alloy, however, decreased abruptly with increases of the Ni concentration over 5 wt.%.

Technology development and production of elongated shell for reactor vessel active zone of WWER-TOI project from steel 15Cr2NiMoVN class 1

International Nuclear Information System (INIS)

Shklyaev, S.Eh.; Titova, T.I.; Ratushev, D.V.; Shul'gan, N.A.; Eroshkin, S.B.; Durynin, V.A.; Efimov, S.V.; Dub, V.S.; Kulikov, A.P.; Romashkin, A.N.

2015-01-01

Production process for the elongated shell blank of the active zone of the reactor pressure vessel made from steel 15Cr2NiMoVN Class 1 with finished sizes Dext=4.655 mm, Dint=4.240 mm, H=4.910 mm (height for heat treatment – 5.750 mm) is presented. For the first time in Russia in production site of OMZ-Special steel LLC a unique elongated shell blank of the reactor vessel active zone was made from ingot 420.0 t for WWER-TOI project fully meeting the specified requirements in terms of metallurgical quality and set of service properties [ru

Kinetics of steel corrosion in water

International Nuclear Information System (INIS)

Vettegren', V.I.; Bashkarev, A.Ya.; Danchukov, K.G.; Morozov, G.I.

2003-01-01

Kinetics of corrosion damage accumulation in steels of different composition (Cr-Ni-Mo-Ti, Cr-Ni-Mn-N-V, Cr-Ni-N-Mn-Mo, Cr-Ni-Nb, Cr-Ni-Ti, Cr-Mn-Ni, Mn-Al-Nb-Si, Mn-Cr-Al-Si and Mn-Al-Si) in NaCl solution and in sea water was studied. It is shown that degree of corrosion damage relates to time according to the first order reaction expression. The values of corrosion activation energy and of parameter characterizing protection properties of corrosion film are determined [ru

Kinetics of Cr/Mo-rich precipitates formation for 25Cr-6.9Ni-3.8Mo-0.3N super duplex stainless steel

Science.gov (United States)

Byun, Sang-Ho; Kang, Namhyun; Lee, Tae-Ho; Ahn, Sang-Kon; Lee, Hae Woo; Chang, Woong-Seong; Cho, Kyung-Mox

2012-04-01

The amount and composition of Cr-rich (σ) and Mo-rich (χ) precipitates in super duplex stainless steels was analyzed. An isothermal heat treatment was conducted at temperatures ranging from 700 °C to 1000 °C for up to 10 days. A time-temperature transformation (TTT) diagram was constructed for the mixture of σ and χ phases. The mixture of the σ and χ phases exhibited the fastest rate of formation at approximately 900 °C. Minor phases, such as Cr2N, M23C6, and M7C3, were also detected using a transmission electron microscopy (TEM). Also, a continuous cooling transformation (CCT) diagram was constructed for the mixture of σ and χ phases using the Johnson-Mehl-Avrami equation. Compared with the known CCT diagram of the σ phase, this study revealed faster kinetics with an order of magnitude difference and a new CCT diagram was also developed for a mixture of σ and χ phases. The calculated fraction of σ and χ phases obtained at a cooling speed of 0.5 °C/s was in good agreement with the experimental data.

Ferritic stainless steels: corrosion resistance + economy

International Nuclear Information System (INIS)

Remus, A.L.

1976-01-01

Ferritic stainless steels provide corrosion resistance at lower cost. They include Type 409, Type 439, 18SR, 20-Mo (1.6 Mo), 18-2 (2 Mo), 26-1S, E-Brite 26-1, 29 Cr-4 Mo, and 29 Cr-4 Mo-2 Ni. Their corrosion and mechanical properties are examined. Resistance to stress-corrosion cracking is an advantage compared to austenitic types

Elevated temperature creep and fatigue damage of a 2.25 Cr--1 Mo steel weldment

International Nuclear Information System (INIS)