Title: Impact behavior of different stainless steel weldments at low temperatures

Authors:Ibrahim,O.H.^; Ibrahim,I.S.^; Khalifa,T.A.F.^

Source:Eng.Failure Anal., 2010, 17, 5, 1069-1076

Abstract: A comparative study was made of the fracture behavior of austenitic and duplex stainless steel weldments at cryogenic temperatures by impact testing. The investigated materials were two austenitic (304L and 316L) and one duplex (2505) stainless steel weldments. Shielded metal arc welding (SMAW) and tungsten inert gas welding (TIG) were employed as joining techniques. Instrumented impact testing was performed between room and liquid nitrogen (−196°C) test temperatures. The resultsshowed a slight decrease in the impact energy of the 304L and 316L base metals withdecreasing test temperature. However, their corresponding SMAW and TIG weld metals displayed much greater drop in their impact energy values. A remarkable decrease (higher than 95%) was observed for the duplex stainless steel base and weld metals impact energy with apparent ductile to brittle transition behavior. Examination of fracture surface of tested specimens revealed complete ductile fracture morphology for the austenitic base and weld metals characterized by wide and narrow deep and shallow dimples. On the contrary, the duplex stainless steel base and weld metals fracture surface displayed complete brittle fracture morphology with extended large and small stepped cleavage facets. The ductile and brittle fracture behavior of both austenitic and duplex stainless steels was supplemented by the instrumented load–time traces. The distinct variation in the behavior of the two stainless steel categories was discussed in light of the main parameters that control the deformation mechanisms of stainless steels at low temperatures; stacking fault energy, strain induced martensite transformation and delta ferrite phase deformation.

Summary:

stainless steel base / duplex stainless steel base and weld metals
impact energy / a slight decrease / A remarkable decrease (higher than 95%)
fracture surface / complete ductile fracture morphology with wide and narrow deep and shallow dimples / complete brittle fracture morphology with extended large and small stepped cleavage facets

Title:Properties of Cr-Ni and Cr-Ni-Mn steels and alloy 36NKhTYu at low temperatures

Authors:Koshelev,P.F.; Nikitin,P.N.; Katkova,V.V.

Source:Metal Science and Heat Treatment, 1976, 18, 10, 866-869

Abstract:1.Precipitation-hardened alloy 36NKhT Yu has high strength, good ductility, a stable structure, low sensitivity to stress concentrations at low temperatures, and can be used for highly stressed components of cryogenic apparatus.2.Austenitic-ferritic steels 15Kh18N12S4T Yu and 12Kh21N5T are characterized by satisfactory strength, ductility, and toughness at temperatures down to 4°K.3.Steel 0Kh20N4AG10 has low ductility and is sensitive to stress concentrations at temperatures below 77°K.

Title:Low-temperature properties of strain-hardened austenitic stainless steels containing nitrogen

Authors:Kvasnevskii,O.G.; Yushchenko,K.A.; Mon'ko, G. G.

Source:Strength of Materials, 1978, 10, 7, 843-846

Abstract: 1.Low-carbon austenitic steels containing nitrogen are strengthened considerably by deformation at normal and low temperatures. The yield strength of stable austenitic steel 03Kh20N16AG6 at 77°K depends only on the preliminary deformation and is prctically independent of the temperature.2.To ensure high strength of stable austenitic steels containing nitrogen the deformation can be conducted at room temperature. The absolute values of the strength characteristics of stable austenitic steel 03Kh20N16AG6 deformed 30% at room temperature and metastable steels 03Kh18N11 and 03Kh19AN12 deformed at low temperature are almost identical.3.The ductility of stable austenitic steel 03Kh20N16AG6 strengthened by deformation at room temperature is quite adequate and the steel can be used for cryogenic equipment. Its yeild strength increases to 190 kgf/mm2 at 77°K and to 110 kgf/mm2 at room temperature.4.The change in the fracture toughness of steel 03Kh19AN12 at 77°K after small preliminary deformations (up to 5%) depends mainly on the reduction of the work of crack initiation. The reduction of the work of crack propagation with increasing preliminary deformation is due mainly to inhibition of the formation of strain martensite. With over 30% martensite the initiation of fracture is facilitated.

Title:Hydrogen environment embrittlement of type 316 series austenitic stainless steels at low temperatures (study on low temperature materials used in WE-NET 18).

Authors:Fukuyama,S.; Sun,D.; Yokogawa,K.

Source:Hydrogen Planet, World Hydrogen Energy Conf., 14th, 2003, 1063-1070

Abstrat: H environment embrittlement (HEE) of 316 series austenitic stainless steels was studied at 300-80 K. H had an effect on the tensile properties of 316, 316L, 316LN and F316LN stainless steels, and no effect on those of type 310S stainless steel. HEE of the materials increased with decreasing temp., reached a max. at .apprx.200 K and decreased rapidly with decreasing temp. down to 80 K. HEE of the materials also increased with increasing H pressure. Sensitization of type 316 stainless steel increased HEE and decreased the min. HEE temp. HEE of the materials from room temp. to the max. HEE temp. depended on the transformation of strain-induced martensite. The behavior below the max. HEE temp. depended on the diffusion of H.

Title:Strengthening mechanism of 316LN stainless steel at cryogenic temperatures

Authors:Li,L.F.; Yang,K.; Rong,L.J.

Source:AIP Conference Proceedings, 2002, 614, 1, 165

Abstract:Using vacuum metallurgical technique, we have fabricated the metastable austenitic stainless steel, 316LN which is aimed to be used as structural materials for superconducting magnets in Tokamak equipment in China. We have studied the basic properties of due materials at cryogenic temperatures, such as tensile strength, yield strength and Young's modulus. The effects of various elements on mechanical behaviors are discussed.

Title:Recent developments in stainless steels

Authors:Lo,K.H.^; Shek,C.H.^; Lai,J.K.L.^

Source:Materials Science & Engineering: R, 2009, 65, 4-6, 39-104

Abstract: This article presents an overview of the developments in stainless steels made since the 1990s. Some of the new applications that involve the use of stainless steel are also introduced. A brief introduction to the various classes of stainless steels, their precipitate phases and the status quo of their production around the globe is given first. The advances in a variety of subject areas that have been made recently will then be presented. These recent advances include (1) new findings on the various precipitate phases (the new J phase, new orientation relationships, new phase diagram for the Fe–Cr system, etc.); (2) new suggestions for the prevention/mitigation of the different problems and new methods for their detection/measurement and (3) new techniques for surface/bulk property enhancement (such as laser shot peening, grain boundary engineering and grain refinement). Recent developments in topics like phase prediction, stacking fault energy, superplasticity, metadynamic recrystallisation and the calculation of mechanical properties are introduced, too. In the end of this article, several new applications that involve the use of stainless steels are presented. Some of these are the use of austenitic stainless steels for signature authentication (magnetic recording), the utilisation of the cryogenic magnetic transition of the sigma phase for hot spot detection (the Sigmaplugs), the new Pt-enhanced radiopaque stainless steel (PERSS) coronary stents and stainless steel stents that may be used for magnetic drug targeting. Besides recent developments in conventional stainless steels, those in the high-nitrogen, low-Ni (or Ni-free) varieties are also introduced. These recent developments include new methods for attaining very high nitrogen contents, new guidelines for alloy design, the merits/demerits associated with high nitrogen contents, etc.

Title:Mechanical properties of 32Mn-7Cr-0.6Mo-0.3N austenitic steel for cryogenic applications

Authors:Ruidong,Fu; Yangzeng,Zheng; Yibin,Ren

Source:Journal of Materials Engineering and Performance, 2001, 10, 4, 456-459

Abstract: The tensile, impact, and fracture toughness tests from ambient temperature to 77 K were carried out on 32Mn-7Cr-0.6Mo-0.3N austenitic steel. The fracture surfaces and the phase constitution were analyzed using scanning electron microscopy and x-ray diffraction. The results show that the relation between yield strength and temperature is σ0.2 � 300 + 1392.4 exp (−0.0106T). The 77 K yield strength is 883 MPa � m1/2 and the K J0.05 value is about 236 MPa � m1/2. The cryogenic intergranular fracture is fully suppressed. The 77 K fracture surfaces exhibit a tough character composed of many dimples and few small quasi-cleavage facets. The results of x-ray analysis show that the austenite phase of the steel is stable even under cryogenic deformation conditions.

Title: Primary:Trends and Advances in Cryogenic Materials

Authors: Primary:Reed,R.P.

Source:Cryogenic Engineering, 2007, 52-83

Abstract:Increased emphasis has been placed on research and development of specialized materials for use in low-temperature applications. Most research has been driven by (1) the construction of large superconducting coils, (2) requirements for transport and storage of liquefied natural gas, and (3) the discovery of superconductors with critical temperatures Tc as high as 90 K. The integration between structural design and material properties for critical low-temperature applications has been facilitated by the incorporation of fracture mechanics concepts. This development has led to measurement of an entirely new set of mechanical properties at low temperatures, to increased nondestructive inspection to measure in-situ flaw sizes, and to the development of fracture control practices for a number of cryogenic applications.

Title:Cryogenic CVN impact study of high nitrogen stainless steels.

Authors:Yuan,Zhi-zhong; Dai,Qi-xun; Cheng,Xiao-nong; Chen,Kang-min; Xu,Wen-wei

Source:Jiangsu Daxue Xuebao, Ziran Kexueban, 2004, 25, 3, 247-251

Abstract: The Charpy (v notch) (CVN) impact properties of two kinds of high nitrogen stainless steels, Fe-24Mn-13Cr-1Ni-0.44N and Fe-24Mn-18Cr-3Ni-0.62N under low temps., were tested. Results show that with the concn. of nitrogen increasing, the ductile property at low temp. decreases rapidly while the DBTT increases, which are at 140 K and 210 K resp.; one feature of brittle fracture is peeled off layers in high nitrogen austenitic stainless steels when impacted at 83 K. The change of fracture modes of high nitrogen austenitic stainless steels with temp. decreasing is prolonged/equiaxial dimple->shallow dimple->mixt. of brittle facet and ductile dimple->peeled off layers within dominated brittle facets.

Title:Temperature Dependence of Tensile Behaviors of Nitrogen-Alloyed Austenitic Stainless Steels

Authors:Wang,Wei; Yan,Wei; Yang,Ke; Shan,Yiyin; Jiang,ZhouhuaSource:Journal of Materials Engineering and Performance

Abstract: The temperature dependence of tensile behaviors of two nitrogen-alloyed austenitic stainless steels, an annealed 316LN steel and a high-nitrogen austenitic stainless steel (Fe-Cr-Mn-0.66% N), was investigated by tensile test at different temperatures from 293 K down to 77 K. It was found that strength of the two steels increased with decrease of temperature. With a decrease in temperature, the uniform elongation increased for the 316LN steel, whereas it increased followed by a decrease for the high-nitrogen steel. A three-stage hardening behavior occurred in the 316LN steel, but not in the high-nitrogen steel, with decrease of temperature. The strain-induced martensite transformation in the 316LN steel could retard void nucleation and increase the strain-hardening rate, resulting in much higher tensile stress and higher uniform elongation of 316LN steel. It was analyzed that stacking fault energy of the high-nitrogen steel decreased with decrease of temperature, which promoted the twinning and planar slipping in the steel, and resulted in brittle fracture at cryogenic temperatures.