Effects of Carbon and Nitrogen on the Tensile Deformation Behavior of SUS304 and 316 Stainless Steels at Cryogenic Temperatures

Abstract

Effects of C and N contents on the tensile properties and deformation behaviors at low temperatures have been investigated to obtain an alloy design basis on SUS 304 and 316 austenitic stainless steels for cryogenic application.Increase in C and N contents led to the increase in temperature dependency of 0.2% yield strength for both SUS 304 and 316 steels. However, SUS 316 steel showed larger temperature dependency than SUS 304 at the same level of (C+N) content, probably due to the solution strengthening effect of Mo.The results of multiple regression analyses on the effects of C and N contents on the 0.2% yield strength at each temperature indicated that the contributions of both C and N increase with decreasing temperature and that the contribution of N is larger than that of C at low temperatures.The deformation behavior of metastable austenitic steels could be comprehensively explained in relation to austenite stability. Increase in austenite stability resulted in increase in onset strain at which straininduced martensitic transformation occurred. And increase in austenite stability also led to the decrease in transformation rate which in turn gave rise to lowering strain-hardening exponent. It has been also found that tensile elongation shows maximum at around Md 30 temperature.

Effects of Temperature and Strain Rate on TRIP Effect in SUS301L Metastable Austenitic Stainless Steel

“…However, the 0.2% proof stress of SUS301L increased with a decrease in temperature. This may be related to the effect of nitrogen (N) on tensile properties 29,30) because the SUS301L contains N content of 0.127 mass%. Miura et al 29) investigated the effects of N and carbon (C) content on the deformation behavior at low temperatures using SUS304 and SUS316 steels.…”

“…This may be related to the effect of nitrogen (N) on tensile properties 29,30) because the SUS301L contains N content of 0.127 mass%. Miura et al 29) investigated the effects of N and carbon (C) content on the deformation behavior at low temperatures using SUS304 and SUS316 steels. The effect of temperature on 0.2% proof stress in the SUS304 with N content of 0.128 mass% 29) agreed well with that of the SUS301L.…”

“…Miura et al 29) investigated the effects of N and carbon (C) content on the deformation behavior at low temperatures using SUS304 and SUS316 steels. The effect of temperature on 0.2% proof stress in the SUS304 with N content of 0.128 mass% 29) agreed well with that of the SUS301L. Figure 5 shows the mechanical properties of the SUS301L 20) and SUS304 steels 19) as a function of the strain rate.…”

In Situ Observation for Deformation-Induced Martensite Transformation (DIMT) during Tensile Deformation of 304 Stainless Steel Using Neutron Diffraction. PART I: Mechanical Response

“…Miura et al suggested a method to determine the strain E MS at which DIMT may start, when fitting the true stress-true strain curve [21]. Considering that their deformation test was conducted at 77 K, the sigmoidal, two-step hardening behavior was evident.…”

In Situ Observation for Deformation-Induced Martensite Transformation during Tensile Deformation of SUS 304 Stainless Steel by Using Neutron Diffraction PART II: Transformation and Texture Formation Mechanisms

“…Although the formation of ε martensite by DIMT is well-known, it has rarely been investigated from an engineering aspect [2]. Several researchers have extensively investigated the relationship between the α' martensite fraction and the mechanical properties of steel, particularly, the strain-hardening rate [2,3]. However, to achieve the desired mechanical properties in steel by controlling its chemical composition and/or microstructure, it is necessary to understand the effects of the γ→ε→α' and γ→α' DIMT mechanisms on the deformation of steel.…”