변형유기 마르텐사이트 변태에 미치는 질소의 영향 = Effect of Nitrogen on Deformation Induced Martensitic Transformation

다국어 초록 (Multilingual Abstract)

Deformation induced martensitic transformation (DIMT) behavior of 304 stainless steel with and without nitrogen was investigated to elucidate the effect of nitrogen on DIMT, through the use of the proposed kinetics relation between the volume fraction f of transformed martensite and inelastic strain ε for DIMT; f/f_8 = 1 - exp[-β(ε-ε_o)^n]. The deformation mode parameter n characterizes the formation rate of nucleation sites and thus depends on the deformation mode providing the value of n = 2.2 for these steels regardless of N contents. Adding N, on the other hand, is found to reduce the value of austenite stability parameter β, which in turn implies more stable austenite to provide significantly enhanced ductility in 304N stainless steel below room temperatures. Nitrogen is also found to reduce the saturation volume fraction f_8 of transformed martensite and also the M_d temperature, above which martensitic transformation cannot occur by plastic deformation.