Martensitic transformation in SUS 316LN austenitic stainless steel at RT

The results of high-accuracy magnetic measurements on SUS 316LN austenitic stainless steel compressively deformed at room temperature (RT) are reported here. Even after the mild deformation of *25% true strain (et), the ferromagnetic phase (a0-martensite) could be clearly observed which increased sharply on further deformation. The amount of a0 was very small (0.18 vol% at et & 60%) when compared to the reported data for other grades of austenitic steels such as 304, 304L, 316, and 316L. The strain-induced a0-martensite is further studied by magnetic hysteresis loops. The coercivity (HC) and remanence (Mr) were analyzed by subtracting the paramagnetic contribution of the bulk austenite structure. While HC was found to decrease with a0, Mr remained the same (*67 emu/g) when normalized to the volume fraction of a0. The decreasing HC with increasing a0 and/or et is presumed to be due to the domain wall pinning at the grain boundaries when the cluster size exceeds the domain wall width