Martensitic transformation in SUS 316LN austenitic stainless steel at RT

Abstract

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 (ε t ), the ferromagnetic phase (α ′ -martensite) could be clearly observed which increased sharply on further deformation. The amount of α ′ was very small (0.18 vol.% at ε t ≈ 60%) when compared to the reported data for other grades of austenitic steels such as 304, 304L, 316 and 316L.The strain-induced α ′ -martensite is further studied by the magnetic hysteresis loops. The coercivity (H C ) and remanence (M r ) were analyzed by subtracting the paramagnetic contribution of the bulk austenite structure. While H C was found to decrease with α ′ , M r remained same (∼67 emu/g) when normalized to the volume fraction of α ′ . The decreasing H C with increasing α ′ and/ or ε t is presumed to be due to the domain wall pinning at the grain boundaries when the cluster size exceeds the domain wall width.

Cryorolling impacts on microstructure and mechanical properties of AISI 316 LN austenitic stainless steel

“…Similarly, the volume fraction of transformed martensite was only 18% when 316LN SS was compressed with a high strain of 60% at room temperature [17]. Based on the above evidences, the deformation-induced martensite transformation depends on the austenite stability (chemical composition and initial austenite grain size) and the rolling conditions (strain, stress state, strain rate, deformation temperature and rolling speed).…”

Tensile Deformation Temperature Impact on Microstructure and Mechanical Properties of AISI 316LN Austenitic Stainless Steel

“…4b). The direction of the slip bands was different among the grains, presenting a typical feature of metals with low stacking fault energy [22,23].When the temperature increased to 300 C, the number of the slip bands reduced and a small amount of annealing twins turns up in the deformed grains. The degree of deformation was smaller than that at room temperature and the austenite grain size increased to 60-70 μm, as shown in Fig.…”

Effect of Rolling Temperature on Microstructure Evolution and Mechanical Properties of AISI316LN Austenitic Stainless Steel

“…The occurrence of the new structure significantly improves the work-hardening ability of ASS and substantially enhances its strength. Studies of martensite transformation during deformation at room temperature have indicated that the volume fraction of transformed martensite increases with the strain, but decreases with the strain rate [ 10 ]. Compared with torsion and compression, tensile deformation is more effective at inducing martensite transformation [ 11 ].…”