Martensite shear phase reversion-induced nanograined/ultrafine-grained Fe–16Cr–10Ni alloy: The effect of interstitial alloying elements and degree of austenite stability on phase reversion

Mechanisms of ultrafine-grained austenite formation under different isochronal conditions in a cold-rolled metastable stainless steel

“…7a. This has also been observed in other investigations [6,14,17,18]. However, after faster heating rates (Fig.…”

“…One of the key microstructural parameters to improve the strength without compromising much the ductility is the austenite grain size (AGS). It is clear from the literature that the application of advanced thermo-mechanical processing treatments to MASSs, as the severe plastic colddeformation followed by a controlled annealing, leads to nano/ultrafine-grained (NG/UFG) microstructures with improved mechanical properties, compared to their coarse-grained counterparts [14][15][16][17][18][19][20][21]. To obtain the desire microstructural refinement, the metastable austenite should be completely transformed into martensite during the cold deformation, for which a great percentage of deformation is required [5,6,[20][21][22][23][24].…”

“…It appears that cold deformations beyond the level needed to form lath-type martensite result in a crystallographic distortion of this morphology, leading to a dislocation-cell-type of martensite, with an increase in the dislocation density and, thus, in the number of nucleation sites. A carefully controlled annealing treatment ensures the grain refinement of the final austenitic microstructure [6,[14][15][16][17][18][19][20][21]. In this manner, Forouzan et al [16] attained grain sizes of 330 nm in an AISI 304 L; Misra and co-authors obtained UFG (100-500 nm) austenitic structures in 17Cr-7Ni-N [6] and in an AISI 301LN [17] and Weidner et al [21] obtained an AGS below 1 μm after annealing a 90% cold-deformed highalloyed austenitic TRIP steel.…”

Development of Nanocrystalline 304L Stainless Steel by Large Strain Cold Working

“…The efficiency of cold working for processing the high-strength ultrafine-grained/nanocrystalline products depends remarkably on the kinetics of grain refinement during plastic deformation. Austenitic stainless steels are typical representative of metallic materials exhibiting rapid grain refinement upon cold working [7][8][9][10]. The grain refinement in these steels is promoted by an intensive grain subdivision, which is associated with deformation twinning followed by strain-induced martensitic transformation [9][10][11][12][13].…”

Martensite and bainite in nanocrystalline steels: understanding, design and applications

“…A practical approach to control instability is to obtain grain structures with a bimodal size distribution, where large grains preferentially accommodate strain and small grains confer high strength such that a combination of high strength and high ductility is obtained as well as significant strain hardening. In this respect, Misra et al [4] describe the attributes of a promising phase-reversion approach that results in nanometre/ultrafine grain structures in austenitic stainless steels characterised by high strength and high ductility. The approach involves severe cold deformation (45-75%) of metastable austenite to produce martensite, which on annealing for short durations reverts to austenite via diffusional or shear mechanisms, depending on the chemical composition of the steel.…”