Enhanced cryogenic tensile properties through cryogenic cyclic plastic strengthening in a metastable austenitic stainless steel

Abstract

Pre-strain with large deformation is an effective method to improve the yield ratio of metastable austenitic stainless steel, but it will lead to a significant reduction in elongation. Therefore, a cryogenic cyclic plastic strengthening method is proposed in this paper. Compared with the base metal without strengthening, the strengthened material improved the yield strength at 77 K and maintained high elongation. It is shown that the strengthening eliminated the yield plateau and changed the characteristics of first adequately nucleating and then rapidly phase transformation. This was achieved by the special microstructure prepared by cryogenic cyclic plastic loading, which allowed the strengthened material to contain a large number of phase transformation while still retained the ability of stable phase transformation, so that the phase transformation induced plasticity effect played a full role in the subsequent tensile process and allowed the material to show an excellent combination of strength and ductility.