Suppressing precipitation during the reverse transformation from martensite to austenite in a cold-rolled austenite stainless steel

Abstract

The precipitation behavior and its influence on the tensile properties of cold-rolled austenitic stainless steel, isothermally aged at 750 °C with and without a pulsed electric field, was investigated. During reverse transformation annealing, a large amount of coarse precipitate forms on the grain boundary and grain interior. However, when a pulsed electric field is applied in reverse transformation annealing, only a small amount of precipitate forms in the stainless steel; moreover, the suppressed precipitation effect did not significantly change with an increased annealing time. Simultaneously, the heat treatment comparison test at the almost same temperature clarifies that the pulsed electric field plays a critical role in inhibiting precipitate formation, rather than temperature. The corresponding mechanism reveals that the pulsed electric field disrupts the diffusion of solute Cr and Mo to the precipitate interface, which restricts precipitation growth. Furthermore, the growing precipitate is dissolved to reduce the difference in electrical resistance between the matrix and precipitate. Therefore, the precipitation behavior is strangled in the early stages with the pulsed electric field treatment, and the ductility of the cold-rolled stainless steel is further improved. The pulsed electric field was explored as a novel pathway to suppress precipitation behavior, and the results confirmed that the pulsed electric field was not only effective in impeding the precipitate growth of austenitic stainless steel, but could also be a useful technique to inhibit deleterious precipitation in other metallic materials.