Phase Transformations in Stainless Cr-Mn-N Steel Activated by Nanostructuring Surface Treatment and Their Influence on Deformation Behavior and Fracture at Cryogenic Temperatures

Abstract

The structure of stainless austenitic Cr-Mn-N steel after deformation treatment of its surface by ultrasonic forging strain (UFS) has been studied. It is shown that UFS activates strain aging in the near-surface layer with the formation of CrN particles. Preliminary ultrasonic treatment of the steel surface contributes to an increase in the yield strength during tensile tests at a temperature of -196oC and provides ductile fracture of the near-surface layer. Keywords: high nitrogen steel, austenite, ultrasonic forgingstrain, strain aging, cryogenic temperature, martensitic transformation.