The effect of plastic deformation and subsequent heat treatment on the acoustic and magnetic properties of 12Khl8N10T steel

Abstract

The results of studying the effect of plastic deformation and subsequent heat treatment on the acoustic and electromagnetic properties of austenitic steel 12KM8N10T (analog AISI 321) are presented. Cryogenic corrosion-resistant austenitic steel 12Khl8N10T undergoes strain-induced martensitic transformation, which significantly changes the electromagnetic, elastic and strength properties of the material. The formation of the new phase in conjunction with the process of plastic deformation affects the crystallographic texture of the alloy. A change in the texture of the material was estimated using the acoustic anisotropy parameter determined by the ultrasonic method. Changes in the magnetic properties attributed to appearance of the ferromagnetic phase of martensite in the paramagnetic austenite matrix were fixed with an eddy current ferritometer. It is shown that at the initial stage of plastic deformation (uniaxial tension) the value of the acoustic anisotropy parameter decreases probably due to the fact that change in the texture is more affected by the process of austenite deformation than the formation of α'-martensite. Further deformation of the material promotes formation of the new phase thus strengthening the impact of the new phase on the crystallographic texture and results in increase in the acoustic anisotropy parameter. It is shown that annealing at a temperature of 350, 600, 700, and 1050°C of pre-deformed stainless steel decreases the parameter of acoustic anisotropy and the volume content of the magnetic phase. It is shown that the parameter of acoustic anisotropy of the material drops to zero after annealing at 600°C, whereas at a temperature of 1050°C the martensitic phase completely disintegrates and the texture is determined only by the austenite phase.