The Influence of Cold Deformation and Annealing on Texture Changes in Austenitic Stainless Steel

Abstract

Austenitic stainless steels are widely used in industry, from heavy industry and power generation to precision mechanics and electronics, accounting for about 2/3 of the stainless steels produced. The stability of austenite influences the properties and behaviour of these steels during deformation and annealing. This paper presents the results of research into austenitic metastable phase X5CrNi1810 steel, which was subjected to cold rolling (in the range of 5 to 80%) and then annealing (at temperatures of 500-900 °C). The research focused mainly on changes in crystallographic texture parameters occurring during the analysed processes. It was found that the observed development of the deformation texture is complex due to the fact that several processes take place simultaneously. Namely, the deformation of austenite, the transformation of austenite into martensite, and the deformation of the resulting martensite. The texture of the deformed austenite was similar to the texture of the alloy type {112}<110>. After 80% deformation, the Goss-type {110}<001> texture component showed the highest intensity. The lack of {112}<111> orientation in the texture was due to the fact that this orientation changes to the {112}<110> martensite orientation as a result of the γ → α' phase transition. Annealing of the deformed steel at 500 °C led to an increase in the degree of texturing (sharpening of the texture), which was related to the improvement of the texture in this temperature range. Above 600 °C, the degree of texturing decreased, which is directly related to the α' → γ reverse transformation and the subsequent recrystallization process. Magnetic studies indicate an increasing proportion of the magnetic phase α' (martensite) together with an increasing degree of deformation. For deformation of 80%, the amount of magnetic phase reached a value of more than 33%. After annealing at a temperature of 800 °C, there is no martensite in the structure, which indicates that, in these heat treatment conditions, the complete reverse transformation of martensite into austenite has already taken place.