Influence of Processing on Texture, Grain Boundary Structure and Corrosion Behaviour of Austenitic Stainless Steels

The present paper deals with the evolution of texture in austenitic stainless steels during cold rolling and sub-sequent annealing of 90% cold-rolled material. After 90% cold rolling, the texture is mainly of brass type {0111}<112> along with a scatter towards S orientation {123}<634> and Goss orientation {011}<100>. It is also obs-erved that during cold rolling, in 304K steel there is a transformation to a'-martensite structure and that infl-uences the texture development in this steel too. During recrystallisation, the overall texture intensity is weak; however, there are some discernible texture components. Major components are centred on Goss and Cu components as well as the BR component {236}<385>. With increasing
annealing temperature, the textural evolution shows eme-rgence of weak texture with another new component i.e. {197}<211>. It was observed that during recrystallisation, most of the grain boundaries are of twinning-induced CSL boundary of E3 type. The tensile properties were found to vary with the processing conditions. The percent elon-gation and strain hardening exponent of the thermo-mechanically processed material was found to be larger than that of the starting material. The increase in the percent elongation was correlated with special coincidence
boundaries. Sensitisation behaviour of thermomechanically processed AISI 304L stainless steel has been characterised for grain boundary character distribution, grain size, and degree of sensitisation (DOS). The increase in annealing
temperature and time following mechanical processing
showed an increase in grain size (upto 37 μm) and in the DOS. The fraction of coincident site lattice (CSL)boun-daries (R3 to R29) was also noticed to increase with the annealing temperature, which implied that an increasing fraction of low energy boundaries did not cause a decrease in the DOS. The grain size through its effect on grain boundary surface area and the effective grain boundary energy correlated well with the extent of sensitisation.