Recrystallisation Characteristics of Cold Rolled Austenitic Stainless Steel during Repeated Annealing

Abstract

The study describes the recrystallisation behaviour of a cold rolled AISI 316L austenitic stainless steel when subjected to repetitive annealing cycles of short durations of 45s. The evolving recrystallising microstructure was examined using both scanning and transmission electron microscope. Electron backscattered diffraction analysis was performed in a FEI NANO SEM 430 Field Emission Gun scanning electron microscope using an EDAX/TSL high-speed Digiview camera for Kikuchi pattern acquisition. The results were compared with the recrystallised microstructure formed by isothermal annealing treatment of short time. Unlike isothermal annealing, wherein grain growth increased with time, increasing number of repetitive annealing cycles showed formation of ultrafine grained recrystallised microstructure. The observed restricted grain growth or grain refinement was correlated with the occurrence of dislocations and subgrains in the microstructure at and above four repetitive annealing cycles. The introduction of these strain heterogeneities were attributed to the rapid cooling of specimens during repetitive annealing cycles