Effect of thermal cycles on heavily cold deformed AISI 304L austenitic stainless steel

Abstract

The solution treated commercial grade AISI 304L austenitic stainless steel plate was heavily cold rolled to 90% of thickness reduction. Cold rolled specimens were annealed at various temperatures by thermal cycles and isothermal annealing. Strain-induced phase transformations and microstructure studies were carried out both in the cold rolled and annealed conditions. The X-ray diffraction and magnetic measurements were used for phase transformation studies. The transmission electron microscope characterisation revealed that the cyclic thermal process resulted in ultrafine grain austenite formation whereas, the isothermal annealing developed coarser grain size microstructure. The different microstructural evolutions by the above two processes largely influenced the development of the recrystallisation texture. The thermal cycling produced a distinct γ-fibre texture while the isothermal annealing resulted in a cube texture component along with the γ-fibre. The γ-fibre texture evolution was attributed to the over critical subgrains or nuclei and {1 0 0} 0 0 1 cube texture to the coarser grains of micrometer size.