The Potentiostatic Etching Figures of Cold-Rolled Austenitic Stainless Steels

Abstract

The potentiostatic etching technique for austenitic stainless steels was studied to observe changes in the microstructures by cold-rolling. The etching potentials of each phase (ferrite, austenite and grain boundaries) were determined from the etching figures of an annealed AISI 321 L stainless steel. 1 N H2SO4 (containing 0.01 g/LNH4 SCN) and conc HNO3 were selected as etching solutions. The α-ferrite phase caused by cold-rolling was etched at a potential of −0.35 (V vs S.C.E) in H2SO4, and the distribution of the ferrite phase was observed by an electron microscope. The slipping bands were etched at −0.2 V that corresponds to the etching potential of austenite phase. The grain boundaries were etched at 1.2 V in conc HNO3, and deformation of the grains by cold-rolling was observed.