Microstructure and Pitting Corrosion of Austenite Stainless Steel after Crack Arrest

Abstract

With synergy of plastic deformation near crack tip and pulse current treatment, complex phase transformation and recrystallization occur in the metallographic structure, with the austenite transforming to fine grain structure and deformation-induced martensite; but, without the plastic deformation, the phase transformation, and recrystallization it was difficult for the crack arrest process to take place only undergoing the pulse current treatment. The nano-indentation experiment showed that the phase transformation region contained the maximum residual compressive stress consisting of four parts: the plastic stress, the explosion stress, the thermal stress, and the transformation stress, which was beneficial to restrain the crack growth. However, the solidification structure and the deformation-induced martensite structure was vulnerable to pitting corrosion through scanning microelectrode technology (SMET) and pitting corrosion experiment, but the pitting corrosion resistance could be improved through the solution heat treatment.