High mechanical performance of AISI304 stainless steel plate by surface nanocrystallization and microstructural evolution during the explosive impact treatment

Abstract

The surface treatment on AISI304 stainless steel plate was successfully carried out by explosive impacting technique. We have obtained a high mechanical performance and corresponding fine microstructures compared to its base metal by the technique. Experimental results indicate that nanograins (around 30 nm of diameter) with random crystallographic orientations formed in the top impacted surface and many deformation bands in the subsurface layers. The explosive impact generated deformation induced martensite (DIM) in the plates, where DIM volume fraction increased firstly and then decreased toward inside. These surface nanocrystallization and microstructural evolution, which can be attributed to the co-actions of the grain-refinement, deformation-bands and phase transformation effects, can enhance surface hardness and mechanical properties remarkably not only near surface but entire plate. Keywords: Explosive impacting, AISI304 stainless steel, Surface nanocrystallization, Grain refinement