High strain rate induced shear banding within additively manufactured AISI 316L

Abstract

The effects of post-processing via cold/hot rotary swaging, combined with high strain rate deformation, on formation of shear bands and deformation induced martensite within AISI 316L steel prepared by Selective Laser Melting are investigated. The as-built sample exhibited randomly oriented grains and residual porosity, which was reduced/eliminated by rotary swaging and subsequent high strain rate deformation. Hand in hand with significant changes in grain morphology after swaging (grain elongation and refinement, especially under cold conditions) and high strain rate processing (formation of shear bands and deformation induced martensite), the combined deformation imparted substantial hardening and resulted in microhardness increase by more than 20 %, primarily due to the occurring martensitic transformation. The structure changes were observed especially for the cold processed sample, due to aggravated plastic flow and hindered movement of generated partial dislocations.