Crystallographic orientation dependence of dynamic deformation behaviours in additively manufactured stainless steel

Abstract

This study reveals the dynamic compressive deformation anisotropy among 316L stainless steel fabricated via wire and arc additive manufacturing process(WAAM). Cylindrical samples extracted from as-built WAAM 316L plate with 35°, 45°, 55°and 90° from scanning direction, were referred to as , , and crystallographic orientations hereinafter, which had been confirmed through backscattered diffraction. Cylindrical samples were subjected to dynamic tests by a split Hopkinson pressure bar. The corresponding mechanical behaviors and deformed microstructures are associated. There are approximately 10% higher dynamic flow stresses from the samples than other samples during dynamic tests at strain rates less than 3500 s−1, which can be attributed to lower density of thinner deformation twins. The lower tendency towards deformation twinning in samples arises from the increase of effective stacking fault energy. WAAM 316L presents an anisotropy of resistance to adiabatic shearing, of which the order is , , and . Two adiabatic shear bands(ASB) in sample present distinct orientation characters, where the sub-grains in the first ASB show and -fiber while that in the subsequent one take -fiber. This micro-texture discrepancy from two ASBs could be contributed to the precondition change of macro texture in the matrix which give birth to.

Keywords

• Stainless steel
• Additive manufacturing
• Crystallographic orientation
• Twin
• Adiabatic shear band