Description of anisotropic material response of wire and arc additively manufactured thin-walled stainless steel elements

Abstract

In contrast to conventionally-produced structural steel and stainless steel elements, wire and arc additively manufactured (WAAM) elements can exhibit a strongly anisotropic material response. To investigate this behaviour, data obtained from tensile tests on machined and as-built coupons extracted from WAAM stainless steel sheets are analysed. The observed mechanical response in the elastic range is described accurately using an orthotropic plane stress material model requiring the definition of two Young’s moduli, the Poisson’s ratio and the shear modulus. In the inelastic range, the anisotropy is captured through the Hill yield criterion, utilising the 0.2% proof stresses in the three different loading directions relative to the deposition direction; plastic Poisson’s ratios are also reported. The presented findings and constitutive description highlight significant variation in the properties of the studied stainless steel with direction, which opens up opportunities to enhance the mechanical performance of WAAM structures by optimising both the location and orientation of the printed material.