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.