Residual Stress Induced in Thin Plates During Additive Manufacturing

Additive manufacturing is a technique for producing complex geometry engineering parts relatively quickly and cheaply; however, residual stresses induced in the part during manufacture can result in significant distortion of the build. In this study, nickel-chromium alloy (Inconel 625) geometrically-reinforced thin plates have been additively manufactured using laser-powder bed fusion, that have comparable flatness to those built subtractively. The residual stresses induced in the thin plates from manufacture are deduced by measuring out-of-plane displacements using stereoscopic digital image correlation. The results demonstrate that residual stresses cause potentially severe out-of-plane displacements which can be alleviated by using buttress supports to reinforce the plate edges during the build. In both landscape and portrait orientation builds, out-of-plane displacement increased upon release from the baseplate but was reduced by incremental release.