Effect of Build Height on Temperature Evolution and Thermally Induced Residual Stresses in Plasma Arc Additively Manufactured Stainless Steel

Plasma arc additive manufacturing (PAM) is receiving an increasing attention because of its efficiency of dimensional size and cost, as compared to other additive manufacturing (AM) techniques. Despite the capacity of building medium to large-scale components by PAM, the heat-transfer behavior could be significantly influenced by component size (or build height) during processing. Understanding this build size effect on heat transfer is critical to predict the microstructure and mechanical properties and optimize the processing parameters. In the present work, the site-specific evolutions of the temperature and residual stresses along the build height were investigated under varying energy densities during PAM processing. A finite element method (FEM) was used to discretize and solve the thermomechanical partial differential equations (expressing the conservation of energy and momentum) governing the plasma arc additive manufacturing process. We studied the transient temperature and subsequent thermally induced residual-stress fields in PAM 304 stainless steel components with different deposition heights. Our study provides general insight into the residual-stress development in wire-based additively manufactured engineering materials.