Controlling Dilution in Multilayer Welding for Additive Manufacturing

Functionally graded material is a type of material characterized by gradual variations in the chemical composition and structure over volume. Dilution is a major concern in producing such materials produced using welding techniques. In this paper, the effects of the number and thickness of weld overlay layers on the dilution were systematically investigated for two common wire arc additive manufacturing processes. Gas metal arc welding and flux-cored arc welding processes were used to clad plain carbon steel substrate by 410 stainless steel and Stellite 6, respectively. Welding speed was varied to create weld layers with a thickness of 2 mm to 8 mm. The results showed that the weld thickness had the main effect on the dilution. Regarding the number and arrangement of the thin or thick weld layers, no direct effects on the dilution were observed. Consequently, by controlling the thickness of the weld overlay, the changes in the chemical composition in each weld layer could be justified.