[16P-T6-08] Effect of Residual Stress on Pore Formation in Multi-Materials Deposited via Directed Energy Deposition
キーワード：Directed Energy Deposition, Pore , Residual Stress, Tool Steel
In this study, a multi-layered deposit comprising a surface layer, buffer layer, and substrate was fabricated using directed energy deposition. The objective was to explore the impact of residual stress on pore formation in the surface layer. Variations in pore size within the surface layer were observed, contingent upon the defects in the buffer layer. Notably, the surface layer exhibited no large pores when cracks were present in the buffer layer. In contrast, larger pores were prevalent in the surface layer when the buffer layer was devoid of cracks. Factors such as increased carbon content and residual stress contributed to both hot and cold cracks in the buffer layer. Unmitigated residual stress from the buffer layer transmitted across the interface to the surface layer, elevating the tensile residual stress therein. This increase in stress intensified the equilibrium pressure inside the gas pores, prompting their expansion as a form of stress alleviation.