Abstract
Additive manufacturing can be used to create complex metal parts, free of defects. Extensive research has been conducted to prevent common imperfections like lack of fusion and gas pores by adjusting deposition parameters, including laser power, deposition speed, and powder feed rate. While these imperfections can be present in both single- and multi-material systems, single-material systems have been more thoroughly studied. Additionally, due to the complexity of multi-material additive manufacturing, unique imperfections not seen in single-materials are possible. In this work, AISI H13 tool steel was deposited onto aluminum bronze with laser-based directed energy deposition (DED-LB), with powder as feedstock. The resulting mix between the two materials created a complex structure with several imperfections not usually seen in single-material deposition. The two primary imperfections identified are unmelted particles near the aluminum bronze–steel interface and significant vertical cracks in the steel. The cracks were found to be mainly caused by the segregation of copper to the previous austenite grain boundaries in the steel, leading to hot cracking. The unmelted feedstock particles likely resulted from rapid cooling of the steel, due to the significant difference in thermal properties between the two materials. Despite the improper melting of the steel feedstock near the interface, good cohesion between the two materials was achieved.