Smart-Alloying - Liquid in-situ re-alloying in additive manufacturing

Smart-Alloying enables local modification of the chemical composition of metallic components within additive manufacturing processes. In the example of laser based powder bed fusion (PBF-LB/M), this new technology uses suspensions to place alloying elements precisely at every requested point of the printed area. It allows a tailormade change of the local microstructure and properties. High chromium-containing stainless steel and carbon as the alloying element serves as a demonstration example. Microprobe and EBSD analyses confirm a locally increasing carbon content, which leads to the formation of fine martensitic structures with chromium-rich carbides at the grain boundaries of the ferritic base material. The associated change in microstructure regarding grain size and phase composition results in modified mechanical properties. Indentation tests carried out show a corresponding locally increased indentation hardness. This decisive influence of even individual alloying elements paves a new way for functional grading of metallic components in additive manufacturing.