Impact of process parameters on mechanical properties and surface characteristics in hybrid metal additive manufacturing of maraging steel

Abstract

Additive manufacturing (AM) refers to a novel group of manufacturing methods where the process takes place by gradually adding material to build the final part. AM offers significant advantages—enhanced design freedom and reduced material waste with the potential to change the paradigm of the manufacturing industry. Direct metal laser sintering (DMLS) is an additive manufacturing method where 3D printing of metal parts is conducted layer by layer from metallic powders. DMLS-hybrid milling is a new addition to additive manufacturing methods. The synergistic approach of additive and subtractive manufacturing methods offers benefits from both manufacturing paradigms. The process parameters—laser power, print speed, layer thickness, hatch distance, etc.—significantly influence the quality of the final part. Hence, the process parameters should be optimized to obtain the desired result. This work focuses on optimizing process parameters for superior surface characteristics and mechanical properties of heat-treated maraging steel manufactured by the DMLS-hybrid milling method. Experimental approaches were adopted, and statistical analyses were performed to evaluate the performance of maraging steel parts printed at multiple process conditions guided by Taguchi L9 orthogonal array of experiment design. Significant improvement was observed in surface quality by adopting milling operation during printing, and mechanical properties were improved by the heat-treatment process.