Laser Powder Bed Fusion of M789 Steel on Wrought N709 Steel Substrate

A newly developed maraging steel, M789, was additively manufactured on top of a wrought precipitation hardening steel, N709, using laser powder bed fusion (LPBF). A fully dense M789 was achieved. The EBSD confirmed a completely martensitic structure with less than 1% retained austenite. The results show that the M789 steel had a lower hardness of 550 HV compared to 680 HV for N709. Moreover, no significant diffusion of alloying elements from the M789 to the N709 material was detected. Based on the initial assessment, a post-processing heat treatment is necessary to achieve homogenous mechanical properties between dissimilar alloys.