In-situ modification of material hardness for low-alloyed steels processed via PBF-LB/M – a view on process related microstructure

Abstract

Laser-based powder bed fusion of metals (PBF-LB/M) enables to generate complex
parts with the downside of using one material. In advance to local in-situ alloying, premixed
metal powder with additional carbon and different tungsten carbide sizes is investigated.
Hardness increases from 44 to 55 HRC were achieved with a low alloyed bainitic steel by
modification to a carbon content of 0.35 w% and 2.5 w% of WC particles for particle
reinforcement. As-built properties for bearing applications are desired. To get a deeper insight in
the hardening and microstructure formation during in-situ modification, the powder is coated with
carbon nanoparticles and WC microparticles (0.9/2.5/8 µm). Samples were built with global
powder modification first, to separate influences of the aspired hardness from powder distribution
effects. Then in-situ modified samples were built and investigated towards their hardness and
microstructure.