Towards carbide-rich tool steels in PBF-LB/M: TiC additivation of AISI H13

Abstract

The range of available alloys for laser-based powder bed fusion of metals (PBF-LB/M) is still quite low and limits the application of this process. In-situ alloying via PBF-LB/M by using powder blends from conventionally available powders enables a more flexible approach of alloy design. Additivated carbides bear large potential as their content in pre-alloyed powder is limited by the alloy's cracking tendency. In general, PBF-LB/M requires spherical particles in the range of around 20-50 µm. However, carbides often differ from that requirement, arising the question to which extent other particle morphologies can be blended. In this study, AISI H13 base steel was blended with 5 wt.-% edged TiC and processed on two different machines to analyze the effects of irregular shaped carbide additions to a tool steel on the PBF-LB/M processability. Small differences in the specimen's chemical composition were identified and related to their position on the substrate plate. In-depth microstructure analysis by EBSD and texture analysis were performed as well as hardness tests to reveal the alloy's potential in the future. Crack-free processing with a pre-heated substrate plate, a shift towards isotropic microstructures and a hardness increase were obtained with the carbide additivation process.