Yining He¹, Nicholas Jones¹, Ming Zhong¹, Bryan Webler¹, Jack Beuth¹; ¹Carnegie Mellon Univ

H13 tool steel is a promising material for selective laser melting (SLM) fabrication. However, its part microstructure and crack susceptibility were significantly influenced by beam power (P) and scan speed (V). This dependence between processing, microstructure, and cracking was investigated in this study with single-tracks, multi-track pads, and 3D cubes, all produced by an EOS-M290 machine. Forty P-V combinations were selected for single-track fabrication. Inhomogeneities in microstructure were observed for some P-V combinations, with a transition from network-like structure to isolated whisker-like structure, often in the same melt pool. A processing map was developed to show expected microstructure inhomogeneity tendency for P-V parameters in different range. Eighteen multi-track pads fabricated by different P-V combinations showed higher cracking tendency for certain microstructure classes. P-V process windows of higher and lower cracking tendency were identified. Analysis of eight cubes printed in different P-V windows showed good correspondence with these tendencies.