Point-by-point laser exposure for crack susceptibility reduction in Powder Bed Fusion processing of H11 tool steel

H11 hot work tool steel (1.2343) belongs to the most commonly used materials in the tooling industry, with significant heritage in producing extrusion dies or injection molds. Those components often are characterized by complex geometries, which makes them a great candidate for additive manufacturing. However, the hot working steel is hard to process by additive manufacturing technologies due to its cracking susceptibility related to high cooling rates occurring during printing. A potential way to reduce cracking tendencies is to utilize a point-by-point laser scanning methodology which influecnes the thermal conditions of the process. To prove this, a series of samples were produced via Powder Bed Fusion with various manufacturing parameters and without build platform preheating. Produced samples have been investigated by light and scanning electron microscopy methods, X-ray analysis, and hardness tests. The obtained results indicate that the use of short laser pulses in Powder Bed Fusion can limit the cracking in printed parts. In addition, the laser pulses play an important role in shaping the microstructure of the processed H11 hot work tool steel. The optimal parameters limiting the crack density to 6 mm−2 with 0.1 % porosity in H11 steel printouts were determined.