Effect of processing parameters and chemical composition of tool steels on integrity and properties of low-thickness part produced by selective laser melting

A modified 304 steel, named 304 CS, containing high amount of C and B was used in selective laser melting experiments to optimize the build process with the aim of producing a hypereutectic tool steel featuring high hardness properties. A standard 316L stainless steel was also considered for the investigation as a reference austenitic material, to preliminarily set process parameters and to evaluate the solidification behaviour. The main parameters under investigation were the power of the laser and the scanning velocity. The microscopic features of the modified 304 steel and of the 316L steel produced by selective laser melting and by casting were compared. In respect to castings in a furnace, the carbide/boride phases in selective laser melting parts were much smaller, and more homogenously dispersed, while the austenitic phase of 316L stainless steel was completely different in morphology, but very similar in grain size. The results suggest that with further optimization, 304 CS alloy could be a suitable material for additive manufacturing processes.