A Novel Approach on Rapid Alloy Development of Tool Steels for Laser Powder Bed Fusion by In Situ Alloying

This work introduces a novel approach for alloy development of steels for laser powder bed fusion. Instead of producing massive samples of one alloying composition at a time, the application of prepressed powder bed samples produced from powder mixtures is presented. Multiple powder bed samples can be laser melted in a single process. Further, guidelines for the selection of precursor materials for the powder mixtures are experimentally developed. On the one hand, the selected materials should allow a high freedom in the alloy design. On the other hand, chemical homogenization should be achieved without additional post‐treatments. To describe the degree of chemical homogeneity of the samples produced from a powder mixture under variation of the particle sizes and the laser exposure parameters, the Gini coefficient is adapted. A correlation between calculated liquidus temperatures of raw materials and their dissolution behavior is established. Furthermore, the admixed number of particles of a certain species which translates to their particle spacing in the powder bed is found to play a crucial role in the intermixing of the alloying elements and therefore in achieving chemical homogeneous samples from chemical heterogeneous powder mixtures.