Mitigation of retained austenite by compositional modification of AISI H13 tool steel processed by powder bed fusion

Abstract

Additive manufacturing (AM) techniques have enabled the manufacture of steel parts with high geometric complexity, such as tools for forging, injection molding and casting with internal cooling channels. Despite reducing the waste of expensive materials, AM, in particular laser beam powder bed fusion (PBF-LB), produces a microstructure in AISI H13 tool steel with a high fraction of retained austenite (RA), a deleterious phase. This research project proposal aims to study the effects of incorporating titanium powder into AISI H13 steel powder as a way to reduce the RA fraction after processing by PBF-LB. RA stabilization is related to the microsegregation of alloying elements, mainly carbon, during processing. Titanium has a high affinity for carbon and forms the intermetallic compound TiC, a stable carbide even at high temperatures. Therefore, the addition of titanium has the potential to reduce the carbon content dissolved in the matrix and, consequently, reduce the RA fraction after processing by PBF-LB. In this project, the aim is to obtain AISI H13 steel parts processed by PBF-LB with titanium incorporation and perform microstructural and mechanical characterization before and after post-processing routes by heat treatment. Among the characterization steps, we highlight the evaluation of microsegregation and carbide precipitation through advanced techniques, such as transmission electron microscopy and atom probe tomography. (AU)