Innovative densification process of a fe‐cr‐c powder metallurgy steel

Abstract

In this study, the efficacy of an innovative ultra‐fast sintering technique called electro-sinter‐forging (ESF) was evaluated in the densification of Fe‐Cr‐C steel. Although ESF proved to be effective in densifying several different metallic materials and composites, it has not yet been applied to powder metallurgy Fe‐Cr‐C steels. Pre‐alloyed Astaloy CrM powders have been ad‐mixed with either graphite or graphene and then processed by ESF. By properly tuning the process param-eters, final densities higher than 99% were obtained. Mechanical properties such as hardness and transverse rupture strength (TRS) were tested on samples produced by employing different process parameters and then submitted to different post‐treatments (machining, heat treatment). A final transverse rupture strength up to 1340 ± 147 MPa was achieved after heat treatment, corresponding to a hardness of 852 ± 41 HV. The experimental characterization highlighted that porosity is the main factor affecting the samples’ mechanical resistance, correlating linearly with the transverse rupture strength. Conversely, it is not possible to establish a similar interdependency between hardness and mechanical resistance, since porosity has a higher effect on the final properties.