Selective laser melting and heat treatment of precipitation hardening stainless steel with a refined microstructure and excellent mechanical properties

In this study, we concentrated on the microstructural characteristics and mechanical properties of precipitation hardening (PH) stainless steel 15-5PH via Selective laser melting (SLM). A large amount of retained austenite was observed in the as-built samples which contribute to excellent ductility. The amount of retained austenite reduced greatly after heat treatment and the remaining minor retained austenite completely transformed to martensite during tensile process. A finer grain structure and a concentration of dislocations around the inclusions and at the submicron grain boundaries following heat treatment promoted SLM 15-5PH to demonstrate a higher strength than those of wrought samples. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.