Microstructure and property of a selective laser melting process induced oxide dispersion strengthened 17-4 PH stainless steel

• Published in: Journal of alloys and compounds Vol. 803; pp. 30 - 41
• Main Authors: Hsu, Tzu-Hou, Chang, Yao-Jen, Huang, Cheng-Yao, Yen, Hung-Wei, Chen, Chih-Peng, Jen, Kuo-Kuang, Yeh, An-Chou
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 30.09.2019; Elsevier BV
• Subjects: 17-4 PH stainless steel; Austenite; Copper; Dislocations; Dispersion hardening steels; Heat treating; Heat treatment; Laser beam melting; Martensite; Martensitic stainless steels; Martensitic transformations; Microstructure; Oxide dispersion strengthening; Oxygen content; Precipitation hardening; Precipitation hardening steels; Selective laser melting; Stainless steel; Tensile properties; Ultrafines; Work hardening; 17-4 PH stainless steel; Heat treatment; Selective laser melting; Tensile properties; Oxide dispersion strengthening
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.06.289

Selective laser melting (SLM) process of 17-4 PH stainless steel has been a subject of research interest due to its complex microstructure-property correlation associated with SLM process. In this work, an oxide dispersion strengthened 17-4 PH stainless steel was successfully fabricated directly by SLM process with an oxygen content of 500 ppm in the chamber. It contained a matrix of ultrafine packet of martensite and reverted austenite with a dispersion of nano Mn-Si oxide particles that could provide strengthening by generation of geometrically necessary dislocations, making 17-4 PH an oxide dispersion strengthened material after the SLM process. Furthermore, post heat treatments could increase fractions of martensite and further induce either formation of ultrafine reverted austenite to promote significant transformation-induced plasticity during work hardening process or Cu-rich phase precipitation strengthening. This article not only describes a clear microstructure-property correlation for a SLM processed 17-4 PH, but also it shows the potential advantage of the SLM process in microstructure engineering. [Display omitted] •An oxide dispersion strengthened 17-4 PH was fabricated by SLM.•As-SLM microstructure consisted of a matrix of fine martensite with nano oxide.•Post ageing could promote ultrafine reverted austenite resulting TRIP effect.•Geometrically necessary dislocations were observed around nano oxides.•Mn-Si nano oxides were stable after post heat treatment processes.