|About this Abstract
||2021 TMS Annual Meeting & Exhibition
||Additive Manufacturing of Metals: Applications of Solidification Fundamentals
||In-situ High-speed X-ray Diffraction Study of Phase Transformation in a Laser-Processed 420 Stainless Steel
||Xuan Zhang, Andrew Chihpin Chuang, Meimei Li
|On-Site Speaker (Planned)
Steels that are martensitic in conventional forms are often found to contain a certain amount of austenite when manufactured by laser additive manufacturing (AM) processes. The amount of retained austenite is known to vary with the processing parameters, but in-depth understanding is lacking. In this study, we use high-speed synchrotron x-ray diffraction to record the melting and solidification processes during the laser scanning of a 420 martensitic stainless steel under different laser parameters. The transformations have been observed to happen in multiple stages: in the ultra-high temperature regime, the phase transformation follows primarily the equilibrium phase diagram; when cooling down to the martensite start temperature, the martensitic transformation happens in a continuous or step-wise manner depending on the laser parameters. This study provides deep insights into the AM of martensitic steels.