|About this Abstract
||Materials Science & Technology 2020
||Phase Transformations in Additively Manufactured Materials
||Real-time Observation of the Competition between Ferritic vs Austenitic Solidification in Micro-laser Welding of 316L Using Synchrotron X-ray Diffraction
||Joseph W. Aroh, Seunghee Oh, Benjamin Gould, Andrew Chihpin Chuang, P. Christiaan Pistorius, Anthony Rollett
|On-Site Speaker (Planned)
||Joseph W. Aroh
It is generally accepted that, at high interfacial velocities, austenite becomes the primary solidification phase in stainless steels with low Cr/Ni ratios (e.g. 316L) for kinetic reasons. Recent developments at the Advanced Photon Source allowed us to critically examine this notion via in-situ synchrotron x-ray diffraction studies of the phase transformation kinetics that occur in micro-laser welding of 316L. A Pilatus 2M detector was employed to capture multiple complete Bragg cones during the relevant phase evolution with acquisition rates of up to 500 Hz allowing solidification rates to range from 1 to 200 mm/s. The experimental results from in-situ XRD were compared to both the predictions from an interface response function model and post-mortem microstructural characterization of the retained ferrite. The insights from these experiments can be advantageous in materials processing such as Laser Powder Bed Fusion which features microstructures completely comprised of micro-laser weld pools.