|About this Abstract
||2021 TMS Annual Meeting & Exhibition
||Additive Manufacturing of Metals: Applications of Solidification Fundamentals
||In-situ Observation of Ferritic vs Austenitic Solidification Mode Competition in 316L Laser Powder Bed Fusion Welds with Synchrotron X-ray Diffraction
||Joseph W. Aroh, Seunghee Oh, Rachel E. Lim, Benjamin J. Gould, Andrew C. Chuang, P. Chris Pistorius, Anthony D. Rollett
|On-Site Speaker (Planned)
||Joseph W. Aroh
It is generally accepted that, at high solidification rates, austenite becomes the primary solidification phase in stainless steels with low Cr/Ni equivalent ratios (e.g. 316L) because of dendrite growth kinetics. Recent developments at the Advanced Photon Source allowed us to critically examine this notion through in-situ synchrotron x-ray diffraction studies of the phase transformation kinetics that occur in Laser Powder Bed Fusion (LPBF) single tracks of 316L. A 2D high-speed detector was employed to capture several complete Bragg rings during the relevant phase evolution with acquisition rates of up to 500 Hz allowing solidification rates to range from 1 to 100 mm/s. The experimental results from the time-resolved XRD were compared to both the predictions from a dendrite growth kinetics model and post-mortem characterization of the solidification microstructure. Invariably, ferrite always appears during solidification of the single track but is fully transformed to austenite upon further cooling.