| Abstract Scope |
The Navy is evaluating laser powder bed fusion (L-PBF) Alloy 625 (A625) for various welded applications. Microcracking was observed in the heat affected zone (HAZ) of gas tungsten arc (GTA) welded L-PBF A625 that was solution treated at 2050°F for four hours prior to welding. Microcracks were generally between 25-100µm in size, located along grain boundaries, and were observed in material produced by four different print suppliers using five different powder lots. High temperature tensile testing in the scanning electron microscope (SEM) and Gleeble® hot ductility testing revealed consistently low ductility at HAZ temperatures in the L-PBF A625 relative to wrought A625. Chemical analysis, light optical microscopy (LOM), SEM, and transmission electron microscopy (TEM) were performed to evaluate the impact of composition and secondary phase formation on microcracking susceptibility. Reducing tramp element concentrations, particularly O and S coincided with improved high temperature ductility and resistance to microcracking. |