Effect of Laser Welding Parameters on the Microstructure and Mechanical Properties of Dissimilar Hastelloy X/Haynes 188 Joints

Laser welding is currently a versatile and reliable assembly technique. To save weight in aerostructures and propulsion units and to reduce thermal distortions and the heat-affected zones in these assemblies, autogenous laser welding seems promising. This experimental work addresses dissimilar autogenous laser welding of thin alloy sheets using a Yb:YAG source and a particular optical fibre setting. Hastelloy X and Haynes 188 are the two base metals studied for this assembly. An experimental design allows us to determine the weldability domain. The macro- and microstructure and mechanical properties of the weld seams are investigated. EBSD and EDS analysis revealed microstructural and chemical heterogeneities in the high-power welded seam, but XRD results demonstrated a homogeneous depletion of the carbide density in its fusion zone. Despite such microstructural features, the mechanical properties of obtained assemblies were found to be satisfactory and slightly greater than those of the weaker Hastelloy X.