Flood Welding for Forging Die Repair Applications: Microstructure and Mechanical Characterization of the Repair Alloy and Repair/Substrate Interface

Abstract Eureka welding alloys are widely used as a potential candidate in the field of forging die repair applications. Eureka 635 (bainitic steel) was deposited as a repair alloy using the flood welding technique on an AISI 4142 tool steel cavity plate. The microstructural and mechanical properties of the 635/4142 interface, along with the bulk Eureka 635 samples from the repair side, were examined using scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray radiography, Vickers indentation, uniaxial tensile testing, and Charpy V-notch impact testing. The results indicated that flood welding provided superior metallurgical bonding and reduced residual stress. The width of heat-affected zone (HAZ) toward AISI 4142 side near the interface is nearly ~ 4.5 mm. The heat-affected zone is notorious for having lower hardness. It requires special attention in die repair to prevent crack initiation. This is attributed to the grain coarsening caused by the thermal flux from the initially deposited layers. The ultimate tensile strength and ductility of the interface samples were consistently lower than the bulk samples in all cases, likely due to the weak heat-affected zones near the interface, which weakened the overall strength of the interface samples.