LAUSR

Abstract Hybrid friction stir welding, adopting an external pre-heat source in front of the friction stir welding (FSW) tool, is known as a way of overcoming the disadvantages of conventional FSW; lack of plastic flow and excessive tool wear. In joining of aluminum alloy to steel, presence of intermetallics (IMC) is essential, but its excessive growth can degrade the joint quality by its brittleness. In this study, joining of 2.5 mm thick Al5052 aluminum alloy and 1.4 mm thick DP590 high strength steel has been carried out by FSW and TIG assisted hybrid friction stir welding (HFSW) through experiments and numerical analysis. Joints characteristics of two process was compared to optimize the process parameters. A 3-D model was developed to estimate the thermal elastic–plastic characteristics of the joints. It was confirmed that the joint efficiency of HFSW joints has been improved to 84% than that of FSW (74%). 2.74 μm thickness of IMC layer was formed in HFSW joints and satisfied the permissible thickness (under 10 μm). The maximum residual stress (σzz) in welding direction was slightly higher at the HFSW joints than at the FSW joints. The overall results from experiment and simulation confirmed that HFSW is an effective way of joining Al5052 to DP590. Graphic Abstract