Self-consumption friction plug spot welding of Ti–6Al–4V plates

Abstract

In this work, a new technique of self-consumption friction plug spot welding (SFPSW) was introduced to spot welding of Ti–6Al–4V alloy sheets using a semi-consumable welding tool, and defect-free joints were successfully produced. The semi-consumable welding tool consists of a nickel-based superalloy shoulder and a titanium alloy plug. The spot welding parameters were discussed, and the effect of welding parameters on the microstructure and mechanical properties of the joints was investigated. The cross-section of the welding zone was divided into five regions: base metal (BM), heat-affected zone (HAZ), thermo-mechanically affected zone (TMAZ), stir zone (SZ), and filled zone (FZ). The final joint interface has a basket-weave structure. The maximum tensile-shear load of the joint was up to 69.5 kN and the hardness value of the welding region was lower than that of base metal. The failure mode of the tensile-shear test was a typical quasi-cleavage fracture.

Keywords

• Friction stir welding
• Friction stir spot welding
• Ti–6Al–4V
• Microstructure
• Mechanical property