Hardness and Microstructure Analysis of Rotary Friction Welded Dissimilar Joint of Cu and Ti-6Al-4V

Abstract

In this paper, the effect of rotary friction welding on hardness and microstructures of weld zones and base metal zones of Ti-6Al-4V and Cu have been investigated. A rotary friction welding technique was used to perform dissimilar joining of Cu and Ti-6Al-4V bars. Friction welding process parameters were optimized process parameters of a 5-ton rotary friction welding machine. The upset pressures were applied from 30 kg/mm2, 40 kg/mm2 and 50 kg/mm2. The dissimilar joint was successfully formed at upset pressure of 50 kg/mm2. The friction welded joints were failed in drop test after welding at the lower upset pressures (30 kg/mm2 and 40 kg/mm2).The hardness and microstructures were characterized for weld joint formed at 50 kg/mm2. The weld zone, base metal and weld interface and base metals were analysed to understand microstructures and elemental diffusion of Ti and Cu. The welded specimens were examined by using an optical microscope and scanning electron microscope. Grain refinement was seen in Cu near the interface of the joint whereas in the case of titanium circular patterns of grains were seen near the interface of the joint. The micro hardness of Ti-6Al-4V was increased from 307 HV to 365 HV and for Cu increased from 240 HV to 290 HV. Intermetallic compounds such TiCu4 and Ti2Cu were found at weld zone by X-ray diffraction analysis.