Joining phenomena and tensile strength of friction welded joint between Ti-6Al-4V titanium alloy and low carbon steel

- Friction welding of Ti-6Al-4V and low carbon steel (LCS) were investigated.
- The joining phenomena at friction pressure of 30 MPa were similar to that of 120 MPa.
- The joint with low friction pressure had the IMC interlayer at the weld interface.
- The fracture of LCS side was obtained at high friction and forge pressures.
- The joint should be made with the whole weld interface temperature below 1350 K.

Dissimilar metal joints (dissimilar joints) have such several advantages as high functionalities for the industrial usage. However, the dissimilar joints have severe problems such as generating the intermediate layer consisting of a brittle intermetallic compound (IMC interlayer) during welding process. Friction welding is very useful for making of dissimilar joint. This paper described the joining phenomena and the tensile strength of friction welded joint between titanium alloy (Ti-6Al-4V) and low carbon steel (LCS). The joining phenomena during the friction process such as joining behavior, friction torque, and temperature changes at the weld interface were measured. The effects of friction pressure, friction time and forge pressure on the joint strength were also investigated, and the metallurgical characteristics of joints were observed and analyzed. Then, the joint, which had 100% joint efficiency, the fracture on the LCS base metal with no crack at the weld interface, and no IMC interlayer on the weld interface, could be successfully achieved. It was suggested that the joint should be made with high friction pressure, opportune friction time to prevent generating of the IMC interlayer, and with high forge pressure in order to achieve completely joining of the weld interface.

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