Characteristic of titanium/steel dissimilar metals joint brazed by bypass-current arc welding

The titanium and steel dissimilar metals were brazed by bypass-current arc welding with S211 copper alloy as filler metal. The macro and microstructure, element distribution, and tensile strength of the brazed joints were analyzed by using optical microscopy, scanning electron microscopy, universal tensile testing machine and other technologies, and the hardness distribution of joint was analyzed by using a micro-hardness tester. A well brazed joint of titanium/steel was obtained, and no obvious welding defects were found. Hardness test found that the hardness in the titanium/copper area was significantly increased, and this was related to the easy formation of Ti-Cu intermetallic compound in the titanium/copper area. The fracture of the titanium/steel brazed joint occured on the copper/titanium side, the fracture mode was ductile-brittle mixed fracture, and the tensile strength reached 291.55 MPa, which was about 88% of the strength of the copper solder.