Microstructure and Mechanical Property of Electron Beam Self-Melting Brazing Joint of Titanium Alloy to Chromium Bronze

Abstract:

Electron beam self-melting brazing experiments of TA15/QCr0.8 dissimilar metals with a copper side beam offset were carried out. Microstructure of the weld was examined by optical microscopy and scanning electron microscopy. Mechanical properties of joints were evaluated by tensile strength tests. Results show that copper content of the weld is increased by adopting copper side beam offset. So the population of Cu-Ti compounds is decreased and solid solution of copper is increased. Consequently, mechanical property of the joint is improved. There is just a little titanium alloy on the top of the weld melted when beam offset is up to 1 mm. And the joint is formed by brazing process according to the filling of the top fluid metal into the butt-weld. Finally, the tensile strength of the joint can reach to 300 MPa. Fracture occurs in copper alloy during tensile strength tests with plastic fracture mode.

Key words:TA15 titanium alloy; QCr0.8 chromium bronze; self-melting brazing; microstructure; mechanical properties