Investigation on microstructural homogeneity in laser beam welding joint superplastic deformation

In this paper, TC4 alloy is welded by laser beam welding. Through the technology of hydrogenation treatment to analyze the structural homogeneity of the welding joint superplastic deformation .The effect of different hydrogen content on the deformation uniformity and deformation uniformity of TC4 titanium alloy laser welding joint was studied. The coefficient structural inhomogeneity of deformation is adopted to express the microstructural homogeneity. The test shows that with the technology of hydrogenation treatment, the phase composition is able to be adjusted and the homogeneity of the welding joint superplastic deformation is able to improved. With increasing hydrogen content, the coefficient structural homogeneity is decreased and the structural becomes more evenly. With the same hydrogen content, the decrease deformation temperature and the reduce initial strain rate both can improve the level of structural homogeneity. With the hydrogen content(1.30% H), the deformation temperature(920 ℃), and the initial strain rate(1×10-4 s-1), the coefficient microstructural homogeneity runs up to 95%.