The Experiment Research Of CO₂ Laser Beam Welding And Electron Beam Welding On Ti-55 Titanium Sheet Material

Titanium and titanium alloys exhibit some attractive features such as their high specific strength, corrosion resistance and heat resistance, increasingly extensive use of this kind of alloy was observed in aerospace, medicines and ocean applications. Ti-55 is a near a high temperature titanium alloy which was developed to meet the rigorous demand of weight reduction of jet engines in china. Its designed maximum service temperature is up to 550℃. This alloy has good balance of various required mechanical properties. However, only limited research work on welding was conducted, which limited the actual application of this alloy.The laser beam welding has such merits as high energy density, high welding speed, high depth-to-width ratio, high weld spot strength, narrow heat-affected zone, and limited shape-deformation after welding, that nearly no destroying effect to the around of the spot weld. What's more, because the welding line is formed by pervasion of the surfaces of the two metals being welded, purity of the materials was thus expected. Now this welding technology has been applied in such fields as national defense, aerospace, transportation and machine engineering.Laser beam welding and electron beam welding of Ti-55 sheet was investigated in this paper. The parameters of CO₂ laser beam welding and electron beam welding were primarily identified.The microstructure of base metal and welding joint are observed in optical and scanning electron microscope (SEM). The distribution and configuration of rare-earth particles in the fusion zone (FZ) are carefully examined. The metallurgical quality of welded joint is analyzed in detail. The welding joint is smooth, compact and homogeneous. No under-cut, surface oxidization, crack and gas cavity was found in...