激光对焊TC4接头微观组织及显微硬度研究

Study on microstructure and microhardness of laser butt welding TC4 joint

激光焊接作为一种飞机上钛合金部件的新型焊接方式而受到国内外广泛关注。本文采用不同功率激光对焊TC4接头,应用体式显微镜、扫描电镜,X射线衍射仪和硬度仪研究了不同工艺参数下各部位的微宏观形貌和显微硬度。结果表明,随激光功率增大,试件逐渐焊透,熔池内物相由等轴树枝晶转变为大β晶粒内的片状α/α′相;等轴树枝晶尺寸增加,α/α′/片层厚度减小;焊接接头的硬度沿测试线的波动随功率增大而增加,激光功率为550 W时硬度分布最为均匀。

Laser welding, as a new type of welding method for titanium alloy parts on aircraft, has been widely concerned at home and abroad. TC4 laser butt welded joints with different power from penetration to incomplete penetration were prepared. The microstructure and microhardness distribution of different parts under different process parameters were observed and analyzed, and the corrosion resistance of different parts of welded joints in marine environment was studied by electrochemical method. The results show that the microstructure in the molten pool changes from equiaxed dendrite to lamellar α/α′ phase in β grains due to the penetration of specimen caused by increase of laser power.the size of equiaxed dendrite increases, α/α′;The lamellar thickness decreases;The hardness fluctuation of the welded joint along the test line increases as the increase of power, and the hardness distribution is the most uniform when the laser power is 550 W.