TC11高强钛合金激光焊接接头的显微组织与力学性能Microstructure and mechanical properties of high-strength TC11 titanium alloy joints welded by laser beam

采用光纤激光进行TC11钛合金对接焊接，分析焊接接头的显微组织和力学性能。结果表明，TC11钛合金焊缝为α′马氏体组织，从母材至熔合线组织由α+β逐渐向α′ 转变；随着热输入量的增加，焊缝柱状晶尺寸变大，马氏体分布更加密集交错，同时热影响区宽度增加，粗晶区晶粒尺寸变大；2 mm厚TC11钛合金在焊接速度2.0 m/min、激光功率2.8 ~3.2 kW的工艺参数下得到的焊缝成形良好；焊缝硬度高于母材硬度，并随热输入量的增加而增大；焊接接头抗拉强度达到母材的97 %以上，塑性明显下降，低于母材的50%，焊缝断口形貌为低塑性沿晶断裂特征。

The titanium alloy TC11 was welded by fiber laser beam, the microstructure and mechanical properties of the laser welded TC11 joints with different welding parameters were studied. The results show that the microstructure of weld metal consists of α′ martensite. From the base metal to fusion line, the microstructure evolves from α+β phase to α′ phase. With increasing the heat input, the size of columnar dendrites increases, the distribution of α′ martensite becomes more dispersive, the width of HAZ and grain size in coarse grain zone increase. Under the welding speed of 2.0 m/min and laser power of 2.8-3.2 kW, the sound welds of 2 mm thick TC11 alloy were obtained. The hardness of the weld increases with increasing the heat input. The tensile strength of welded joints reaches at least 97% of that of the base metal, while the plasticity decreases significantly. The fracture topography of welded joints shows brittle fracture character.

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