中厚板钛合金激光-CMT复合焊接工艺特性分析

Characterization of laser arc hybrid welding process for medium-thick titanium alloy plate

关键词:  激光-CMT复合焊接|TC4钛合金|微观组织|力学性能

Key words:  laser-CMT hybrid welding|TC4 titanium alloy|microstructure|mechanical properties

摘要:

通过采用激光-CMT焊接的方法对10 mm厚TC4钛合金实现了不开坡口单面焊双面成形，并对焊缝的组织、力学性能及腐蚀性能进行了测试分析. 结果表明，该最优参数下形成的焊接接头中主要由大量的α'马氏体及初生的α相构成，且存在网篮状组织，焊缝区域的显微硬度大于母材区域，可达380 HV，且由于激光作用区拥有更大的冷却速度，焊缝底部生成了更多的α'马氏体，导致焊缝底部硬度比电弧作用区更高. 焊接接头抗拉强度可达到916 MPa，断后伸长率达到16.08%，拉伸断裂结果为韧性断裂，焊缝组织的性能明显优于母材.焊缝处的抗腐蚀性能优于母材，这是因为焊缝组织有更细小的晶粒及大量位错，提升了钝化能力并阻碍了Cl⁻的扩散.

Abstract:

Laser-CMT welding method was used to achieve one-side welding with back formation without beveling for 10 mm thick titanium alloy. The microstructure, mechanical properties and corrosion performance of the weld are tested and analyzed. The experimental results show that the welded joint formed under the optimal parameters is mainly composed of a large amount of α' martensite and incipient α term, and there is a net basket organization, the microhardness of the welded area is up to 380 HV, greater than the parent material area, and due to a faster cooling rate of the laser zone, more α' martensite generated at the bottom of the weld. The tensile strength of the welded joint can reach 916 MPa, the fracture elongation reaches 16.08%, tthe tensile fracture exhibits typical ductile fracture characteristics，and the microstructural properties in the seam are significantly better than in the base material area. The corrosion resistance of the seam is better than that of the base material because of the finer grains and large number of dislocations in the microstructure, which enhance the passivation ability and hinder the diffusion of Cl⁻.