Microstructure and mechanical properties of thin-walled TA1 titanium pipes fabricated by high-frequency induction welding

• Published in: Journal of materials research and technology 2024-11, Vol.33, p.5448-5456
• Main Authors: Li, Juying, Li, Weijie, Xie, ZhiXiong, Dong, Shijie, Xie, Jianying, Ye, Feng, Mei, Qingsong
• Format: Article
• Language: English
• Subjects: High frequency induction welding; Mechanical property; Microstructure; Thin-walled titanium pipes; Weld joint
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2024.10.187

High frequency induction welding (HFIW) was effectively employed for the high-speed fabrication of thin-walled TA1 titanium pipes (TWTPs) with a nominal wall thickness of ∼0.6 mm. The microstructure and mechanical properties of TWTPs manufactured under varying welding parameters were investigated. The weld zone (WZ) exhibits a waist shape measuring ∼622 μm in width, and the width of the heat-affected zone (HAZ) spans between 763 and 864 μm. Both the WZ and HAZ are composed of a mixture of coarse serrated α grains with fine acicular and twins, while the BM retains equiaxed grains. This unique microstructure was resulted from the thermal cycling during HFIW, contributing to a notable increase in microhardness within the WZ compared to both the HAZ and the BM. Optimal manufacturing conditions were identified at a welding power of 14.4 kW, a welding speed of 60 m/min, an opening angle of 6°, and a squeeze displacement of 0.2 mm, yielding the TWIP with a tensile strength of ∼307 MPa and tensile elongation of ∼27%. Tensile fracture analysis revealed that failure predominantly occurred within the BM, underlining a ductile fracture mode characterized by pronounced dimple formations. The enhanced mechanical performance of the weld joints can be attributed to the heterogenous microstructure in the WZ, where the presence of large serrated α-grains enhances ductility, and the fine martensite and twins contribute to the high strength.