Cheng Zhigang, Lang Qiang, Zhang Zhaodong, Song Gang, Liu Liming
School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China.
Key Laboratory of Liaoning Advanced Welding and Joining Technology, Dalian University of Technology, Dalian 116024, China.
Materials (Basel). 2025 Jun 21;18(13):2937. doi: 10.3390/ma18132937.
Traditional narrow gap welding of thick titanium alloy plates easily produces dynamic molten pool flow instability, poor sidewall fusion, and excessive residual stress after welding, which leads to defects such as pores, cracks, and large welding deformations. In view of the above problems, this study takes 16-mm-thick TC4 titanium alloy as the research object, uses low-power pulsed laser-GTA flexible heat source welding technology, and uses the flexible regulation of space between the laser, arc, and wire to promote good fusion of the molten pool and side wall metal. By implementing instant ultrasonic impact treatment on the weld surface, the residual stress of the welded specimen is controlled within a certain range to reduce deformation after welding. The results show that the new welding process makes the joint stable, the side wall is well fused, and there are no defects such as pores and cracks. The weld zone is composed of a large number of α' martensites interlaced with each other to form a basketweave structure. The tensile fracture of the joint occurs at the base metal. The joint tensile strength is 870 MPa, and the elongation after fracture can reach 17.1%, which is 92.4% of that of the base metal. The impact toughness at the weld is 35 J/cm, reaching 81.8% of that of the base metal. After applying ultrasound, the average residual stress decreased by 96% and the peak residual stress decreased by 94.8% within 10 mm from the weld toe. The average residual stress decreased by 95% and the peak residual stress decreased by 95.5% within 10 mm from the weld root. The residual stress on the surface of the whole welded test plate could be controlled within 200 MPa. Finally, a high-performance thick Ti-alloy plate welded joint with good forming and low residual stress was obtained.
传统的厚钛合金板窄间隙焊接容易产生动态熔池流动不稳定、侧壁熔合不良以及焊接后残余应力过大等问题，进而导致气孔、裂纹和较大焊接变形等缺陷。针对上述问题，本研究以16mm厚的TC4钛合金为研究对象，采用低功率脉冲激光-GTA复合热源焊接技术，利用激光、电弧和焊丝之间空间的灵活调节来促进熔池与侧壁金属的良好熔合。通过对焊缝表面实施即时超声冲击处理，将焊接试板的残余应力控制在一定范围内，以减少焊接后的变形。结果表明，新的焊接工艺使接头稳定，侧壁熔合良好，且不存在气孔和裂纹等缺陷。焊缝区由大量相互交错的α'马氏体组成，形成篮状编织结构。接头的拉伸断裂发生在母材处。接头的抗拉强度为870MPa，断后伸长率可达17.1%，为母材的92.4%。焊缝处的冲击韧性为35J/cm，达到母材的81.8%。施加超声后，距焊缝趾部10mm范围内平均残余应力降低了96%，峰值残余应力降低了94.8%。距焊缝根部10mm范围内平均残余应力降低了95%，峰值残余应力降低了95.5%。整个焊接试板表面的残余应力可控制在200MPa以内。最终获得了成型良好、残余应力低的高性能厚钛合金板焊接接头。
