Zr-Ni中间层对TC4钛合金/304SS不锈钢激光焊接头组织性能的影响

Microstructure and Mechanical Properties of Laser Welding Joints between TC4 Titanium Alloy and 304SS Stainless Steel Using Zr-Ni Multi-Interlayer

钛合金/不锈钢异种金属焊接结构在现代工业应用中日益广泛,但因母材理化性能差异,导致焊接难度大。根据金属元素冶金相容性选用Zr-Ni组合结构设计填充金属,并使用超声波焊接方法制备填充材料。研究Zr-Ni中间层对TC4/304SS Nd:YAG(掺钕钇铝石榴石)脉冲激光焊接金属间化合物(IMCs)生长行为与机械性能的影响,确定填充材料的可行性。通过扫描电镜(SEM)、能谱仪(EDS)和X射线衍射(XRD)分析接头微观结构。使用显微硬度仪及抗拉强度测试评价接头力学性能。表明:在最优参数下TC4/304SS接头无宏观裂纹,沿界面均匀分布的IMCs呈现2层颜色明显不同的组织结构,焊缝生成了FeTi,Fe_(2)Ti和少量Ti_(5)Cr_(7)Fe_(17)IMCs,接头在正应力作用下发生脆性解理断裂;制备的Zr-Ni中间层有效阻隔了母材混合,边界形成的固溶体有助于提高接头强度,同时形成的Zr/Ni IMCs具有延展性,TC4/Zr-Ni/304SS接头抗拉强度达213.7 MPa。所制备的填充层对提升该异种金属接头力学性能和分析其焊缝组织变化具有重要意义。

Titanium alloy/steel dissimilar metal welding structures have become more and more widely used in modern industrial applications. However,welding is difficult due to the significant differences in physical and chemical properties of the base metals. In this paper,composite Zr-Ni filler metal layer was designed according to the metal element metallurgical compatibility,and the filling material was prepared by ultrasonic welding. The influence of Zr-Ni multi-interlayer on the intermetallic compounds(IMCs)growth behavior and mechanical properties of TC4 titanium alloy/304 SS stainless steel Nd:YAG(neodymium-doped yttrium aluminum garnet)pulsed laser welding was studied,and the feasibility of filler materials was determined. The microstructure of the welded joint was analyzed by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD). The mechanical properties of the joint were evaluated using the micro-hardness tester and the tensile strength tester. The results showed that there was no macroscopic crack in the TC4 titanium alloy/304 SS stainless steel laser welded joint under the optimal parameters,and the evenly distributed IMCs along the welding interface exhibited 2 layers of color distinctly different microstructure. The welds interface generated FeTi,Fe2 Ti and a small amount of Ti_(5)Cr_(7)Fe_(17) IMCs. The brittle cleavage fracture of the welded joints occurred under normal stress.The Zr-Ni composite filler metals prepared by ultrasonic welding effectively prevented the base metal from mixing. The solid solution formed at the boundary helped to improve the joint strength,and the Zr/Ni IMCs had a certain ductility. The tensile strength of the TC4 titanium alloy/Zr-Ni/304SS stainless steel welded joint was 213.7 MPa. The prepared composite filler metals had important significance for improving the mechanical properties of the joints and analyzing the changes of the interface structure.