铜镍合金与低碳钢无针搅拌摩擦搭接焊研究

摘要

Cu-Ni alloy (C71000)and low-carbon steel (Q235)were joined by friction stir lap welding (FSLW)with pinless FSW tool with the help of nickel coating.The influence mechanism of the thickness of the nickel coating on the steel side on tension-shear strength of the weld was studied by means of tension-shear tests,SEM and EDS.Researches show that Ni coating could prevent Fe from oxidizing and reduce the micro-voids of the joint face of the weld.High interface temperature and contact pressure during the welding could promote diffusion of the Fe and Cu atom into the Ni coating through the interface and form seamless connection.Increasing the thickness of the nickel coating on the steel side could contribute to the improvement of the tension-shear strength of the weld.When the thickness of the Ni coating on Cu-Ni side and steel side reached 5μm and 20μm respectively,the maximum tension-shear strength of 295MPa was achieved,which was 2.76 times that of the weld without Ni coating and close to Cu-Ni alloy.%利用无针搅拌头，对 C71000铜镍合金和 Q235低碳钢进行了搅拌摩擦搭接焊。借助拉剪试验、SEM 和 EDS，研究了搭接面低碳钢侧镀镍层厚度对接头拉剪强度的影响机制。研究表明：镀镍层可阻止 Fe 元素在焊接过程中发生氧化，减少焊缝接合面上的微孔隙。焊接过程中的高温以及高压作用，使 Fe 和 Cu 原子扩散到镀镍层中，实现两板料间无缝接合。增大接合面的低碳钢侧镀镍层厚度，有利于提高焊缝的拉剪强度，当铜镍合金侧和低碳钢侧镀镍层厚度分别达5μm 和20μm 时，接头拉剪强度最大，约为295 MPa，为无镀层接头拉剪强度的2．76倍，接近铜镍合金母材的剪断强度。