Research On Technology Of Vacuum Hot Roll Welding Of Titanium Alloy And Stainless Steel Using Ni,Nb Interlayers

Vacuum hot roll welding of titanium alloy (Ti-6Al-4V) and austenitic stainless steel (00Cr18Ni10Ti) was investigated using Ni and Nb as interlayer,respectively. The tensile strength was examined by electronic testing machine, and the microstructure of joints was analyzed by optical microscope, SEM, EDAX and XRD.Experimental results show that the hot roll welding of titanium alloy and stainless steel can be achieved using Ni as interlayer. The best property is obtained when the rolling temperature is 800℃and the compression ratio is 25%, and the maximum tensile strength is 414MPa. Ni/SS interface is free from intermetallic, and the microstructure changes little with the rolling temperature. A mechanical compression layer and diffusion layers are seen at Ni/TC4 interface, and their thickness increase with the rolling temperature. The tensile strength reduces as the rolling temperature increases. The failure takes place at the Ni/TC4 interface, and it exhibits brittle.Hot roll welding of titanium and stainless steel can also be achieved using Nb as interlayer. The best property is obtained when the rolling temperature is 800℃and the compression ratio is 25%, and the tensile strength is up to 430MPa. Until 1000℃the SS/Nb interface exhibits the presence of metal intermetallic. However, a solid solution layer exists at Nb/TC4 interface at every rolling temperature, and its thickness increases with the rolling temperature. The tensile strength increases with the rolling temperature. The fracture occurs along Nb/TC4 interface at 800℃, in the niobium interlayer at 900℃, and SS/Nb interface at 1000℃.The compression ratio has no significant effect on the microstructure of interface. The tensile strength increases with the increment of compression ratio, and it changes little when the compression ratio comes to one extent.