Research On Phase Transformation Superplastic Diffusion Bonding Of Titanium Alloy And Steel

The titanium is regarded as the third development metal material, occupied 4th, next to accurately only aluminous, iron, magnesium in the metal. Because the titanium and the alloys have a series of characteristics such as the high intensity, the small density, anti-corrosive, no magnetism, well welding performance and so on, they are important received by the various countries continuously and develop rapidly. In recent years, titanium alloys have become essential metal material in the new technology, new technical and new equipment, applied in domains of petroleum, chemical, automobile, biomedicine, cultural and athletic equipment. For bonding of the heterogeneous materials, it is very difficult to realize the reliable connection used the traditional melt welding method. Diffusion bonding as one of solid phase bonding methods, has the simply craft, the easy operating, bonding of the big cross section attachment, slightly distorts of the components and well quality of joint and so on merits .Diffusion bonding of TC4 titanium alloy and the Custom 465 stainless steel, the TC4 titanium alloy and the 25 steel have been studied in the paper. Used the scanning electron microscope (SEM), Energy spectrometer and XRD and so on, the surface microstructures and the phase composition of bonding Joint have been systematic analysis. The law of the element diffusion and the intermetallic compound formed in titanium alloy and steel has also been studied. In the foundation analysis of the stretch failure mechanism, the way about diffusion bonding of the titanium alloy and the steel has been contrast analysisThe results indicated that in the direct diffusion bonding research of titanium and stainless steel the diffusion layer is formed between the titanium and the stainless steel, Fe has obviously diffused in titanium alloy and phase of the contact surface mainly contain FeC3, TiC, FeTiO3 and so on. Indicated to the research of TC4/Ni/Custom 465 joints, the intense mutual diffusion between titanium alloy and the Ni intermediate level has occurred and an obvious bright diffusion layer has formed. Diffusion of Fe, Ti has not penetrated the Ni intermediate level. The Ni intermediate level effectively impedes mutually diffusion of Fe and Ti in both sides. Contrasts the direct diffusion bonding, welding together ratio of joins with Ni intermediate level have the remarkable increased, and the tensile strength can reach 348.45MPa. Therefore, the reasonable intermediate level has the vital role to diffusion bonding the heterogeneous materials. Used SEM it discovered that the multi-level structures has been formed in the contact surface of diffusion bonding joins of titanium alloy and the 25 steel with Ni intermediate level. With Energy spectrometer analysis and XRD analysis indicated many kinds of intermetallic compounds such as NiTi2, NiTi, Ni3Ti, FeNi3, FeNi and so on exist in the contact surface. The fracture analysis indicated that there exist cracks in the TC4 titanium alloy side, and exist cleavage plane and the strong nest shape pit in the partial region. The fracture is the mixed type, explained the joins has certain toughness. Research of diffusion bonding joints of titanium alloy and the 25 steel under the high pressure condition the without Ni intermediate level used SEM, Energy spectrometer analysis, XRD analysis indicate that a clear zone exists in the contact surface and the phase mainly is composed of FeC3,α-Ti, Ni3Ti, Al3Ti, FeTiO3and so on.