钛合金与不锈钢的相变超塑性扩散焊工艺

Phase transformation diffusion bonding technology for titanium alloy to stainless steel

用相变超塑性扩散焊法实现了钛合金TA17与不锈钢0Cr18N i9Ti之间的连接。研究了工艺参数对接头强度的影响,得到试验条件下钛合金与不锈钢焊接的优化工艺参数为循环上限温度890℃,循环下限温度800℃,循环次数10,焊接压力5 MPa,循环加热速度30℃/s。在优化的工艺条件下,接头强度达到307 MPa,而焊接时间仅为160 s。对拉伸断口进行了扫描电镜观察、能谱分析和X射线衍射分析,发现断裂沿FeTi和β-Ti层之间的某一个位置发生,FeTi金属间化合物层是接头的最薄弱环节。对接头进行了能谱分析,结合Fe-Cr-Ti三元相图发现,钛合金与不锈钢之间的反应区内依次形成了σ、Fe2Ti、FeTi和β-Ti层。

The joints of titanium alloy(TA17) and stainless steel(0Cr18Ni9Ti) were obtained by phase transformation diffusion bonding.Effect of parameters on strength of the joint was investigated,and the optimum parameters for bonding are as follows: maximum cyclic temperature is 890℃,minimum cyclic temperature is 800℃,number of cyclic times is 10,bonding pressure is 5MPa and heating velocity is 30℃/s.Strength of the joint under the optimum condition is 307MPa,and the time for bonding is 160s.Scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD) were used to study the fracture appearance of the joint.The study showed that the fracture takes place at somewhere between FeTi and β-Ti layers,and the FeTi layer is the weakest point in the joints.The joint was analyzed by EDS and the ternary phase diagram for Fe-Cr-Ti.The results indicated the presence of σ,Fe_2Ti,FeTi and β-Ti in the reaction zone between stainless steel and titanium alloy.