Influence of Ni coating on mechanical properties of titanium/steel resistance brazing joint

Reliable connection of titanium alloy with stainless steel is a basic problem in implementation of their connection.By means of preparing a Ni coating on the substrate surface of the stainless steel with thermo-spraying technique,and taking Ni coating as transient layer and Ag45 CuZn as solder,the implementation process of resistance brazing lap joint of titanium alloy with stainless steel was investigated.The influence of Ni coating on the microstructure and mechanical properties of the joint was explored,also.It was shown by the test of the mechanical properties of the joint that the intervention of Ni coating made the joint shear strength increased remarkably and its maximum would amount to 243 MPa.By means of SEM,EDS,XRD and other methods,the joint fracture morphology and structure were analyzed and the result showed that element Ni in its coating not only participated in the metallurgical reaction of the solder but also as a physical layer,it made the direction of diffusion process of Fe,Ti,and other atoms altered oppositely,so that a various Ni-base compounds were obtained in the joint structure,making the mechanical properties of titanium/steel heterogeneous braze joint increased.