Microstructure and mechanical properties of diffusion bonding joints of 316L stainless steel

For diffusion bonding joints of 316L stainless steel with Ni interlayer bonded at different process parameters,tensile tests were performed to evaluate the strength of joints at room temperature and elevated temperature of 550℃.The microstructure and phase structure were identified by scanning electronic microscopy,optical microscopy and X-ray diffractometry,respectively.The results indicate that as the bonding temperature increases,the strength of joints decreases at room temperature,whereas increases at elevated temperature.The XRD analysis reveals that Fe_(0.64)Ni_(0.36) produced in the diffusion bonding process results in the inhomogeneity at the bonded zone of the joints.At elevated temperature tensile tests,Fe_(0.64)Ni_(0.36) of the DB2 and DB3 joints is transformed to FeNi_3 with higher plasticity and strength,it is the reason for the improvement in the strength of these joints.