316L不锈钢扩散焊接头的微观结构和力学性能

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

针对不同焊接参数的含镍中间层316L不锈钢扩散焊接头,进行室温和550℃高温拉伸实验,采用SEM、XRD和金相显微镜分析接头区域的微观结构和相分布。结果表明:接头的室温力学性能随焊接温度的提高而降低,而高温力学性能随温度的提高而提高。XRD分析表明,焊接过程中产生的Fe0.64Ni0.36导致接头区域的相组成不均一;在高温拉伸实验时,DB2和DB3接头中的Fe0.64Ni0.36发生相变,强度和塑性更好的FeNi3是接头高温强度提高的原因。

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 Fe0.64 Ni0.36 produced in the diffusion bonding process results in the inhomogeneity at the bonded zone of the joints. At elevated temperature tensile tests, Fe0.64 Ni0. 36 of the DB2 and DB3 joints is transformed to FeNia with higher plasticity and strength, it is the reason for the improvement in the strength of these joints.