紫铜/Al_2O_3陶瓷/不锈钢复合结构钎焊接头残余应力研究

采用有限元数值模拟的方法研究AgCuTi钎焊紫铜/Al_2O_3陶瓷/不锈钢复合结构的形变和残余应力分布情况,并对模拟结果进行实验验证。结果表明:残余应力主要分布在接头区,并且该区形变较小。陶瓷端的残余应力对接头性能影响较大,由于线膨胀系数差异过大,不锈钢陶瓷侧易产生裂纹缺陷,接头倾向于在该区域断裂,紫铜侧陶瓷端TiO反应层的形成导致该区域裂纹的出现,降低了接头的性能。研究各应力分量对最终残余应力的贡献,结果显示环向应力和轴向应力在陶瓷端所产生的拉应力是造成接头强度降低的主要因素。接头拉剪实验表明,接头主要在靠近不锈钢侧的陶瓷端断裂,验证了模拟结果的准确性。

Research on Residual Stress in Copper/Al2O3 Ceramic/Stainless Steel Composite Structure Brazed Joint

The distribution of deformation and residual stress in copper/Al2O3 ceramic/stainless steel brazed joint was investigated by means of finite element numerical simulation.Brazing experiments were conducted to verify the accuracy of simulation results.The results show that residual stress is mainly distributed in the joint area where the deformation is not obvious.Residual stress at the ceramic side has a significant effect on properties of the joints.The fracture tends to occur in the ceramic near stainless steel due to the mismatch of their linear expansion coefficients.The brazed joints may also crack in the ceramic at copper side when TiO reaction layer is formed,and the mechanical properties of the joint are reduced.The contribution of stress component to final residual stress was also analyzed.The tension stress generated by hoop stress and axial stress is the principle factor which decreases the properties of brazed joint.The brazing specimens mainly fracture in the ceramic side near stainless steel,and the accuracy of simulation has been proved by brazing experiments.