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

Abstract

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.

Keywords

• copper/Al₂O₃ ceramic/stainless steel composite structure
• brazing
• deformation
• residual stress
• finite element numerical simulation