钎焊金刚石接头热应力场有限元仿真及试验研究

FEM Simulation and Experimental Research on Thermal Stress Filed of Diamond Brazed Joint

根据实际金刚石钎焊微观界面特征,建立有限元几何模型,采用弹塑性有限元方法,仿真分析金刚石钎焊接头在感应钎焊冷却过程中的热应力场动态变化及残余热应力分布特征,并采用显微激光拉曼光谱法测量金刚石磨粒残余热应力大小。结果表明,热物性差异是影响钎焊接头热应力的主要因素;金刚石磨粒形状特征对热应力有较大影响;钎料的塑性变形对热应力具有一定的缓解作用;在金刚石钎焊接头残余热应力场中,金刚石层侧旁的Ti C层主要承受拉应力,而其他部位主要承受压应力;残余热应力测试验证结果与仿真热应力大小基本相符合。

FEM geometric model of brazed diamond joint was established,and the model has taken similar micro-interface characters as the real one. Based on elastic plastic mechanical finite element method, the numerical simulation was done on the instantaneous and residual thermal stress field in the brazed joint during the cooling process. The experiment of the residual stress measurement in the brazed diamond grains by Micro-Raman was finished. The results indicate that the thermal properties mismatch is the main factor for influencing on the thermal stresses; The plastic deformation can release thermal stress in some extent. In residual thermal field, Ti C layers at the side of diamond grit mainly endure tensile stresses,while the other parts mainly endure compressive stresses. The corresponding experimental results indicate that the measured residual stresses are basically accordance with the predicted ones.