Finite Element Analysis of Residual Stress in Cu-20Sn-10Ti Alloy Brazed Diamond

Abstract The interfacial thermal stress in brazed diamond tools originates from the mismatch of thermal expansion coefficients among constituent materials; non-coordinated deformation induced by temperature-field variations leads to thermal-stress concentration. Interfacial residual compressive stress can enhance the holding force of the brazing filler on diamond grits, but excessively high interfacial residual stress may induce cracks and reduce the service life of diamond tools. To accurately characterize the interfacial stress distribution, this study takes single-layer diamond brazed with Cu-20Sn-10Ti filler alloy as the research object. A three-dimensional thermo-mechanical coupled finite element model comprising diamond, the Cu-Sn-Ti filler layer and a 45-steel substrate was established using ABAQUS, and the residual-stress distribution under different brazing temperatures (850–1050°C) and holding times (1–9 min) was systematically simulated. The results show that both brazing temperature and holding time exhibit a nonlinear trend of first decreasing and then increasing. At 950°C and 7 min the residual stress reaches minimum values of 417.3 MPa and 402.1 MPa (FEM), respectively, or 463 MPa (Raman measurement); 950°C / 7 min is thus identified as the optimal process window. Raman spectroscopy verifies the reliability of the finite element simulation: the measured and simulated values share the same trend, fully confirming the accuracy of the method. Grinding tests show that, under the 950°C/7 min process, diamond grits exhibit a moderate micro-fracture ratio, combining good self-sharpening ability with bond strength, and the tool achieves optimal wear resistance. This study provides a scientific basis for the control of residual stress and process optimization of brazed diamond tools.