Numerical analysis on the residual stress distribution and its influence factor analysis for Si3N4/42CrMo brazed joint

Abstract

The residual stress distribution in Si3N4 ceramic-42CrMo steel joints brazed with TiNp-doped Ag–Cu–Ti composite filler has been investigated. The stress distribution in the specimens during cooling and four-point bending was simulated by finite element (FE) calculations using an elastic-plastic model. The FE simulation results indicate that the peak tensile axial residual stresses appear at the Si3N4 edge close to the interface. The experimentally determined joint strength based on the four-point bending test was compared with the results of the FE analysis, showing a reasonable agreement. The residual stress in the Si3N4-42CrMo joint decreases and then increases with the increase of TiNp content, resulting in an optimized joint strength. The consistency of the obtained results suggests that the stress distribution in the brazed joints can be reasonably predicted within the framework of this elastic-plastic FE model. Then the effect of the thickness of brazing layer and interfacial reaction layer on the stress distribution and joint strength was investigated. The FE results indicate that mechanical properties can be improved by increasing the brazing layer thickness and decreasing the thickness of the interfacial reaction layer. Nevertheless, to improve the experimental joint strength, we should carefully consider all critical properties of the joint rather than simply increasing the brazing seam thickness and decreasing the interfacial reaction layer thickness.