Residual Stress Distribution of Silicon Nitride Joined to Carbon Steel

Abstract

Recently, attempts have been made to be join ceramics to metals in order to make up for the brittleness of ceramics. The difference in the coefficients of linear expansion of the two materials joined at high temperature will cause residual stress, which has a strong influence on the strength of the joined materials. The residual stress distribution of silicon nitride plates brazed to a carbon steel JIS-type S45C was determined by X-ray diffraction using thd Gaussian curve method. The measured residual stress distribution agreed approximately with the result from the three-dimensional thermo elastoplastic stress analysis by FEM, but did not agree with the result from the plane stress analysis. This is because the stress concentration occurs and the stress distributes three-dimensionally at the interface of the silicon nitride and metals. The tensile residual stress perpendicular to the interface on the surface of the silicon nitride has maximum values at the center and the edge of the interface.