Residual Stress Analysis of Silicon Nitride to Carbon Steel Joint

The residual stress distribution of a ceramic-metal joint specimen was determined by both two- and three-dimensional thermoelastoplastic stress analyses using the finite element method (FEM). The residual stress on the surface of the specimen was also measured by x-ray diffraction. A specimen was prepared by brazing a silicon nitride plate to a carbon steel plate. The highest tensile stress σx perpendicular to the interface appeared at the corners of the silicon nitride adjacent to the interface. The maximum compressive stress σy parallel to the interface occurred at the center of the interface of the silicon nitride. The residual stresses in the silicon nitride and the steel plates distribute antisymmetrically with respect to the center of the specimen. Around the interface, the high stress concentration occurs and the residual stress distributes three-dimensionally, giving a wrong result by the two-dimensional FEM. The residual stress distribution measured by x-rays was similar to that calculated from the three-dimensional FEM.