Effect of thickness on residual stress in joining sialon to AISI 420

Upon cooling down from a high fabrication temperature, residual stress will be generated within the joint of ceramic-metal components. The stress is originated from the difference in thermal expansion between ceramic and metallic substrates. The excessive internal stress always leads to premature failure of the joint due to cracking or debonding. In this work, distribution and magnitude of residual stress in cylindrical sialon-AISI 420 stainless steel-sialon joining have been evaluated numerically using ANSYS software by varying the thickness of the steel. The simulation has been performed under pure elastic deformation and several other assumptions. Three stresses are evaluated namely radial, axial, and shear stress. Most parts of the sialon are in compressive mode whereas majority of the regions in the steel have experienced tensile radial stress. The maximum tensile axial stress is located at the free edge of the sialon and at the centre of the joint. Meanwhile, the maximum shear stress is concentrated at the edge of the interface. Increasing the thickness of the steel has reduced the radial stress but the stress that acts in axial direction is increased. The radial and axial stress exhibit constancy in joining to steel with thickness more than 10.0 mm. Regardless of any thickness of the steel, the shear stress practically remains unchanged. Comparison to diffusion bonded sample has validated that the developed stress is lower than the fracture stress of the sialon since neither sialon nor reaction layer contains any crack. © 2006-2016 Asian Research Publishing Network (ARPN).