Development of Residual Stresses in Al–Si Engine Blocks Subjected to Different Metallurgical Parameters

Abstract

Light aluminum alloy engine blocks have successfully replaced heavy ferrous materials in order to enhance automobile fuel efficiency. Aluminum engine blocks with gray iron cylinder liners are prone to tensile residual stresses along the cylinder bridges, which may cause distortion and reduce engine efficiency. In this study, the sectioning technique was used as a means for measuring average residual stresses in critical regions in engine blocks subjected to different metallurgical parameters. It was found that the stresses could be higher than 100\xa0MPa in tension after casting. Relaxation of residual stresses was observed after solution heat treatment, freezing treatment, and aging compared to the initial stage, depending on the geometry and size of the workpiece. Relaxation rate was found to be affected by the size of the workpiece.