스프링강의 부식저항성에 미치는 쇼트피닝의 영향

Abstract

Shot peening is generally performed to increase fatigue resistance of spring steel. The shot peening process causes a compressive residual stress on the surface and in suppresses crack growth when subjected to tensile stress. However, the effects of shot peening on the corrosion resistance of spring steel have not been studied profoundly. Therefore, we investigated how the residual stress by shot peening affects the corrosion and passivity of a coil spring steel. The hardness of the surface specimen with higher than that of the middle part of the spring. Potentiodynamic polarization curves and potentiostatic polarization curves showed that the corrosion resistance of the surface was lower than mid. The concentration of oxygen vacancy was measured to be lower for the specimen with compressive stress than the specimen wihtout residual stress.