Texture of Valve Spring Materials by Quenching and Oil-tempering

Abstract

Since the metal texture of springs is related to fatigue, creep, and especially strength, we investigated the microstructure in order to clarify the changes of the texture during the manufacturing process of the springs, and to contribute to further strengthening of springs. In this study, the crystal structure of the austenitized and oil-tempered wires was observed by electron backscattering diffraction (EBSD) and confirmed that axial direction of the specimen was 〈110〉. We simulated the texture of a wire produced by drawing in the spring manufacturing process according to the predictive theory of crystal rotation presented by Katoh, which is based on the theorem of minimizing resultant of shear strain and maximizing plastic work and the result shows that the crystal orientation of axial direction rotates toward 〈110〉. Comparing the simulation results with the experimental results, it was confirmed that the metal structure of spring formed 〈110〉//RD texture, which is produced during drawing in the manufacturing process. Furthermore, austenitizing and oil-tempering have almost no effect on the texture.