Snap ring spring steel is used under shock, vibration or long-term alternating stress, so spring steel is required to have high tensile strength, elastic limit and high fatigue strength. In the process, the spring steel is required to have a certain hardenability, not easy to decarburize, and good surface quality. Carbon spring steel is high-quality carbon structural steel with a carbon content of WC in the range of 0.6%-0.9%. Alloy spring steels are mainly silicon-manganese steels, their carbon content is slightly lower, and their performance is mainly improved by increasing the silicon content Wsi; in addition, there are alloy spring steels of tungsten, tungsten and vanadium. In recent years, combined with Chinese resources and according to the requirements of new technologies for automobile and tractor design, new steel grades with boron, niobium, molybdenum and other elements added to silicon-manganese steel have been developed, extending the service life of the spring and improving the quality of the spring. . The arm tip of the snap ring is located in the undercut area, which is the main part of the retaining effect of the snap ring. During the process of entering and exiting the undercut area of u200bu200bthe retaining arm through the high point of the abutment shape, the horizontal component force generated by the retaining arm on the abutment should be offset by the correspondingly designed clasp opposing arm or guide plane plate, small connecting body, etc. To avoid damage to the abutment by lateral force. The initial part of the clasp arm should be rigid and placed in the non-undercut area to stabilize and prevent lateral displacement of the denture. The shape of the snap ring arm is different according to the material used and the production method, and the commonly used three are circular, semicircular and flat.