1. The mechanical function of the nut mainly depends on the hardness of the nut, the height of the nut, and the wall thickness of the nut. Therefore, the requirements for materials are not high. Of course, if the nut has tolerance requirements, higher-level materials should also be used, such as chemical industry.Fastener nuts have requirements for durability and require higher-grade materials.
2. The plasticity target required by bolts, the higher the functional level, only the higher-level material can be reached. The lower-level material only needs to reduce the tempering temperature to meet the strength requirements, but it cannot meet the requirements of plasticity and resistance. In fastener testing, Brittle fractures were judged as unqualified. Steel structure bolts also stipulated higher tensile strength, which is to ensure the plastic resistance of the bolts.