Fasteners such as bolts and nuts made of high-strength steel

Abstract

The invention relates to a fastener with high performance and low cost, such as a screw bolt, a screw nut and the like made from high-strength steel. The raw material steel of the fastener contains the following ingredients in percentage by mass: 0.2-0.25% of C, 0.05-0.1% of Si, 0.3-0.4% of Mn, 0.08-0.1% of Al, 0.5-0.8% of Mo, 1.2-1.4% of Cr, less than 0.5% of Ni, 0.05-0.07% of Ti, 0.05-0.07% of Nb, 0.05-0.07% of V, 0.6-0.8% of Cu, 0.5-0.8% of W, 0.001-0.002% of B, less than 0.008% of P and less than 0.008% of S. An economical preparing process which has no need of carrying out annealing treatment before cold-processing is realized by using the unique processing steps, such as hot-rolling processing, drawing processing, cold-processing, quenching and tempering and the like and the excellent-malleability fastener with high tensile strength over 1300 MPa and over 4% percentage elongation.

Description

technical field [0001] The invention relates to a mechanical part, in particular to a fastener such as a bolt, a nut and the like prepared from high-strength steel. Background technique [0002] With the rapid development of modern industry, various production departments such as automobiles, machinery, construction, and light industry have put forward higher requirements for various fasteners (such as bolts, nuts, etc.). Especially in the field of the automobile industry, in order to meet the increasingly strong requirements for high performance and lightweight of various structural parts, it is undoubtedly the most effective to implement high-strength and lightweight bolts and nuts that are used to manufacture fastening parts. means. In addition, due to the requirements of weather resistance, corrosion resistance and other aspects, there are more and more strict requirements for the corresponding performance of bolts and nuts. [0003] While meeting the performance requi...

AI Technical Summary

Problems solved by technology

[0004] However, no matter it is annealing before cold working or heat treatment of quenching and tempering after cold working, it not only wastes energy, but also prolongs the production cycle and reduces productivity, especially the annealing before cold working will cause surface oxidation after annealing. It is necessary to further implement the process of removing the oxide film by pickling and covering the surface with a lubricating film. These are obviously not suitable for the requirements of the modern society for the steel industry, and urgent improvements are needed