Cr-B system low-carbon high-strength cold forging steel wire rod and manufacturing method thereof

Abstract

The invention belongs to the technical field of cold forging steel and particularly relates to a Cr-B system low-carbon high-strength cold forging steel wire rod and a manufacturing method of the Cr-Bsystem low-carbon high-strength cold forging steel wire rod. The main chemical ingredients of the Cr-B system low-carbon high-strength cold forging steel wire rod comprise 0.16-0.24% of C, 0.55-0.90%of Cr, 0.032-0.065% of Ti, 0.0020-0.0040% of B and not larger than 80ppm of N, wherein Ti / N is controlled to be larger than 4. The manufacturing method includes the procedures of converter smelting,LF refining, square billet continuous casting and wire rod rolling. According to the Cr-B system low-carbon high-strength cold forging steel wire rod and the manufacturing method of the Cr-B system low-carbon high-strength cold forging steel wire rod, by optimizing ingredient design of the elements of Cr, B, Ti, N and the like, the hardenability of the steel is effectively improved, the cold forging performance of the steel is improved, it is achieved that the low-carbon cold forging steel wire rod can be used for producing 12.9-grade high-strength fastener without annealing, and the machiningcost of producing high-strength fasteners for a downstream industry is significantly lowered.

Description

technical field [0001] The invention belongs to the technical field of cold heading steel, relates to a Cr-B series low-carbon high-strength cold heading steel wire rod, and also relates to a manufacturing method of the Cr-B series low-carbon high-strength cold heading steel wire rod. Background technique [0002] Cold heading steel is also known as cold heading forming steel. Cold heading is formed by one or more impact loading at room temperature. It is widely used in the production of screws, pins, nuts and other fasteners. It is widely used in automobiles and shipbuilding. , equipment manufacturing, electronics, home appliances, bicycles, tools, light steel structures, construction and other industries. The cold heading process can save raw materials, reduce costs, and increase the tensile strength of the workpiece through cold work hardening to improve performance. The steel for cold heading must have good cold upsetting performance, and the surface quality of the steel...

AI Technical Summary

Problems solved by technology

However, it can only be used to produce fasteners such as hexagonal bolts and hexagonal nuts, and cannot meet the production of flange fasteners; and the cold heading cracking rate will increase in the production process of downstream users

In the prior art, there are cold heading steels with low carbon content, such as CN201510525604.2, a production method of boron-containing cold heading steels, but its quenching performance is not outstanding enough, and it can only meet the requirements of grade 10.9 bolts

In CN201010127837.4 boron-containing cold heading steel for high-strength fasteners and its preparation process, the low-carbon steel boron-containing cold heading steel can only meet the strength requirements of 8.8-grade bolts, and it is difficult to meet higher requirements

In CN200710053097.2, a niobium-vanadium composite microalloyed low-carbon boron steel for cold heading and its production method, although it can reach grade 10.9 to grade 12.9, it needs to add Nb, V Elements, which pointed out that Nb, V composite microalloying has an important impact on the performance, niobium, vanadium elements are expensive