Non-quenching and tempering double-phase cold heading steel for high-strength fastener and method for manufacturing same

Abstract

The invention relates to a non quenching and tempering dual phase cold heading steel used by high strength fasteners and a manufacturing method for the dual phase cold heading steel; the components and the weight percentages of the invention are provided as follows: 0.06 to 0.15 percent of C, 0.60 to 0.90 percent of Si, 1.40 to 2.0 percent of Mn, less than or equal to 0.025 percent of P, less thanor equal to 0.025 percent of S, less than or equal to 0.04 percent of Al, less than or equal to 0.0060 percent of N, with Fe being the allowance. By adopting the non quenching and tempering dual phase cold heading steel used by high strength fasteners and the manufacturing method of the invention, the tissues and performances needed by raw materials can be obtained by adjusting the chemical constituents and controlled rolling and controlled cooling, which not only saves energy but also brings about no pollution to the environment.

Description

technical field [0001] The invention relates to a non-quenched and tempered dual-phase steel wire rod, in particular to a non-quenched and tempered dual-phase cold heading steel for high-strength fasteners of grade 8.8 or 9.8 and a manufacturing method thereof. Background technique [0002] According to the current GB / T3098.1-2000 "Mechanical Properties of Fastener Bolts, Screws and Studs" standard, the material used for quenched and tempered cold heading steel for high-strength fasteners of grade 8.8 is low alloy cold heading steel or medium Carbon steel, its chemical composition is: C: 0.15-0.55%, Si: 0.10-0.35%, Mn: 0.30-90%, P: ≤0.035%, S: ≤0.035%, B: ≤0.003%. [0003] U.S. Patent US4613385 discloses a high-strength, low-carbon dual-phase steel wire rod with a strength level of 830MPa (120ksi). Given the Mn element, the Mn element can be used to strongly improve the hardenability of the material, play a role in solid solution strengthening and refine ferrite grains, and...

AI Technical Summary

Problems solved by technology

[0004] Chinese patent CN1017351B discloses a heat treatment method for producing fine-grain dual-phase steel, the main components are: 0.05-0.15% C, 0.5-1.0% Si, 0.5-2.5% Mn, but the patent mainly emphasizes the heat treatment method, And the V element that can precipitate carbides or carbonitrides in ferrite is not added to the material

Annealing, quenching and tempering process not only increase the cost, but also pollute the environment

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