Steel for high-strength bolts and wire rod reforming process that can shorten the wire rod process

Abstract

The invention discloses a high-strength bolt steel capable of shortening wire rod procedures and a wire rod modifying process thereof, and belongs to the technical field of high-strength bolt steel. The steel is composed of, by weight, 0.25-0.32% of C, Si smaller than or equal to 0.10%, 0.15-0.30% of Mn, P smaller than or equal to 0.010%, S smaller than or equal to 0.005%, 1.10-1.20% of Cr, 0.15-0.40% of Mo, 0.001-0.003% of B, 0.08-0.14% of Ti, 0.015-0.030% of Al, N smaller than or equal to 0.004% and the balance Fe and inevitable impurities. The wire rod modifying process comprises the steps of acid pickling, rough drawing, spheroidizing annealing, acid pickling, phosphatizing, saponifying and fine drawing. Compared with the prior art, the content of carbon of steel with the same strength grade is greatly lowered, the grain structure is refined, the carbon diffusion distance is shortened, single-time large-deformation drawing and single-time spheroidizing annealing can be realized, the wire modifying procedure of the high-strength bolt steel with the grade higher than 10.9 can be shortened, and the economic benefit is obvious.

Description

technical field [0001] The invention belongs to the technical field of steel for high-strength bolts, and in particular provides a steel for high-strength bolts that can shorten the wire flow process and a wire rod reforming process, which is suitable for manufacturing high-strength bolts with a tensile strength between 1040-1450 MPa and 10.9-14.9 grades Strength bolts. By obtaining the precipitated nano-scale strengthening phase and ultra-fine grain structure, the precipitation strengthening and fine grain strengthening can replace part of the solid solution strengthening, reduce the carbon content in the steel, reduce the diffusion time of C, and improve the cold deformation ability of the hot-rolled wire rod, which can simplify a process. Steel for high-strength bolts and its wire rod restructuring process. Background technique [0002] With the development of energy, automobile, machinery, construction, light industry and other industries, higher requirements are put fo...

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Problems solved by technology

[0004] The invention provides a high-performance bolt steel with a tensile strength in the range of 1000-1450 MPa, good quality stability, and high economical wire rod reformation and a wire rod reforming method, which solves the problem of poor quality stability of high-strength bolt steel and the process flow of wire rod reformation at present. long wait question

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