High-strength bolt steel capable of shortening wire rod procedures and wire rod modifying process thereof

A technology of high-strength bolts and wire rods, which is applied in the direction of improving process efficiency, etc., can solve the problems of poor quality stability of high-strength bolt steel and long process of wire rod reforming, etc., to solve poor quality stability, improve spheroidization rate, and stable quality good sex effect

CN105624563AActive Publication Date: 2016-06-01CENT IRON & STEEL RES INST
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2016-06-01

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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.
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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...

Examples

specific Embodiment

[0066] Table 1. Chemical composition of example and comparative steels, % by weight

[0067]

[0068] Table 2 Embodiment Wire Rod Transformation Process

[0069]

[0070] Table 3 Example Wire Rod Reforming Process Parameters

[0071]

[0072]

[0073] Table 4 embodiment heat treatment process

[0074] Numbering

Quenching temperature

tempering temperature

a

880

400

b

880

450

c

880

500

7 --> d

880

550

e

880

600

f

880

650

[0075] Table 5 specific embodiment and test result

[0076]

[0077] It can be seen from Table 1 that after the invention steel adopts precipitation strengthening instead of solid solution strengthening, the C content in the steel is reduced from 0.42% of the traditional high-strength bolt steel to 0.25-0.32%, and the precipitation of the microalloying element Ti refines the original austenite. Grain to 3-8μm ( Figure 10 ), improve ...