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High strength bolting steel with excellent delayed fracture resistance and cold working performance

A delayed fracture-resistant, high-strength bolt technology, applied in the field of alloy steel, can solve the problems of restricting large-scale industrial applications and increasing costs, and achieve the effects of excellent cold working performance, low cost, and excellent delayed fracture resistance

Inactive Publication Date: 2005-04-06
CENT IRON & STEEL RES INST
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Problems solved by technology

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Japanese patent JP8-176747 proposes a high-strength bolt steel with a tensile strength above 1400MPa, which has good cold forgeability and delayed fracture resistance, but its Ni content is as high as 7.0-10.0%, which significantly increases the cost of the steel. Limits its high-volume industrial application

Method used

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Embodiment Construction

[0023] According to the chemical composition range designed above, 4 furnaces of the steel of the present invention and 3 furnaces of comparative steel were smelted on a 50kg vacuum induction furnace. In addition, 1 furnace of commercial steel 42CrMo was used as the comparative steel. The specific chemical composition is shown in Table 1. Among them, furnace numbers 1-4# are the steels of the present invention, and furnace numbers 5-8# are comparative steels. Molten steel is cast into ingots and forged into rods. The sample was normalized at 900°C for 30 minutes before processing, and then the sample was processed from a hot-rolled bar into a standard room temperature tensile sample (L 0 =5d 0 , d 0 =5mm), notched tensile delayed fracture specimen (diameter d=5mm, d at the notch N =3mm, notch 60°±2° / 0.15R±0.025) and the blank of the cold deformation sample (diameter d=10mm, height h=20mm). The above tensile and delayed fracture samples were quenched and tempered at 850°C t...

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Abstract

The name in religion belongs to the alloy steel domain, mainly is suitable above tensile strength 1200MOa, has good bears the detention break and cold finishing the performance high strength bolt steel. The steel concrete chemical composition (weight %) is: C0.25~~0.4%, Si is smaller than is equal to 0.1%, Mn0.4~~1.4%, P is smaller than is equal to 0.01%, S is smaller than is equal to 0.008%, Cr0.1-0.5%, Mo0.15~~0.35%, B0.0005~~0.003%, Ti0.01~~0.1%, RE0.005~~0.04%, Al0.005~~0.05%, N0.004~~0.01%, -odd is Fe. The steel concrete chemical composition (weight %) center also may join 0.01~~0.1% Nb, in Zr any a kind of or two kind of sums. The invention and the existing technology compare, this steel not only tensile strength very high, moreover bears the detention break and cold finishing the performance fine, the cost is low.

Description

technical field [0001] The invention belongs to the field of alloy steel, and is mainly suitable for high-strength bolt steel with a tensile strength above 1200MPa and good delayed fracture resistance and cold working performance. Background technique [0002] High-strength bolts are widely used in machinery, automobiles, bridges, construction and other industries. When the tensile strength of bolts made of quenched and tempered low-alloy steel exceeds about 1200MPa, the problem of delayed fracture becomes very prominent. Therefore, the tensile strength of high-strength bolts actually used at present is generally lower than 1200MPa. With the development of various production departments, higher and higher requirements are put forward for the materials used in the manufacture of various fasteners (such as bolts, screws, nuts, etc.). Some bolts for automobiles and construction machinery even require strengths above 1400MPa. In recent years, the research and development of st...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/32
Inventor 惠卫军董瀚时捷翁宇庆
Owner CENT IRON & STEEL RES INST
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