Preparation method for cold heading steel material used for bolt

A technology of cold heading steel and bolts, which is applied in the field of steel materials, can solve problems that affect the safety of use, easy to split, crack or break, and achieve high mechanical properties and good cold heading performance

Inactive Publication Date: 2013-12-11
张信群
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current fastener materials mostly use cold heading steel, and now cold riveting steel is easy to split, crack or break during cold heading, which affects the safety of use

Method used

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Embodiment Construction

[0008] A preparation method of bolt cold heading steel material, including melting, oxidation, detection and adjustment of alloy composition, refining, casting, hot rolling, heat treatment, the weight percentage of its chemical elements is: C0.15-0.25, Si0.45-0.55 , Mn1.30-1.50, P≤0.030, S≤0.050, magnesium 0.3-0.45, Nb0.06-0.08, V0.2-0.4, Cr1.2-1.4, Pr0.02-0.04, Hf0.18-0.22, Bi0.15-0.18, Ni0.2-0.3, Zr0.06-0.09, the balance is iron;

[0009] The rolled piece is first heated to 940-960°C at a rate of 160-170°C / hour, and kept for 2-3 hours; then heated to 1020-1050°C at a rate of 50-60°C / hour, and kept for 3-4 hours; Cool at -140°C / hour to 320-350°C and keep warm for 2-3 hours, then raise the temperature to 760-780°C at 80-90°C / hour, keep warm for 1-2 hours; then heat at 120-140°C / hour Cool down to 160-180°C, keep warm for 3-4 hours, then cool naturally in the air to room temperature, then heat to 120-150°C, keep warm for 1-2 hours, then cool naturally to room temperature.

[0...

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Abstract

The invention provides a preparation method for a cold heading steel material used for a bolt. The preparation method comprises the following steps: fusing; oxidation; detection of alloy components and adjustment; refining; casting; hot rolling; and heat treatment. The material is characterized by comprising the following chemical elements by weight: 0.15 to 0.25% of C, 0.45 to 0.55% of Si, 1.30 to 1.50% of Mn, no more than 0.030% of P, no more than 0.030% of S, 0.3 to 0.45% of Mg, 0.06 to 0.08% of Nb, 0.2 to 0.4% of V, 1.2 to 1.4% of Cr, 0.02 to 0.04% of Pr, 0.18 to 0.22% of Hf, 0.15 to 0.18% of Bi, 0.2 to 0.3% of Ni and 0.06 to 0.09% of Zr, with the balance being Fe. The cold heading steel material provided by the invention directly undergoes cold heading and molding after heat treatment, so the material has good cold heading performance; a bolt prepared through cold heading can obtain high mechanical properties through TRIP effects during cold heading without quenching and tempering heat treatment; and the bolt has high strength and high plasticity and accords with performance requirements for grade-12.9 high-strength bolts.

Description

technical field [0001] The invention relates to a steel material, in particular to a method for preparing a bolt cold heading steel material. Background technique [0002] Fasteners are a type of mechanical parts that are used for fastening connections and are widely used. All kinds of fasteners can be seen on various machinery, equipment, vehicles, ships, railways, bridges, buildings, structures, tools, instruments, meters and supplies. Fasteners are the basic parts of the mechanical industry and are in great demand. Fasteners include various bolts, riveted joints, nuts, rivets, etc. Since fasteners are used to connect various structural materials, they need to withstand a lot of pressure, Shear force. The current fastener materials are mostly cold heading steel, and now cold riveting steel is easy to split, crack or break during cold heading, which affects the safety of use. Contents of the invention [0003] The purpose of the present invention is to provide a method...

Claims

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Application Information

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IPC IPC(8): C22C38/50C21D8/00
Inventor 张信群唐小兵邵军王元军张志
Owner 张信群
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