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A kind of preparation method of high-strength fastener

A fastener and high-strength technology, applied in the field of parts manufacturing, can solve the problems of deterioration of material manufacturability, increase of alloy elements, increase of material cost, etc., to reduce the cost of raw materials and the difficulty of obtaining, and avoid the effect of adding a large amount

Active Publication Date: 2020-11-17
LUOYANG SUNRUI SPECIAL EQUIP
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, a large increase in alloying elements not only increases the cost of the material, but also sharply deteriorates the manufacturability of the material, which limits the popularization and use of the material.
Patents for improving the delayed fracture performance of fasteners by preparing fibrous grain structures have not yet been reported

Method used

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  • A kind of preparation method of high-strength fastener
  • A kind of preparation method of high-strength fastener

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preparation example Construction

[0025] A method for preparing high-strength fasteners. The fastener raw materials are subjected to heat treatment and cold deformation to obtain fasteners with an upper limit of tensile strength of 1400 MPa and a performance level of 10.9-12.9. The specific preparation steps are as follows:

[0026] Step 1. Perform quenching and high-temperature tempering heat treatment on the fastener raw material, and the tensile strength of the fastener raw material after heat treatment is Rm≥650MPa;

[0027] Step 2, using cold drawing or cold rolling process to cold deform the fastener raw material after the heat treatment in step 1 with an area reduction rate of more than 60%, to obtain a fastener blank;

[0028] Step 3: Perform thread processing or / surface treatment on the fastener blank obtained in step 2 to obtain a fastener whose tensile strength is greater than 1300 MPa.

[0029] The general surface treatment process can be carried out with the process operating temperature below the...

Embodiment 1

[0036] Commercially available 35CrMo φ40 steel bar is used, the chemical composition of the material: C: 0.37%, Si: 0.22%, Mn: ≤0.56%, S: ≤0.005%, P: 0.013%, Cr: 0.92%, Mo: 0.18%, and the rest for iron.

[0037] A method for preparing high-strength fasteners is:

[0038] Step 1. The steel bar is subjected to 860°C quenching + 640°C tempering heat treatment. After the heat treatment, the surface is shot blasted and textured to remove the surface scale. At this time, the tensile strength of the steel bar is Rm=785MPa.

[0039] Step 2. Use the drawing process to draw the bar in 6 passes to φ22mm, and the dimensions of each drawing pass are φ40-φ36.5-φ32.8-φ29.6-φ26.8-φ24.2 -φ22. The total area reduction rate is 69.75%.

[0040] Step 3, using the thread rolling process to roll the drawn bar material into an M24 thread, and manufacture it into an M24 screw fastener.

[0041] Step 4, surface degreasing, phosphating treatment, and dehydrogenation treatment at 200°C / 12h.

[0042]...

Embodiment 2

[0047] Commercially available 34CrNi3MoV φ120 steel bar material is used, the material chemical composition: C: 0.352%, Si: 0.234%, Mn: 0.305%, S: ≤0.005%, P: 0.0060%, Cr: 1.17%, Ni: 2.93%, Mo : 0.322%, V: 0.118%.

[0048] Step 1, the steel rod is subjected to 900°C quenching + 670°C tempering heat treatment, and the tensile strength of the steel rod at this time is Rm=823MPa.

[0049] Step 2: Heat the bar to a temperature below the recrystallization temperature of 350°C, and roll it into a φ55mm bar through 9 passes with a three-roll bar mill, with an area reduction rate of 79%.

[0050] Step 3. Use centerless turning to turn the bar to φ52.5, and use centerless grinding to cut the outer circle of the bar to the diameter of the blank before M56 screw rolling. Use the thread rolling process to roll the bar into M56 thread and manufacture it into M56 screw fastener.

[0051] Test the mechanical properties of the screw, and the tensile strength of the screw is σb=1365MPa. Mee...

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Abstract

A method for preparing a high-strength fastener. The raw material of the fastener is subjected to heat treatment and cold deformation to obtain a fastener with an upper limit of tensile strength of 1400 MPa and a performance level of 10.9-12.9. Step 1: Quenching the raw material of the fastener Add high temperature tempering heat treatment, the tensile strength of the fastener raw material after heat treatment is Rm ≥ 650MPa; step 2, use cold drawing or cold rolling process to cold the fastener raw material after heat treatment in step 1 with an area reduction rate of more than 60% Deformation to obtain a fastener blank; step 3, thread processing or / surface treatment is performed on the fastener blank obtained in step 2 to obtain a fastener whose tensile strength is greater than 1300 MPa. The present invention improves the preparation and heat treatment process of fasteners on the basis of existing materials, changes the microstructure of high-strength fasteners, and obtains fibrous crystal grains with conventional quenched and tempered equiaxed grains through the preparation process of the present invention. granular tissue. Effectively improve the delayed fracture resistance of the material.

Description

technical field [0001] The invention belongs to the field of part manufacturing, in particular to a method for preparing a high-strength fastener. Background technique [0002] With the rapid development of the economy, the rapid development of transportation, marine engineering and other industries has put forward higher requirements for large steel structures, and the requirements for bridge span and application safety have been continuously improved. Higher requirements are put forward for the strength and delayed fracture resistance of high-strength fasteners used for steel structure connections. [0003] High-strength fasteners on steel structures and other facilities in transportation, marine engineering and other industries, due to long-term exposure to the wild environment, especially steel structure bridges and marine engineering, are usually located on rivers, rivers, lakes, seas and other water surfaces, with high humidity , The environment is harsh, and the surf...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D1/18C21D3/06C21D6/00C21D9/00C22C38/02C22C38/04C22C38/22C22C38/44C22C38/46
CPCC21D1/18C21D3/06C21D6/004C21D6/005C21D6/008C21D9/0075C22C38/002C22C38/02C22C38/04C22C38/22C22C38/44C22C38/46
Inventor 范芳雄孙永伟梁晓辉朱晓锋赵轶鹏
Owner LUOYANG SUNRUI SPECIAL EQUIP
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