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A kind of high-strength bolt material and its preparation method

A high-strength bolt and alloy composition technology, applied in the field of bolt materials, can solve the problems of low temper softening resistance of boron steel, high susceptibility to delayed fracture of bolts, and inability to meet the tensile strength, so as to achieve high yield and low Delayed Fracture Sensitivity, Effect of Improving Delayed Fracture Resistance

Active Publication Date: 2019-10-08
NINGBO ZHENHAI YONGDING FASTENER
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] In the prior art, Chinese patent literature with application number 201210468134.7 reports a high-strength bolt and its processing method. The bolt is made of high-strength bolt steel through cold heading, quenching and tempering, finishing and blackening. The high-strength bolt has the characteristics of good strength, hardness, plasticity and toughness, good cold working performance and long service life. However, it is easy to deform and crack the workpiece during the quenching and tempering process, which reduces the yield of the bolt. Process energy consumption is high and economical is not high
The Chinese patent literature with the application number 201380015695.4 reports a boron-added high-strength bolt steel. Even if the tensile strength is above 1100MPa, the delayed fracture resistance is still excellent. Structural steel is low, and its tempering temperature is 50-100°C lower. Therefore, the delayed fracture sensitivity of bolts made of this material is relatively large. At the same time, this material cannot meet the use of tensile strength above 1400Mpa, and its limitations are relatively Big

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  • A kind of high-strength bolt material and its preparation method
  • A kind of high-strength bolt material and its preparation method

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preparation example Construction

[0025] Correspondingly, the present invention also provides a method for preparing the high-strength bolt material described in the above technical solution, comprising the following steps: smelting 42CrMo steel, ferro-titanium, ferro-vanadium, ferro-niobium and ferronickel in a vacuum induction furnace, casting A steel ingot is obtained; the steel ingot is heated to 1100-1300° C. for heat preservation, forged, and air-cooled to obtain a high-strength bolt material.

[0026] As a preferred solution, the mass of the steel ingot is 20kg. In the present invention, the steel ingot is heated to 1100-1300° C. for heat preservation, and the heat preservation time is preferably 1-4 hours; and the round rod with a diameter of 16 mm is preferably obtained by forging. In the step of obtaining high-strength bolt material, the final forging temperature is preferably 800-1000°C.

[0027] It can be seen from the above scheme that the present invention has the following advantages: the high-...

Embodiment 1

[0031] 42CrMo steel, ferro-titanium, ferro-vanadium, ferroniobium and ferronickel were smelted and poured into a 20kg ingot in a 250kg vacuum induction furnace, and then the ingot was heated to 1100°C for 4 hours and then forged into a round bar with a diameter of 16mm. The forging temperature is 800°C, air cooling after forging, to obtain high-strength bolt material, the weight percentage of each chemical composition is: C: 0.2%, Si: 0.2%, N: 0.004%, Mn: 0.4%, Cr: 1.5%, V : 0.02%, Ti: 0.02%, Mo: 0.3%, Nb: 0.02%, Ni: 0.5%, P: 0.004%, S: 0.003%, and the balance is Fe.

Embodiment 2

[0033]42CrMo steel, ferro-titanium, ferro-vanadium, ferro-niobium and ferronickel were smelted and poured into a 20-kg steel ingot in a 250-kg vacuum induction furnace. The forging temperature is 900°C, air cooling after forging, to obtain high-strength bolt material, the weight percentage of each chemical composition is: C: 0.4%, Si: 0.8%, N: 0.01%, Mn: 0.5%, Cr: 1.0%, V : 0.15%, Ti: 0.05%, Mo: 0.4%, Nb: 0.05%, Ni: 0.8%, P: 0.004%, S: 0.003%, and the balance is Fe.

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Abstract

The invention provides a high strength bolt material and a preparation method thereof. An appropriate amount of microalloy elements of Ti and Nb are added on the basis of 42CrMo steel. The microalloyelements and elements of C and N can form carbon nitride particles to refine austenite grains to form a hydrogen trap, so that material strength and toughness are improved and material resistance to delayed fracture is also improved. The elements of Mo and the like improve the drawing temperature and reduces the content of hydrogen invading from the surface of the material, so that increasing of sensitivity of material delayed fracture is effectively prevented. According to the high strength bolt material, the element of Ni is added. On the one hand, the mechanical property of the material isimproved by the element of Ni cooperating with Ti, Nb and the like. On the other hand, the material resistance to delayed fracture is improved by matching of the element Ni and the element Mo. According to the high strength bolt material, the contents of elements of P, S, Mn and the like are reduced; the amount of non-metallic inclusions in steel is greatly reduced and sensitivity of material delayed fracture is reduced.

Description

technical field [0001] The invention relates to the technical field of bolt materials, in particular to a high-strength bolt material and a preparation method thereof. Background technique [0002] High-strength bolts are widely used in automobiles, machinery manufacturing, energy, transportation, bridges, construction, chemicals, aerospace and other fields, and the reliability of their product quality plays an important role in the performance of the main body and the safety of the structure. With the development of manufacturing technology, the requirements for the quality, reliability and stability of bolts have been further improved. At the same time, higher requirements have been put forward for the strength, corrosion resistance, processing performance and fatigue performance of bolt materials. [0003] In the prior art, Chinese patent literature with application number 201210468134.7 reports a high-strength bolt and its processing method. The bolt is made of high-stre...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/50C22C38/46C22C38/44C22C38/48
Inventor 潘剑波
Owner NINGBO ZHENHAI YONGDING FASTENER
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