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High-strength bolt

一种高强度螺栓、抗拉强度的技术，应用在螺钉、螺纹紧固件、炉子类型等方向，能够解决螺栓形状和尺寸制约、无法冲击韧性改善等问题，达到耐冲击性优异的效果

Active Publication Date: 2012-07-18
NAT INST FOR MATERIALS SCI +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But their premise is cold forming into bolts, so the shape and size of bolts are restricted
In addition, in order to achieve high strength, the amount of carbon must be increased to more than 0.7%wt, and the impact toughness cannot be greatly improved.

Method used

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Examples

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Effect test

Embodiment

[0062] Table 1 shows the steel composition used in the bolt material. The A material has a steel material component excellent in delayed fracture characteristics disclosed in Patent Document 2, and the B material corresponds to JIS-SCM440 steel. As a tempering material, prepare a cross-sectional area of ​​about 2 cm 2 of bars. Material A and material B were quenched at 950°C and 920°C respectively, and then tempered at 500°C and 400°C for 1 hour. On the other hand, for particle-dispersed fibrous tissue materials, first prepare 2 For the square bar, material A and material B were quenched at 950°C and 920°C, respectively, to obtain a single structure of martensite approximately close to 100% by volume. It should be noted that the prior austenite grain size in the quenched structure is about 50 μm. Next, material A and material B were tempered at 500°C and 400°C for 1 hour respectively, and then the cross-section was shrunk to a cross-sectional area of ​​2 cm using a grooved...

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Abstract

Provided is a high-strength bolt having a tensile strength of 1200 MPa or more, which further has excellent ductility and delayed fracture property, and excellent impact resistance which could not be obtained before. The high-strength bolt has a tensile strength of 1.2 GPa or more, and has a threaded portion and a neck cylindrical portion. In the high-strength bolt, if the effective section area of the neck cylindrical portion having a diameter larger than that of the threaded portion is represented by Ao, the hardness of a portion at which Ao is measured is represented by Ho, the effective section area of the threaded portion is represented by As, and the hardness of the threaded portion is represented by Hs, K=(Ao * Ho) / (As * Hs) is 0.8 or more, and Ho < Hs is satisfied.

Description

technical field [0001] The invention relates to high-strength bolts with tensile strength above 1200 MPa. Background technique [0002] In recent years, along with the increase in the size of structures and the reduction in weight of automobile parts and the like, there has been a demand for higher strength and tougher high-strength metal materials than ever before. Among them, not only the strengthening of steel plates and section steels but also the strengthening of bolts used for connecting these steel materials is strongly desired (for example, Patent Document 1, Non-Patent Document 1). [0003] Mechanical properties required for bolt materials include: (1) easy molding / processing, (2) excellent delayed fracture resistance, (3) no material deterioration due to environmental influences, and (4) excellent impact resistance Wait. However, there is a trade-off relationship between these properties and the strength increase. [0004] In steel materials having a tensile str...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F16B35/00C22C38/00C22C38/58C21D8/06C21D9/00
CPCC22C38/06C22C38/34F16B35/041C22C38/02C22C38/04C22C38/22C22C38/001C21D8/06C21D9/0093C21D9/00C22C38/58F16B35/00
Inventor 木村勇次井上忠信村崎收二福田又一
Owner NAT INST FOR MATERIALS SCI
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