Paste capable of reducing fatigue crack growth rate of metal material, and metal material coated with the paste

A technology for metal materials and fatigue cracks, applied in metal processing equipment, welding/welding/cutting items, manufacturing tools, etc., can solve problems such as unclear alumina, slurry viscosity regulations, and inability to protect slurry penetration, etc., to achieve Good fluidity, reduced progress rate, excellent entry effect

Active Publication Date: 2014-05-07
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] In this Patent Document 2, although the viscosity of the oil to be mixed with fine particles is regulated, the viscosity of the slurry is not regulated, so there is a problem that the slurry cannot be protected from fatigue cracks. entry
However, in Patent Document 2, the experimental results show that only one type of alumina with a particle size of 10 to 20 μm is effective, and it is unclear which particle size range of alumina is suitable.

Method used

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  • Paste capable of reducing fatigue crack growth rate of metal material, and metal material coated with the paste
  • Paste capable of reducing fatigue crack growth rate of metal material, and metal material coated with the paste
  • Paste capable of reducing fatigue crack growth rate of metal material, and metal material coated with the paste

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach

[0044] The slurry of the present invention is produced, for example, by putting particles that reduce the rate of fatigue crack progression into a liquid, stirring it with a stirrer, and finally mixing it completely with a stirrer. In addition, this slurry can also be produced by other methods, as long as the method can mix the particles and the liquid.

[0045] In this case, it is preferable to use a particle having a hardness higher than that of the metal material on which the slurry is applied among the particles that reduce the rate of progress of the fatigue crack. In the present invention, a high-hardness substance means a substance with a small amount of deformation. Specifically, it means a substance that has a large Young's modulus and is difficult to generate elastic deformation, or various types of hardness represented by Vickers hardness or Shore hardness. Any value of hardness is large, and plastic deformation is difficult to occur. The material of the particles ...

Embodiment 1

[0051] Alumina is used as the particle to reduce the fatigue crack progress rate, and a liquid with a viscosity of 5.5×10 is used as the liquid mixed with the particle. -2 Pa·s oil. By mixing these two, slurries (alumina slurries) of various viscosities are prepared.

[0052] Hereinafter, the results when using a slurry with a viscosity of 32 Pa·s (particle diameter: 15.9 μm) and the results when not using a slurry will be described.

[0053] For 4 test pieces produced from the same batch of SS400 (JIS), 2 of them were coated with the above-mentioned slurry with a viscosity of 32 Pa·s, and the other 2 were not coated with the slurry, and loads were repeatedly applied to perform a fatigue test.

[0054] figure 1 It is an enlarged view (photograph) showing a fatigue cross section after a fatigue test. It can be seen that the slurry coated on the surface of the material enters the fatigue crack. Slurry with this viscosity can penetrate into the interior of fatigue cracks due ...

Embodiment 2

[0058] As the particles for reducing the fatigue crack progress rate, 15.9 μm alumina having the same particle diameter as in Example 1 above was used. In addition, as a liquid mixed with the particles, a viscosity of 1.2×10 -1 Pa·s turbine oil (turbine oil). By changing the amount of turbine oil when mixing the two, slurries (alumina slurries) of various viscosities were produced. The viscosities of various slurries are 2.6Pa·s, 3.4Pa·s, 6.4Pa·s, 32Pa·s, 35Pa·s, 70Pa·s.

[0059] These slurries were applied to the same test pieces as in the above-mentioned Example 1 and subjected to a fatigue test to observe the cross-section after fatigue fracture to investigate the penetration of the slurries into the fatigue cracks. As a result, it was found that the intrusion into fatigue cracks was confirmed in any of the slurries, and that the use of these slurries can be expected to reduce the rate of progress of fatigue cracks.

[0060] At this time, the slurry with a viscosity of 7...

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Abstract

Disclosed are a paste (grain-paste) which can reduce the fatigue crack growth rate of a metal material and can be well incorporated into a fatigue crack, and a metal material coated with said paste. The paste, which comprises a mixture of grains capable of reducing the fatigue crack growth rate of a metal material with a liquid, is characterized by having a viscosity of 0.01-300 Pa·s.

Description

technical field [0001] The present invention belongs to the technical field related to the suppression of fatigue crack progression of metallic materials. Background technique [0002] It is generally known that foreign substances such as fretting oxides are generated in the fatigue crack surface due to metal fatigue, and that the fatigue crack progress rate is reduced due to the span effect (also called the wedge effect). [0003] The reason why the fatigue crack growth rate decreases under the cross-gap effect is that the displacement of the crack front opening decreases due to the incorporation of foreign matter. In this way, the fatigue crack progress rate in each cycle of stress fluctuation is closely related to the opening displacement of the fatigue crack front. [0004] In the technique for reducing the fatigue crack growth rate described in Non-Patent Document 1, the cross-gap effect derived from the adhesive is utilized. That is, a method using an adhesive has be...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B23P6/00B23P6/04
CPCB23K1/20B23K2203/04B23K2103/04B23P6/00B23P6/04
Inventor 河本恭平山田岳史市川靖生内藤纯也
Owner KOBE STEEL LTD
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