Novel contactless nondestructive method of measuring material hardness

A non-contact, non-destructive testing technology, applied in the direction of measuring devices, analyzing materials, using wave/particle radiation for material analysis, etc., to achieve the effect of eliminating damage and avoiding damage

Active Publication Date: 2016-10-26
LIAOCHENG UNIV
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  • Abstract
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  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the shortcomings of traditional hardness measurement methods and provide a new hardness testing technology that can accurately characterize the hardness of materials and completely avoid damage to the measured materials

Method used

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  • Novel contactless nondestructive method of measuring material hardness
  • Novel contactless nondestructive method of measuring material hardness
  • Novel contactless nondestructive method of measuring material hardness

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Embodiment Construction

[0023] Provide following embodiment in conjunction with content of the present invention:

[0024] (1) Raw material shot blasting

[0025] The selected brand is GCr15 steel, heat treatment process: oil quenching after heating at 840°C for 15 minutes, annealing at 200°C for 120 minutes. After wire cutting, the size is: 30×20×5mm 3 . Using a pneumatic shot peening machine, the sample is subjected to composite shot peening treatment. The shot peening process includes three processes: the first process has a shot peening intensity of 0.50mmA, the second process has a shot peening intensity of 0.30mmA, and the two shot peening The shot medium of the shot peening is unchanged (cast steel shot, diameter is 0.6mm), the shot peening intensity of the third process is 0.15mmA, and the shot medium of the third shot peening is ceramic shot, and the particle size is smaller (0.3mm in diameter).

[0026] (2) Annealing treatment

[0027] The samples were annealed at different temperatures...

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Abstract

The invention relates to a novel contactless nondestructive method of measuring material hardness. The method is technically characterized in that GCr15 steel after being subjected to shot blasting of 0.50+0.30+0.15mmA is used as a studying object, the surface of the GCr15 steel has large residual pressure stress and refined tissue structure, the tissue structure can restore during high-temperature annealing, change of the tissue structure can be indirectly expressed actually through FWHM change, the residual pressure stress can be reduced, and lowering of surface hardness can be caused. Through change tendency of FWHM and the residual stress along with annealing time at different temperatures, a relational expression between the material surface hardness and the FWHM as well as the residual stress at different annealing temperatures is established. When hardness of same materials is tested, a hardness value can be acquired through calculation by measuring corresponding FWHM and residual stress through XRD technology and combining with the relational expression acquired. The method is an extension of XRD testing technology, and no contact with the sample occurs during testing, so that completely nondestructive testing is realized. The method is convenient, quick and more effectively and can be widely applied in measuring hardness of metal materials.

Description

technical field [0001] The invention relates to the use of X-ray diffraction (XRD) technology to measure the hardness of metal materials, which can be used in the field of non-contact and non-destructive measurement of the surface hardness of metal materials or parts. Background technique [0002] In order to establish the relationship between the microstructure of the material and the relationship between residual stress and hardness, this method uses the surface layer of the shot peened part with a large change in the microstructure and residual stress gradient for technical characterization. Shot peening is to use a large number of high-speed projectiles to continuously impact the surface of the material, which produces a large residual compressive stress on the surface of the material, and makes the surface grain size smaller, the microscopic distortion increases, and the residual compressive stress and microstructure changes on the surface. Form a hardened layer, both o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N23/207
CPCG01N23/2076
Inventor 付鹏徐志军初瑞清李伟黄宝绪王长征
Owner LIAOCHENG UNIV
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