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Device for measuring change of material residual stress

A technology of residual stress and measurement system, which is applied in the measurement of the change force of the magnetic property of the material caused by the applied stress, the measurement of the magnetic variable of the material, the measurement of the magnetic property, etc., so as to achieve the effect of not causing the deformation of the material

Active Publication Date: 2007-08-08
WUHAN JINGTAI TECH CO LTD
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  • Application Information

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Problems solved by technology

[0004] The residual stress measurement method that has been reported so far has not been carried out through the change of the magnetostriction coefficient. The existing technology to reduce the residual stress through the magnetic field is empirical, and there is no method to directly determine the required magnetic field parameters through the measurement of a certain parameter.

Method used

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  • Device for measuring change of material residual stress
  • Device for measuring change of material residual stress

Examples

Experimental program
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Effect test

Embodiment 1

[0032] Example 1 Effect of high temperature annealing at 600°C on residual stress of 45# steel

[0033] Take a 45# steel rod with a diameter of 8mm and a length of 25mm, paste a piece of DY-120 resistance strain gauge in the middle of the sample along the length direction, connect the dynamic strain gauge, computer and excitation power supply according to the measurement method written above, and put it into the iron core In the air gap, the average value of initial magnetostriction measured after preheating is 15με. The sample was annealed at 600°C for 1 hour, and after cooling to room temperature, the average value of magnetostriction was measured again with the same method to get 28με, and the residual stress change caused by this annealing process was calculated by formula 2 as (15-28) / 15=-0.87, indicating that the residual stress can be reduced by 87% after this annealing process.

Embodiment 2

[0034] Example 2 Effect of 400°C Medium Temperature Annealing on Residual Stress of 45# Steel

[0035] Take a 45# steel rod with a diameter of 20mm and a length of 50mm, paste a piece of DY-120 resistance strain gauge in the middle of the sample along the length direction, connect the dynamic strain gauge, computer and excitation power supply according to the measurement method written above, and put it into the iron core In the air gap, the average value of initial magnetostriction measured after preheating is 15με. The sample was annealed at 400°C for 1 hour, and after cooling to room temperature, the average value of magnetostriction was measured again with the same method to get 21με, and the residual stress change caused by this annealing process was calculated by formula 2 as (15-21) / 15=-0.40, indicating that the residual stress can be reduced by 40% after this annealing process.

Embodiment 3

[0036] Example 3 Effect of low temperature annealing at 200°C on residual stress of 45# steel

[0037] Take a 45# steel rod with a diameter of 30mm and a length of 75mm, paste a piece of DY-120 resistance strain gauge in the middle of the sample along the length direction, connect the dynamic strain gauge, computer and excitation power supply according to the measurement method written above, and put it into the iron core In the air gap, the average value of initial magnetostriction measured after preheating is 15με. The sample was annealed at 200°C for 1 hour, and after cooling to room temperature, the average value of magnetostriction was measured again with the same method to get 18με, and the residual stress change caused by this annealing process was calculated by formula 2 as (15-18) / 15=-0.20, indicating that the residual stress can be reduced by 20% after this annealing process.

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Abstract

A device and method to measure material residual stress changes, its characteristic is using magnetostrictive to measure residual stress changes of ferromagnetic material, which includes two parts, the measurement system and data processing method. The measurement system includes two parts, the magnetic field generation equipment and the equipment to measure and record magnetostrictive. The equipment to measure and record magnetostrictive includes the resistance strain slice, the dynamic strain device and the computer acquisition system. The data processing method uses a formula to process the initial magnetostrictive average and the final magnetostrictive average, to obtain the residual stress changes instance. It solves the problems to reduce, control and measure residual stress in existing technology. The invention is characterized by fast, efficient, no material deformation, and so on.

Description

technical field [0001] The invention relates to the field of residual stress measurement, in particular to a device and method for estimating residual stress changes by measuring magnetostriction. Background technique [0002] Residual stress widely exists in various stages of material preparation, processing and use, and usually reduces the service performance and service life of materials. Therefore, how to reduce and control residual stress has always been a major issue in the field of materials science and engineering. In recent years, it has been reported that the residual stress of structures can be reduced by the action of a magnetic field. [0003] Patent CN1737519A uses the relationship between residual stress and magnetic permeability to measure residual stress, and utilizes the magnetic properties of materials. Since the magnetic field is difficult to observe directly, stress measurement is also a difficult problem in the detection field. How to measure the chang...

Claims

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Application Information

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IPC IPC(8): G01N27/72G01L1/12G01R33/12
Inventor 王明道陈洪强
Owner WUHAN JINGTAI TECH CO LTD
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