Due to the redistribution of residual stress after vibratory stress relief equipment, the macro size changes. The aging effect is determined by testing the stability of the dimensional accuracy of the workpiece before and after vibratory stress relief equipment. It usually needs to be placed for a long time and tested regularly, and the detection instrument requires high precision to accurately monitor the micro changes of macro size. This method is inefficient and not suitable for large-scale use.
It is one of the methods to evaluate the effect of vibratory stress relief equipment by directly measuring the change of residual stress before and after vibration. This method can quantitatively determine the residual stress relief and the effect of ultrasonic vibratory stress relief equipment. The residual stress detection methods of vibratory stress relief equipment can be divided into damage detection method and non-destructive detection method.
1. Destructive stress relief equipment
The measurement principle of damage detection is to deduce the original stress by the displacement generated when the stress is completely or partially released during the material removal process. This kind of method depends on the measurement of deformation, which is caused by the release of residual stress during the material removal process. The common detection methods include slicing method, contour method, blind hole method, ring core method, deep hole method, etc., while the other uncommon methods include cutting method, splitting method, curvature method, peeling strain method, slotting method, etc. Because the damage detection method will cause a certain degree of damage to the components, it is usually suitable for small batch experiments, not suitable for large-scale industrial applications.
2. Nondestructive stress relief equipment
X-ray diffraction method: this method is the most commonly used nondestructive testing method of residual stress, measuring the surface 10 μ The surface stress is about 0. The basic principle is to calculate the stress by measuring the lattice strain, which can be detected by X-ray diffraction. The detection area of X-ray diffraction method is limited to the lattice structure of the material surface and sub surface. Chemical cleaning of the material surface is required to expose the crystal. The accuracy of the detection results is greatly affected by the grain size, surface roughness, surface curvature and other factors, as well as the volume and weight of the equipment and the complexity of the operation.
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