A Method for Predicting and Measuring Residual Stress of Cold Rolled Sheet

Abstract

The invention discloses a method for predicting and measuring residual stress of a cold-rolled plate, which belongs to the technical field of stress-strain detection methods for iron and steel materials. Its technical scheme is: use wire cutting to select two groups of two groups whose size is a certain size length×width×length from the cold-rolled plate before forming by wire cutting method, and form a total cube sample X; Paste strain gauges or strain rosettes on the geometric center of the material in the rolling direction and transverse direction, and measure the initial strain of each group of samples in this state; use bending equipment and contour scanning equipment to obtain the relationship between sample bending moment and dimensional change; use contour scanning The curvature of the sample is detected by the instrument; the relationship between the sample surface strain and the radius of curvature is obtained; the residual stress is calculated by the calculation formula. The invention can effectively predict the residual stress distribution along the thickness direction of the plate through the pure bending method, and can provide accurate data for the control of the residual stress of the subsequent cold-rolled plate, thereby providing reliable technical support for improving product quality.

Description

Technical field [0001] The present invention relates to a simple and efficient residual strain and stress detection method, belonging to the technical field of steel material stress strain detection method. Background technique [0002] The modern industry requires high mechanical properties and shape accuracy requirements, so in the production rolling process of the slabs, the complex roll surface curve and rolling process control will cause the strip rolling. Higher residual stress and uneven distribution, these will affect the board type and the quality of the subsequent deep processing products. Excessive residual stress causes the steel plate straightness to have warpage, affecting the rebound when the part is formed, and the stability of the welding process. Therefore, the residual stress in the steel sheet is therefore accurately predicted and the residual stress is controlled is one of the technical difficulties of sheet production. The final residual stress of the plate ...

AI Technical Summary

Problems solved by technology

[0006] X-ray methods are very poorly penetrating and can only reach the surface of the material

Only suitable for small samples, there are radioactive safety issues, only the surface of the sample can be detected, the equipment is expensive, and it is not suitable for industrial applications

[0007] Neutron detection is considered to be the most accurate means of residual stress detection, it can detect the residual stress distribution along the thickness direction, and the measured strain accuracy can be as high as 10 -4 to 10 -5 .However, this method requires high investment costs, and the detection time is usually very long. At present, there are very limited civilian neutron detection equipment in the world, mainly concentrated in the United States, Europe, Japan, Australia and other developed countries

This method, like the X-ray method, is only suitable for small samples, has radiological safety issues, expensive equipment, and is not suitable for industrial applications

[0008] Ultrasonic testing method is not intuitive for the display of sample defects, the technical operation is difficult, the subjective and objective factors are greatly affected, the results are inconvenient to save, and the working surface is required to be smooth, which is mainly suitable for large samples

[0009] Therefore, several detection methods commonly used at present have great limitations, and cannot meet the prediction and measurement of residual stress in steel in the production of steel industry. How to quickly predict and measure residual stress in steel, especially the development and adaptation The detection method of industrial production has become a problem that plagues enterprises and technicians. So far, there is no effective solution, and technical personnel are urgently needed to carry out innovative research

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