Magnetic detection method of stress concentration region and microcrack on surface of magnetic metal component

Abstract

The invention provides a magnetic detection method of a stress concentration region and a microcrack on the surface of a magnetic metal component. The method includes the steps that an alternating magnetic field of certain strength is applied to the direction of the metal surface, and weak magnetic signals at all positions of the near surface of metal are detected through a magnetic sensor; the detected weak magnetic signals are processed through a phaselock technique, feature signals related to the stress concentration region are extracted according to the features of the weak magnetic signals on the surface of the stress concentration region, and the magnitude of the magnetic signals corresponding to the stress concentration region or the microcrack is obtained; finally, drawing is conducted through a computer to obtain a metal surface stress concentration region distribution diagraph, the quantitative relationship of size, strength and shape of the stress concentration region is given out, and thus early warning is provided for the possible fracture locations of the metal component. According to the magnetic detection method of the stress concentration region and the microcrack on the surface of the magnetic metal component, the stress concentration region distribution diagraph is drawn according to the features of the weak magnetic signals on the surface of the stress concentration region, the quantitative relationship of size, strength and shape of the stress concentration region is given out, and thus early warning is provided for the possible fracture locations of the metal component.

Description

technical field [0001] The invention relates to a magnetic detection method for stress concentration areas and microcracks on the surface of magnetic metal components, which is applied to the detection of stress concentration areas and microcracks of ferromagnetic metal materials. Background technique [0002] Ferromagnetic metal materials widely used in engineering practice (such as various carbon steels, alloy steels, etc.) often have hidden discontinuous areas inside due to factors such as inclusions, segregation, and external stress. The action will develop into a microscopic or quasi-microscopic stress concentration zone. Stress concentration will cause fatigue cracks in metal materials, and gradually accumulate to form macroscopic defects, causing metal components to fracture. It is one of the important reasons for mechanical structure and equipment failure and even accidents. The detection and evaluation of the damage and stress concentration of metal materials has a...

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Problems solved by technology

[0008] In the traditional metal magnetic memory detection technology, the judgment method of the stress concentration area is mainly based on the zero-crossing point of the normal magnetic field component. The disadvantage of this method is that the leakage magnetic field caused by the background magnetic field and the shape of the component itself is easy to dilute the magnetic memory characteristics. , resulting in missed and wrong judgments. In addition, the magnetic signal is greatly affected by external noise and interference, and it is difficult to accurately determine the stress concentration area in practical engineering applications.

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