Method for evaluating stress concentration degree of remanufactured blank by using self-emission magnetic signal
A technology of stress concentration and magnetic signal, applied in the direction of material magnetic variables, etc., can solve the problems of difficulty in quantitatively comparing the degree of stress concentration of ferromagnetic remanufactured blanks, and the lack of calibration standards for the degree of stress concentration.
Inactive Publication Date: 2014-07-02
ACADEMY OF ARMORED FORCES ENG PLA
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However, for different ferromagnetic components, the correlation between its chemical composition, geometric size, service environment, service load and many other influencing factors and the variation law of spontaneous magnetic emission signals has not yet been clarified, and there is a lack of calibration standards for the degree of stress concentration. According to the formula (1) It is only possible to qualitatively evaluate the degree of stress concentration of similar parts, and it is difficult to quantitatively compare the degree of stress concentration of ferromagnetic remanufactured blanks with different structures, functions and service conditions
[0008] Among the existing technologies, there is only the Chinese invention patent with application number 200710119911.6 and publication number CN101122578A—a magnetic memory detection method for fatigue cracks and stress concentration of ferromagnetic metal components. A magnetic stress concentration factor is proposed to characterize the degree of stress concentration of ferromagnetic materials method to spontaneously emit the horizontal component of the magnetic signal H p (x) The ratio of the maximum value to the minimum value of the signal magnetic field strength is used as a comparison standard. This method is still a qualitative evaluation method of stress concentration and is not suitable for comparison of different parts.
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[0023] The present invention is realized by following measures:
[0024] The material of the tested component is 42CrMo steel, and the self-emission magnetic signal detection instrument is EMS-2003 metal magnetic memory detector (detection normal component H p (y) signal) and RM-1 magnetic memory detector (detection level component H p (x) signal).
[0025] 1) Select the ferromagnetic material 42CrMo steel which is the same as the material of the tested component, and make the stress concentration factor K according to the national standard t = Stress concentration factor specimens of five kinds of prefabricated notches from 1 to 5, surface roughness R a The upper limit value is 0.4μm, heated to 860°C, held for 30 minutes, oil quenched, then tempered at 540°C for 2 hours, cooled to below 200°C with the furnace and air-cooled to obtain a pure initial magnetic state.
[0026] At the prefabricated incisions on both sides of the specimen surface, each detection line is spaced 1...
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The invention discloses a method for quantitatively evaluating the stress concentration degree of a waste and used ferromagnetic part by using a self-emission magnetic signal, belonging to the technical field of nondestructive detection. The method comprises the following steps of: manufacturing a test piece by using a material which is the same as that of the tested waste and used ferromagnetic part, designing different tests for corresponding bending, torque, impact, fatigue and the like, and scanning a stress concentration region on the surface of the test piece according to a fixed lift-off value by using a magnetic sensor in the testing process to obtain a self-emission magnetic signal of the stress concentration region; computing the obtained signal, extracting multiple characteristic parameters, and establishing a mapping relation model between the characteristic value of the self-emission magnetic signal of the stress concentration region and the stress concentration degree by using a nerve network; and detecting a self-emission magnetic signal of a potential dangerous region on the surface of a tested member by using the same lift-off value, and quantitatively evaluating the stress concentration degree of a tested ferromagnetic test piece according to the mapping relation model between the characteristic value of the self-emission magnetic signal and the stress concentration degree. The evaluation reliability of stress concentration with a metal magnetic memory technology is enhanced, operation is simple and convenient, and high repeatability is achieved.
Description
technical field [0001] The invention relates to a method for evaluating the stress concentration degree of remanufactured blanks by using spontaneously emitted magnetic signals, and belongs to the technical field of nondestructive testing. Background technique [0002] Remanufactured blanks are the production objects of remanufacturing, and they are waste mechanical parts that have gone through a service cycle. These waste parts may be damaged or even defective during service. Before remanufacturing, the degree of damage of the remanufactured blank must be evaluated to determine whether it has remanufacturing value. Only waste parts with remanufacturing value can be remanufactured. [0003] For remanufactured blanks that have generated macroscopic defects, conventional nondestructive testing methods, such as ray, ultrasonic, eddy current, magnetic force, penetrant testing, etc., can be found, but these methods cannot diagnose the early hidden damage of remanufactured blanks...
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IPC IPC(8): G01N27/83
Inventor 徐滨士董丽虹董世运王慧鹏薛楠
Owner ACADEMY OF ARMORED FORCES ENG PLA