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Open AccessArticle

Influence of Crack Size on Stress Evaluation of Ferromagnetic Low Alloy Steel with Metal Magnetic Memory Technology

by Bin Liu 1,*, Peng Fu 1, Ruifeng Li 1, Peng He 2 and Shiyun Dong 3
1
Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China
2
State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
3
National Key Laboratory for Remanufacturing, Academy of Armored Forces Engineering, Beijing 100072, China
*
Author to whom correspondence should be addressed.
Materials 2019, 12(24), 4028; https://doi.org/10.3390/ma12244028
Received: 9 October 2019 / Revised: 23 November 2019 / Accepted: 2 December 2019 / Published: 4 December 2019
(This article belongs to the Special Issue Non-destructive Testing of Structures)
Based on the magneto-mechanical effect, the influence of crack size on stress evaluated with metal magnetic memory (MMM) technology was discussed in this paper. Based on equivalent theory, the regular rectangular grooves, with different widths and depths, were precut in the surface of an experimental sample for simulating surface crack, and a three dimensional electrically controlled displacement system was used to collect the Hp(y) signal of the sample under different stresses, and the fracture morphology was observed by using scanning electron microscopy (SEM). The results show that the influence of detection line on Hp(y) signal can be ignored; as stress increases, the Hp(y) signal turns counterclockwise around zero-crossing point and its mutation, corresponding to the location of groove, becomes distinct gradually. When groove depth is constant, the magnetic intensity gradient changes in the form of quadratic polynomial as groove width increases, and when the groove width is the same, the magnetic intensity gradient is a linear function of groove depth. When stress reaches the yield strength of the material, the magnetic intensity gradient decreases gradually as stress increases further, and the orientation of magnetic domain is seen as the main reason for that result. At last, the experimental results are discussed based on the piezomagnetic effect and leakage magnetic field theory of finite depth slit model, and the change of magnetic domain orientation is considered to be the main reason. View Full-Text
Keywords: non-destructive evaluation; crack effect; metal magnetic memory; magnetic intensity gradient; stress non-destructive evaluation; crack effect; metal magnetic memory; magnetic intensity gradient; stress
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MDPI and ACS Style

Liu, B.; Fu, P.; Li, R.; He, P.; Dong, S. Influence of Crack Size on Stress Evaluation of Ferromagnetic Low Alloy Steel with Metal Magnetic Memory Technology. Materials 2019, 12, 4028.

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