Fatigue damage evaluation by metal magnetic memory testing

Abstract

Tension-compression fatigue test was performed on 0.45% C steel specimens. Normal and tangential components of magnetic memory testing signals, H_p(y) and H_p(x) signals, with their characteristics, K of H_p(y) and H_p(x)_M of H_p(x), throughout the fatigue process were presented and analyzed. Abnormal peaks of H_p(y) and peak of H_p(x) reversed after loading; H_p(y) curves rotated clockwise and H_p(x) curves elevated significantly with the increase of fatigue cycle number at the first a few fatigue cycles, both H_p(y) and H_p(x) curves were stable after that, the amplitude of abnormal peaks of H_p(y) and peak value of H_p(x) increased more quickly after fatigue crack initiation. Abnormal peaks of H_p(y) and peak of H_p(x) at the notch reversed again after failure. The characteristics were found to exhibit consistent tendency in the whole fatigue life and behave differently in different stages of fatigue. In initial and crack developing stages, the characteristics increased significantly due to dislocations increase and crack propagation, respectively. In stable stage, the characteristics remained constant as a result of dislocation blocking, K value ranged from 20 to 30 A/(m·mm)⁻¹, and H_p(x)_M ranged from 270 to 300 A/m under the test parameters in this work. After failure, both abnormal peaks of H_p(y) and peak of H_p(x) reversed, K value was 133 A/(m·mm)⁻¹ and H_p(x)_M was −640 A/m. The results indicate that the characteristics of H_p(y) and H_p(x) signals were related to the accumulation of fatigue, so it is feasible and applicable to monitor fatigue damage of ferromagnetic components using metal magnetic memory testing (MMMT).

Keywords

metal magnetic memory testing / MMMT signal / tension-compression fatigue test / feature extraction

References

[1] KhotsyanovskiiA O. Life prediction of titanium and aluminum alloys under fretting fatigue conditions using various crack propagation criteria. Part 2: Application of the technique to cylindrical specimens with semi-elliptical crack and account of the residual stresses [J]. Strength of Materials, 2011, 43(1): 42-55

[2] StepashinA M, YuninG N. Express evaluation of an index characterizing the contact fatigue strength of railroad rails [J]. Metallurgist, 2009, 53(9/10): 555-559

[3] DubovA A. A study of metal properties using the method of magnetic memory [J]. Metal Science and Heat Treatment, 1997, 39(9/10): 401-402

[4] DubovA A. Express method of quality control of a spot resistance welding with usage of metal magnetic memory [J]. Welding in the World, 2002, 46(Spec): 317-320

[5] DongL-h, XuB-s, Dongs-y, SongL, ChenQ-z, WangDan. Stress dependence of the spontaneous stray field signals of ferromagnetic steel [J]. NDT&E International, 2009, 42: 323-327

[6] JianX-l, JianX-c, DengG-yong. Experiment on relationship between the magnetic gradient of low-carbon steel and its stress [J]. Journal of Magnetism and Magnetic Materials, 2009, 321: 3600-3606

[7] BonavolontàC, PelusoG, ValentinoM, IorioA D, PentaF. Detection of magnetomechanical effect in structural steel using squids and flux-gate sensors [J]. Journal of Superconducting and Novel Magnetism, 2009, 22: 833-839

[8] DongL-h, XuB-s, DongS-y, ChenQ-z, WangDan. Monitoring fatigue crack propagation of ferromagnetic materials with spontaneous abnormal magnetic signals [J]. International Journal of Fatigue, 2008, 30: 1599-1605

[9] LengJ-c, XuM-q, XuM-x, ZhangJ-zhong. Magnetic field variation induced by cyclic bending stress [J]. NDT&E International, 2009, 42: 410-414

[10] KatsuyukiK, EdsonC, SantosT H, HitonobuK, JustynaR. Observation of magnetic flux density around fatigue crack tips in bearing steel using an SHPM with a three-dimensional small-gap probe [J]. International Journal of Fatigue, 2012, 39: 38-43

[11] WangZ-d, YaoK, DengB, DingK-quan. Theoretical studies of metal magnetic memory technique on magnetic flux leakage signals [J]. NDT&E International, 2010, 43: 354-359

[12] WangZ-d, YaoK, DengBin. Physical model of plastic deformation on magnetization in ferromagnetic materials [J]. Journal of Applied Physics, 2011, 109: 083928

[13] RoskoszM. Metal magnetic memory testing of welded joints of ferritic and austenitic steels [J]. NDT&E International, 2011, 44: 305-310

[14] RoskoszM, GawrilenkoP. Analysis of changes in residual magnetic field in loaded notched samples [J]. NDT&E International, 2008, 41: 570-576

[15] SunY-h, KangY-h, QiuChen. A new NDT method based on permanent magnetic field perturbation [J]. NDT&E International, 2011, 44: 1-7

[16] DongL-h, XuB-s, Dongs-y, ChenQ-z, WangD, YinD-wei. Metal magnetic memory signals from the surface of low-carbon steel and low-carbon ally steel [J]. Journal of Central South University of Technology, 2007, 14(1): 24-27

[17] JiangS-t, LiWeiMagnetic physics of the condensed matter [M], 2003, Beijing, Science Press: 258-289

[18] DevineM K, KaminskiD A, SipahiL B, JilesD C. Detection of fatigue in structural steels by magnetic property measurements [J]. Journal of Materials Engineering and Performance, 1992, 1: 249-254

[19] JilesD C, UtrataD. Effects of tensile plastic deformation on the magnetic properties of AISI 4140 steel [J]. Journal of Nondestructive Evaluation, 1988, 6(3): 129-134

[20] MisraA. Theoretical study of the fracture-induced magnetic effect in ferromagnetic materials [J]. Physics Letter A, 1977, 62(4): 234-6

[21] DongL-h, XuB-s, Dongs-y, ChenQ-z, WangDan. Variation of stress-induced magnetic signals during tensile testing of ferromagnetic steels [J]. DNT&E International., 2008, 41: 184-198