Variation regularity of metal magnetic memory signals with inspecting time-interval and location

Abstract

Influences of inspecting time-interval and location on varying behavior of metal magnetic memory (MMM) signals of defects were studied. Different areas in two precracked weldments were inspected at different time-intervals by type TSC-1M-4 stress-concentration magnetic inspector to obtain MMM signals. Mechanisms of MMM signals varying behavior with inspecting time and space were analyzed and discussed respectively. It is found that MMM signals don’t change with inspecting time-interval, since stress field and magnetic leakage field maintain unchanged at any time after welding. On the other hand, MMM signals differ greatly for different inspecting locations, because stress field and magnetic leakage field are unevenly distributed in defective ferromagnetic materials.

Keywords

nondestructive testing / metal magnetic memory / inspecting interval / inspecting location

References

[1] DubovA. A.. A rapid method of inspecting welded joints utilizing the magnetic memory of metal[J]. Welding International(UK), 1997, 11(5): 410-413

[2] DoubovA.. Screening of weld quality using the magnetic metal memory effect[J]. Welding in the World(UK), 1998, 41(3): 196-199

[3] DOUBOV A A. Express method of weldments inspection using metal magnetic memory[C]// Proceedings of 7th European Conference on Non-destructive Testing. Copenhagen, Denmark, 1998: 1266–1273.

[4] DoubovA. A., DeminE. A., MilyaevA. I., et al.. The experience of gas pipeline stress-strain state control with usage of the metal magnetic memory method as compared with conventional methods and stress control means[J]. Welding in the World, 2002, 46(9/10): 29-33

[5] DubovA.. Principle features of metal magnetic memory method and inspection tools as compared to known magnetic NDT methods[J]. Canadian Institute for NDE Journal, 2006, 27(3): 16-20

[6] ChenX., LiL.-m., HuB., et al.. Magnetic evaluation of fatigue damage in train axles without artificial excitation[J]. Insight, 2006, 48(6): 342-345

[7] RenJ.-l., LinJ.-m., ChiY.-b., et al.Metal Magnetic Memory Technique[M], 2000, Beijing, China Electric Power Press

[8] LiL.-m., HuangS.-l., WangL.-f. e. a1.. Research on magnetic testing method of stress distribution[J]. Trans Nonferrous Met Soc China, 2002, 12(3): 388-391

[9] HuangS.-l., LiL.-m., ShiK.-r., et al.. Magnetic field properties caused by stress concentration[J]. Journal of Central South University of Technology, 2004, 11(1): 23-26

[10] HuangS. L., LiL. M., WangX. F.. Magnetic evaluation method for stress annealing of ferromagnetic materials[J]. Materials Technology (UK), 2005, 20(1): 5-6

[11] LiL.-m., HuangS.-l., WangX.-f. e. a1.. A study of stress induced magnetic field abnormality[J]. Trans Nonferrous Met Soc China, 2003, 13(1): 6-9

[12] LiW.-s., DiX.-j., BaiS.-w., et al.. Feature analysis of metal magnetic memory signals for weld cracking-based on wavelet energy spectrum[J]. Insight, 2006, 48(7): 426-429

[13] YamasakiT., YamamotoS., HiraoM.. Effect of applied stresses on magnetostriction of low carbon steel[J]. Non-Destructive Testing and Evaluation International, 1996, 29(5): 263-268

[14] BulteD. P., LangmanR. A.. Origins of the magneto-mechanical effect[J]. Journal of Magnetism and Magnetic Materials, 2002, 251: 229-243

[15] DOUBOV A A. About physical base of method of metal magnetic memory[C]// 8th ECNDT Proceedings Abstracts Book. Barcelona, Spain, 2002. 132.

[16] TianX.-tang.Welded Structure[M], 1982, Beijing, China Machine Press: 47-52