IWPDF2023

Effect of Ferromagnetic Materials Composition on Magnetic Flux Leakage Signals during Fatigue Crack Growth in Steel

A. Arifin ∗ , S. Abdullah, A.K. Ariffin, S.S.K. Singh

Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built En vironment, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

∗ azli@ukm.edu.my

Keywords: fatigue, crack growth, magnetic flux leakage

Fatigue cracks in steel structures can have catastrophic consequences if undetected or not properly managed. The Metal Magnetic Memory (MMM) testing, utilising changes in the self-magnetic leakage field (SMFL), is a widely used non-destructive evaluation technique for detecting and monitoring cracks. However, the lack of an accurate description of the SMFL changing mechanism under elastic and plastic cyclic loads [1,2] makes it crucial to understand this relationship in order to enhance the accuracy of MMM testing for identifying and characterising fatigue cracks in steel structures. Therefore, there is a need to investigate the effect of varying ferromagnetic materials composition on MMM signals to improve crack detection and monitoring techniques and ensure the structural integrity and safety of steel components [3]. This study aims to investigate the effect the percentage of ferromagnetic material composition in steel on MMM signals during fatigue crack growth and to analyse the relationship between the percentage of ferromagnetic materials in steel and the MMM signals, specifically focusing on the material constant parameter in the Paris law. To achieve this objective, a constant cyclic loading method was employed, and an MMM scanning device was used to scan the SMFL signals. The study utilised three different types of pre-cracked CT steel specimens, namely ASSAB 705, ASSAB 709 and ASSAB 760, with stress ratios, R set at 0.1 and 0.3. Through the experimental setup, the MFL signals were captured and analysed, correlating them with the percentage of ferromagnetic materials composition in the steel samples. The Paris law was then used to determine the material constant parameter. Based on the results obtained, it is concluded that the material constant parameter in the Paris law increases as the percentage of ferromagnetic material composition in the steel increases. References [1] Ma, X., Su, S., Wang, W., Yang, Y. (2021). Experimental and theoretical analysis of the correlation between cumulative plastic damage and SMFL of structural steel under low cycle fatigue. Journal of Magnetism and Magnetic Materials, 538 : 168292. [2] Su, S., Ma, X., Wang, W., Yang, Y., Hu, J. (2021). Quantitative evaluation of cumulative plastic damage for ferromagnetic steel under low cycle fatigue based on magnetic memory method. Strain, 57, no. 3: e12379 [3] Xu, Y., Xu, K., Wang, H., Zhao, L., Tian, J., Xie, Y., Liu, J. (2022). Research progress on magnetic memory nondestructive testing. Journal of Magnetism and Magnetic Materials, 170245.

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