Stainless steel is used in many applications because of its excellent mechanical properties at elevated temperatures. Material fatigue is a major problem in steel structures and can cause catastrophic damage resulting in significant economic consequences. Conventional nondestructive evaluation techniques can detect macro defects, but do not perform well when it comes to material degradation due to fatigue, which happens at a microstructure level. It is well known that stress applied on a material will have an impact on the microstructure and produces a change in the magnetic properties of the material. Hence magnetic nondestructive evaluation techniques that are sensitive to changes in magnetic properties play a major role in the early-stage fatigue detection, i.e., before the macro crack initiates. This paper introduces the Magnetic Barkhausen Noise technique to garner information about fatigue state of the material under test. Experimental results prove that the sample categories, based on the percentage of remaining fatigue life, can be differentiated using this technique with a system performance slightly over 80%.

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