QUANTITATIVE EVALUATION OF MATERIAL DEGRADATION BY BARKHAUSEN NOISE METHOD

摘要

Evaluating the life of nuclear power plant becomes inevitable to extend the plant operating period. This paper applied the magnetic method using Barkhausen noise (BHN) to detect the degradation by fatigue and thermal aging. Low alloy steel (SA 508 cl.2) was fatigued at the strain amplitudes of ±1% and±0.4%, and duplex stainless steel (SCS14A) was heated at 400°C for a long period (thermal aging). For the degraded material by thermal aging, BHN was measured and good correlation between magnetic properties and absorption energy of the material was obtained. For fatigued material, BHN was measured at each predetermined cycle and the effect of stress or strain of the material when it measured was evaluated, and good correlation between BHN and fatigue damage ratio was obtained.