Nondestructive estimation of fatigue damage for steel by Barkhausen noise analysis

Abstract

Magnetic Barkhausen noise (BHN) signals are detected when magnetized domain walls move discontinuously in a ferromagnetic material. This non-uniform motion is sensitive to the microstructures of material which vary continuously with the increase of applied stress and loading cycles. In this paper, the possibility of evaluation of residual fatigue life under cyclic loading conditions is discussed based on BHN analysis. The material used in the test is mild steel. Both static loading tests and load-controlled axial pulsating fatigue tests are performed on plain plate specimens. The BHN signals are measured for each increment of tensile load during static tests and for each interval of cyclic loading during fatigue tests. The main results obtained are as follows: (1) When the applied stress range is below the fatigue limit, the BHN signal keeps nearly constant. (2) When the applied stress range is above the fatigue limit, the ratio of the BHN peak voltage of the stress level S to 0 MPa at the Nth cycle, V ns V n 0 , varied clearly with loading cycles. (3) The procedure of residual life prediction is proposed.