Non-destructive evaluation of the railway wheel surface damage after long-term operation via Barkhausen noise technique

This paper reports the non-destructive evaluation of railway wheels via the Barkhausen noise technique across the wheel width. This study correlates non-destructive Barkhausen noise parameters with conventional destructive analyses expressed in terms of metallographic and SEM observations, microhardness profiles, residual stress, and average grain size measurements. The condition of the wheel surface was altered remarkably due to the real and long-term wheel operation. The results of investigations indicate non-homogenous distribution of Barkhausen noise emission as well as the corresponding surface state with respect to the wheel width. Severe plastic deformation and superimposed elevated temperatures alter the grain size considerably in the near-surface as well as the subsurface region. It was found that Barkhausen noise is strongly correlated with the average grain size within the Barkhausen noise sensitive depth, whereas the correlation with the residual stress distribution is quite poor.