Non Destructive Evaluation of Surface Integrity Produced by Milling and Grinding Using Barkhausen Noise Signals

This paper deals with investigation of hard milled and ground surfaces via non destructive Barkhausen noise (BN) technique. The paper compares the raw BN signals, extracted BN features such as effective (rms) values and appearance of hysteresis loops produced by grinding and milling cycles. Information about surface state is correlated and confronted with metallographic observations, SEM readings as well as residual stress state. The paper also discusses the specific character of BN signals (and the corresponding BN features) produced by hard milled surface as a result of the magnetic shape memory effect when the machined surface undergoes severe plastic deformation at elevated temperatures