Monitoring of components made of duplex steel after turning as a function of flank wear by the use of Barkhausen noise emission

This paper discusses the use of the Barkhausen noise technique to monitor duplex steel components after turning. The surface of duplex steel 1.4470 after face turning is investigated as a function of increasing tool flank wear (VB, width of the flank wear) as the major factor affecting severe plastic deformation of the machined surface at elevated temperatures. The Barkhausen noise emission and its extracted features are correlated with residual stresses as well as microstructure. It was found that the subsurface layers are preferentially strained in the cutting direction due to severe plastic deformation during the cutting. For this reason, the machined surface exhibits remarkable stress and magnetic anisotropy and the preferential orientation of the duplex steel matrix plays a major role with respect to the increasing Barkhausen noise emission with increasing flank wear VB. On the other hand, the contribution of increasing dislocation density is only minor.