Detection of Iron Oxide Layer in Quenched and Tempered Gear Steel Using Magnetic Barkhausen Noise

International audienceThis paper deals with the non-destructive evaluation of surface oxidation of gear steel using magnetic Barkhausen noise profiles analysis. Martensitic specimens are subjected to tempering at various temperatures in a muffle furnace. Tempering induced changes result in Barkhausen profile height increase and peak centers shift to lower fields. Single peak profiles are associated with specimens tempered up to 500 °C. Double peak profiles are seen with specimens tempered at 600 °C and 700 °C. Single peak profiles are observed after removing the oxide layer. The utilization of MBN method for this purpose is based on the difference in the inherent magnetic properties between the degraded surface layer and the sub-surface unaffected bulk. The observations are discussed in the light of established models of Barkhausen noise

Using Barkhausen Noise to Measure Coating Depth of Coated High-Speed Steel

Coated high-speed steel tools are widely used in machining processes as they offer an excellent tool life to cost ratio, but they quickly need replacing once the coated layer is worn away. It would be therefore useful to be able to measure the tool life remaining non-destructively and cheaply. To achieve this, the work presented here aims to measure the thickness of the coated layer of high-speed cutting tools by using Barkhausen noise (BHN) techniques. Coated high-speed steel specimens coated with two different materials (chromium nitride (CrN), titanium nitride (TiN)) were tested using a cost-effective measuring system developed for this study. Sensory features were extracted from the signal received from a pick-up coil and the signal features, Root mean square, peak count, and signal energy, were successfully correlated with the thickness of the coating layer on high-speed steel (HSS) specimens. The results suggest that the Barkhausen noise measuring system developed in this study can successfully indicate the different thickness of the coating layer on CrN/TiN coated HSS specimens

Magnetic Barkhausen noise in steel

EThOS - Electronic Theses Online ServiceGBUnited Kingdo