INFLUENCE OF MICROSTRUCTURE ON MICROMAGNETIC BARKHAUSEN EMISSIONS IN AISI-4140 STEEL

The effects of microstructure on the micromagnetic Barkhausen signal e missions in AISI 4140 steel ale reported. The Barkhausen signal amplit ude is known to be highly sensitive to the type and distribution of mi crostructural inhomogeneities, such as grain boundaries, precipitates and dislocations. The Barkhausen measurements were taken on samples ha ving pearlitic, spheroidized and bainitic microstructures. The Barkhau sen emissions were measured in terms of rms voltage, peak-to-peak volt age and number of events per cycle. It is shown that Barkhausen signal s can be used to distinguish between pearlitic and bainitic microstruc tures.