Nondestructive evaluation of carbon contents and microstructures in plain carbon steel bars by Barkhausen emission

Plain carbon steels with different carbon contents have been widely used in industry. There is a pressing need for the nondestructive inspection of steel parts during their fabrication and when they are in service. Barkhausen emission (BE) is one of the nondestructive testing methods that is being used. Recently, we find that the following parameters of the BE signals depended strongly on the carbon content in steel sample, namely, the rising slope of the BE profile, the root-mean-square of the signals, and the half-maximum-width of the profile. The values of these parameters increase as the amount of carbon in the sample increases. The dependence is similar to that of the mechanical hardness on the carbon contents in the samples.