Nondestructive magnetic measurements in weld and base metals of service exposed Cr-Mo steel

Magnetic hysteresis and micromagnetic Barkhausen parameters were measured in base and weld metals of a service exposed Cr-Mo steel. Although the coercivity was higher in the welds, the difference in hysteresis parameters between welds and base metals was small. Hence, hysteresis parameters were not suitable to distinguish service exposed weld and base metals. However, a significant variation in Barkhausen waveforms was observed between base and weld metals. The difference in Barkhausen activity was most prominent at low magnetizing fields. The results of this study have been correlated with the microstructure of the samples.