Effect of microstructures on magnetic Barkhausen noise level in the weld HAZ of an RPV steel

Microstructural state and magnetic Barkhausen noise (BN) level have been correlated in the weld heat-affected zone (HAZ) of a pressure vessel steel. The BN level increased with increasing size of carbide, and the tempered bainite structure showed higher BN signal than the tempered martensite. The results indicated that heat-treated materials may result in microstructurally different domain wall pinning obstacles at different thermal cycles.