The effect of cyclic deformation in a 13% Cr ferritic steel on structure and Barkhausen noise level

It has been demonstrated that there is a relation between changes in the microstructure of the chromium ferritic steel and the Barkhausen noise (BN) intensity resulting from cyclic deformation. The non-linear dependence of the BN on the number of cycles has been shown. The dislocations formed in the course of cyclic deformations have been identified as prefect screw ones of Burgers vector b=a/211̄1. It was found that both the cell size and dislocation structure and redistribution of vacancies considerably affect the BN intensity. Dislocation structures and redistribution of vacancies have been correlated with the course of the BN intensity, which enables non-destructive assessment of the condition of the chromium ferritic steel microstructure subjected to cyclic deformation. Persistent slip bands were identified after a large number of cycles, close to the crack initiation. They are of the highest density near the crack tip. Their structure is similar to that of deformation bands in a heavily deformed material.