The effect of changing loads affecting the martensite steel on its structure and the Barkhausen noise level

The intended aim of the paper is to demonstrate how changes in the Barkhausen noise (BN) intensity depend on changes in the microstructure of rotor blades of an axial compressor, ones made of the martensite steel exposed to changing loads. What has been explained is the non-linear dependence of the BN on the number of steel-deformation cycles applied on a test stand under service-loading conditions. The modification of the dislocation structure emerging in the course of steel fatigue has been presented. It has also been shown that any change in the dislocation distribution and the accompanying increase in the misorientation of sub-grains as well as the modification of retained austenite precipitates both considerably affect the BN intensity. The dependence of the BN on the blade's operation time has been compared with that of the BN on the number of service-loading cycles. It has been found that results of both the stand tests and metallographic examination can be used to determine the level of blade material fatigue in the course of operational use thereof.