With the UK's aging power generation network, life-extension of steel plant components is a critical issue. However, in order to evaluate the likelihood of component failure, techniques must be developed to properly assess the level of degradation in power station steels. Electromagnetic inspection has the potential to quantify the level of degradation in power station steels through in-situ measurements at elevated temperatures. In this work, magnetic hysteresis measurement and magnetic Barkhausen noise (MBN) are employed to inspect steel samples with differing levels of degradation, using a field deployable device developed at the University of Manchester. The tests show that by exploiting the link between the microstructure and magnetic domain structure of steels, the level of material degradation can be assessed through factors such as magnetic hardness and dislocation density. These results will be used as a basis for the further development of a fully field deployable for use in power stations.