Measurement of the magnetic properties of P9 and T22 steel taken from service in power station

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 through in-situ measurements at elevated temperatures. This paper reports the results of tests carried out on thermally treated P9 and T22 steel samples with different microstructural states using major and minor B-H loop measurements and magnetic Barkhausen noise measurements. The results show that by careful selection of minor loop parameters, specific to the material under inspection and the material change under consideration, correlations can established between EM properties and material properties such as Vickers hardness. These results will be used as a basis for the further development of a fully field deployable device.