•Samples with different chemical composition showed the same behavior in relation to their magnetic response.•Samples with aging state I exhibits magnetic response at the carbide boundaries.•For advanced aging states no magnetic response is observed at microscopic scale. HP steels are commonly used in steam reforming tubes, which are exposed to harsh operational conditions causing microstructural changes. These microstructural changes cause variations in the magnetic properties, which can be measured by different techniques. This work aims at the measurement of the magnetic and electric variations in HP-Nb modified alloys with different chemical composition using scanning probe microscopy (SPM) techniques. The results show that, despite the microstructural change due to variation of chemical composition, samples with aging state I exhibit a magnetic response at the carbides boundary, while for advanced aging states, the magnetic response is not evidenced.