On monitoring the incubation stage of stress corrosion cracking in steel by the eddy current method

The eddy current method is traditionally used for monitoring the latest stages of metal deterioration (appearance of multiple surface cracks that cause reduction of electric conductivity). However, the preceding incubation stage may take up to 80–90% of the total lifetime, and its monitoring is of obvious importance. Experiments reported in the present work suggest a new monitoring methodology is suggested – of extending the eddy current monitoring to the incubation stage, based on changes of the electromagnetic properties at this stage. The said changes are caused by the migration of carbon atoms from grains interior to grain boundaries and the formation of cementite, Fe3C, along the boundaries.