The results are presented of an investigation by resistivity and electron-microscopy methods into the formation of vanadium and molybdenum carbide in ferrite. The resistivity increased and subsequently decreased during ageing after quenching. The resistance changes are related to the structural changes observed by electron microscopy. No G.P. zones were observed and an explanation of the resistivity increase is proposed that does not take their presence into account. Estimates of the activation energies for the processes are given and the kinetics is analysed by means of Avrami's equation.
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