Zone‐refined iron corrodes at the same rate whether cold‐worked or annealed. Cold‐working of iron containing 0.007–0.15% carbon increases the corrosion rate in , the rate increasing still more after heat treating the iron at 77°–100°C for 2 hr. Cold‐working of iron containing 0.01–0.02% nitrogen increases the corrosion rate only after heat treatment at 77°–200°C. Two maxima in the rate appear for heat treated N alloys but only one for C alloys, corresponding to precipitation of two different nitrides but only one iron carbide. Heat treatment above 200 °C reduces the corrosion rate for both alloys, but pure iron is not affected by any heat treatment schedule. Polarization measurements show that corrosion in all instances is controlled cathodically.