A Study of the Mechanism of Corrosion Resistance for Mo+C and Ti+C Dual Implanted H13 Steel

The behaviors of corrosion resistance of Mo, Ti as well as the Mo+C and Ti +C implanted H13 steel were studied and compared. The results showed that the corrosion currents of Mo ion and Ti ion implanted HIS steels were 10. 8 and 125 times smaller than the H13 steel respectively. It was found from TEM and SEM observations that smaller dispersive phases of Ti-or Mo-compounds combined into large complexes which inhibited the corrosion. The dispersive phases of the FeMo, MoC and Fe2MoC were formed and scattered in the grain boundary in H13 steel by Mo+C dual implanting. The grain boundary net was filled by MoC phases. It was found from SEM observation that after 700 minutes of corrosion, the successive anti-corrosion layers was formed from dense MoC grain boundary nets. The corrosion current for the Mo + C implanted steel is 533 times smaller than H13 steel. The continuous layers of Ti-iron and TiC phases were formed in H13 steel by Ti + C dual ion implant. It made substantial improvement on the corrosion resistance performance. The corrosion current was reduced by a factor of 640. It was observed from the SEM observation that after 500 minutes of corrosion, no surface morphology changes were observed. This showed that the implanted layer has similar characteristic to ceramic layer which is the best material for corrosion resistance.