Corrosion behavior of borided AISI H13 hot work steel

The corrosion behavior of borided hot work steel H13 (AISI) in specific acid solutions (HCl 5 vol.%, H2SO4 5 vol.%, H3PO4 30 vol.%) was studied. Boriding was done by pack cementation. The corrosion behavior was evaluated by potentiodynamic polarization experiments and immersion corrosion tests. The borided steel showed a better corrosion behavior in H2SO4 and H3PO4 environments for short exposure periods, up to about 100 h, when compared to H13 steel. On the contrary H13 steel presented a better corrosion resistance in HCl acid environment in comparison to the borided H13 steel. The main corrosion mechanisms in order of appearance were crevice corrosion observed in the coating, galvanic corrosion between coating and H13 steel substrate and pitting corrosion of the substrate.