Effects of cold working on corrosion resistance of Co-modified Ni-16Cr-15Mo alloy in hydrofluoric acid solution

We examined the effects of cold working on the corrosion resistances of Ni-30Co-16Cr-15Mo and Ni-16Cr-15Mo in 5.2 M HF acid solution at 100 °C. After cold working, the Ni-30Co-16Cr-15Mo samples exhibited a more significant increase in hardness compared to Ni-16Cr-15Mo as well as a more localised microstructure that contained a greater number of planar slipping bands and mechanical twinning. Both alloys exhibited a decrease in corrosion resistance, with the decrease being much greater in the case of Ni-30Co-16Cr-15Mo. The difference in the corrosion resistances of the alloys was ascribable to the differences in their microstructures.