Coatings of Ni-17 at.%W were electroplated on a steel substrate, and their corrosion behavior was investigated between 600 and $800^{circ}C$ in an Ar-0.2%$SO_2$ atmosphere. They delayed the corrosion of the steel substrate. They were corroded into an outer NiO-rich layer, and an inner ($WO_3+NiO+NiWO_4$)-mixed oxide layer. Below these oxide layers, a sulfide layer gradually formed.