Corrosion of T91 and pure iron in flowing and static Pb-Bi alloy between 450 °C and 540 °C: experiments, modelling and mechanism

•“In the present experimental conditions, corrosion of T91 and Fe are characterized by a pure dissolution phenomenon”.•“Pure dissolution rates of T91, and iron are similar”.•Modelling of the corrosion process shows that for liquid natural convection, corrosion is controlled by iron diffusion in the diffusion boundary layer.•For flowing liquid alloy, corrosion is controlled by a mixed process combining both the interfacial reaction rate of iron dissolution and the iron diffusion rate in the diffusion boundary layer. T91 (Fe-9Cr steel) and pure iron were corroded in pure dissolution domain in liquid lead bismuth eutectic (LBE) from 450 to 540 °C in static and in dynamic LBE flow. The modelling showed that corrosion rates were controlled: (i) for static condition (LBE natural convection), by the iron diffusion in the diffusion boundary layer; (ii) for flowing LBE, by a mixed process combining both the interfacial reaction rate of iron dissolution and the iron diffusion rate in the diffusion boundary layer. By fitting the modelling on the experimental points, the constant of interfacial reaction rate was determined.