Grain size distribution effects on the corrosion behaviour of materials

► Effect of grain size distribution on corrosion current has been studied. ► Mathematical relationship to understand this effect has been established. ► Broader grain size distribution leads to higher corrosion resistance in active environment. ► Broader grain size distribution leads to lower corrosion resistance in passivating environment. ► Effect of grain size distribution on corrosion behaviour of bimodal microstructure is discussed.