RELATIONSHIP BETWEEN THE EFFECTS OF VELOCITY AND ALLOY CORROSION-RESISTANCE IN EROSION-CORROSION ENVIRONMENTS AT ELEVATED-TEMPERATURES

Erosion-corrosion by either solid particle or liquid impact in a wide variety of industrial environments which range from coal conversion processes to steam turbines in nuclear power generation. The effects of erosion-corrosion depend on properties of the particle, the target and the nature of the corrosion environment. Various regimes of erosion-corrosion interaction have been identified, ranging from ''erosion-dominated'' (erosion of the substrate) to ''corrosion-dominated'' (erosion of the corrosion product). In studies of erosion-corrosion, the effects of impact velocity are generally not well understood. In some environments in which corrosion occurs, high velocity exponents have been reported have been reported, while, in others, the values are close to 1. In addition, the effects of alloy corrosion resistance in environments of different velocities have been puzzling with differences in the exponents reported, as alloy corrosion resistance is increased. This paper considers the effect of velocity for various erosion-corrosion studies from the literature. The effects of alloy corrosion resistance for such results are evaluated. Some general provisos for the interpretation of the effects of velocity will be made for alloys of different corrosion resistance in erosion-corrosion environments. It is shown that relative erosion-corrosion resistance of alloys in one environment cannot be used arbitrarily to predict resistance in other environments, particularly if parameters such as velocity are varied significantly.