What causes Erosion Corrosion? The mechanical effect of flow
or velocity of a fluid combined with the corrosive action of
the fluid causes accelerated loss of metal. The initial
stage involves the mechanical removal of a metal's
protective film and then corrosion of bare metal by a
flowing corrosive occurs. The process is cyclic until
perforation of the component occurs. Erosion-corrosion is
usually found at high flow rates around tube blockages, tube
inlet ends, or in pump impellers. The photo shows erosion
corrosion of a cast aluminum pump casing due to excessively
high flow rate of the coolant. Cavitation-corrosion is a
special form of erosion-corrosion. It is caused by water
bubbles produced by a high-speed impeller, which then
collapse and cause pits on the metal surface.
