Corrosion on container crane hoisting gear. Photo courtesy GEARTECH © 2013.

Definition: Corrosion is a chemical or electrochemical reaction between a gear and it’s environment.

Identification: Corrosion results in the formation of stained or rusty surfaces with reddish brown deposits.

Discussion: Corrosion is very damaging to gears and bearings. It can cause the formation of pits which lead to spalls. Corrosion also reduces the fatigue strength of materials, in most cases by a substantial amount. Corrosion can be caused by contamination from water, acid, or salt. Overly reactive lubricant antiscuff additives can cause corrosion. Corrosion attacks grain boundaries first, and then parent grains.

Prevention: Remove contaminants. Drain, flush, and replace oil. Use an oil with good corrosion inhibiting properties.

More Information: For more information on corrosion, please submit a question to our “Ask an Expert” link. For assistance with a gearbox failure analysis, please visit our “Consulting” page.