Surface analysis of gas-turbine-blade material before and after exposure to the combustion products of residual fuel oils, demonstrates the corrosive effect of these products, and a measurable indication may be obtained in a fraction of the testing time required to produce appreciable weight loss. Surface analysis has the further advantage that it is possible to measure corrosion in specific regions on a specimen where the specimen has been exposed to a gas-flow pattern with a well-defined temperature profile. Weight-loss measurements following long-time tests have shown good agreement with this method of analysis. The fusion temperature of the fuel ash appears to be a reliable criterion for judging the potential corrosivity of residual fuel oil, and good correlation has been obtained between ash-fusion temperatures and corrosion both for untreated oils and oils with additives.

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