Oxidation and corrosion testing were conducted on three commercial high temperature alloys used in heavy-duty engine applications. The tests were conducted at 700 to 900 o C under environments of water vapor and sulfur dioxide and in mixtures of salts. The corrosion was found to be highly dependent on the test temperature as well as on the salt composition. At 900°C the depth of corrosive attack was much higher than that at 700°C under the same test conditions, and salt mixtures containing sodium sulfate were more corrosive than those of calcium sulfate only. A cyclic oil and ash immersion test was developed wherein the samples were immersed in engine oil and heated to 750 o C to ash the oil. The samples were then removed from the furnace, allowed to cool slightly and the cycle repeated two more times to allow ash to accumulate on the samples. The samples were then heated for 48 hours. The corrosion performance resulting from this test was similar to that observed in service applications. This test can be further utilized to facilitate the materials selection of high temperature alloys for possible applications in heavy-duty engines. The test can also be used to discriminate between engine lubricants and their compatibility with alloys exposed to high temperatures.
Keywords: High Temperature Corrosion, Oil and ash immersion test