Sulfidation & Chlorine Environment Resistance of High-temperature Alloys

 

Corrosion Resistance in Aggressive Industrial Environments

Sulfidation Resistance

The following test results were generated by exposing alloy coupons in a gas mixture consisting of 5% hydrogen, 5% carbon dioxide, 1% carbon monoxide, 0.15% hydrogen sulfide, and the balance argon. Exposures were at the temperatures and for the times shown. Average metal affected was determined metallographically by adding the observed metal loss, or thinning, to the observed average depth of internal sulfide penetration. This is a severe test, with sulfur partial pressures ranging from 10-6 to 10-7, and oxygen partial pressures between 10-17 and 10-22.

Values shown as “greater than” indicate samples were consumed in the test. *Partially consumed

Hot Corrosion Resistance

The following results were generated for standard burner rig low-velocity hot corrosion tests. No.2 fuel oil containing approximately 0.4% sulfur was combusted at an air:fuel ratio of 35:1, with synthetic sea salt (conforming to ASTM D1141- 52) injected at a level of 50 parts per million. Samples were exposed to the combustion gas at 1650°F (900°C) for 1000 hours in a rotating carousel, which was cycled out of the gas stream once-an-hour, and cooled by forced air to less than 400°F (205°C). Samples were evaluated metallographically to determine the extent of metal loss, or thinning, and the average depth of internal penetration. Average metal affected is the sum of these two quantities.

Chlorine-Contaminated Oxidizing Environment

Results were generated by exposing coupons to a gas mixture consisting of argon, 20% oxygen and 0.25% chlorine for 400 hours at various temperatures shown. Samples were cycled to room temperature every 50 hours and removed from the gas mixture for weighing. The average metal affected after 400 hours was determined metallographically, and is the sum of the metal loss, or thinning, and the average depth of internal penetration.