Creep and corrosion testing of aluminide coatings on ferritic–martensitic substrates

Pack and chemical vapor deposited (CVD) aluminide coatings on commercial ferritic–martensitic Fe–9Cr–2W steel are being investigated by creep and corrosion testing at 650 °C. Results from different coating thicknesses show that the coated region makes no contribution to the creep strength. The creep behavior of uncoated material was studied after various heat treatments to simulate the coating process and typical secondary heat treatments. Alternating creep and corrosion exposures showed little effect on the creep strength of uncoated material but coated materials became progressively weaker. The coatings were protective in wet air at 650 °C after creep testing.