Metal dusting corrosion of austenitic alloys at low and high pressure with the effects of Cr, Al, Nb and Cu

Abstract

Listen

Translate article

Commercial and model alloys were exposed at 570°C to metal dusting conditions at 1 and 21bar in CO-H2-H2O and CO-H2-CO2-CH4-H2O atmospheres, respectively, with similar ac and PO2. γ” precipitation beneath the surface of 625 superalloy was due to Nb diffusion toward the Cr-depleted zone formed during oxidation. 693 superalloy was more carburised than 690 superalloy. α-Al2O3 formation was believed to induce cracks through the oxide scale, resulting in the alloy carburisation. Cu addition to a FeNiCr model alloy lead to the formation of an almost continuous Cu layer at the oxide/metal interface, greatly improving the metal dusting resistance.