High temperature corrosion behaviour of a new Ni‐30Fe‐10Al‐Cr‐Alloy

Abstract

Dedicated to Dr. U. Heubner on the occasion of his 65th birthdayThe high temperature corrosion behaviour of a new duplex nickel-base alloy containing about 30 mass% iron, 10 mass% aluminium and 8 mass% chromium was determined in both air and hot process gases containing methanekydrogen, sulphur dioxide and hydrogen sulphide, respectively. It was found that the corrosion resistance against carburisation, sulphidation and oxidation was excellent due to the formation of a dense, protective alumina scale. The adherence of the alumina scale was increased by an addition of 0.1 mass% hafnium. The concentration of chromium was found to have a remarkable impact on the oxidation and high temperature corrosion resistance. Alloys without chromium showed increased corrosion rates in both air and sulphur-containing gas atmospheres due to the initial formation of nickel oxides. In sulphidising SO,-and H,S-containing gases at least 4 mass% chromium are required to stabilise the formation of alumina and to prevent the formation of nickel/sulphur compounds.Das Hochtemperaturkorrosionsverhalten einer neuen Duplex-Nickelbasislegierung mit etwa 30 Masse% Eisen, 10 Masse% Aluminium und 8 Masse% Chrom wurde an Luft und in heiSen Prod g a s e n mit Methan, Schwefeldioxid oder Schwefelwasserstoff untersucht. Es zeigte sich, daB die Legierung wegen der Bildung dichter, schutzender Aluminiumoxidschichten eine ausgezeichnete Korrosionsbestandigkeit aufweist. Durch einen Zusatz von 0,l Masse% Hafnium kann die Haftung der Oxidschicht verbessert werden. Der Gehalt an Chrom hat einen erheblichen EinfluS auf die Oxidations-und Hochtemperaturkorrosionsbestandigkeit der Legierung. Legierungen ohne Chrom wiesen hohe Korrosionsraten sowohl an Luft als auch in schwefelhaltigen Atmospharen auf, dieser Effekt kann auf die anfangliche Bildung von Nickeloxiden zuruckgefiihrt werden. In sulphidierenden SO,-und H,S-haltigen Gasen sind mindestens 4 Masse% Chrom erforderlich, um die Bildung von Aluminiumoxid zu begiinstigen und die Bildung von Nickel-Schwefel-Verbindungen zu verhindern.sures of some industrial processes are listed, clearly shows, that in several coal conversion and petrochemical processes chromia becomes unstable whereas alumina A1,0, is even formed under conditions with very low oxygen partial pressures due to its high thermodynamical stability. Materials forming alumina scales have other advantages, too. The rate constant of alumina formation is lower than that of chromia formation and unlike chromia, alumina does not evaporate at temperatures above 950 "C. Consequently there are 0 VCH Verlagsgesellschaft mbH, D-69451 Weinheim, 1997

Fe–Al materials for structural applications at high temperatures: Current research at MPIE

“…During creep testing the DS alloy showed high microstructural stability, i. e. only slight coarsening was observed [117]. These results are in accordance with results for a DS eutectic A1 + B2 Fe -Al -Ni alloy, which also showed increased creep resistance that was proportional to the reciprocal lamellae spacings [143,144].…”

Concentration dependence of Cr for alleviating environmental embrittlement in Fe30Ni20Mn35Al15

“…Therefore the addition of chromium to Fe 3 Al resulted in a change in the nature of the protective oxide coating [12]. It has also been observed that Cr additions accelerated the formation of a continuous Al 2 O 3 scale in Ni-30Fe-10Al-Cr alloy [21]. XPS analysis by Velon et al [22] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 7 showed that the oxide on Cr-containing Fe 3 Al consisted of a continuous layer of (Al, Cr) 2 It is worth noting that Zamanzade et al [13] showed that for Fe 3 Al, the presence of hydrogen decreased the shear modulus, the energy for dislocation nucleation and the dislocation mobility.…”