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Microprocesses of metal dusting on nickel and Ni‐base alloys
Author(s) -
Schneider Reinhard,
Pippel Eckhard,
Woltersdorf Jörg,
Strauß Silke,
Grabke Hans Jürgen
Publication year - 1997
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199701796
Subject(s) - inconel , carburizing , carbide , metallurgy , nickel , metal , chemistry , graphite , oxide , alloy , materials science
Microstructural and microchemical investigations were carried out on nickel and Inconel 600 after exposure to strongly carburizing atmospheres at temperatures of about 600 to 650°C to study their metal dusting behaviour. Contrary to iron and low‐alloy steels, where metal dusting proceeds via the formation and disintegration of a metastable carbide M 3 C, both nickel and Inconel 600 directly disintegrate. Inside the metal this disintegration proceeds by formation of thin graphite filaments of nearly 10 nm in diameter, the atomic basal planes of which are oriented perpendicular to the surface thus effecting a high reactivity at the growth front. Subsequently, fine particles or larger parts of the metal surface layer are released, which are buried in the deposited graphite layer on the surface. In case of Inconel 600, containing Cr with mass contents of about 15%, the disintegration can be delayed by the formation of a chromium oxide layer, but no safe protection against metal dusting is obtained.