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Hydrogen attack on steel for high‐pressure hydrogen service as a result of the alteration of carbides by ammonia synthesis gas
Author(s) -
Heuser Albert,
Wagner Gerhard H.,
Heinke Günter,
Číhal Vladimir
Publication year - 1993
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199301053
Subject(s) - hydrogen , carbide , nitriding , ammonia , nitride , metallurgy , chemistry , carbon fibers , materials science , nitrogen , composite number , layer (electronics) , nanotechnology , composite material , organic chemistry
Certain ammonia synthesis conditions lead to nitriding of a relatively thin surface layer of low‐alloyed “hydrogen‐resistant” steels. For reasons of thermodynamic stability of carbides and nitrides this causes a modification of the first, releasing carbon which can effuse from the steel and can react with diffusing hydrogen to form methane. Depending on the level and the direction of the total component stresses, small separations of grains, parallel to the surface, or cracks across the wall may slowly develop. Thus, the Nelson diagram has only limited validity in the case of materials selection for NH 3 ‐containing synthesis gases.