SYMPOSIA PAPER Published: 01 January 1979

Microstructure and Mechanical Properties of INCOLOY Alloy 800 After 14 Years of Service as a Catalyst Tube in a Steam-Methane Reformer


An INCOLOY Alloy 800 catalyst tube, which served satisfactorily in a steam-methane reformer for more than 14 years, was removed for examination. The tube had been heated to temperatures varying along its length from 540 to 815°C (1000 to 1500°F).

The deepest penetration of intergranular oxidation was only 0.33 mm (0.013 in.) on the outer surface.

Room-temperature tensile properties and stress-rupture properties improved significantly with the precipitation of carbides at higher temperatures and gamma prime at the lower temperatures. Gamma prime was the principal strengthening phase, and mechanical properties show that ductility was retained.

Rare, discrete, blocky particles of sigma phase found in one section of the tube were determined to be innocuous.

Author Information

Mankins, WL
Huntington Alloys, Inc., Huntington, W. Va.
Wenschhof, DE
Huntington Alloys, Inc., Huntington, W. Va.
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Developed by Committee: E04
Pages: 616–632
DOI: 10.1520/STP36893S
ISBN-EB: 978-0-8031-4742-3
ISBN-13: 978-0-8031-0517-1