Metal treatment – Compositions – Heat treating
Patent
1982-12-27
1984-01-03
Silverberg, Sam
Metal treatment
Compositions
Heat treating
C22F 111
Patent
active
044240830
ABSTRACT:
Protection of cast austenitic stainless steel tubes is provided against initiation of carburization by (a) cold-working the inner surfaces of said tubes to deform the surface to such a degree that upon the subsequent heat treatment of step (b) below, dissolution of the M.sub.23 C.sub.6 carbides in the deformed region is accompanied by recrystallization resulting in a refined micrograin structure in the deformed regions to a substantially uniform minimum depth of about 20 microns; and (b) heating the cold-worked inner surfaces of said tubes, for an effective amount of time, at a temperature between its recrystallization temperature and its melting temperature, in an atmosphere of which the oxygen partial pressure is at least oxidizing with respect to chromium.
REFERENCES:
patent: 3704333 (1972-11-01), Spengler
patent: 3844846 (1974-10-01), Friske
patent: 3919073 (1975-11-01), Bagmoli
patent: 4086104 (1978-04-01), Kinoshitg
The Gaseous Carburization of Austenitic Steels, Werkstoffe und Korrosion, vol. 30, 785-794 (1979).
First Petten Colloguium on Advanced High Temperature Materials: Technology & Industrial Aspects, Jan. 20-30, 1976, H. Krockel.
Carburization of Centrifugally Cast Pipe in the Petrochemical Industry and Explanation of this Behavior Through Laboratory Experiments with Chrome-Nickel Steels and Materials in the 800.degree.-1500.degree. C. Range, W. Steinkusch, Werkstoffe und Korrosion 28 (1):1-6 1977.
A Newly Developed Extruded Tube for Reformer and Cracking Tubes, by S. Ohta, from Chemical Economy and Engineering Review, vol. 3, No. 10 (No. 42), Oct. 1971.
Krutenat Richard C.
Polizzotti Richard S.
Exxon Research and Engineering Co.
Naylor Henry E.
Silverberg Sam
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