Carburization resistance of austenitic stainless steel tubes

Mineral oils: processes and products – Chemical conversion of hydrocarbons – Cracking

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585636, 148 12E, 148 635, 208 47, C22F 100, C22F 111

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043797458

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), Spangler, Jr. et al.
patent: 3844846 (1974-10-01), Friske et al.
patent: 3919073 (1975-11-01), Bagnoli et al.
patent: 4086104 (1978-04-01), Kinoshita et al.
Harrison et al., "The Gaseous Carburisation of Austenitic Steels", Werkstoffe and Korrosion, vol. 30, 785-794 (1979).
First Petten Colloquium on Advanced High Temperature Materials: Technology and Industrial Aspects, Jan. 20-30, 1976, p. 146t.

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