Inco Alloys International, Inc.

Pasupathy Ganesan

Gaylord Darrell Smith

Curtis S Tassen

Jack M Wheeler

Edward F Clatworthy

James R Crum

Jerry A Harris

William G Lipscomb

Charles R Conder

There is provided a nickel-base alloy with service enhanced strengthening properties. When exposed to ethylene pyrolysis conditions, namely a carbon containing environment and at temperatures of at least about 900.degree. C., the alloy forms M.sub.6 C and MC carbides that strengthen the alloy. The alloy may be formed into internally finned tubing. The alloy includes about 0.08-0.11% carbon, 41-45% nickel, 23-26% chromium, 0.6-0.95% manganese, 1-1.7% silicon, 0.2-0.6% titanium, 0.25-0.55% aluminum, 1.3-1.7% molybdenum, 0.25-0.6% niobium, 0.15-0.45% tantalum, 0-0.2% tungsten, 0.001-0.005% boron, 0.01-0.03% zirconium, and the balance iron with trace commercial impurities.

Strengthenable ethylene pyrolysis alloy

A nickel-chromium-molybdenum-cobalt alloy has additions of tantalum and tungsten to provide superior stress rupture strength in the presence of grain size control agents, and has the following composition:

Nickel-base alloy with superior stress rupture strength and grain size

A nickel-chromium alloy exhibiting enhanced stress rupture strength and grain size stability at elevated temperatures up to about 1260.degree. (2300.degree. F.) due to the affirmative formation of M.sub.6 C carbide within the alloy. The alloy is especially useful for turbine and engine applications.

Nickel-base alloy

A heat treatment of alloy 617 generally including 732.degree. C.-927.degree. C. (1350.degree. F.-1700.degree. F.) for about one hour. The resultant discontinuous carbide network in the grain boundaries inhibits stress corrosion crack growth in polythionic acid environments.

Heat treatment method for reducing polythionic acid stress corrosion

The stress-rupture strength of a nickel-chromium-molybdenum-cobalt alloy is enhanced by reason of a special morphological microsctructure which in terms of carbides present is characterized by a predominant amount of the M.sub.6 C carbide.

An oxidation resistant nickel-chromium based alloy possessing good stress rupture characteristics at elevated temperature and, in addition to nickel and chromium, containing correlated percentages of aluminum, titanium, nitrogen, carbon, etc.

High nickel chromium alloy

A process for heat treating alloy objects which comprises solution treating a nickel-base alloy containing chromium, molybdenum, copper, titanium, aluminum and iron at a temperature in excess of 955.degree. C. and then aging the alloy without intervening cold work at a temperature in the range of 700.degree. C. to 720.degree. C. This treatment provides non-cold worked structure which is tough, not susceptible to stress corrosion cracking in a test environment simulating a sour gas well environment and which exhibits high level of fracture energy in a slow strain rate tensile test in that environment.

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Huntington, WV, United States of America

Pasupathy Ganesan