Austenitic stainless alloy with superior corrosion resistance
AssigneeChemetics Inc.
InventorGrant Harding
Life of this patent
Estimating the term…
Abstract
Austenitic stainless alloys have been discovered that exhibit unexpectedly superior corrosion resistance, particularly to sulfuric acid solutions, when compared to that exhibited by conventional alloys with closely related compositions. These alloys advantageously are corrosion resistant to a relatively wide range of sulfuric acid concentration and temperature and are thus particularly suitable for use in the industrial production of sulfuric acid.
Claims16
1-5. (canceled)
A method for making an austenitic stainless alloy comprising the steps of:
- obtaining sources of chromium, nickel, manganese, nitrogen, and iron in a selected ratio;
- vacuum induction melting the sources thereby forming a molten mixture;
- casting the molten mixture thereby creating a solid precursor alloy;
- hot working the solid precursor alloy;
- solution annealing and quenching the solid precursor alloy thereby creating a quenched alloy;
- and
- removing heavy oxide scale from the quenched alloy thereby creating the austenitic stainless alloy;
- wherein the austenitic stainless alloy comprises the following composition in weight %:
- 36
- -
- 40
-
- %
-
- chromium
- ;
- 32.5
- -
- 36
-
- %
-
- nickel
- ;
- 1.55
- -
- 1.75
- %
-
- manganese
- ;
- 0.37
- -
- 0.48
- %
-
- nitrogen
- ;
- 0.03
- -
- 0.43
- %
-
- silicon
- ;
- <
- 0.02
- %
-
- carbon
- ;
- <
- 0.02
- %
-
- phosphorus
- ;
- <
- 0.04
- %
-
- molybdenum
- ;
- <
- 0.02
- %
-
- copper
- ;
- <
- 0.005
- %
-
- sulfur
- ;
- and
- remainder consisting essentially of iron.
A method comprising employing an austenitic stainless alloy in a component exposed to high temperature and a concentrated solution of sulfuric acid, wherein the temperature of the solution is greater than or equal to 175° C., wherein the average concentration of sulfuric acid in the solution is greater than or equal to 98%, and wherein the austenitic stainless alloy comprises the following composition in weight %:
- 36
- -
- 40
-
- %
-
- chromium
- ;
- 32.5
- -
- 36
-
- %
-
- nickel
- ;
- 1.55
- -
- 1.75
- %
-
- manganese
- ;
- 0.37
- -
- 0.48
- %
-
- nitrogen
- ;
- 0.03
- -
- 0.43
- %
-
- silicon
- ;
- <
- 0.02
- %
-
- carbon
- ;
- <
- 0.02
- %
-
- phosphorus
- ;
- <
- 0.04
- %
-
- molybdenum
- ;
- <
- 0.02
- %
-
- copper
- ;
- <
- 0.005
- %
-
- sulfur
- ;
- and
- remainder consisting essentially of iron.
A method for making an austenitic stainless alloy comprising the steps of:
- obtaining sources of chromium, nickel, manganese, nitrogen, and iron in a selected ratio;
- vacuum induction melting the sources thereby forming a molten mixture;
- casting the molten mixture thereby creating a solid precursor alloy;
- hot working the solid precursor alloy;
- solution annealing and quenching the solid precursor alloy thereby creating a quenched alloy;
- and
- removing heavy oxide scale from the quenched alloy thereby creating the austenitic stainless alloy;
- wherein the austenitic stainless alloy comprises the following composition in weight %:
- 36.01
- -
- 38.93
- %
-
- chromium
- ;
- 32.95
- -
- 35.4
- %
-
- nickel
- ;
- 1.62
- -
- 1.7
- %
-
- manganese
- ;
- 0.42
- -
- 0.43
- %
-
- nitrogen
- ;
- 0.03
- -
- 0.43
- %
-
- silicon
- ;
- <
- 0.02
- %
-
- carbon
- ;
- <
- 0.02
- %
-
- phosphorus
- ;
- <
- 0.03
- %
-
- molybdenum
- ;
- <
- 0.02
- %
-
- copper
- ;
- <
- 0.005
- %
-
- sulfur
- ;
- and
- remainder consisting essentially of iron.
Dependencies are inferred from the claim text.