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US 9,869,003 B2Granted
Methods for processing alloys
AssigneeATI Properties, Inc.
InventorsRobin M. Forbes Jones, Erin T. McDevitt
Life of this patent
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Abstract
A method of processing a workpiece to inhibit precipitation of intermetallic compounds includes at least one of thermomechanically processing and cooling a workpiece including an austenitic alloy. During the at least one of thermomechanically working and cooling the workpiece, the austenitic alloy is at temperatures in a temperature range spanning a temperature just less than a calculated sigma solvus temperature of the austenitic alloy down to a cooling temperature for a time no greater than a critical cooling time.
Claims38
A method of processing a workpiece to inhibit precipitation of intermetallic compounds, the method comprising:
- at least one of thermomechanically working and cooling a workpiece including an austenitic alloy, wherein during the at least one of thermomechanically working and cooling the workpiece, the austenitic alloy is at temperatures in a temperature range spanning a temperature just less than a calculated sigma solvus temperature of the austenitic alloy down to a cooling temperature for a time no greater than a critical cooling time;
- wherein the austenitic alloy comprises, in weight percentages based on total alloy weight, up to 0.2 carbon, up to 20 manganese, 0.1 to 1.0 silicon, 14.0 to 28.0 chromium, 15.0 to 25.43 nickel, 2.0 to 9.0 molybdenum, 0.1 to 3.0 copper, 0.08 to 0.9 nitrogen, 0.1 to 5.0 tungsten, 0.5 to 5.0 cobalt, up to 1.0 titanium, up to 0.05 boron, up to 0.05 phosphorus, up to 0.05 sulfur, 0.01 to 1.0 vanadium, 20 to 60 iron, and incidental impurities;
- wherein the calculated sigma solvus temperature is a function of the composition of the austenitic alloy in weight percentages and, in Fahrenheit degrees, is equal to 1155.8−(760.4)·(nickel/iron)+(1409)·(chromium/iron)+(2391.6)·(molybdenum/iron)−(288.9)·(manganese/iron)−(634.8)·(cobalt/iron)+(107.8)·(tungsten/iron);
- wherein the cooling temperature is a function of the composition of the austenitic alloy in weight percentages and, in Fahrenheit degrees, is equal to 1290.7−(604.2)·(nickel/iron)+(829.6)·(chromium/iron)+(1899.6)·(molybdenum/iron)−(635.5)·(cobalt/iron)+(1251.3)·(tungsten/iron);
- and
- wherein the critical cooling time is a function of the composition of the austenitic alloy in weight percentages and, in minutes, is equal to, in log10, 2.948+(3.631)·(nickel/iron)−(4.846)·(chromium/iron)−(11.157)·(molybdenum/iron)+(3.457)·(cobalt/iron)−(6.74)·(tungsten/iron), and wherein the critical cooling time is in a range of 10 minutes to 30 minutes.
3 more elements
A method of processing an austenitic alloy workpiece to inhibit precipitation of intermetallic compounds, the method comprising:
- forging the workpiece;
- cooling the forged workpiece;
- and
- optionally, annealing the cooled workpiece;
- wherein the austenitic alloy comprises, in weight percentages based on total alloy weight, up to 0.2 carbon, up to 20 manganese, 0.1 to 1.0 silicon, 14.0 to 28.0 chromium, 15.0 to 25.43 nickel, 2.0 to 9.0 molybdenum, 0.1 to 3.0 copper, 0.08 to 0.9 nitrogen, 0.1 to 5.0 tungsten, 0.5 to 5.0 cobalt, up to 1.0 titanium, up to 0.05 boron, up to 0.05 phosphorus, up to 0.05 sulfur, 0.01 to 1.0 vanadium, 20 to 60 iron, and incidental impurities;
- wherein during forging the workpiece and cooling the forged workpiece the austenitic alloy cools through a temperature range spanning a temperature just less than a calculated sigma solvus temperature of the austenitic alloy down to a cooling temperature for a time no greater than a critical cooling time;
- wherein the calculated sigma solvus temperature is a function of the composition of the austenitic alloy in weight percentages and, in Fahrenheit degrees, is equal to 1155.8−(760.4)·(nickel/iron)+(1409)·(chromium/iron)+(2391.6)·(molybdenum/iron)−(288.9)·(manganese/iron)−(634.8)·(cobalt/iron)+(107.8)·(tungsten/iron);
- wherein the cooling temperature is a function of the composition of the austenitic alloy in weight percentages and, in Fahrenheit degrees, is equal to 1290.7−(604.2)·(nickel/iron)+(829.6)·(chromium/iron)+(1899.6)·(molybdenum/iron)−(635.5)·(cobalt/iron)+(1251.3)·(tungsten/iron);
- wherein the critical cooling time is a function of the composition of the austenitic alloy in weight percentages and, in minutes, is equal to, in log10, 2.948+(3.631)·(nickel/iron)−(4.846)·(chromium/iron)−(11.157)·(molybdenum/iron)+(3.457)·(cobalt/iron)−(6.74)·(tungsten/iron), and wherein the critical cooling time is in a range of 10 minutes to 30 minutes.
6 more elements
Dependencies are inferred from the claim text.