Nickel-base alloy heat treatments, nickel-base alloys, and articles including nickel-base alloys

Abstract

A method for heat treating a 718-type nickel-base comprises heating a 718-type nickel-base alloy to a heat treating temperature, and holding the alloy at the heat treating temperature for a heat treating time sufficient to form an equilibrium or near-equilibrium concentration of δ-phase grain boundary precipitates within the nickel-base alloy and up to 25 percent by weight of total γ′-phase and γ″-phase. The 718-type nickel-base alloy is air cooled. The present disclosure also includes a 718-type nickel-base alloy comprising a near-equilibrium concentration of δ-phase grain boundary precipitates and up to 25 percent by weight of total γ′-phase and γ″-phase precipitates. Alloys according to the disclosure may be included in articles of manufacture such as, for example, face sheet, honeycomb core elements, and honeycomb panels for thermal protection systems for hypersonic flight vehicles and space vehicles.

1 . A method for heat treating a nickel-base alloy, comprising:
 heating a nickel-base alloy to a heat treating temperature in a heat treating temperature range, wherein the nickel-base alloy comprises nickel, chromium, and iron, is strengthened by niobium, and optionally comprises one or more of aluminum and titanium alloying additions;   holding the nickel-base alloy within the heat treating temperature range for a heat treating time sufficient to form an equilibrium or near-equilibrium concentration of δ-phase precipitates in grain boundaries of the alloy and up to 25 percent by weight of total γ′-phase and γ″-phase within the alloy; and   cooling the nickel-base alloy.   
     
     
         2 . The method of  claim 1 , wherein the heat treating temperature range is in the range of a temperature that is 20° F. (11° C.) greater than the nose of the TTT diagram for delta phase precipitation to a temperature that is 100° F. (55.6° C.) below the nose of the TTT diagram. 
     
     
         3 . The method of  claim 1 , wherein the heat treating time is in a range of 30 minutes to 300 minutes. 
     
     
         4 . The method of  claim 1 , wherein cooling the nickel-base alloy comprises air cooling. 
     
     
         5 . The method of  claim 1 , wherein cooling the nickel-base alloy comprises cooling the alloy at a cooling rate no greater than about 1° F. per minute (0.56° C. per minute). 
     
     
         6 . (canceled) 
     
     
         7 . The method of  claim 1 , wherein the nickel-base alloy comprises, in percent by weight: up to 0.1 carbon; 12 to 20 chromium; up to 4 molybdenum; up to 6 tungsten; 5 to 12 cobalt; 6 to 14 iron; 4 to 8 niobium; 0.6 to 2.6 aluminum; 0.4 to 1.4 titanium; 0.003 to 0.03 phosphorus; 0.003 to 0.015 boron; nickel; and incidental impurities; wherein a sum of the weight percent of molybdenum and the weight percent of tungsten is at least 2 and not more than 8; a sum of atomic percent aluminum and atomic percent titanium is from 2 to 6; a ratio of atomic percent aluminum to atomic percent titanium is at least 1.5; and the sum of atomic percent aluminum and atomic percent titanium divided by atomic percent niobium is from 0.8 to 1.3. 
     
     
         8 . The method of  claim 1 , wherein the nickel-base alloy comprises, in percent by weight: 0 to about 0.08 carbon; 0 to about 0.35 manganese; about 0.003 to about 0.03 phosphorous; 0 to about 0.015 sulfur; 0 to about 0.35 silicon; about 17 to about 21 chromium; about 50 to about 55 nickel; about 2.8 to about 3.3 molybdenum; about 4.7 percent to about 5.5 niobium; 0 to about 1 cobalt; about 0.003 to about 0.015 boron; 0 to about 0.3 copper; 12 to 20 iron; aluminum; titanium; and incidental impurities; wherein the sum of atomic percent aluminum and atomic percent titanium is from about 2 to about 6 percent; the ratio of atomic percent aluminum to atomic percent titanium is at least about 1.5; and the sum of atomic percent of aluminum plus titanium divided by atomic percent of niobium equals from about 0.8 to about 1.3. 
     
     
         9 . The method of  claim 1 , wherein the nickel-base alloy comprises, in percent by weight: 0.01 to 0.05 carbon; up to 0.35 manganese; up to 0.035 silicon; 0.004 to 0.020 phosphorus; up to 0.025 sulfur; 17.00 to 21.00 chromium; 2.50 to 3.10 molybdenum; 5.20 to 5.80 niobium; 0.50 to 1.00 titanium; 1.20 to 1.70 aluminum; 8.00 to 10.00 cobalt; 8.00 to 10.00 iron; 0.008 to 1.40 tungsten; 0.003 to 0.008 boron; nickel; and incidental impurities. 
     
     
         10 . The method of  claim 1 , wherein the nickel-base alloy comprises, in percent by weight: 50.0 to 55.0 nickel; 17 to 21.0 chromium; up to 0.08 carbon; up to 0.35 manganese; up to 0.35 silicon; 2.8 to 3.3 molybdenum; greater than 0 to 5.5 niobium and tantalum, wherein the sum of niobium and tantalum is from 4.75 to 5.5; 0.65 to 1.15 titanium; 0.20 to 0.8 aluminum; up to 0.006 boron; iron; and incidental impurities. 
     
     
         11 . The method of  claim 1 , wherein the nickel-base alloy comprises at least one of a foil, a honeycomb core, and a honeycomb panel. 
     
     
         12 . The method of  claim 1 , further comprising, subsequent to cooling the nickel-base alloy, stabilizing heat treating the nickel-base alloy, wherein stabilizing heat treating comprises:
 heating the nickel-base alloy to a stabilizing heat treating temperature of 1700° F. (926.7° C.) or less, wherein the heat treating temperature is equivalent to an expected maximum in-service temperature of an article comprising the nickel-base alloy; and   cooling the nickel-base alloy from the stabilizing heat treating temperature.   
     
     
         13 . The method of  claim 12 , wherein cooling the nickel-base alloy from the stabilizing heat treating temperature comprises air cooling. 
     
     
         14 . The method of  claim 12 , wherein cooling the nickel-base alloy from the stabilizing heat treating temperature comprises cooling at a cooling rate no greater than about 1° F. per minute (0.56° C. per minute). 
     
     
         15 . A method of heat treating a nickel-base alloy, comprising:
 heating a nickel-base alloy to a heat treating temperature in a range of 1700° F. (926.7° C.) to 1725° F. (940.6° C.);   holding the nickel-base alloy at the heat treating temperature for a heat treating time in a range of 30 minutes to 300 minutes; and   air cooling the nickel-base alloy;   wherein the nickel-base alloy comprises, in percent by weight, 17.00 to 21.00 chromium, 2.50 to 3.10 molybdenum, 5.20 to 5.80 niobium, 0.50 to 1.00 titanium, 1.20 to 1.70 aluminum, 8.00 to 10.00 cobalt, 8.00 to 10.00 iron, 0.008 to 1.40 tungsten, 0.003 to 0.008 boron, 0.01 to 0.05 carbon, up to 0.35 manganese, up to 0.035 silicon, 0.004 to 0.020 phosphorus, up to 0.025 sulfur, nickel, and incidental impurities.   
     
     
         16 . The method of  claim 15 , further comprising, after cooling the nickel-base alloy, stabilizing heat treating the nickel-base alloy, wherein stabilizing heat treating comprises:
 heating the nickel-base alloy to a stabilizing heat treating temperature that is an expected maximum in-service temperature of an article comprising the nickel-base alloy and is about 1700° F. (926.7° C.) or less; and   air cooling the nickel-base alloy.   
     
     
         17 . The method of  claim 15 , wherein the nickel-base alloy comprises at least one of a foil, a honeycomb core, and a honeycomb panel. 
     
     
         18 . A 718-type-nickel-base alloy comprising:
 an austenite matrix including grain boundaries;   an equilibrium or near-equilibrium concentration of δ-phase precipitates at the grain boundaries; and   up to 25 percent by weight of total γ′-phase and γ″-phase precipitates; and   wherein the 718-type nickel-base alloy comprises nickel, chromium, and iron, and is strengthened by niobium, and optionally one or more of aluminum and titanium alloying additions.   
     
     
         19 . The 718-type nickel-base alloy of  claim 18 , comprising in percent by weight, up to 0.1 carbon, 12 to 20 chromium, up to 4 molybdenum, up to 6 tungsten, 5 to 12 cobalt, 6 up to 14 iron, 4 to 8 niobium, 0.6 to 2.6 aluminum, 0.4 to 1.4 titanium, 0.003 to 0.03 phosphorus, 0.003 to 0.015 boron, nickel, and incidental impurities;
 wherein a sum of the weight percent of molybdenum and the weight percent of tungsten is at least 2 and not more than 8;   wherein a sum of atomic percent aluminum and atomic percent titanium is from 2 to 6;   wherein a ratio of atomic percent aluminum to atomic percent titanium is at least 1.5; and   wherein a sum of atomic percent aluminum and atomic percent titanium divided by atomic percent niobium is from 0.8 to 1.3.   
     
     
         20 . The 718-type nickel-base alloy of  claim 18 , comprising, in percent by weight: 0 to about 0.08 carbon, 0 to about 0.35 manganese; about 0.003 to about 0.03 phosphorous; 0 to about 0.015 sulfur; 0 to about 0.35 silicon; about 17 to about 21 chromium; about 50 to about 55 nickel; about 2.8 up to about 3.3 molybdenum; about 4.7 to about 5.5 niobium; 0 to about 1 cobalt; about 0.003 to about 0.015 boron; 0 to about 0.3 copper; 12 to 20 iron; aluminum; titanium; and incidental impurities; wherein the sum of atomic percent aluminum and atomic percent titanium is from about 2 to about 6 percent; the ratio of atomic percent aluminum to atomic percent titanium is at least about 1.5; and the sum of atomic percent of aluminum plus titanium divided by atomic percent of niobium equals from about 0.8 to about 1.3. 
     
     
         21 . The 718-type nickel-base alloy of  claim 18 , comprising, in percent by weight: 0.01 to 0.05 carbon; up to 0.35 manganese; up to 0.035 silicon; 0.004 to 0.020 phosphorus; up to 0.025 sulfur; 17.00 to 21.00 chromium; 2.50 to 3.10 molybdenum; 5.20 to 5.80 niobium; 0.50 to 1.00 titanium; 1.20 to 1.70 aluminum; 8.00 to 10.00 cobalt; 8.00 to 10.00 iron; 0.008 to 1.40 tungsten; 0.003 to 0.008 boron; nickel; and incidental impurities. 
     
     
         22 . The 718-type nickel-base alloy of  claim 18 , comprising, in percent by weight: 50.0 to 55.0 nickel; 17 to 21.0 chromium; up to 0.08 carbon; up to 0.35 manganese; up to 0.35 silicon; 2.8 to 3.3 molybdenum; greater than 0 to 5.5 niobium and tantalum, wherein the sum of niobium and tantalum is from 4.75 to 5.5; 0.65 to 1.15 titanium; 0.20 to 0.8 aluminum; up to 0.006 boron; iron; and incidental impurities. 
     
     
         23 . An article of manufacture made by a process comprising the method of  claim 1 . 
     
     
         24 . The article of manufacture of  claim 23 , wherein the article of manufacture comprises at least one of a face sheet, a honeycomb core, and a honeycomb panel of a thermal protection system for a hypersonic flight vehicle or a space vehicle. 
     
     
         25 . An article of manufacture comprising an alloy according to  claim 12 . 
     
     
         26 . The article of manufacture of  claim 25  comprising one of a face sheet, a honeycomb core, and a honeycomb panel of a thermal protection system for a hypersonic flight vehicle.