US 3368888 A
Description (OCR text may contain errors)
United States Patent 3,368,888 NICKEL BASE ALLOY Heinrich Winter, Eschborn, Taunus, Germany, assignor to The Federal Republic of Germany as represented by the Secretary of Defense No Drawing. Filed July 9, 1964, Ser. No. 381,548
Claims priority, application Germany, July 19, 1963,
2 Claims. (Cl. 75171) This invention relates to nickel base alloys having improved properties.
The nickel mixed crystal of the composition 7% Cr, 3% Al, 3% Mo, 3% W, 2% Nb, the balance being nickel, forms with titanium carbide a quasi-binary system having an eutectic at about 5 percent by weight of TiC and an eutectic temperature of about 1345 C. At said temperature, about 3 percent by weight of TiC are taken up in solution; with decreasing temperature, the solubility decreases rapidly and is at 900 C. practically zero.
The strength of said alloys at room and elevated temperatures increases considerably with increasing TiC content but from about 1 percent by weight of TiC on, the ductility decreases strongly. Alloys with about 0.5 percent by weight of TiC exhibit already very good room and elevated temperature strength and still excellent ductility. By increasing the Al content to 5 and the Cr content to percent by weight, the room temperature and elevated temperature properties are considerably improved; however, the elongation values at elevated temperatures of 800-900 C. are no longer satisfactory.
I have found that alloys of the following composition have a much improved ductility at low as well as at high temperatures while at the same time the tensile strength values are considerably increased over the whole temperature range: 8-12% by weight of chromium, 510% cobalt, 47% aluminum, 36% molybdenum, 13% niobium, 13% vanadium, 13% tungsten, 0.5-2% titanium, 0.2 to 1% zirconium, 0.05 to 0.3% carbon.
In this alloy, the proportion of tungsten remains so low as not to increase noticeably the density of the alloy while it exerts its strengthening etfect. The titanium and carbon ratio must be adjusted to about 67:1 so as to correspond essentially to the composition TiC.
With an alloy of the composition 66.3% Ni, 10% Cr, 7% Co, 5% Al, 4% Mo, 2% Nb, 2%V, 2% W, 1% Ti, 0.5% Zr, and 0.2% C the following values were measured in the as-cast state:
1 At about 25% elongation.
(The HV values designate the Vickers hardness, the numbers 30 etc. referring to the load in kg. applied for the test, in accordance with the official German testing standards, published as DIN 50133.)
The room temperature and high temperature strength properties of said cast alloy are, therefore, far above the average of the presently known nickel base superalloys. Hence, alloys of this type are particularly suitable for making blades and other parts of gas turbines.
1. A nickel base alloy having improved high temperature strength consisting essentially in percent by weight of about 8-12 chromium, 5-10 cobalt, 4-7 aluminum, 3-6 molybdenum, 1-3 niobium, 1-3 vanadium, l-3 tungsten, 0.5-2 titanium, 0.2-l zirconium, 0.05-0.3 carbon, the balance being essentially nickel, the Ti/C ratio being about 6-7: 1.
2. A nickel base alloy as claimed in claim 1 consisting essentially in percent by weight of 10 chromium, 7 cobalt, 5 aluminum, 4 molybdenum, 2 niobium, 2 vanadium, 2 tungsten, 1 titanium, 0.5 zirconium, 0.15 carbon, the balance being essentially nickel.
References Cited UNITED STATES PATENTS 2,920,956 1/1960 Nisbet et al 17l 3,061,426 10/1962 Bieber 75171 3,155,501 11/1964 Kaufman et al. 75171 3,183,084 5/1965 Heydt et al. 75-171 DAVID L. RECK, Primary Examiner.
RICHARD O. DEAN, Examiner.