US2940845A - Columbium-titanium base oxidationresistant alloys - Google Patents

Description

United States Patent Office 2,940,845 Patented June 14, 19

COLUMBIUM-TITANIUNI BASE OXIDATION- RESISTANT ALLOYS Robert I. Jafiee, Fred R. Schwartzberg, and Dean N. Williams, Columbus, Ohio, assignors, by mesne assignments, to Kennecott Copper Corporation, New York, N .Y., a corporation of New York No Drawing. Filed Feb. 24, 1958, Ser. No. 716,835

This invention relates to columbium-base alloys containing titanium and aluminum. More particularly it relates to alloys containing more than 50 percent columbium, together with from about 5 to 49 percent titanium and up to about percent aluminum. Some alloys of the present invention contain additional metals, but all contain the three already mentioned, namely: columbium, titanium, and aluminum.

The alloys of this invention are characterized by their outstanding oxidation resistance. In addition, the present alloys possess good room-temperature strength and good bend ductility, are readily fabricable, and have high-temperature strength as indicated by their hot hardness properties.

It is, therefore, a primary object of this invention to provide oxidation-resistant alloys.

It is another object of this invention to provide alloys having good strength both at room temperature and at high temperatures.

Other objects and advantages of-the present invention will be apparent from the following detailed description thereof.

In general, this invention comprises oxidation-resistantalloy compositions including columbium, titanium, and aluminum and wherein the columbium is present in the amount of at least 50 percent, titanium in amounts ranging from 5-49 percent, and aluminum in amounts ranging from 1-10 percent. Other metals may be included 2 in the present compositions; for example, chromium, tantalum, and vanadium have been used in alloys of this invention.

To demonstrate the oxidation resistance of the present alloys, experimental studies have been made on specimens of the alloys. are tabulated in Table I below. The tabulated data illustrate the resistance of these alloys,'in either the cast or wrought condition, to oxidation in a static atmosphere at elevated temperatures. Test specimens measured about 0.25 x 050x 0.04 inch and were prepared as follows: Each specimen was carefully finished on 400-grit paper, cleaned in a solvent, Weighed, and measured. The

finished specimen was then placed on a small ceramic ring and set inside a crucible cover with a second, larger ceramic ring placed around the specimen to insure retention of any spattered scale. Each test assembly, prepared as described above, Was placed on a firebrick, and,

thus supported, inserted into a furnace which had been brought up to the test temperature. Specimens were in this manner exposed to air oxidation for periods of 16 hours at test temperatures of 1400 F. and 1800 After exposure for the prescribed time, the treated specimens were covered with a second crucible cover and cooled, thus avoiding loss of oxidation products during the cooling period. After the speciments had been cooled, they were each weighed to determine the weight gain. From this, the weight increase per unit original area was computed for each specimen. After being weighed, the test specimens were brushed with a wire brush to remove loose scale, and the percentage of original sample remain- In some cases the scale was ing was then determined. tightly adherent and could not be removed entirely. As a result, some of the values reported under percent of original sample remaining are in excess of 100. The specimens were next sectioned centrally, mounted, polished, and etched for microexamination. Finally, hardness" readings were taken in the center of the cross section.- Values obtained at 1400 F. and at 1800" F., and in accordance with the procedures described above, are listed in Table I which follows.

TABLE I Oxidation resistance of columbium base alloys containing titanium and aluminum The rmults of these studies or tests 16 Hours at 1,400 F. 16 Hours at 1,800 F.

Material Nominal Composition, Weight Increase Percent of Welght Increase Percent of Form or Wt. percent Original per Unit Area Original Final per Umt Area Original Fin Oxidation V'HN Sample N Sample VHN Specimen (10 kg Remain- (10 kg Remain- (10 kg loa G ./sq. Mg./sq. 111g loa G ./sq. Mg./sq. ing loa 1n. cm. m. cm.

2. 387. 0 0 Wrought. 50Cb50Ti 138 0. 0166 2. 58 101 202 0. 4756 73. 7 18 370 Do. 50Cb-49'1l-1AL. 179 0. 2130 33. 0 91 345 Cast. 500b-47Ti-3Al---. 201 0. 1036 16. 0 100 327 Do. 50Cb-45T1-5Al 243 0. 0243 3. 77 101 238 0. 1476 22. 9 88 322 Wrought 500b-43T1-7Al 314 O. 0109 1. 69 100 302 0. 0691 10. 7 101 292 Do. Cb-30Ti-5 A1 253 0. 0992 15. 4 97 285 Cast; 65Cb28Tl-7Al 289 0. 0835 12. 9 99 306 Do. 850b10Ti5Al 327 0. 1935 29. 9 345 Do. 50Cb-47.5Ti-2.5Cr 187 0. 0218 3. 37 196 0. 2686 v 4.1. 6 82 394 Wrought 50Cb-451i50r 215 0. 0119 1. 85 100 227 0. 0629 9. 8 91 325 Do.

' 50Cb-40Ti-100r 289 0. 0345 5. 35 97 281 0. 0597 9. 3 96 380 Do.

50Cb42Ti -4Al-40r- 281 a. 0. 0477 7. 4 102 383 Do. 65Cb10Tl--5Al20Ta 330 0. 1140 17. 7 98 322 Cast. 500b-7Ti3Al-40Ta-- 294 0. 2670 41. 4 88 g 130. 50Cb-40Tl-2Al-8V- 240 0. 0310 4. 88 100 218 0. 2108 32. 7 89 405 Wrought. 500b-30T13A1-17V- 317 0. 1250 19. 4 97 294 0. 9087 140. 9 0 Do.

;As has been noted above, the alloys of this invention possess useful mechanical properties such as room-temperature and high-temperature strength. Table 2 below lists mechanical properties for illustrative alloy compositions of the present invention These representative data serve to illustrate the desirable mechanical properties of thealloysof this invention. r a

TABLE 2 4 Specimens for this test were prepared and tested as described in detail'above in connection with Table 1. In addition, the scale thickness and depth of contamination were measured. Scale thickness was determined by com- 5 paring the original thickness of the specimen with the thickness of the unafiected base material. In determining depth of contamination, contamination was COIlSld- Meclzanical properties of Cb-Ii-Al alloys Hardness (VHN kg. load) Room Temperature Tensile Properties of 7 Sheet Material 5 v i h Yld El n D tiil Nominal Com osition Wrong t ie onga on 7 up Wt. pem m Ultimate Strength, percent Q nednct-y, '1:

a Cast, Tensile (0.2% tion in 80 F. Strength, ofiset), 7 Area, 80 F. 930 F. 1,290 F. 1,650 F. 1,000 psi. 1,000 Uniform Total perp.s.i. cent '50Cb-45Ti5Al. 176 107 99 12 13 28 0. 5 50Cb43Tl-7Al- 202 145 135 2 2 5 5. 0 50Cb--47.5Ti2.5Cr 203 75 10 Y 15 64 0 5OCb45Ti5Cr 251 94 93 11 18 48 0 50Cb-40,Ti100r 322 130 124 7 7 15 6. 2 50Gb4DTi8V2Al 228 93 4 13 35 0 50Gb-30Ti17V-3Al 325 139 136 6 10 28 0 50Cb-42Ti-4Cr-4Al- '266 152 147 16 27 1. 4

Referring to the data in Table 1, it is seen that 16 hours exposure at 1400 F. had no unduly severe efiects on alloysof this invention; The data obtained at 1800 F.

ered to have occurred where a Vickers Hardness Number increase of 75 had taken place (over the VHN of v the original material).

TABLE 3 Oxidation resistance of wrought Cb4-2T14A14Cr Weight Increase Depth of a Time, per Unit Area Oxidation Scale Gontami- Temperature, F. hours Rate, Mg./ Thickness, nation,

7 emfi/hr. inch inch G./sq.in. MgJcm.

alloy. The inclusion of even a small amount of aluproduces a significant improvement in oxidation The alloys of this invention exhibit good fabricabilityin some cases as much as 99% reduction by cold working, after the initial breakdown of the original cost structurehas been possible. 7

It will be apparent that new and useful alloys havresistance. This may be easily seen by comparing the ing desirable characteristics and propertim have been dis- V refractory metals such as chromium, vanadium, and tantalum rnay be made in these oxidation resistant alloys. Operableranges are indicated to be from 0.5 to 10.0 percent chromium, from 0.5 to 10 percent vanadiumyand from lto 40 percent tantalum. An especially good composition is the'50Cb42Ti 4Al-4Cr alloy;

Toillustrate further the extremely. outstanding oxidation-resistance properties which alloys of this invention are capable of exhibiting; a series of oxidation-resistance studies was madeiat temperatures in the range of from in llP 'Results are tabulated in Table3, below.

closed. It is, therefore, desired to further describe the invention as set forth in the appended claim.

What is claimed is: 7

An oxidation-resistant alloy consisting essentially of 6 about 50 percent columbium, about 42 percent titanium,

about 4 percent aluminum, and about 4 percent chromium.

References Cited in thefile of this patent a r 2 UNITED STATESZPATENTS Pension PA) Em Germany ;'Mar. 24, 1942