US2892704A - Titanium base alloys - Google Patents

Description

United States Patent TITANIUM BASE ALLOYS Robert 1. Jatfee, Worthington, and Horace R. Ogden and Daniel J. Maykuth, Columbus, Ohio, assignors, by mesne assignments, to Crucible Steel Company of JAmerica, Flemington, N.J., a corporation of New ersey No Drawing. Application July 9,1956 Serial No. 596,459

1 Claim. (Cl. 75-'175.5)

This invention pertains to improvements in titanium base alloys, and provides a series of alloys of high strength and ductility, and, as to certain analyses, also of high contamination resistance and high strength at elevated temperatures, and containing as essential constituents ti- ,tanium and tin, together with one or more additional metals selected from the groups comprising alpha promoters, beta promoters and compound formers as enumerated below.

This application is a continuation-in-part of our applications Serial Nos. 285,076, filed April 29, 1952, now US. Letters Patent No. 2,669,513, dated February 16, 1954; 294,262 and 294,263, both filed June 18, 1952, and

- both now abandoned; 344,686, filed March 25, 1953, now

abandoned; and 396,756, filed December 7, 1953, now Patent No. 2,797,996, granted July 2, 1957.

The tin content may be present over a broad range of about 0.5 to 23%, with a preferred lower limit of about 2.5%, as adjudged from the standpoint of good room temperature mechanical properties, and a preferred lower limit of about as regards the imparting of high contamination resistance at elevated temperatures. To the titanium-tin alloy aforesaid, there may advantageously be added up to about 18% in aggregate of one or more of the alpha promoters, up to about 50% in aggregate of one or more of certain of the beta promoters, and up to about 2 or 3% in aggregate of the compound formers, all as set forth more in detail hereinafter. For further enhancing the mechanical properties, the alloys of the invention may contain controlled amounts of the interstitials, carbon, oxygen and nitrogen. For certain analyses, as set forth below, carbon may be present up to about 1%, oxygen up to about 0.5% and bined with adequate ductility for both hot and cold forming operations, i.e., forging, rolling, drawing, extruding, etc. For tin contents up to about 16%, they may likewise, in general, be welded without appreciable loss of ductility in the welded as compared to the nonwelded portions. This is particularly true as regards those alloys having an all-alpha microstructure, and also as to certain of those having a beta-containing microstructure, as explained more in detail below.

For imparting a high degree of contamination resrstance, i.e., resistance against penetration by atmospheric gases, particularly oxygen and nitrogen, at elevated temperatures up to about 1100 C., the alloys should contain upwards of about 5% tin, although lesser amounts down to about 2% tin are materially beneficial in this respect. Tin alloyed with titanium base metal appears to be unique in imparting this contamination resistance, and its effect is quite critical with respect to the degree of contamination resistance imparted. commencing at a minimum of about 5% tin.

These contamination resistant alloys are also characterized by free scaling properties resulting from explosure to elevated temperatures up to about 1100 C. and to atmospheric, oxidizing, or alternately oxidizing andreducing conditions. That is to say, the scale formed is easily brushed ofi or flakes off during hot forming operations, such as forging or rolling.

As is known, the metal titanium in the pure state, is capable of existing in either of two allotropic forms. Below a temperature of about 885 C. or 1625 F., it assumes a close-packed hexagonal structure known as the alpha phase, while at this temperature and above it assumes a body-centered cubic structure known as the beta phase.

Certain substitutional alloying additions to the titanium base metal, among which may be mentioned tin, antimony, indium, silver, bismuth, lead, cadmium, zinc, and thallium as well as the interstitials carbon, oxygen, and nitrogen may be termed alpha stabilizers or alphapromoters. The term alpha stabilizer includes those elements which raise the transformation range sharply, such as oxygen and nitrogen. Also alpha stabilizers include elements such as carbon, which have a relatively small solubility in alpha titanium, but which raise the transformation temperature for that amount which is in solution. Alpha stabilizers also include those elements such as tin, antimony, indium, and silver which have relatively large solubilities, of about the same magnitude, in both the alpha and beta phases and which have little effect on the transformationtemperature range, neither raising nor lowering it markedly. A common characteristic of the alpha stabilizers, as we are considering them here, is that little or no hardening occurs in the thermal processing. The resulting alloys are, at room temperature, always all alpha in structure regardless of the heat treatment, including quenching or aging. Actually little is known concerning the specific eifects of bismuth, lead, cadmium, zinc, and thallium on the transformation range. These alloying elements produce alloys which fit the criteria given, namely, that they form all-alpha alloys, which do not retain any substantial content of beta phase nor harden appreciably on quenching from the beta field. Hence these elements appear properly classified as alpha promoters, and will be so treated in this application.

Other substitutional alloying elements, when added in progressively increasing quantities, stabilize the beta phase at progressively lower temperatures, until a mixed alphabeta or stable all-beta microstructure is obtained at normal or atmospheric temperatures, or the beta phase undergoes a eutectoid reaction, depending on the character and amount of the beta stabilizers added as discussed below.

Speaking in broadest terms, the beta stabilizers are Mo, V, Cb, Ta, Zr, Mn,'Cr, Fe, W, Ni, Co and Cu.

3 Silicon and beryllium may also be considered as beta stabilizing elements, but their solubilities in titanium are relatively so slight and the tendency of the beta phase stabilized by these elements to decompose into eutectoid products so great, that it is equally proper to consider them as compound-forming elements. Within this broad category, however, only certain of the elements mentioned are suitable for producing mixed-phase, alphabeta alloys, or all-beta alloys. -These are the elements which have beta-isomorphous diagrams, or which have beta-eutectoid diagrams such that the decomposition of the beta phase into eutectoid is so sluggish that the alloys behave like those in a beta-isomorphous system. The beta stabilizing elements of this type are Mo, V, Cb, Ta, Mn,"Fe and Cr. Tungsten is a borderline element as between the sluggishly decomposing and rapidly decomposing types and hence may be classified either way. Within this limited group only Mo, V, Cb. and Ta are beta-isomorphous. They form the most thermally stable beta-containing alloys, as a result of their beta-isomorphism.

Zirconium is a beta promoter or stabilizer in the sense that the lowest temperature at which alloys thereof with titanium are entirely beta, becomes progressively lower with increasing amounts of zirconium, until a composition is reached at which this so-called beta transus temperature starts to increase again with further additions of zirconium. While zirconium thus lowers the transformation temperature of titanium, the alloys eventually revert to the alpha phase at lower temperatures unless other beta-promoters are present. Zirconium is isomorphous with titanium both in the alpha and beta fields. As a result, it is proper to consider zirconium together with vanadium, molybdenum, columbium and tantalum as all being beta-isomorphous with titanium.

The use of copper alone as an alloying addition to titanium, does not fit into the above-mentioned grouping of beta-isomorphous and sluggishly decomposing eutectoil beta promoters, because the beta phase stabilized by copper always decomposes rather rapidly into proeutectoid and eutectoid products, and the same is generally true with respect to cobalt, nickel, silicon and beryllium, above listed under the broad category of beta stabilizers. Copper, however, is a useful addition when present as a minor alloying element, for example,

up to a few percent, in alloys containing larger amounts of other beta-stabilizing elements, within the narrow group of elements last mentioned above since, in these low concentrations and in the presence of such other beta-stabilizing elements, the tendency of the beta phase stabilized in part by copper to decompose into eutectoid products is minimized or entirely eliminated.

The tolerance of the ductile TiSn base alloys of the invention with respect to additions of the various beta promoters above mentioned, varies considerably for the individual elements of the group, being greatest with respect to those which form beta-isomorphous systems with titanium, and least for those which decompose most readily into eutectoid decomposition products. Thus, the TiSn base alloys may be strengthened without undue embrittlement by additions of up to about 50% in aggregate of elements composing the. beta-isomorphous group, viz., molybdenum, vanadium, columbium, tantalum and zirconium, since these elements are soluble in all proportions in beta titanium. Of the sluggishly decomposing elements, the base alloy will tolerate additions of up to about 20% of either or both chromium and tungsten, up to about 10% manganese, and up to about 7% iron. Copper may be added up to about 7%. Metal of the group cobalt and nickel 'may be added up to a total of about For additions of all of the abovementioned beta-promoters, the lower effective limit is about 0.5% and preferably about 1%.

The tolerance of the ductile TiSn base alloys for the alpha promoters depends on the amount of tin present, the less tin present the greater the amount of alpha-promoters that can be added and vice versa. Antimony may be added to a maximum content of 18%. The proportioning of antimony content in relation to the tin content is given below. Indium may be added up to a maximum content of 15 Silver may be added up to about 20%. Cadmium, zinc, thallium, bismuth and lead may be added up to 15% each, added to the charge in melting. The lower eflective limit for the alpha promoters is about 0.5% and preferably about 1%.

The elements Ce, Be, As, S, Te and P are strictly compound-forming elements. They do not have appreciable solubilities in either the alpha or beta phases, but form intermetallic compounds with titanium. The beta promoters silicon and beryllium are likewise best grouped as compound-forming elements, in view of their above-mentioned low solubilities in titanium and the tendency of the beta phase stabilized by these elements to decompose rapidly into eutectoid products. The Ti- Sn alloys of the invention will tolerate only relatively small amounts of these compound-forming elements, i.e., up to a total of about 2 or 3% maximum, the lower effective limit being about 0.1 or 0.2%.

Substantially pure and ductile metallic titanium may be produced at considerable expense by the so-called iodide process described in U.S. Patent 1,671,213 to Van Arkel; while ductile titanium of commercial purity is produced more cheaply by the magnesium reduction of titanium tetrachloride by the process described in U.S. Patent 2,205,854 to Kroll. Both procedures, particularly the latter, result in some contamination of the titanium metal with one or more of the interstitials, carbon, oxygen and nitrogen. But since, as noted above, these are all alpha-promoting orstabilizing elements, the resultant somewhat contaminated titanium metal obtained, has at room temperatures a single phase, all-alpha microstructure.

The all-alpha, all-beta and mixed alpha-beta alloys of titanium have their respective advantages and disadvantages. Generally speaking, the alpha alloys provide good all-around performance, having good weldability, and being strong and resistant to oxidation, both cold and hot, but are somewhat inferior as to ductility. The all-beta alloys, on the other hand, have excellent benedability and ductility, are strong both hot and cold, but are somewhat vulnerable to atmospheric contamination, particularly at elevated temperatures. The mixed alpha-beta alloys provide a compromise performance as between all-alpha and all-beta alloys, being strong when cold and warm, but weak hot, while possessing good bendability and ductility, with a moderate degree of resistance to atmospheric contamination.

Since the TiSn base alloys have, as above noted, an all-alpha microstructure, they may be readily welded in tin contents up to about 16%, with no appreciable impairment of ductility in the welded as compared to the non-welded portions. They also form an excellent base alloy for the ternary and higher component alloys of the invention, that may be also welded without appreciable loss of ductility in the welded as compared to the non-welded portions. This is particularly true as regards the above-mentioned alpha-promoter additions to the base alloy. Also, in general, the ternary and higher component alloys made by additions of the beta-isomorphous elements above designated are weldable without appreciable impairment of ductility. It may furthermore be stated that in general the alpha-beta alloys according to the invention can be produced to have ductile welded portions if suitable post-welding heat treatments are applied as described in the co-pending application of laffee et al., Serial No. 585,177, filed May 16, 1956, which is a continuation-in-part of application Serial No. 305,- 504, filed August 20, 1952 and now abandoned.

Tin is soluble in alpha titanium to the extent of at least 15%, and alloys of titanium with up to 15% tin are all in the alpha phase. As the tin content is increased, the beta transformation temperature rises, and at a tem- 19%, a peritectoid reaction occurs. In alloys containing about 20 to 23% tin, two intermediate phases formed at ,difierenttemperatures have been tentatively iden The following Table I gives, for comparative purposes with the further test data presented hereinafter, test results showing the improvement in mechanical properties, resulting from additions of tin over the range of about 1 to 23%, to both iodide and commercial purity 15 titanium base metal, with and without further controlled additions of one or more of the interstitials, carbon,

m 0 w f O t m n O c m a d m 0 0 n m m m o H a m f d O e m m m 4 m n w w M a a 5 m n a u a mmmaam w wu .PM O m tm cu om mmmrmm W323 a v O Mm m vmm m V M Pm a imm mum Wm H A, mamw w m emma pmtm m m m p mm m .m .m a. n. d m mmmm mmmmmw ue mm mwmawm Min. Bend T wunnmnw wnwmmamum mmmmmwm maw Percent Rednc- Vickers tion in Hard- Percent Elonga- TABLE I Ultimate tion in 1" Area Ti-Sn binary alloys [Annealed condition] Tensile Properties: p.s.t. 1,000

571 856 77 79 m%m4wm%mmfln3aufiwslfio w nfl%33fln mfi3w 212 2333333343433 "9033333333 E S A 6 0 3018325 957265 1 765 12837 6 V 148 5991 1 E U S n I A m 1 9 1 1 11 1 05767 8216199684 9986 B mnmmmmimwzn uuunnn winmmmmmm T zznnimi 22 a 1 ziiim i I m T m. m n u m m nmn nmmmm mmwmnmm umnm m imnimmmmnnmh mnmiwin... t B T P E L mm m m 7 6 7 9m 4 07 s 7 58755 9 7 9 91 74 00 86 1 11839 319 69214 9 e 5 311 m Mm w nm mm mm fi nmn m u mn m mnn nmmnminmmiim mom I E 1917 M 8 3 8 4 N 221212 M 2n 1 1 1 a 0000000 0 00 0 o 0 0 O 0 0 0 0 Q0 0 0 u 0 0 00 u 0 0 7 6 8 0 0 U o 10 0 nw 0 0 0 000 O 0 Composition, Percent (Balance Titanium) D 5 v mwmm mmmmmmmmmmwm Z From these results it will be observed that additions oftin up to about 23% greatly strengthens the metal while retaining adequate ductility for fabrication pur-. For the iodide tita-.

poses, i.e., forging, rolling, etc. nium base the yield strength is more than quadrupled from 27,000 to 135,000 p.s.i., while the ultimate strength is more than tripled from 43,000 to 149,000 p.s.i. For any giventin content further strengthening results from controlled additions of one or more of the interstitialsone or more of the alpha promoters, beta promoters, or 20 compound formers above discussed the following Table II gives test results for additions of one of the more important beta promoters, namely, manganese:

of ductilitys l n fact, for. additions of manganese up to about 6%, the ductilityisactually-increased as compared to the alloy omitting manganese, while at the same time, increasing the ultimate strength up to about 150,000 p.s.i. The effect of interstital ,additions to the manganese-containing alloy againenhances the strength without serious effect on ductility as shown by comparison of the 9% tin, 2.5% and Mn analyses.

The following Tables HI and IV show the effects of molybdenum additions to the titanium-tin base alloy. In Table III all alloys are in the annealed condition; whereas Table IV gives the properties of the alloys in various heat treated conditions. Here again, as in the case of manganese, the molybdenum additions greatly increase the strength of the alloy while retaining adequate ductility. For example, with the 10% tin analysis and a 7.5% molybdenum addition, the ultimate strength is increased from 110,000 to 140,000 p.s.i. with no loss in ductility, as shown by comparison with Table I. At the tin level the ultimate strength is increased from 123,000 to 167,000 p.s.i. with no loss in ductility upon the addition of 5% molybdenum. The effect of adding interstitials TABLE II T1Sn-Mn alloys (commercial titanium base) [Annealed condition] Composition, Percent (Balance Tensile Properties:

Titanium) p.s.i. 1,000 Percent Elongation i 1!! Sn Mn 0 0 N 0.2% Ofiset Ultimate Yield Strength Percent 'Reduction Vickers Min.

in Area Hardness Bend T 50 276 1. 7 48 261 1. 6 49 273 1. 7 55 369 1. 5 45 364 1. 6 46 344 1. 5 46" 336 1. 2 39 369 1. 8 39 389 1. 8 46 397 2.8 90 353 1. 7 37 424 4. 7 36 421 4. 8 38 426 2. 3 11 350 1. 6 r 36 296 1. 5 44 341 1. 6 48 326 1.7 51 356 1.4 39 363 1. 6 25 375 1. 4 38 369 1. 4 35 385 1.2 27 386 2. 9 29 377 3. 7 B1" 404 Br 49 316 0. 8 41 324 1. 6 15 481 7. 0

Comparing the results of the above table with those 70 is shown by comparison of the values for the 9% tin,

given in Table I, it will be seen, for example, that for the 10% tin alloy containing no manganese, the ultimate creases ranging up to about 160,000 p.s.i. with additions-of 2.5% molybdenum analysis wherein the ultimate strength is increased from 113,000 to the order of 130,000 to 140,000 p.s.i. with no appreciable effect on ductility. The same order of increase occurs at the 9% tin, 5% molybmanganese up to about 9%, without serious impairment 7 denum level.

iron analyses:

TABLE VI TiSn-Fe alloys [Annealedtconditiom] previous data, the addition of the interstitials enhances be seen by comparison of the 9% tin, 0.5%

" and a titanium base of commercial purity, the addition of 2% iron increasesjthefultimate strength from 123,000 to 177,000 p.s.i. withsubstantially no change in ductility. At the 10%11'1'1 1evel,*the ultimate strength is increased 5 from 110,000 to 150,000 p.s.i. with no change in ductility the strength properties with no loss in ductility as can 45 upon the addition of 4% iron. Here again; as in the TABLE V Ti-Sn-Cr alloys [Annealed condition] Other .T mi 641 MM 11?]. 0 1 LLLLQQLnLLQL LLLLLZZOmLZLZZ B s s r t r r 7 i e 519 9108118903858616199810866352 S 6 2 712 35 38546678658956 H tw 7 m mmmm 195 E 5352637 1689 4 268 0 5 74 5 e n A t P .1 E B s A m n B m 1 207 78 91 mmmm M 11 I w BMWMHHMHMHNH HH$WM 21BB12 PE w m N T e I 1 23 41 0 60 61915 m 4422 mm mm m m u umm mmmunnnmmmmmwnmmmnimii1 D. I. T. 01 Us E 0 mm D R 81 t I E H! an D 857 24201 72 3 1 1 15 4445326896 0 1 l 300 mp m m 1 m mun u mnmnmummmmuumnmhri T 0 O It will be noted byv comparison with Table V below shows the eifcct of chromium additions to the titanium-tin base. The observed improvement is of the same general order of magnitude as for the Composition, Percent (Balance Titanium) molybdenum addition and hence requires no detailed comment.

Q 00 233:5"5. .LIYIQQQQQQQQQQQQ 55 5 5 5 4 4mfl .0 1 2 5m 24.68m4L0QQLZQ0L20Q 506 r 5 9 9999999 Table VI shoyvs the effect of adding iron to the titanium-tin base.

Table I that the iron addition tremendously..incr eases the ultimate strength accompanied in general by retention of adequate ductility. With the 15% tin analysis .T E 7 If .1 090 3065763 Mm 1L3 LaaaaLL .B ne it W e t e k- 733 5 84 952 m 7 nan amamawa t a r n 6 r I Cunt t t t 3% "mm m ewaowrsw PR .m t t E M s t A M fiw. B V U Y t mmm M w m mumwmmm PE m A t T wk I u e n T T mm mm 1 wmm L manwtwnnmm 6 T 11 A 111 1111 m ms E 0 mx 7 n R 9 1 t T. E H5 em D m 2mm 0 men M nwmnm n 0 1 1 M 1 1 n n O C m m u n u n u n u n n u n n wm m u n n u n n n n n n m P m 6 no 5 T r 555 13 fl 2 2 2 262001257 new m m n 5 05 145999999 0B c( s 11 t TABLE VI--Cont1nued m osition, Percent Tensile Propertieli' (B 00 Titanium) p.s.i. 1,000 Percent Percent Elonga- Reduc- Vieker Min.

tion tion Hard- Bend T 0.2% Ultimate in 1" in Area ness 8n Fe Other Ofiset Strength Yield COMMERCIAL TITANIUM BASE-Continued 10 1.5 108 120 18 40 330 1.8 10 2 121 132 9- 31 347 1.5 10 3 133 147 14 36 359 2. 0 10 4 137 150 10 87 370 1. 5 5 185 190 5 16 446 B1 10 7.5 176 179 Y 8 31 426 6.1 2 170 177 12 32 411 2. 3 9 0. 25 0.250 113 119 25 54 343 2. 5 9 0. 25 0. 20 106 122 21 38 341 2. 3 9 0. 0. IN 109 21 36 304 2. 3 9 0. 5 0. 250 104 125 24 50 338 1. 3 9 0.5 0.20 105 125 16 321 1.8 9 0. 5 0. IN 91 105 17 42 306 2. 4 9 1. 25 0. 2C 123 134 17 27 362 1. 7 9 1.25 0.20 110 123 17 42 383 1.9 9 1. 25 0. 2N 126 142 16 45 380 1. 7 9 2. 5 0. 20 143 152 18 396 1. 5 9 2. 5 0. 20 139 152 15 41 408 2. 3 9 2.5 0.2N 153 164 15 34 404 B1 Table VII below shows the efleets of additions of the I copper, zirconium, cobalt, and nickel to the titanium-tin 7 beta stabilizers vanadium, tungsten, columbium, tantalum, base.

TABLE "II Ti-Sn base plus V W, Cb, Ta, Cu, Zr, Co, Ni. Si; Be alloys [Annealed condition unless otherwise indlcated.]

Tensile Properties: MBR,T. Omfiposition, Percent p.s.i. 1,000 Percent Percent -V1ekers (B anee Titanium) Elongation Reduction Hardness 0.2% Oflset Ultimate in L T Yield Strength IODIDE TITANIUM BASE 10Sn2.5V.- 78 97 10 16 0. 5 84 106 7 36 0.6 54 76 10 47 1.1 68 81 12 53 1.7 72 19 32 3.1 75 94 15 29 2.0 112 9 29 2.9 98 108 22 38 1.9 3 94 108 14 37 3.4 114 128 11 28 6.3 94 20 40 2.2 106 117 18 43 2.1 99 113 18 42 3.7 129 136 15 39 3.3 123 138 1 9 5.7 98 121 2 14 2.0

OMMERCIAL PURITY TITANIUM BASE Vlckers Hardness u 089622622r-1 0 u o-larszozrsrrr r u n 38068478 m aeaeaaeei no oe L eeoe a B 00 oeoiiesle a n n n u n n R u n n u u u m u n u n u u m 8o7786666rr00 06 r241876775r1 90 13 02523435 12 12422azo LzoLooo LLzLLaLaL e LLoooooaoLLzL L v 990 u B 1 22 oLnLLzzz L2 5 5 LL25 1 T n .u R u B 88 m m m m M L222 5457 59925 9 88012 m zone 2235 .m m i v n Percent in Area Percent in Area Percent Elongation Reduction 841 12745 g 1 7 1 111w11111 m1m1mum 1mn m nm m m mnmm uw m Percent Elongation Reduction Hardnc inl 1113L04440l491380L33989-1 1.11 1112122111 111 21111 Strength TABLE VIII [Annealed condition] p.s.i. X 1,000

Strength Tensile properties:

0.2% 7 Ultimate Offset Yield TABLE VIIContinued Tensile Properties: p.s.i.Xl,000

Yield 0.2% Ofiset Ultimate Mechanical properties of Ti-Sn base alpha-beta alloys containing two beta stabilizers (commercial purity titanium base) Composition, Percent (Balance Titanium) COMMERCIAL PURITY TITANIUM BASEContinued l 1,600 F. quenched. I 8 hrs. at 1,400 F. I 16 hrs. at 1,4o0 F.

Table VIII below shows the efl'ects of adding a mul plicity of beta promoters to the titanium-tin base.

Composition, Percent (Balance Titanium) 1 r186d6r0 r0090456958 6 m7 5730022706211 5097281 Idle r4650 r r r666 28 2 A" L lulu; Bend Radius Vickm A 1 wmwwmmmmmmammmmwwwmmwmam mmmmmmwwmmmmManamaaammmmmmwmmmmmmmmwmmmmmWm Percent Reduction Hardness in Area ma mmamma aa mewemnmaa aaneooeaawanwoundnenwmnmw mmuwwnwm eunuauamnmama Percent Elongation i 1!! m h M H t w e 832906432208135571721924.61345G5 0 e t 1 1111.....1 1111 11 1 1111111miunumunmmmmmumrmmr w mmmwm mm mmnnmumw strengths, acceptable tensile ductil 7 Ultlmate Strength TABLE VIIIContinued Tensile properties: p.s.1. X 1,000

0.2% Ofiset Yield Composition, percent (Balance Titanium) 1 The tensile strength was reached before the 0.2% ofiset yield strength,

1 Detective sample.

From the test results of Tables II to VIII, inc., the following general conclusions may be drawn with respect I dn ma w Ph. X ma h m m eam mwm wd u 1 ductilities, poor thermal stability, to the eflfect of single and multiple beta stabilizer addiof the TiSn-5W alloy are in tions to the titanium-tin base. The beta isomorphous welded, except for extremely low additi elements V, Cb, Ta, Mo and Zr alone or in combination ments. On the other hand, by judicious selection and with each other, produce alloys having similar propcombination of the beta promoters from one of the erties. These alloys have medium strengths, good duca groups above mentioned with those of the other groups, tility, good thermal stability and, as shown below, are multiple beta stabilizer alloys may be produced which generally ductile as welded. The elements Fe, Cr and combine the good qualities imparted by the elements Mn which form systems containing sluggish eutectoid from the groups selected, while tending to suppress and reactions, produce alloys which have high strengths, good minimize their undesirable qualities. Thus, for example, ductility, fair thermal stability and are generally brittle as the combination of beta isomorphous elements with the welded, except for low alloy contents of such additions; sluggish eutectoid elements results in alloys that have The elements with rapidly transforming eutectoids, Co, improved thermal stabihty and weld ductility as com- Ni, Cu and W, produce alloys which have medium pared'to those made with the sluggish eutectoid elements TABLE IX [Annealed condition.]

Thus it will be seen by a comparison of Tables I and properties of additions of the alpha stabilizer antimony to the titanium tin base,withand'withoutadditions 'of therinterstitia ls carbon, oxygen and nitrogen:

Ti-Sn base plils Sb alloys d mT 235779 ou 32 ULnMLrZ LK ZLLZZBZZLLZA BZQwZ-m N V 9 1 245328 368 H %MM%%6M filwflmflm902344m343 V 2 23333 23233322 333333 3 t n w GOT 195674 64 000337978 00066 MMA $535333 fifl441 444343 342 G P m t R E s m A t mau B V. 3 272 818776 90 m2m211M M NMUH 121111 MW 8 i a a PM E m E S N A A mm B m g M e n 7860575 T 6 7415684160348524 11353 m mm m ummm n nmm mnmn11111 wm Us N T R t a m n T U us at I n SD Nuwm T 2247317 P 69406 190745 985 n n 6 e 12 .024 P o m m m m M m mu m mll 111 n m I I 0 D C t 2 R N I 0 E M 8 m m u a I o "I B I1 I I" I r\ n) .6, m m a "I n :1 a ,t 1 M 5 0 1 tw nties 1 T a. .7 n w ,"1 ;1l1 wmmm ma n mios p m 55 5 5 5 2 5-07 a mmmmmm 19 alone. On the other hand, the test data shows that combinations of beta isomorphous elements "with the rapid eutectoid elements do iiot ult in improved thermal 40 IX that antimony has about the same strengtheningefiect as an equivalent weight of tin and may be substituted therefor without undue embrittlement within the range of proportions set forth in the above'table incolumn 20.

The following Table X shows-the effect on mechanical properties of additions of the alpha stabilizers bismuth, indium, cadmium, silver, thallium, lead and zinc to the titanium-tin base .Min.

Percent TABLEX [Annealed condition .1

"cal

Ti-Sn base plus 'In, Bi, Pb, Ag,Cd, T1 and Zn alloys Titanium Composition, Percent (Balance Co and Ni.

The following ,TablegIX: shows the eflfeet :on mech m OLLZZLDMLZZDMZLLZZZAAML T B 55012486672U81181268 6 V 2 4 2283 wlw N%NZMWHM%% MZNM%3332 8 n r 17 0015134644396 557 m 83%445444544 434M445 9 m 4 r E 8 216 m s mwwmmmmwmwmlmzimmmw m A m a B 0 M I E U v t I 3 6 676388891183459 mh N 4%6wm000280017770003fi n A 1111 111 .1111. mm m H.. T U E l D I 6 34 13953912330 t W5: u%%09fl%09055590936 qe 1 1 1 1 1 1 2mm 0 Q Y I O CON 00 ooN m 34 l o mfimd 11.11.11 I Sggggg L ZmJCAAA A mmmmmm 22 221 11m1m2 O 000 000 0 mwmwmlm lll mmll l S TABLE X-Contmued Composition, I 7 Percent (Balance g f gfi I Percent itamum) Percent ..Reduo- Viekers Min. e Elongation tion in Hard- Bend Sn Other, 0.2% Ultimate iin 1" vArea ness '1 a Oflset Strength V Yield 1 COMMERCIAL. PURITYTITANIUM BABE 49 70 24 44 197 1.3 6 71 90 '14 v 42 246 1.5. 10 1B1 82 97 i 48 297 1.5 10 2.631 86 99 -17 297 .2.

0 2.531 74 24 49 206 1.1 10 1111 79 94 25 61 283 1.7 10 2.5In 88 101 21 48 297 1.6 ,10 61in 92 104 17 49 289 1.9 10 10111 102 111 20 '45 325 4 2.7 v 10 1006. 79 92 18 41 270 1.8 I 10 lAg "80 96 17 48 252 1. 7 10 2.5Ag 82 95 18 47 287 1.5 10 fiAg 87 102 19 51 809 1. 7 10 10Ag 91 104 18 45 309 2.5 10 10Pb ,87 101 23 47 314 2. 8 10 10211 73 86 22 62 268 1.6

* Considerable weight loss occurred during melting.

Table XI below shows the efiects of additions of the various compound formers'to the titanium-tin base:

. IABLE x1 Alloys 0 Ti--Sn base plus compound formers Si, Be,- Ce, B, Te, etc.

tendency to become embrittledas a result of welding. As

further shown in said application, beta-containing alloys -'[Annealed condition] Composition, Tensile Properties: Percent (Balance psi.Xi,000

Titanium) Percent Percent Vicirers Min.

Elonza- Reduction Hardness Bend T tion in 1" in Area Sn Other 0.2% 011- Ultimate 1 i set Yield Strength IODIDE TITANIUM BABE 10' 85 99 20 36 298 1.5 '10 10c 67 76 16 B4 250 2.0 10 We 61 78 17 48 232 2.7 10 Y 2.5Te 72 88 7 20. 242 1.1 10 0.513 54 72 21 38 236 1.8 10 2.5T]: 22 67 238 1.9 10 mi 97 16 38 305 1.6 10 0.2Be 70 90 12 22 273 1.6

COMMERCIAL PURITYTITAN IUM BABE 10 91. 110 11 i 30 296 1.6 10 10a 80 .94 17 39 285 2.4 .10 2.500 75 92 y .15 a 33 276 3.2 10 0.581 I 17 45 325 1.5 10 151 97 109 17 35 330 5. 0 10 281 104 a 108 3 v 8 383 7.0

"Considerable weight loss occurred during melting.

The welding characteristics of the various types of alloys of the present invention, are described, and the weldable alloys thereof, coveredby. the above-mentioned co-pending joint application of the applicantsJafiee and Ogden herein, 'Serial No. 585,177. As therein shown,

the all-alpha or substantially all-alpha titanium-tin base alloys of the present invention, containing up to about 16% tin, are weldable' without serious impairmentfiof ductilities, substantially throughout the entire range of analyses that such alloys are ductile in the cast or wrought condition. The same'is shown in said application to be generally true with respect to the beta or mixed alphabeta titanium-tin alloys obtained by additions of betapromotersof thebeta-isomorphous group, i.e., Mo, V, Ob, Ta and Zr, although certain of the molybdenum-conformed by additions of the sluggishly eutectoid beta promoters, Cr, Mn and Fe, are generally productive of brittle welds when present insubstantial amounts, i.e., about 23%, although certain of the higher alloy analyses restricted to Cr and/ or Mn additions are ductile as welded or can have their ductilities restored by post welding heat treatment as above mentioned, i.e., those containing up to about 7-8% Mn or up to about.l8% Cr. The beta alloys formed by additions of Co, Ni, Cu and W having rapidly transforming eutectoids are intrinsically brittle in the welded condition when these additions are present in excess of about 2 to 3%, Le, their ductilities cannot be restored by post welding 'heat treatment. The compound formers likewise impart intrinsic brittleness as welded to the titanium-tin base alloy when present in amounts exceeding about 2 to 3%.

Our investigations have e'stablished'thatthe alloys in accordance with the invention containing about 10 to 15% tin are wholly contamination resistant attemperatures up to 1050 C. and probably higher regardless of the type of alloy, i.e., whether all-alpha, mixedalphabeta or all-beta. They have further established thaflthere is a marked or critical reduction in contamination resistance commencing at about tin as compared to that of the same alloy containing no tin. Themtin addition produces free scaling alloys in most cases, but this tendency to free scaling appears to be reduced when large quantities of beta stabilizers are present. p

The findings above stated are based on the .test results set forth in the following Table XII, the data for which was obtained by are melting 15-grambuttons of each of the compositions indicated in the table,;including the tin-free alloy bases. The buttons were "f orged at 850 C. to about square x 1% long. forged billet was then descaled and sectioned into two. samples. One sample was heated in air for four hours fat 1050 C. and furnace cooled. The second sample rec;e'ived the same treatment in argon. These samples were furnace men, with resillts as recorded in the'tablef TABLE XII Oxidation test data for Ti-Sn base alloys containing Ta, W, Cb, W, Mo, Fe, Cr or Mn [Oonditionz 4 hr. at 1050 C. in air and furnace cooled] Metal- Depth of 1 Increase Composition, percent Weight Thiclmess Oontamiin VHN (Balance Titanium) Gain Loss, nation, f oMils gJdm. Mils Mfls Below Surface 3.5 60 240 15. 5 18 40 13. 5 19 Nil Nil 11. 9 18 N 11 "Nil 2.00 Nil 80 350 6.49 Nil 55 200 16.09 21 30 3 60 19.41 28 Nil Nil 3. 52 1 80 220 23.80 36 40 i 60 20. 60 29 30 30 12.27 11 N11 Nil 1.66 Nil 70 230 5.19 N11 40 150 14.80 20 Nil Nil 18.67 26 Nil Nil 5. 18 2 85 300 12.38 15 35 50 14.88 18 Nil Nil 18. 70 35 Nil Nil 2.8 2 so 280 5.0 22 40 I 50 20.9 32 10 50 20.9 30 20 40 3.8 4 20 '80 12. 7 21 15 50 12.4 22 Nil Nil 15.5 21 20 60 3.8 3 120 280 112.0 7 16 T 25 80 10.7 18 M50 8.5 14 N11 20 3.7 2 80 250 6. 6 a 9 9.4 14 'N11 Nil 7. 5 1 6 -Nil J 90 4.6 0.5 q 280 9;9 7 6. 6 10 Nil Nil 12.8 24 Nil Nil 3.5 0.5 40 300 3.6 0.5 Nil Nil 4.8 A 8 .Nil Nil 3. 1 6 Nil Nil 3.0 2 80 300 .12. 1 18 5 100 '14. 9 '21 'Ni1 20 12.8 20 Nil Nil 3. 7 2 so .250 6. 6 3 9 40 50 9.4 14 N11 Nil 7. a 6 ,Nil a N11 As above .stated thegrnajority of the specimens were found to.befree scaling, but the -Ti (5-15)Sn-10Cr alloyshad rather adherent sealeswith little loss in metal 5 orridation and no noticeablecontamination as measured by hardness. The Ti .10(;r control alloy had a similar scale, but; the underlying rnetal was highly contaminated. --Thus, when-10% chromium-is present,-tin appears to m iaiiai ljt iaat aiet .raiateaa yithqu the re ing. characteristics, thus indicating utility of these alloys at elevated temperatures.

Q ur investigations have f urther shown that the Ti (5-1-;5)n10Cr alloy, with and withoutadditions of.-,up to of onepr moreof iron, molybdenum and manganese have expellent eleyated temperature hardnesses combined with contaminationresistance at temperaturesashigh as- 800 to 900 F., and good hardness at :temperatures up to 1100 to, 1200; F. is: shown byl the test results submittedin the following Table XIII.

Hot hardness values of Ti-Sn base alloys for elevated 30 .temperature service n hotrolledandann ealed] Composition, v ,250 v 1500 760 1000 1.250 1,500 80 gereengtfiglialnnca 80]. ,F. F. F. iii, F. F. F. .2 H. .7 35

195 rd 116 72 as 233 221 ms 133 107 so 23 287 235 189 "1152 "132 11 27 292 276 223 123 .32 18 476 235 269 241 '160 "51 27 351 294 261 235 144 42 24 359 e13 275 254 -55 26 was 327 1219 ;265 179 as 32 317 5Sn10Cr5Fe 353 322 315 244 92 37 409 ""6Sn 100r5M0' ans --290 246 "240 -75 333 '34s 5Sn--10Cr -5Mn- 324 314 .286 271 186 as 31 376 Mn e77 340 2 69 235 106 4a Hardness at room temperature after being heated to 1,500 F. tztmefled 2 hours at 85010. prior to testing; other analypes annealed a z -Referringto-the above-data, a comparison of the hardne ss values of the binary Ti4n alloys with the binary Ti Cr.alloys shows that it thef chromium or beta addition which promotes the higher hardness at. temperatures up to 800 to 900 F. As further shown by the above data,;,t he.combination of tin and .chromium provides an added hardening increment, due to the tin, h. .n im ne at eyate u te p am e As ..ther. shown, the.substitutionofimanganese, iron and molybdenum for part of the chromium-has varied efiects. LIron additions resultjn. higher hardnesses, Zwhich pre- ---.va temperam nt? wt 2 M n ne .-.ditions do. not. change the. hardness. ofthe -TiSn-Cr alloy, while molybdenum additions produce some -decrease hardness which prevails at all temperatures re- I ferredto- On the basis ofhardness alone, the Ti.5Sn- 1 0Cr 5 Fe alloy is best. However, onthe ,basislof strong .and ductile. room temperature properties as well as eler te t e a u .sent afiaafi n re i a and hardness, theTi Sn- Cr Q/Io, Mn) alloys are of best all-around utility.

The room temperature properties of these alloys are given in the following Table XIV:

TABLE XIV 26 ultimate strengths at least 30 to 50% in excess of the unalloyed titanium base Mechanical properties of TiSn-Cr base alloys for elevated temperature service [These alloys were 980 0. forged, hot rolled at 1,400 F. to 0.080 inch, descaled, hot rolled at 1,300 F. to 0.040 inch, held minutes at 1,300 F., furnace cooled at 1,100 E, and

air cooled to room temperature] The alloys of the invention may be made :by melt casting in a cold mold, employing an electric arc in an inert atmosphere, or may be produced in other ways in which the alloy is rendered molten before casting.

Where the alloys are to be used in the form of sheets, the minimum bend ductilities may range as high as T, and where they are to be used in massive form, as in forgings, the percent tensile elongation may range as low as l or 2%. Minimum bend ductility T is defined as the minimum radius to which a specimen can be bent through an angle of 75 without fracture, expressed as a multiple of the specimen thickness.

It will be observed from the data in the tables above set forth that the alloys of the invention have ultimate tensile strengths at least 10% in excess of the unalloyed titanium base metal, and in the vast majority of instances,

References Cited in the file of this patent UNITED STATES PATENTS 2,779,677 Jafiee et a1. Jan. 29, 1957