US2779677A - Ti-sn-al alloys with alpha, beta and compound formers - Google Patents

Description

Jan. 29, 1957 R. l. JAFFEE ET AL 2,779,677

TISNAL ALLOYS WITH ALPHA, BETA AND COMPOUND FORMERS Filed Dec. 28, 1953 COMPARATIVE STRENGTHENING 519 mvojn 56 ANDS 4140) I AUDIT/0N5 r0 COMMEEC/AL Pc j/e/rr Ti-BAsE EFFEcrs oFA tkl vzumk n Qdruvm lhuh bsld o kzunu kmmw ADDED ELEMENT, I'VE/6H7" PER CENT ..H. 5 ir y mi? M Z R mg: m WMRMOATM a: i x 50W Y B United States Patent Ti-Sn-Al ALLOYS WITH ALPHA, BETA AND CQMPOUND FORMERS Robert I. Jafiee, Worthington, and Horace R. Ogden and Daniel J. Maykuth, Columbus, Ohio, assignors, by mesne assignments, to Rem-Cm Titanium, Inc., Midland, Pa., a corporation of Pennsylvania Application December 28, 1953, Serial No. 400,744

14 Claims. (Cl. 75-1755) 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 titanium, tinand aluminum, 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 applicants prior applications Serial Nos. 151,314, filed March 22, 1950, now abandoned; 209,905, filed February 7, 1951, now abandoned; 253,564, filed October 27, 1951, now abandoned; 213,681 to 213,687, inc., all filed March 2, 1951, now abandoned; 235,076, filed April 29, 1952, now

Patent No. 2,669,513, granted Feb. 16, 1954; and 294,263,

filed June 18, 1952, now abandoned.

The aluminum content may be present over a broad range of about 0.25 to 8% and preferably about 1 to 8%. The tin content may be present over a broad range of about 1 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 titaniurn-tin-aluminum alloy aforesaid, there may advantageously be added up to about 20% in aggregate of one or more of the other 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 nitrogen up to about 0.4%. When the total tin and aluminum content is below about 5%, and particularly when below about 2.5%, substantial additions of one or more of the inter- ,stitials carbon, oxygen and nitrogen or of metal of the alpha and/ or beta promoter groups, is required for imparting high tensile properties for commercial applications, as elaborated upon below.

-As above stated, the alloys of the invention are in general characterized by excellent room temperature mechanical properties, possessing high tensile strength as compared to the unalloyed titanium base metalor as compared to the corresponding binary titanium-tin ar d titanium-aluminum alloys, combined withadequat'e duhtility for both hot and cold forming operations, i. e., forging, rolling, drawing, extruding, etc. For tin contents'lnp 'to about 16%, they maylikewise, in general, be weldedfwithout appreciable loss of ductility in the welded as compared to the non-welded portions. This is particularly true as regards those alloys having an all-alpha microstructure, and also as to certain of those having a beta- 2,779,677 Patented Jan. 29, 1957 'ice containing microstructure, as explained more in detail below.

' fFor imparting a high degree of contamination resisttime, i. 'e., resistance against penetration by atmospheric gases, particularly oxygen and nitrogen, at elevated tem' peratures 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 exposure to elevated temperatures up to about 1100 C. and to atmospheric, oxidizing, or alternately oxidizing and reduc ing conditions. That is to say, the scale formed is easily brushed off or flakes off during hot forming operations, such as forging or rolling.

Test results in support of the above are given in a copending joint application of the present applicants Jalfee and Ogden and W. L. Finlay, Serial No. 341,796, filed March 11, 1953, now Patent No. 2,669,514.

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 aluminum, tin, antimony, indium, silver, bismuth, lead, cadium, zinc, and thallium as well as the interstitials carbon, oxygen and nitrogen may be termed alpha. stabilizers or alpha promoters. The term alpha stabilizer includes those elements which raise the transformation range sharply, such as aluminum, oxygen, and nitrogen. Also alpha stabilizers 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 effects 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. Silicon andberyllium 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, alpha-beta alloys, or all-beta alloys. These are the elements which have beta-isomorphous diagrams, or which have betaeutectoid 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 eutectoid beta promoters, because the beta phase stabilized by copper always decomposes rather rapidly into pro-eutectoid 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 betastabilizing 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 Ti-Sn-Al base alloys of the invention with respect to additions of the various beta promoters above mentioned, varies considerably for the individual elements of this group, being greatest with respect to those which form beta-isomorphous systems with titanium, and least for those which decomposemost readily into eutectoid decomposition products. Thus, the Ti-Sn-Al 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. Metal of the group cobalt, nickel and copper may be added up to a total of about For additions of all of the above-mentioned beta promoters, the lower effective limit is about 0.5% and preferably about 1%.

The tolerance of the ductile Ti-Sn-Al base alloys for the other alpha promoters depends on the amount of tin and aluminum present, the less tin and aluminum present,

.the greater the amount of other alpha promoters that p can be added, and vice versa. Antimony may be added to a maximum content of 18%. The preferred proportioning of the antimony content in relation to the tin and aluminum contents are 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 effective limit for the alpha promoters is about 0.5% and preferably about 1%.

The elements Ce, B, 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 baryllium are likewise best grouped as compound forming elements, in view of their abovementioned low solubilities in titanium and the tendency of the beta phase stabilized by these elements to decompose rapidly into eutectoid products. The Ti-Sn-Al base 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 or stabilizing 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 allbeta alloys, on the other hand, have excellent bendability 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 allalpha and all-beta alloys, being strong when cold and warm, but weak hot, while possessing good bendability and ductibility, with a moderate degree of resistance to atmospheric contamination.

Since the Ti-Sn-Al 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 quaternary 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 quaternary and higher component alloys made by additions of the betaisomorphous 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 Robert I. Jaifee, Horace R. Ogden and Ralph A. Happe, Serial No. 305,504, filed August 20, 1952 bearing common ownership.

" In the ductile Ti-Sn-Al base alloys of the invention, the following Table A shows the preferred maximum aluminum content for any given tin content throughout the range above specified for these elements:

tin or mpanying gths for the varying per- -Al alloys of aluminum substituted shear the other on *a basis, i. e., percent for percent. that 1% aluminum is roughly equivalent to 3% of antimony in strengthening effect.

5 This equivalency is also shown by the acco drawing giving the 0.2% oifs'et yield' :stren Ti- 1, Ti-Sn and Ti-Sb binary alloys for centages of the alloying additions. I

For additions of antimony to the Ti-Sn "10 the invention, the following Table B ferred maximum antimony content for and tin contents s, the 15 Percent Aluminum Max.

TABLEA Percent Tin Thus, for best results, as the tin content increase aluminum content should be decreased in the above proportions and vice versa.

In m n 5 MR 3197 65 mi M 11 A m Wm 555555 HT P m 5 m 2 W 0 123 5 Pm A 0 2 ammm mama 0 r1 arm 6 e l h m PM t y b m n n w n o h S .E m T Antimony is a particularly valuable addition to the Ti-Sn-Al base alloys of the invention, as it imparts thereto about the same strengthening effect as equivalent additions of tin or aluminum.

ing Table I presenting test data on room te mechanical properties which establish the for various combinations of antimony,

in titanium base alloys 67272 5290 3 61721572557349.52mn o T 3766776 555% l4335 234T 3 1343223335233 23 15 387227 3w 6 n\ 00 B0 6 B B 3 2 2 22 5550 559v. 5 5 52759579846865082058819898 8883 Vickers Percent Hardness Reduction in Area Percent Elongation in 1" l l 5 7420 5350685565557477 7779 HHUH NUM m HMHBW1MN111B11121 111111 11 74114 1138 1.6 1648217168755879677617932104 554 5 1 11 11114. 5 41 111.13 3333 HBH UBN um n1u1lHH11111B1M11m11111 1111 Ti-Sb-Sn-AI alloys Tensile Properties: p. s LXLOOO.

10.2 i Percent Ultimate Ofiset Stren Yield Table I.-Mechanical properties of Ti-Sb-Sn ana' (COMMERCIAL PURITY Tl-BASE) [These alloys wera980 O. forged, 850 0. rolled and annealed two hours at 850 0.1

Composition, Percent (Balance Titanium) KIT" 1 Could not be fabricated.

The data ofthe above Table I establishes that aiiti- For alloys of the invention containing tin approximafi mony and tin are equivalent in strengthening effect when ing its lower limit, the following Table C shows the 8 TABLE D given Annealed Hardness, Min. Bend Vickers The properties are for 15 without and with various additions of the interstitials carbon, ogygen and nitrogen. these alloys as hot rolled to thin gauge, i. e., about 0.04 inch and thereafter annealed in argon for two hours at 850 C., unless otherwise noted.

Table II.-Mechanical properties of Ti-Sn-Al alloys with and without additions of O, O and N (Balance Titanium) 5 5 4 545545m4123qm44534.

n mmw 7 6%.... 8566 82 7 26205964240 035 .8 5 781 46.0 8 406 4789916 54 884497 2 mMA 5554 m45fl2 56554442421141Q 4M@5M. M224%22 3%332 4434344 34%522344wm4 m Pmm t m Ow v S m m A n B an n m m M e 1 59101509 71299 331 14 1 1 5 4062867881715699059 S mwm B 6%2222212 .d23211m111 1 mm m BWI 7 U 2212111112221111211 I e1 I m PEN M n u N s t .m U A an I T e e N. 1 W E A T 68602464 20722124563 mn T 7093675269090043317394871770362991547860173 9 Y 79102101 .1890222212 .1 I 3575869004576970950333850059698046794111022 0 111111 .1 1111111 e I fi m P t D 7 m L 97604678084323 7055 e 0 9.0046057309110121066 .154 505%6089400496 .53557 A 48091090107890 1201 Jfii I 23738596042749608492 .849 .38 9703409401 2130 I 1 11 111 111111 R E 6645 M N -0122 2 --I uouu 0 M O m C 0 .....................2.. r e 0 P Y 5 5 5 5 5 5 D 2 .%.mw..z.%.2 %.2..... .%.%.2 2..%.2... 0 M 0 0 0 0 0 0 0 0 0 0 0 000 0 0 0 me 0 m 0 C ible antimony content for any h mm m1 H mm m e v .wn i a e m y e n m n0 0 w u e m mnwm mm A an .m t 1 mm 3? HT 112 P bL. T e g .3 mm mm o a f I 6P he h 0 0 1 m 7 mm 13 Cr nt mmnmuw E Pn L A B A m T wmm %00000 1 aLa Zs PA tent:

maximum permlss aluminum con Conversely, if the aluminum content approximates i lower limit, the following Table D shows the maximum permissible antimony content for any given tin content Tabla lL-Mechanical properties of Ti-Sn-Al alloys with and without additions of O, O and N-Oontinued Composition, Percent Tensile Properties: p. s. i. 1,000

Balan e T um Annealed c "am Hardness, Min. Bend 0.2% Ultimate Percent Percent Vickers T Ofiset Strength Elonga- Reduction 811 Al O O N Yield tion in 1 1n Area (COMMERCIAL PURITY TITANIUM BASE)-Oontinued 10 3 0. 4 165 165 8 24 433 Br 10 3 0. 6 455 Br 10 a 0.8 47s I Br 13 1 0.2 122 148 13 23 390 2. 6 13 1 0. 26 139 144 22 43 383 3. 1 13 1 0. 2 134 140 15 31 376 3. 3 13 l 0. 14 149 151 16 35 413 3. 3 13 2 0. 143 153 18 20 411 4. 7 13 2 0. 2 140 150 4 5 386 3. 5 13 2 0. 16 134 154 9 23 387 3. 6 13 3 0. 2 164 164 12 13 416 Br 13 3 0. 2 156 159 5 13 420 Br 13 3 0. 22 166 4 331 Br 10 2. 0. 2 140 141 6 29 395 5. 5 3 0. 2 136 146 40 383 2. 8

' Very brittle.

It is thus apparent that the ternary alloys of titanium with aluminum and tin, with or without additions of the interstitials, constitute an outstandingly versatile and desirable group, offering a wide range of properties and a composition tolerance for any given set of properties which greatly facilitates their production. 7

The alloys of this invention, in general, will withstand Moreover, these titanium-aluminum-tin alloys are susceptible to a variety of useful modifications by additions of one or more of the various other metals above mentioned. V

For example, the following Table III shows the eflect on mechanical properties of additions of the various alpha promoters:

Table III (Ti-Sn-Al BASE PLUS ALPHA PROMOTERS) Composition, Percent (Balance Tensile Properties: p. s. i. X 1,000

Titanium) Min. VHN Bend 0.2% Ultimate Percent Percent T Sn Al Other 0, 0, N Ofiset Strength Elongation Reduction Yield in 1" in Area (IODIDE TITANIUM BASE) Sb 2. 5 5 0. 5 0. 25 C 150 157 14 23 390 4. 1 2. 5 5 1. 0 0. 25 C 137 138 17 26 403 2. 1 2. 5 5 1. 5 0. 25 O 143 144 5 11 418 Br 2.5 5 2.5 0.25 C 142 143 3 9 392 Br 2. 5 5 5 0. 25 C 134 1 5 409 Br Bi 2.5 5 0.5 0.25 O 131 133 15 28 403 4.1 2. 5 5 1 0.25 O 132 133 23 36 387 2.3 2. 5 5 1.5 0.25 0 141 143 3 10 415 Br Ag 2. 5 5 0. 5 O. 25 C 130 132 22 382 1. 6 2.5 5 1 0.25 O 132 133 20 45 383 2.3

(COMMERCIAL PURITY TITANIUM BASE) Sb 2. 5 2. 5 7. 5 15 48 339 2. 6 5 2. 5 5 114 118 13 44 343 2. 8 7. 5 2. 5 2. 5 110 117 15 40 345 2. 6 2. 5 2. 5 7. 5 136 137 8 24 402 2. 5 5 2. 5 5 154 157 5 18 400 6. 2 7. 5 2. 5 2. 5 144 146 5 21 390 3. 0 0. 5 5 2 103 109 15 43 351 I 2.8 1 5 1. 5 106 113 15 37 346 2. 1 1. 5 5 1 103 112 17 46 343 2. 9 2 5 0. 5 100 111 14 43 348 2. 8 5 2 l 5 1. 5 132 135 17 42 394 2. 8 1. 5 5 1 131 135 17 48 396 2. 8 2 5 0. 5 134 7 28 391 2. 8

1 Cracked during forging.

prolonged aging at temperatures as high as 460 C. with out material embrittlement. Hence, they are particularly The efiect on mechanical properties of adding the various beta promoters is shown by the following Table adapted for use under high temperature conditions. 75 IV:

Min.

VHN Bend Reduction in Area Percent Percent Table I V.-Continued 1 um mmiu Ultimate Elonga- Strength tionin Table V Tensile Properties: p. s. i. X 1,000

s Yield [Commercial purity titanium base] Other 0, O, N

5 5.0 55 5 88Am1L0 1L0 1L m 7483860198981387O6 44 4 1459697204 2 5 fl\n WW 2 2Z2 2 2 4-5 7 2 Z2&2 &6 &L@L44 LL ZA SImLEYmO aw 0 B 5 5 N 16.07 18 9 5M123781 77m 88 2 4fi315 8 6 6 \I) 565 78 3 65\I23 55 7 9 193 1 m m m m m m m m m m fiouandna uoomwmw MN4M43G33 3333333432 m m 2 n1 W M 026 63541 5471127616234m55080 4 584%92761 uA m 004 41%32322 4333433343111 3( 44 @212 33212 W P m m R m 1 x n t 1 L w E u 1 l) 1 6 59 11 6 55 7 2255 65 S M snnmwmm m 79 10811 lull IMH .1 0. PM B @m E m M t. I h e t D. g m 960376999 66612 7512773357mm5 25 79665 m7577 8 3 \1) 7 6 67 4 m mm A flemmummmmmu unmmmmmmmnumfi? 1 01 mmmwflmlm 1 m r t T 0 U I "m T e Y T t T 8 i1) 6 11 1 1 315 367 m R vommmnmwmmu mummummummmw? 101ml 1n1111111m u Q N m m m 0 O Titanium) Composition, Percent (Balance mmmmmmmmmmm 6 mmwmmmmmmmmmmmmmm lmmm 5 mmmmmmmmm 1 Broke while machining tensile specimens.

I Could not be fabricated.

The effect of addition of a multiplicity of beta promoters is shown in the following Table V (Ti-Sn-Al BASE PLUS MULTIPLE BETA PROMOTER ADDITIONS Composition, Percent (Balanco Titanium) It will be seen from comparison of the data given in the above Tables III-V inc. with that given in Table II, that the addition'of one or more metals of the alpha pro moting, beta promoting and cbmpound forming groups, to the Ti-Sn-Al base alloy of any given analysis, results in an increase in tensile strength. For certain additions, such for example as bismuth, silver or copper, the enhancement in strength is relatively slight per percent of such alloying addition, i. e., on" the order of a few percent. For other additions the enhancement in tensile strength per percent of the alloying addition is relatively great, on the order of to 30% or more, as in the case of such additions as antimony, beryllium, manganese, molybdenum, chromium, iron and vanadium, etc. Moreover as further shown by the test results, the degree to which'the base alloy is thus strengthened varies considerably with the amount of tin and/or aluminum present in the base alloy.

. Thus, by way of illustration of thepoints above noted, the comparative data in the tables referred to, shows that the addition of 1% of bismuth, silver or copper to the Ti-2-5Sn-Al-0.25C base alloy, increases the tensile strength from about 130,000 to 133,000p. s. i., an increase of about 2% per percent of alloying addition. On the other hand the addition of 1.5 Sb to the Ti-lSn-SAl base increases the tensile strength from 116,000 to 135,000 p. s. i., an increase of about 11% in tensile strength perpercent of the antimony addition. Similarly for the Ti-SSn-ZAl base, the tensile strength, of which is 92,000 p. s. i., the addition of 4% manganese increases this value to 126,000 p. s i., the addition of 5% molyb denum increases it to 130,000 p. s. i., and the addition of 4% chromium provides an increase to 147,000 p. s. i. The tensile strength is thus increased by about 8 to 15% per percent of alloy addition for such elements. On the other hand the addition of 1% manganese, molybdenum or chromium to the Ti-10Sn-1Al base increases the tensile strengths about 11% in the case of manganese and about 31% in the case of molybdenum and chromium, namely from 104,000 p. s. i. to 118,000, 136,000 and 136,000 p. s. i., respectively. Generally similar results are obtainable by vanadium additions as shown by the addition of 1.5% vanadium to the Ti-lOSn-lAl base resulting in an increase in tensile strength from 104,000 to 127,000 p. s. i., an increase of about 15 per percent of vanadium addition. Iron likewise has a high strengthening effect as shown by the addition of 2% Fe to this base resulting in an increase in tensile strength from 104,000 to 161,000 p. s. i., an increase of about 28% in tensile strength per percent of iron addition.

The above comparisons are merely illustrative of the fact above stated that additions of other metals from the groups referred to, to the Ti-Sn-Al base in general produce pronounced enhancement of the tensile strength of the resulting alloy. And this is accomplished without any material reduction in the ductility of the alloys as shown by the values for the percent elongation and minimum bend ductilities as tabulated in the various tables referred to. In this latter connection, it should be pointed out that Where the alloys are to be used in sheet form, as in foils for airplane wings and the like, the minimum bend ductility may range as high as about T; and where the alloys are to be used in massive form, as in forgings, the tensile elongations may range as low as 1 or 2%.

The alloys of the invention may be made by are melting in a cold mold furnace in an inert or argon atmosphere or by other procedures.

Tests in the arc welding of alloys in accordance with the invention establish that those which are predominantly alpha in structure and some of those containing beta stabilizers, notably chromium and molybdenum, may be welded without impairment of their annealed strength and ductility characteristics. Thus, arc welded specimens of the Ti-1Sn-3Al alloy were found to have in the weld zone an ultimate strength of 88,000 p. s. i., an elongation as of 14%, an area reductionof 48 a minimum bend'T of 1.5 longitudinal and 3.0 transverse. Similarly" the Ti-9Sn-3A1 alloy had in the weld zone. an ultimate strength of 125,000 p. s. i., an elongation of 10%, an area reduction of 38%, a minimum bend T of 2.5 longitudinal and 4.5 transverse. In addition, minimum bend tests made on arc weldedspecimens of various analyses, estab lish that, in'general, the bend ductility in the weld zone is as'goo'd or better than that of the base metal. These CODCiUSlOllS are substantiated by the following test results of Table Vi Table VI Comp osition, Pen Minimum Bend '1 cent (Balance (Longitudinal) l,itanium) Sn A1 Other Welded Unwelded Sample Sample 0. 2 0. 2 1 5 1. 8 2. 7 2 5 2. 7 2. 5 3 y 5 l. 8 3. 3 4 5 1 l. 7 5. 7 5 l 0. 2 0. 9 5 2 l. 9 1. 7 5 3 1 6 1. 8 5 5 t a 2. 5 2. 5 10 1. 4 1. 4 10 1 1. 5 l. 7 10 2 2. 0 2. i 9 4 4. 4 4. 0 9 5 r 5. 0 3. 0 13 0. 9 l. 4 13 l 2. 5 2. 3 l3 3 2. 5 2. 3 l0 1. 101' 5. 3 1. 7 10 2 401- i 71. 0 2. 5 10 1 5M0 2. 7 2. 2 l0 2 5M0 7. 1 2. 1 107 1 10310 0. 9 0 10 2 10Mo 4. s 1. 7 5 2 5M0 7. 0 2. 0 10 1 Shin 6. 0 2. 0

in the appended claims: by the expression other alpha promoters is meant elements of the group Sb, In, Ag, Bi, Pb, Cd, Zn and Th; by the expression beta promoters is meant elements of the group Mo, V, Cb, Ta, Zr, Mn, Cr, Fe, W, Ni, Co and Cu; and by the expression compound formers is meant elements of the group Si, Be, Ce, B, As, S, Te and P.

What is claimed is:

1. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 20% of at least one other alpha promoter, balance titanium, characterized in having an uitimate strength substantially in excess of that of the corresponding base alloy without such other alpha promoter addition, said alloy also having a minimum bend ductility of not over 20 T.

2. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5 oxygen, up to 0.4% nitrogen, 0.5 to 50% of at least one beta promoter, balance titanium, characterized in having an ultimate strength substantially in excess of the corresponding base alloy without such beta promoter addition, said alloy also having a minimum bend ductility of not over 20 T.

3. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to nitrogen, 0.5 to 20% of at least one other alpha promoter, 0.5 to 50% of at least one beta promoter, balance titanium, characterized in having an ultimate strength substantially in excess'of the corresponding base alioy without such other alpha promoter and bet-a promoter additions, said alloy also having a minimum bend ductility of not over 20 T.

4. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aliuminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.1 to 3% of at least one compound former, balance titanium, characterized in having an ultimate strength substantially in excess of that of the corresponding base alloy Without such compound former addition, and a minimum bend ductility of not over 20 T.

5. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 20% of at least one other alpha promoter, 0.5 to 50% of at least one beta promoter, 0.1 to 3% of at least one compound former, balance titanium, characterized in having an ultimate strength substantially in excess of the Corresponding base alloy without such other alpha promoter, beta promoter and compound former additions, said alloy also having a minimum bend ductility of not over 20, T.

6. An alloy consisting of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 20% of at least one other alpha promoter, balance titanium.

7. An alloy consisting of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 50% of at least one beta promoter, balance titanium.

8. An alloy consisting of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 20% of at least one other alpha promoter, 0.5 to 50% of at least one beta promoter, balance titanium.

9. An alloy consisting of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.1 to 3% of at least one compound former, balance titanium.

10. An alloy consisting of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 20% of at least one other alpha promoter, 0.5 to 50% of at least one beta promoter, 0.1 to 3% of at least one compound former, balance titanium.

11. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to, of at least one additional element selected from the group consisting of molybdenum, vanadium, columbium, tantalum, zirconium, balance titanium, characterized in having an ultimate strength substantially in excess of that of the corresponding base alloy Without such addition, said alloy also having a minimum bend ductility of not over 20 T.

12. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 20% of at least one additional element selected from the group consisting of chromium and tungsten, balance titanium, characterized in having an ultimate strength substantially in excess of that of the corresponding base alloy without such addition, said alloy also having a minimum bend ductility of not over 20 T.

13. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 10% manganese, balance titanium, characterized in having an ultimate strength substantially in excess of the corresponding base alloy Without such manganese addition, said alloy also having a minimum bend ductility of not over 20 T.

14. An alloy consisting essentially of about: 1 to 23% tin, 0.25 to 8% aluminum, up to 1% carbon, up to 0.5% oxygen, up to 0.4% nitrogen, 0.5 to 7% iron, balance titanium, characterized in having an ultimate strength substantially in excess of the corresponding base alloy without such iron addition, said alloy also having a minimum bend ductility of not over 20 T.

References Cited in the file of this patent UNITED STATES PATENTS 2,669,513 Jafiee Feb. 16, 1954

Claims (1)

1. AN ALLOY CONSISTING ESSENTIALLY OF ABOUT: 1 TO 23% TIN, 0.25 TO 8% ALUMINUM, UP TO 1% CARBON, UP TO 0.5% OXYGEN, UP TO 0.4% NITROGEN, 0.5 TO 20% OF AT LEAST ONE OTHER ALPHA PROMOTER, BALANCE TITANIUM, CHARACTERIZED IN HAVING AN ULTIMATE STRENGTH SUBSTANTIALLY IN EXCESS OF THAT OF THE CORRESPONDING BASE ALLOY WITHOUT SUCH OTHER ALPHA PROMOTER ADDITION, SAID ALLOY ALSO HAVING A MINIMUM BEND DUCTILITY OF NOT OVER 20 T.

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