IL32017A - Fabrication of articles from the high strength precipitation hardened alloys - Google Patents

Description

pnn mVya nuioaos o*asn ns»* y p'p »Mp pptng? n aa ^ ^ Fabrication of articles from the high strength precipitation hardened, alloys UNITED AIRCRAFT CORPORA ION Ce 30325 The present invention relates to the high strength, ig temperature alloy field and, more particularly9 to fabrication methods utilising such alloyw.

In the gas turbine engine industry, to which the present invention has particular application, the engine design criteria require the use of alloys with good high temperature strength and oxidation-erosion resistance. In response to the need, a number of alloys have been developed and used* Unfortunately, however, while the high temperature strength demands have been satisfied, they have generally beenachieved only at the expense of alloy fabricabllity, and in the manufacture of jet engines, comprising thousands of individual parts of intricate shape formed to close tolerance, fabricabllity of the alloy is a major factor in determining the extent of its utility* While in many industries the solution to the fabricabiHty problem may be conveniently provided b alteration of the allow chemistry, there are so many related criteria imposed on the gas turbine engine alloys tha improvestents in fabrication methods are necessarily made, if at all, despite the alloy chemistr ♦ Ihe prior art as exemplified by O.S» atent ί?ο. 2,666,721 discloses a process for producing a fine grained molybdenum base metal and includes deforming the alloy in the range of at least 60-90 at temperature below its recrystallizati temperature and thereafter annealing at a temperature in excess of the reerystallization temperature* British Patent No. 1,065,100 discloses a process for improving the ig temperature strength and low temperature ductility of niobium base alloys by subjecting the alloy to a high temperature while compressing i from 33 to 9¾¾* Such a Israel Patent Bo. 22274 discloses a process for fabricating beryllium products obtained with a reorientation of the elemental crystallites in parallel relationship to the direction of extrusion.

These processes are not applicable to the fabrication of high strength precipitation alloys, where the problem is to facilitate the workability of the alloy during its fabrication.

In the present invention the method of fabricating articles from the high strength precipitation hardened alloys comprisesΪ working the alloy in compression at a temperature below but within about 250°C of its normal recrystallization temperature to a compressive strain equivalent to that provided by at least about a 4 to 1 reduction in cross-sectional area to depress the recrystallization temperature below normal alloy recrystallisation temperature, producing a recrystallized mlcrostructure having a grain size not exceeding about 35 microns and temporaril placing the allow in a condition of high ductility, forging the allow to the desired configuration in hot dies at a forging temperature within about 194°C bu not exceeding on a sustained basis? the normal recrystallization temperature of the alloy, while inhibiting a substantial grain growth and heat treating the forged alloy to restore it to its normal condition of high strength and hardness.

In a more preferred embodiment, the strong precipitation hardened nickel base and titanium base alloys are worked in compression and forged below but within abou 111°C of their normal recrystallization temperature in hot dies in an inert atmosphere; and subsequently heat treated to restore their high strength.

She Initial development work was directed to the improvement in the fabrication techniques utilized with the titanium base alloys and the precipitation-hardened nickel base superalloys. Representative of the elements of particular interest are those nickel base alloys designated in the industry as Kar M 200, IlflOO, Inconel 718, Waspaloy, Astroloy, Odliaet 500, Rene 41» Inconel X and Inconel 625 and the titanium base alloys, Ti-6Al-lMo-lY and Ii-6Al-2Sn-42r-2I-!o. In the discussion which follows it will be convenient to make reference to several of these alloys, the nominal composition„ by weight* of which is as followss IN100 10 chromium, 15 cobalt, 4.5$ titanium, · 5% aluminum, 3% molybdenum, 0.17% carbon, 0.75% vanadium, 0.015% boron, 0.05% zirconium, balance nickel Waspaloy: 19-5% chromium, 13.5% cobalt, 0.07% carbon, 3% titanium, 1.4% aluminum, 4% molybdenum, 0.005% boron, 0.08% zirconium, balance nickel Astrolo : 15-5% chromium, 17% cobalt, 0.07% carbon, 3-5% titanium, 4.0% aluminum, .0% molybdenum, 0.025% boron, balance nickel Titanium 8-1-1 : 7.9% aluminum, 1.0% molybdenum, 1.0% vanadium, balance titanium The precipitation hardened alloys are those which have been strengthened by the precipitation or aging of a second phase from a matrix that has been heated high enough to take the second phase into, solid solution. In the nickel base alloy system the precipitated phase usually contains aluminum titanium or columbium, or some combination thereof. These alloys find particular utility in the hot section of gas turbine engines, the IN100 alloy, for example, often being utilized in vanes and blades, while turbine disks may be formed of Waspaloy. In general, the alloys are strong and hard.

In terms of hardness, most of the nickel base super-alloys have a hardness at room temperature in the range of Rockwell C 38 to 44. A low carbon structural steel is about Rockwell C 20, a high carbon tool steel about Rockwell C 65· In the condition of high ductility, as hereinafter discussed in greater detail, the nickel base superalloys are in the range of Rockwell C 38-44 at room temperature.

IN100 is the strongest. This alloy, specifically designed for casting application, is one of the most difficult to work using conventional forging practices. Because of its resistance to deformation and strength at high temperatures it is normally utilized only in the cast condition, blades and vanes being fabricated therefrom by investment casting techniques which can be adapted to provide parts of precise dimension. While it would be desirable to utilize the strength properties of this alloy in other applications, such as turbine disks, a wrought microstructure is usually preferred and, accordingly, the IN100 alloy is not presently used in the fabrication of disks or similar components.

Even the lower strength materials which can be forged, such as Waspaloy, are so worked at the present time only with great difficulty in heavy presses and hammers and to relatively simple shapes. Consequently, subsequent machining of most if not all surfaces is required.

The initial effort was directed toward improved fabrication techniques for the IN100 alloy which, as mentioned, is one of the strongest alloys and, concomitantly, one of the most difficult to work by conventional techniques. Despite the fact that this alloy is formulated as resistant to deformation, it was found that a certain combination of fabrication parameters could be applied to the 110.00 alloy whereby it could be readily forged to close tolerances and very complex shape. Utilizing the discovered techniques, it has been found possible to stretch IN100 test specimens to over a 1300% elongation. The results have been so promising that it is now considered perfectly feasible to forge the IN100 alloy into components such as turbine disks , and the forging may be accomplished in relatively conventional probable that not only can these alloys be readily forged " into components such as turbine disks, but also that the disks can be made with the blading formed integral therewith. And it will be remembered that the IN100 chemistry is such that this alloy has previously been considered virtually unforgeable .

Illustrative of the significance of the improvement in forgeability of the alloys processed by this technique is the fact that, while the stress required to press forge conventional Astroloy to a disk configuration at 1177°C is in the range of 3160 kg/cm , the processed Astroloy of the present invention can be press forged at 1038°C and approxi-mately 84 kg/cm . This is a reduction in stress of greater than 37 to 1 along with a 139°C reduction in temperature.

Representative date from a number of tests performed with the INIOO alloy to determine the preferred fabrication parameters are set forth in Table 1. Similar data are provided for the Astroloy and Waspaloy materials in Table II and III, respectively, and for titanium alloy 8-1-1 in Table IV. Tensile test results for the various materials are set forth in Tables V, VI and VII.

TABLE I STRESS RUPTURE TEST RESULTS IN-100 BAR STOCK Test Type Reduction Reduction Test No. Reduction Ratio Temperature Temp. % Elong.% RA C°c) (°C) 1. Extrusion 6 to 1 1149 982 326 99+ 2. " 10 to 1 1149 982 187 87 3. 16 to 1 1149 982 46 53 . 6 to 1 1149 plus 982 358 99+ 6 to 1 1093 - 10 to 1 1149 plus 982 398 99+ to 1 1093 . 10 to 1 1149 plus 982 720 99+ to 1 1093 . 16 to 1 1149 plus 16 to 1 1093 871 4-5 50 899 240 90+ 927 217 99+ 982 556 99+ 1038 1330 99+ 1093 1220 99+ 1 Q 2 0 90+ . 5-3 to 1 1121 871 33 3 899 52 52 927 41 55 982 108 93 1038 125 93 1093 192 98 - 5-3 to 1 1121P1US 982 147 93 3 step TABLE II STRESS RUPTURE TEST RESULTS OP ASTROLOY BAR STOCK Test Type Reduction Reduction Test % Elong* % RA No. Reduction Ratio Temperature Temp. (°c) °c) 1. Rolling 2.6 to 1 IO52 Plus 927 99+ 2.8 to 1 995 982 525 99+ 1038 622 99+ 2. 2.6 to 1 1038 927 387 99+ 2.8 to 1 1010 982 636 99+ 982 10 99+ 1038 578 99+ 1038 465 99 3. 7- 3 to 1 1038 927 592 99+ 982 620 99+ 982 473 99+ 1038 734- 99+ 1038 575 99+ . 7- 3 to 1 IO52 927 420 99+ 982 376 99+ 1038 498 97 - 7- 3 to 1 1066 927 406 99+ 982 758 99+ 1038 540 No failure . Extrusion 10 to 1 IO52 IO52 64 55-8 TABLE III STRESS RUPTURE TEST RESULTS WASPALOY BAR STOCK Test Type Reduction Reduction Test No. Reduction Ratio Temperature Temp. % Elong. % RA C°c) <°C) 1. Extrusion 10 to 1 1038 9 -1 12 42 It 995 111 81 1038 122 96 2. II 6 to 1 995 995 62 99 It II IO38 86 99 3. It II 968 968 61 67 4. II tl 941 94-I 75 79 II 1038 148 99 . If to 1 94-1 94-I 15 98 1» it It 941 160 96 It II II 982 148 98 It It II 982 142 97 . II to 1 94-1 Plus 94-1 99 93 It It 995 235 99+ 1038 116 99+ 7. Rolling 7- 3 to 1 982 Plus 927 225 99+ 3- 9 to 1 968 982 695 99+ 1038 173 99+ TABLE IV STRESS RUPTURE TEST RESULTS TITANIUM ALLOY 8-1-1 BAR STOCK Test Type Reduction Reduction Test No. Reduction Ratio Temperature Temp. % Elong. % RA (°o) (°C) 1. Extrusion 10 to 1 927 816 221 99+ 2. " 10 to 1 871 816 303 "99+ 3. " 10 to 1 816 816 322 98 II It It tt 240 97 4. " 10 to 1 760 760 228 99+ II II II 760 246 99+ II II It 816 229 99+ - " 4 to 1 760 760 177 98 II It 760 159 95 It 816 177 97 6. " to 1 704 704 90 99+ 704 121 95 816 253 99+ Since the rupture testing was in air, tests above 816°C resulted in oxygen diffusion into the base metal increasing the strength and lowering the ductility. This condition required continuous uploading of specimens.

TABLE V TENSILE TEST RESULTS ASTROLOY BAR STOCK Test Type Reduction Reduction Test Flow No. Reduction Ratio Temperature Temperature Stre 1. Rolling 2.6 to 1 1038°C Plus 927°C i l05 2.8 to 1 1010 2. 927 1975 3. 982 2210 k. 982 2½90 . 982 1000 6. 1038 1596 7. 1038 930 8. 1038 59 ½ 9. 1093 1142 . 1093 3 11. 11^9 988 12. 11^9 580 TABLE V (Continued Test Type Reduction Reduction Test Flo No. Reduction Ratio Temperature Temperature Str 13. Rolling 7.3 to 1 103δ 927 471 14. 927 285 . 982 7 16 , 982 104 17. 1038 176 18. 1038 77 19. 1038 33 20. 1038 16 21. 1038 5 22. 1093 117 23. 1093 61 24. 1149 96 . 1149 58 TABLE V (Continued) Test Type Reduction Reduction Test Flow No. Reduction Ratio Temperature Temperature Stress 26. Forging 8.5 to 1 1038 °c 1038 °c 829 27. 956 28. 98k 29. ? . 815 31. 766 32. 790 33. 7^0 3½. 910 35. 883 36. 78Ο 37. 1012 38. IO26 39. ½ * >. 620* 593* TABLE V (Continued) Test Type Reduction Reduction Test No. Reduction Ratio Temperature Temperature 42. 43. 44. 45. 46. 7. 48, 49. 50. 51. 52. Forging 8.5 to 1 IO66 IO58 53.

TABLE V (Continued) Test Type Reduction Reduction Test No. Reduction Ratio Temperature Temperature ^· Forging 8.5 to 1 1066 °C 1038 °C 55. 56. 57. 58. 59. 60. 61. 62. 63. 6* . 65.

TABLE V (Continued) Test Type Reduction Reduction Test No- Reduction Ratio Temperature Temperature 66. 67. 68. 69. 70. Forging 8.5 to 1 IO38 IO38 71. 72. 73-7 . 75. 76. 77. 78.

* Transverse specimens TABLE VI TENSILE TEST RESULTS WASPALOY BAR S Type Reduction Reduction Test Reduction Ratio Temperature Temperature Forging 8 .5 to 1 96 982 I I TABLE VI (Continued) Test Type Reduction Reduction Test No. Reduction Ratio Temperature Temperature . 1 16. 1 17. 1 18. 1 19. 1 . 1 I H 21 . i CO I 22. 1 23. 1 24. 1 . 1 26. 1 27. 1 TABLE VI (Continued) Test Type Reduction Reduction Test Flow No. Reduction Ratio Temperature Temperature Stres 28. Forging 8.5 to 1 968 982 2299 29. I683 . I695 31. I660 32. 2D 33 33. 1905 3 . I835 . l64o 36. 1590 37. 1580 38. 1893 39. 1705 0. 1 65 41. 1635 TABLE VI (Continued) Test Type Reduction Reduction Test Flow No. Reduction Ratio Temperature Temperature Stresi 42. 2104 43. 1633* 44. 1 35* 45. 1 7* 46. 1557* 47. 1535* 48. 1546* 49. 1560* 50. 1675* 51. 1720* 52. 1315* 53. 1390* 54. 1590* * Transverse specimen TABLE VII TENSILE TEST RESULTS Ti 8-1-1 Test Type Reduction Reduction Test No. Reduction Ratio Temperature Temperature 1 . Extrusion 10 to 1 92? °C 816 °C 2. II 92? 927 3. II 927 92? If . II 871 8l6 11 871 927 6. » 1» 8l6 70k 7 . II 816 760 8. II 816 816 9. II 816 816 . II 8l6 871 11 . II 816 927 12- to 1 760 816 13. II 76Ο 927 In addition to the aforementioned tests, a number of actual forgings were made. In one test an IN100 alloy bar was extruded at 1121°C using 5· 3 to 1 reduction to provide a cylindrical billet 5· 08 cm in diameter and 10.16 cm in length. It was pressed in heated dies at 1038°C and 40 tons pressure with no dwell time to produce a shaped pancake 13· 55 cm in diameter. A similar specimen forged at 1038°C in heated dies at 60 tons pressure with a three minute dwell produced a 15·2 cm diameter pancake. Following one such test it was discovered that the die has developed a hairline crack which was exactly reproduced in the pressed pancake in the form of a thin walled fin. A further indication of the ductility of the material was the fact that grain structure evident on the surface of the die was reproduced on the exterior of the pancake. In later forging experiments a similarly produced billet was forged in a die designed to cause metal flow diametrically inward and then axially forward into the die to form a thin annular flange portion on the end of the pressed article. This particular forging expe-riment was selected as representative of one of the more difficult types of forging, and the inward and forward flow of the I 100 material was effected.

It is evident that a particular combination of temperature and compressive working places the material in a condi-tion of very high temporary ductility, very high relative to the ductility in the unprocessed condition. The ductility is temporary in the sense that it is maintained only as long as grain growth is prevented and thus it is present only during the alloy fabrication process. Once the fabrication has been completed and the article is heat treated to produce grain growth and to restore the alloy to its original high its operating environment will restore it to a condition of very high ductility.

In the fabrication process, therefore, significant grain growth of the alloy should be avoided not only during the initial working of the billet but also during the forging process. It has been found that the alloy billet should be worked in compression preferably at a temperature within about 250°C of the normal recrystallization temperature of the material. In addition, the forging must be performed at a temperature approaching the normal recrystallization temperature. For this reason, a departure from the normal forging practice is dictated. Except in exceptional circumstances, the forging will be accomplished utilizing dies heated to the forging temperatures in an inert atmosphere and with the use of high temperature lubricants.

The hot dies used in the forging operations to date were made from TRW 2278 , a nickel base casting alloy similar in composition and strength to MAR M 200. Other suitable materials will be evident to those skilled in the art. Since an inert gas cover is preferentially utilized in the forging process, alternative die materials such as TZM molybdenum alloy will also be suitable. Further, because of the use of an inert atmosphere, the dies have been heated by induction coils. Numerous alternative die heating methods will, however, be found satisfactory.

The fabrication parameters for production of billet stock are selected so that the combined effect of heating resulting from that applied from an external heat source and that generated internally of the material as a function of the working does not result in a temperature rise sufficient to cause substantial grain growth. As a general rule, there the lesser the preferred working temperature. In the more » preferred processes, the total required reduction is effected in a plurality of passes.

In the original work, because of the evident relation-ship of the process parameters to the alloy recrystalliza-tion temperature, it was initially thought that recrystalli-zation should be avoided in the hot cold-working and forging steps. Subsequent analysis of the hot cold-worked material revealed it to be hot-worked, hence, recrystallized even though the grain size was too small to be visible by conventional light microscopy. Recrystallization apparently takes place simultaneously with the "hot cold-working" but with substantial inhibition of grain growth. Further, it is apparent that the "hot cold-working" lowers the recrystalli-zation temperature of the alloy very significantly below that found in the same material as conventionally processed.

Because processing as taught herein does inhibit grain growth short transients of up to 10 minutes above the normal re-crystallization temperature, while preferably avoided, are yet not fatally detrimental to the achievement of the intended advantages .

With respect to the total reduction necessary to achieve the desired temporary ductility, it appears that a reduction of at least about to 1 is the practical minimum necessary at the most preferred working temperature. No maximum working limit has been discovered except, of course, insofar as it results in an internal heat buildup during processing as previously discussed.

Initially, the compressive working was provided by extrusion, particularly in the case of the IN100 alloy. Utilizing these results for background information, Astroloy, Waspaloy, and titanium alloy 8-1-1 were similarly extruded.

Astroloy extruded at 105 C using an extrusion ratio of 10 to 1 did not exhibit the desired high temporary ductility.

Similarly, Waspaloy extruded at 1010°C, 968°C and 9 1°C at an extrusion ratio of 6 to 1 was not satisfactory. How-ever, Waspaloy extruded at 94-l°C with an extrusion ratio of to 1 and double extruded at to 1 followed by to 1, showed a degree of ductility suitable for close tolerance o forging. Also, titanium alloy 8-1-1 extruded at 927 C,871 C, 316°C and 760°C with an extrusion ratio of 10 to 1 and at 760°C and 704-°C with an extrusion ratio of 4- to 1 shows the desired degree of ductility.

A review of the microstructure of various of the Waspaloy and Astroloy extrusions revealed that in some cases the expected ductility was not achieved due to a buildup of in-ternal heat resulting from the compressive working. In other words, the combination of externally applied heat together with that generated internally during working resulted in excessive grain growth.

This extrusion work indicated that, depending to some extent upon the working temperature, the total reduction may advantageously be made in two or more extrusion operations. Furthermore, since the buildup of internal heat during rolling or forging operations is much less than that developed in extrusion, these forms of compressive working may in some instances advantageously be utilized to provide the requisite reduction, particularly in the case of Waspaloy and Astroloy, or to supplement the work produced by other methods.

Application of the described techniques to commercial quantities and sizes of the various materials was under-taken and the temporary ductility was produced. A series of 3Ο.5Ο cm diameter ingots of both Waspaloy and Astroloy were rolling temperatures. From the 22.86 cm square stock, the ™ material was reduced to 8.89 cm round stock by a combination of rolling and press forging.

The particularly preferred process parameters for the IN100, Astroloy, Waspaloy and Titanium 8-1-1 alloys are set forth below. A variety of starting materials have been utilized, including a powder product of IN100 and a vacuum induction melted fine grain ingot of IN100, a vacuum induction followed by a vacuum consumable melted controlled grain size ingot of both Waspaloy and Astroloy, and a double vacuum consumable ingot of Titanium 8-1-1.

In the .case of INlOO a minimum reduction in billet stock of 5. to 1 is required in the temperature range of 1093°C -114-9°C Press forging is accomplished with a die temperature and material temperature of 1038°C - 1093°C in an inert atmosphere with a strain rate of approximately 0.5 cm/cm/min.

With Astroloy the minimum reduction in billet stock is 4· to 1 in the temperature range of 995°C - 1093°C. Press forging is done at 1038°C at a strain rate of 0.5 cm/cm/min.

Waspaloy is reduced in billet form at least to 1 at 9 1°C - 995°C and forged at 982°C at a strain rate of 0.5 cm/cm/min.

Titanium 8-1-1 is reduced at least to 1 in the temperature range of 704-°C - 927°C and forged at about 927°C with a strain rate of 0.5 cm/cm/min.

For the achievement of very close tolerances there appears to be an advantage for all alloys in the use of very low strain rates of perhaps 0.05 cm/cm/min.

The precise metallurgical mechanism by which the aforementioned results are attained has not as yet been completely resolved. It has been reported in the literature that a " " materials. See, for example, an article in the Transactions of the ASM, Vol. 53 (1965) by D.H. Avery and W.A. Backofin. In the present case, however, the basic considerations leading to the development of the alloy chemistry are ini-mical to a condition of superplasticity. The present invention provides a method whereby the strong, high temperature alloys may be placed in a condition of low strength and high temporary ductility and forged into useful configurations, not because of their chemistry, but despite it. And this is of fundamental importance, since an inherent condition of low strength and high ductility which exists because of the alloy chemistry at any temperature within a jet engine operating regime cannot be tolerated. In other words, it is of the utmost importance that the condition of low strength and high ductility be temporary and hence present only during the fabrication process.

To restore the particular alloy to its normal condition of high strength and hardness subsequent to the fofging operation, the conventional stabilization and precipitation heat treatment is all that is required. In the case of the IN100 alloy having a normal recrystallization temperature of about 114-9°C, the preferred heat treatment involves solution heat treatment at about 1190°C to produce grain growth which is followed by stabilization and precipitation heat treatment. The solution heat treat temperature of the various other alloys specifically mentioned herein are set forth in Table VIII.

TABLE VIII Wrought Normal Solution.

Recrystallization Alloy Temperature (°C) Heat Treat ( C) Mar M200 1218 1204 Inconel 718 968 954 Waspaloy 1010 1018 Astroloy 1121 1121 Udimet 500 1052 1080 Rene 1 IO52 1066 Inconel X 95^ 982 Inconel 625 9 4 982 Although the invention has been described in detail in connection with numerous specific examples, in its broader aspects it is not limited to the specific steps, methods, compositions and combinations described, but improvements to and departures therefrom may be made without departing from the principles of the invention and without sacrificing its chief advantages.

Claims (4)

CLAIMSi

1. .The method of fabricating articles from the high strength precipitation hardened alloys- comprisings ¾ork ^ the alloy in -compression at a temperature eloid but within about 250°C of its normal recrystallization temperature to a compressive strain equivalent to that provided by at least about a 4 to 1 reduction in cross-sectional area to depress the recrystallization temperature below normal alloy recrystalliza ion temperature, producing a recrystallised microstructure having a grain size not exceeding about 35 microns "and temporarily placing the alloy in a condition of high ductility, forging the alloy to the desired configuration in hot dies at a forging temperature within about 194°C but no exceeding" on a sustained basis the normal reerystallization temperature of the alloy, while inMb-ttlng a substantial grain growth and heat treating the forced alloy to restore it to its normal condition of high strength and hardness. -

2. The method according to Claim 1, characterized in that the working in compression is made by extrusion.

3. The method according to any one of the preceding claims, characterized in that the forging is conducted in an inert atmosphere.

4. The method according to any one of the preceding claims, characterized in that the worked alloy is a precipitation -hardened alloy of nickel or titanium. ·. . .. . . 5 J. The method according to anyone of the preceding claims, characterized in that the alloy to be worked in compression is in the form of a dense, sintered powder metallurgical billet. 5 5 6 The method according to anyone of the claims characterized in that the alloy which is a strong, high temperature nickel base alloy is worked at a temperature of at least 899°C, and forged at a temperature between °A1°C and its normal recrystallization temperature. 5 10 7 The method according to anyone of the claims L*-?", characterized in that the alloy which is a strong titanium base alloy is worked at a temperature of at least 704-°C and forged between 760°C and its normal recrystallization temperature. 5 15 8 , Γ. The method according to anyone of the claims 1?^ characterized in that the alloy, which is a "IN 100" alloy, is worked in compression at a temperature of about 1038°C- 11 9°C to provide a compressive stress equivalent to at least about a 5 to 1 diametrical reduction, forged at about 20 982°C-1093°C and heat treated at about 1190°C. 8 9 HT. The method according to claim JJrt characterized in that the working in compression is performed by extrusion and that the extrusion is performed in at least two steps to effect a total extrusion ratio of at least 16 to 1. 5l0 The method according to anyone of the claims 1^? characterized in that the alloy, which is "Waspaloy", is worked in compression at a temperature of about 84-3°C- 968°C, forged at a temperature of about 899°C-995°C and heat treated at 1018°C. 5 3011 ". The method according to anyone of the claims lySf characterized in that the alloy which is "Astroloy" is worked in compression at about 899°C-1066°C to a total red ction ratio exceeding about 6 to 1, forged at about 927°C-1066°C, and heat treated at about 1121°C. ^C. The method according to anyone of the claims l-j^, characterized in that the alloy, which is the titanium base alloy 8-1-1 is worked at about 704-°C-982°C , forged in a non-contaminating atmosphere at 872°C-982°C, and heat treated at 913 C-995°C.