Titanium Past, Present, and Future (1983) / Chapter Skim
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Chapter 7: Titanium Melting, Alloying, Mill Processing, and Heat Treating
Chapter 7: Titanium Melting, Alloying, Mill Processing, and Heat Treating
Pages 63-86
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From page 63... ...
Positioning consumable electrodes in vacuum arc furnaces for initial melting and locking up, evacuating, and backf illing furnace with inert gas at partial pressure. (Evacuating and backfilling is repeated as necessary to secure acceptable contamination-free conditions)
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From page 64... ...
These companies use similar equipment but it may vary in detail so that each company's overall process may be somewhat different from that of the others. Nevertheless, most companies apparently melt ingots to the same rigorous specif ications because the end products from different melters are markedly similar.
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From page 65... ...
_ ._Wa~er r - inlet | ~Water ~ Ingot outlet conditioning Water-cooled copper crucible _m - 3 <~ Stub Weld Second Malting Log Am, Ingot conditioning Titanium consumable electrode (ingot from initial melting} l - 6 Water inlet Figure 9 Flow diagram for the production of double-melted titanium ingots using consumable electrode methods. Triple-melted ingots are made similarly.
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From page 66... ...
Y2O Raw materials selection Sponge titanium Alloying additions A1-V master alloy Other make-up (Al, TiO Scrap Raw materials preparation Component weigh up Constituent blending Blend storage Consumable electrode preparation Charge consolidation (block press)
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From page 67... ...
5. Highly alloyed or otherwise difficult to melt ingots and their mill products have experienced relatively small demand.
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From page 68... ...
TABLE 8 Titanium Alloys of Current General Interest Offered by Producers in the Uni ted States Nominal Compositions, Weight Pe rcent Common Name 'Type Unalloyed Ti, 99.2a Commercially Pure Alpha Ti-O. 15 ~ o O .20 Ed Pd alloy Alpha Ti-O .3 Mo-O .8 Ni Ti-cod~ 12 Alpha Ti-SAl-2 .
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From page 69... ...
This material also is hardenable by heat treatment to greater thicknesses than other commonly available alpha-beta alloys. Thus, it is expected that this material will be used in increasing quantities in forging applications where high strength in thick sections is a requirement.
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From page 70... ...
Alph~Stabilizing Elements For example: Aluminum Oxygen Nitrogen 70 Eleta~sabilizing Elements for example: Molybdenum Iron Vanadium Chromium Manganese Increasing Quantities of Alpha Stabilizers Promote Alpha Phase ~ncreasing Quantitics of Bem Stabiliz~s Promote Bem Phase l Alpha Mi ed Near Stru ur Alpaha Alpha-8e B a S u ur | | (some beta) | Structure | (some alpha)
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From page 71... ...
In this respect, a small but versatile family of titanium alloys contributes to a healthy industry. On the other hand, the matter of improved use of scrap titanium might be addressed by an alloy development program.
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From page 72... ...
The growing importance of precision-cast and of powder-metallurgymolded titanium shapes may well prompt the development of alloys that possess special combinations of properties but that are not feasible using conventional ingot metallurgy. Mill Processing Ingots of titanium and titanium alloys are fabricated in high-temperature, metal-working operations to produce mill products.
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From page 73... ...
Most mill products are produced with relatively coarse microstructure and indefinite amounts of residual cold work. The term "coarse microstructure" is used with respect to the
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From page 74... ...
If beta working at high strain rates, with intermediate water quenching, were practiced, a variety of fine-grained lamellar mill products with superior fracture toughness and creep strength could be developed. Heat Treating Heat treatments devised for titanium materials are used to develop the desired combinations of strength, ductility, toughness, and thermal stability in the manufactured end item.
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From page 75... ...
Schedules listed below are commonly used: Step Time Temperature Cooling Rate First 0.2 to 1 hour 870°-950°C Air cooling Second 2 to 4 hours 680°-730°C Air cooling An emerging processing and heat treatment schedule, known as "bi-modal," is a form of duplex annealing designed to produce an extremely fine "rained recrystallization microstructure. After an initial beta quench, material for hi "odal processing is worked to over 60 percent reduction in the alpha-beta field and again water quenched from the working operation.
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From page 76... ...
The treatments are terminated by air cooling. The Future of Heat Treating The heat-treatment response of titanium alloys is relatively modest and no breakthroughs are expected.
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From page 77... ...
The martens~tic structures thus produced can be annealed to form lamellar structures or reworked in the alpha-beta f ield and recrystallized by heat treatment to form equiaxed-lamellar structures. Specifications for Titanium-Base Ingots, Mill Products, and Alloying Additions Ingot No public specifications are issued exclusively for the control of titanium ingots of either unalloyed or alloy grades.
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From page 78... ...
A schematic scrap flow diagram is presented as Figure 11. Alloying Addition No public specifications cover the master alloy additions used In the preparation of titanium alloys.
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From page 79... ...
TABLE 9 Aerospace Materials Specifications for Titanium Materials O EYE. 1l~le 4900F Plate, sheet and strip-annealed-55,000 psi yield (unalloyed Ti)
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From page 80... ...
, premium quality 4 998 Po wafer, 6A1-4V ~ premium quality Titanium and Titanium Alloys Military Handbook, MIL-HD8K-697A, June 1, 1974.
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From page 81... ...
81 TA_LE 10 AMS Materials and Product Form Correlation Plate Sheet Sttlp Tubing Extrusions Composition, Weight Percent Pure Ti, ._9 9 .
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From page 83... ...
ASTM No . Specif ication Ti tie B348-7 8 B381-78 B2 65-7 9 1333 7-78 B338-78 B363-78 B36 7-7 8 F6 7-7 7 Titanium Titanium Titanium Seamless Seamless and Titanium Alloy Bars and Billets and Titanium Alloy Forgings and Titanium Alloy Strip, Sheet and Plate and Welded Titanium Pipe and Welded Titanium and Titanium Alloy Tubes for Condensers and Heat Exchanger s Seamless and Welded Unalloyed Titanium Welding Fittings Titanium and Titanium Alloy Castings Titanium for Surgical Implants TABLE 13 Military Specif ications for Titanium and Titanium Alloys Specif ication No.
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From page 84... ...
, impurity limitations, particle size range limits, and preferred packaging and marking instructions. The master alloy manufacturing facilities and operations usually are approved by end users of titanium products (e.g., the engine manufacturers)
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From page 85... ...
. Miscellaneous Specifications In addition to the material speclficat~ons issued specifically for titanium products, other specs fications cover specific processes uniquely applicable to titanium alloys.
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