TITANIUM FACTS ? ?
Do you think of titanium as an exotic, “spaceage” metal used in aircraft and jet engines?
An expensive, precious metal found onmuseum walls in Spain and a credit card inthe US?
A novelty found in golf clubs and mountainbikes?
INTERNATIONAL TITANIUM ASSOCIATION
2655 West Midway Blvd., Suite 300
Broomfield, Colorado 80020 USA
(303) 404-2221 Phone
(303) 404-9111 Fax
WHAT DO YOU THINK OF
WHEN YOU THINK OF
Well, you’re half right.
Titanium isn’t exotic, expensive, new or anovelty.
Titanium is used to build aircraft and jetengines; as an architectural material (and anattractive bankcard image); and in a varietyof sporting gear.
In fact, titanium is more commonplace thanyou probably think.
Titanium lets us fly higher and faster, get moreenjoyment from our recreation, rely on ourelectrical power without worry, produce thechemicals and oil and gas we need at a lowercost, make the roofs of buildings last longer,and even save lives through medicine.
Titanium improves goods and services and ourquality of life in countless ways everyday.
And you probably don’t even know its atomicnumber.
Titanic, the most famous ship since Noah’sArc, lay undisturbed under 13,000 feet ofwater for more than 70 years, until a
submersible three-person sphere made oftitanium, the Nautile (built by RMS Titanic, Inc.)allowed scientists to investigate the wreckagein water that exerts 6000 pounds of pressureper square inch.
The Basics - Part I —Titanium is a common element.
Titanium isan element— number22 on thePeriodicTable, fallingsomewhatnear iron,nickel andcopper.
It is the ninth most abundant element in theearth’s crust, and the fourth most abundantmetallic element.
In nature, titanium is found in the forms of rutile(titanium dioxide, TiO2) and ilmenite (titaniumiron oxide, FeTiO3). These two mineral forms arethe most common and commercially exploitable.
Other forms of titanium occur as leucoxene, anatural alteration of ilmenite, anatase, a naturallyoccurring mineral of titanium dioxide, andperovskite, (CaTiO
Ilmenite is common in igneous rocks, with majordeposits found in South Africa, Norway, Australia,Canada, Finland and the US.
Major deposits of rutile and ilmenite are foundin beach sand, near continental coastlines whereerosion and wave action have elevated concen-trations of the minerals.
The majority of the naturally mined rutile todaycomes from Australian beaches, where it appearsas common black sand.
The main economic reserves of rutile are foundin South Africa, India, Sri Lanka, Australia andSierra Leone.
The world reserves of ilmenite and rutile totalabout 80 years of current ilmenite and rutileproduction.
Today, while ilmenite provides 90% of the totalworld titanium mineral supply, it is almost totallyused to upgrade the titanium content tosynthetic rutile, and titanium slag. Together, thesynthetic and natural rutile are the principal rawmaterial for titanium production.
However, of all of the mined and synthetictitanium minerals, only about 5% is used tomake titanium metal. The other 95% is usedto manufacture pure titanium dioxide, TiO
Titanium dioxide, TiO2, is a pigment that imparts
whiteness, brightness and opacity to paints,paper and ink, plastics and even food productsand cosmetics.
The Basics Part II: TitaniumProperties Are Unique
While titanium as a mineral is fairly common,titanium’s metallurgical properties make it unique.Or, more accurately, its combination of properties— it’s the synergy of characteristics that drives theuse of titanium in hundreds of applications.
Titanium is both strong and lightweight — asstrong as steel, but weighing only 56% as muchas steel. That gives it the highest strength-to-weight ratio of any of today’s structural metals.To produce structures of the same strength, farless titanium is required than other metals. Or,put another way, if plates of the same weightare made from titanium, copper and stainlesssteel, the titanium plate will be twice as large asthe copper one and 75% larger than the stainlesssteel one.
Titanium naturally resists corrosion from acids,alkalis, and natural, salt and polluted waters.In fact, titanium’s resistance to seawater isequivalent to that of platinum. This is becausetitanium is a reactive metal, spontaneouslyforming a hard, protective oxide film when itcomes in contact with any oxygen — as in airor water. If the film is scratched or damaged,as long as oxygen is present it will heal itself.
The protective film also makes titanium veryresistant to erosion. In high velocity processstreams and in rapidly flowing seawater, it canbe at least twenty times more erosion resistantthan copper-nickel alloys. Titanium is the onlymetal completely immune to microbiological-induced corrosion (MIC) in seawater.
Titanium’s naturally occurring oxide film alsogives the metal its unique, softly shimmeringbeauty. When the thickness of the film isincreased (through anodic oxidation) it changesthe appearance of the metal over a spectrumof colors.
Titanium has a low modulus of elasticity — abouthalf that of steel. This gives it excellent flexibility.
It is the most biocompatible of all metals. It isnon-toxic, it resists attack from bodily fluids, it’sstrong and light, and its flexibility is close to bone.
Titanium is an environmentally friendly metal. Itcomes from an abundant natural resource whichis mined with minimal impact, no harmful by-products are generated in its production and95% of its scrap is recycled.
During the Barcelona Summer Olympics, theOlympic flame burned in a cauldron madeof titanium. The cauldron’s designer chose
titanium for its image of technological advance-ments and its unusual beauty.
Add it up: Titanium Pays Off
Titanium’s remarkable combination of metallur-gical and physical characteristics use in a givenapplication can generate a synergy of benefits.It is most successfully employed when the initialdesign exploits its unique attributes, rather thanwhen it is merely substituted for another metal.
In some applications, like jet engines and medicalimplants, titanium allows the item to perform toits maximum potential.
In other cases, titanium improves an item’sperformance so dramatically, it is worth a costthat’s a little more than a competing material.This is the case in golf clubs, for example, wherepeople will pay a little more for a titanium clubthat enhances their playing experience.
In chemical processing and marine environments,for example, titanium’s long (and often virtuallyunlimited) lifespan makes it the choice over othermetals because, while its upfront cost may behigher, its total life cycle cost is lower.
Finally, in some situations, the use of titaniumcan impact the entire design, making it moreefficient and cost-effective. This is the case inoffshore oil and gas platforms, where titaniumriser pipe below the surface saves three timesits weight on the overall structure andanchoring system.
Titanium: Elegant ApplicationSolutions
The Aerospace Industry Wouldn’t FlyWithout It
Because it is light weight, strong, corrosionresistant, and has excellent elevated temperaturecharacteristics, one of titanium’s largest use is injet engines, where it is employed for fan blades,compressors, discs and critical rotating compo-nents. In a typical gas turbine engine, titaniummakes up to 30% of the weight. In total, it’sestimated that engines account for about 42%of US titanium demand and 37% of titaniumdemand in Europe.
Titanium is also used in airframes, in partsranging from massive forged wing structuresand landing gears to critical small fasteners,springs and hydraulic tubing.
The Boeing 787 requires over 100 tons of titaniumper aircraft including the engines, accounting fornearly 17% of its empty operating weight.
Since the 1950’s, titanium has been an aircraftmetal. It was first used in flight in 1952 on theexperimental Douglas Aircraft X-3 Stiletto afterthe US Department of Defense recognized themetal as a solution to high-speed designchallenges.
In military aircraft, the percentage of titaniumhas progressively increased with technologicaladvances. In the 1960’s, the Phantom F-4 wasabout 9% titanium by weight; today’s F-22is over 39% titanium. The military’s SR-71Blackbird, though no longer in production, stillholds all speed and altitude records and wasmade 90% from titanium alloys.
In spaceflight, titanium was used on the earlyMercury missions, the Apollo missions and isnow used in the Space Shuttle and its solidrocket booster cases. An important use is inthe International Space Station.
One of the most unusual uses of titaniumis in clothing, although only two knownexamples exist. The first was in a brassierre
manufactured by Wacoal America, which usednickel-titanium alloy underwires that returnedto their original, comfortable shape if bent,the second was in sport jacket made of smalltitanium plates that was presented to architectFrank O. Gehry in recognition of his use oftitanium to clad the exterior of the GuggenheimMuseum in Bilbao, Spain.
Industrial Applications Are As VariedAs The Industries Themselves
Titanium’s first use in industry was for condensertubing in sea-water-cooled electrical powergenerating plants, due to its corrosion immunity.Since 1971, over 300 million feet of titaniumtubing has been installed in power plantswithout any incidence of corrosion-or erosion-related failure.
In chemical processing, titanium is used to makeheat exchangers, vessels, pipe and tubing thatresist aggressive oxidizing acidic and chloridesolutions, temperatures and pressures. In thelate 1950’s, it was discovered that small alloyingadditions of palladium group metals (Pt, Pd, Ru)improved titanium’s resistance to non-oxidizingacids by as much as 1500 times.
For general marine use, titanium is immune tocorrosion in natural and polluted seawater, wherecopper and stainless steels are susceptible. It’s forthis reason, and its strength, that titanium isfinding utility for everything from screw propel-lers to shipboard sprinkling systems. Titaniumperforms so well that some producers warrantyit for up to 100 years in certain applications.
In Saudi Arabia, nearly 46% of the drinkingwater comes from desalination, and thin-walltitanium tubing is used in the multi-stageevaporation plants in the rejection, heatrecovery, and heat input stages, as well asthe more critical rejection stages.
Consumer and Commercial Uses MakeTitanium an Everyday Material
Many people recognize that titanium golf clubwoods soared in popularity in 1996, when theyconsumed nearly 20% of total US titaniumproduction. Just five years prior, they werevirtually non-existent in the US.
Club heads made from titanium are lighter andtherefore can be larger than those made of othermaterials, affording the club a bigger “sweetspot” which increases distance and accuracy.In Japan, it’s estimated that better than 10%of amateur golfers use titanium clubs.
High performance bicycles, skis, tennis racketsand even lacrosse sticks made from titanium arebecoming more common. Softball bats madefrom titanium have been tried, but there is adanger that the speed they impart to hit the ballis so extreme that players will not be able fieldthe hit before it injures them.
Other consumer products are diverse andimaginative: titanium eyeglass frames arelightweight, comfortable and attractive, andif they’re bent, they snap back to their originalshape; titanium watches have been massproduced since 1987; camera cases of titaniumare strong, corrosion resistant, dent-resistant andlight; non-stick titanium coatings on cookingutensils are corrosion- and scratch-resistant.
In construction, titanium’s natural resistanceto environmental attack, as well as its strength,modulus and beauty are creating a market forthe metal. It was first used for roofs in Japan,where it must withstand salt air, and nowconstruction use accounts for 9% - 10% ofthe Japanese titanium market.
The dramatic, flowing Guggenheim Museum inBilbao, Spain, designed by famed architect FrankO. Gehry, is clad in 343,000 square feet ofinterlocking titanium flat seam panels, givingit a softly shimmering appearance.
Titanium has been used in medical applicationssince the 1950’s. It is the most biocompatibleof all metals and in prosthetic and replacementdevices, it actually allows human bone growthto adhere to the implants, so they last longer.
Pacemaker cases are made from titaniumbecause it resists attack from bodily fluids, islight weight and flexible and is non-magnetic.Artificial heart valves are also made of titanium.
The titanium industry is devoting significanteffort to developing automotive applications,as even a pound of titanium on every new carwould make this a larger market than aerospace.
You probably know a 25th Anniversary is aSilver Anniversary, and the 50th is Gold,but do you know which Anniversary is
titanium? It’s the 45th.
Titanium valve train components have demon-strated they can improve a car’s fuel efficiencyby up to 4%. Titanium suspension springs couldoffer weight savings up to 70% compared tosteel, as well as complete corrosion resistance.Titanium engine springs could allow fasterengine speeds and better fuel economy.
The Honda NSX sports car uses connecting rodsmade from titanium that reduce the weight ofthe car enough that a turbocharger isn’t neededto achieve maximum performance. One modelof the Corvette has a titanium muffler.
Concept cars built using titanium have beentested since 1956, when GM built an all-TiFirebird.
The automotive racing industry uses titaniumvalves, valve springs, suspension springs,connecting rods and rocker arms.
The Thrust SSC car, which broke the world landspeed record a few years ago uses titanium forthe rear fuselage skin section and fin.
In fiction and movies, titanium has played avariety of supporting roles. It is found inRussian Alfa submarines in Tom Clancy’s
Hunt for Red October, as massive wedding bandin The Abyss, written by James Cameron, as aprosthetic material for Lieutenant Day’s new legsin the movie Forrest Gump, and it’s miscast in themetaphor “the atmosphere seems heavy enoughto be made of titanium” in The Prince of Tides byPat Conroy.
Titanium was discovered in 1790 when ReverendWilliam Gregor, an amateur geologist, identifiedthe element in black sand on the Cornishbeaches in England. He suggested the newmetallic substance be called Manacannite, aftera nearby parish.
Five years later, an eminent German chemist,Martin Heinrich Klaproth, recognized a dioxideof the same metal in rutile ore (TiO2) and callediit “Titanium” after the Titans, mythologicalGreek gods of enormous strength. However,his attempts to isolate the metal failed.
It wasn’t until 1910 that an American chemist,M. A. Hunter, finally succeeded in extractingtitanium metal from the ore and this markedthe birth of the titanium industry.
Hunter’s process involved mixing TiO2 with cokeand chlorine and applying heat, to yield titaniumtetrachloride (TiCl4), which he then reduced withsodium. For many years the titanium metal wasconsidered a potential alloying element in steel.
At the most celebrated temple of ancientGreece, the Parthenon, high atop theAcropolis, the marble pillars have been
restored using more than 1000 reinforcingrods and clamps made of titanium, becauseit won’t rust and expand, and thus crack themarble.
Titanium dioxide was also a by-product of theHunter Process and it was recognized as havingproperties which make it an excellent whitepigment. By 1913, TiO2 began to replace leadoxide in paint.
Hunter’s Process using sodium as a reductantwas used in three commercial metal plants thatoperated between the 1950’s and 1992.
In the 1930’s, Dr. Wilhelm Kroll invented the firstviable, large-scale industrial method for reducingtitanium — a production process that bears hisname. The Kroll process uses magnesium as areducing agent, and while the process can yieldlarge amounts, it leaves a chloride residue anddoes not recover unreacted magnesium metal.
The emergence of vacuum distillation to removethat contamination and improve processeconomics overcame the last significant barrierto producing mass quantities of commerciallypure titanium. Today, the Kroll process withvacuum distillation is the most widely usedmethod of winning the metal from the ore.
At the Denver International Airport, sculptorDavid Griggs’ Dual Meridian features whatis believed to be the largest titanium arch
in the world. It vaults over the internationalconcourse. It connects two sides of the sculpturethat honors railroads on one side and a visionof the future of transportation on the other.Although it measures 139 feet it weighs only1400 pounds.
Sponge First: How TitaniumIs ProducedTo produce pure titanium — or sponge, ore ismixed with coke or tar and chlorine gas andheated to form titanium tetrachloride (TiCl
a colorless liquid. The TiCl4 is then reacted in
the Kroll process, which uses magnesium as areducing agent under an inert atmosphere. Theresultant metal is known as “sponge” for itsresemblance to the texture of ocean sponge.
The metal sponge then typically vacuum distilledto remove the excess magnesium chloride andunreacted magnesium metal, which are recycled.The pure titanium sponge must meet stringentspecifications to assure control of the ingot’scomposition.
Pure titanium exists in two crystallographic forms.The first is alpha, stable up to 1620oF (880oC),at which point it transforms to the beta phase(termed beta transus), which is stable to themelting point. As alloying elements are added topure titanium, they change the temperature atwhich the phase transformation occurs and theamount of each phase present, and therefore thecharacteristics of the metal.
A flute maker from Vermont is crafting theworld’s first titanium flute, which has theadvantages of light weight, durability and
beauty, as well as acoustical advantages. Themetal is ideally suited to high audio frequencies,as its acoustical response is extremely fast and itsnatural resonance is much higher than any othermaterial in use today.
The family of titanium alloys offers a full rangeof strength properties from the highly-formable,lower strength to the very high-strength. Mostof the alpha-beta and beta alloys can providea myriad of strength-ductility propertycombinations via alloy heat treatment and/orcomposition. With the wide selection oftitanium alloys available, optimum choice fora given environment is almost always possible.
Once the sponge is crushed and mixed withalloying elements, melting to ingots, whichweigh up to 30,000 pounds, is the next step.
For Vacuum Arc Remelting (VAR), typically usedfor aerospace applications, the titanium spongeand alloying elements are pressed into briquetswhich are welded together to form anelectrode. In the VAR furnace, the electrodeis “consumable melted.”
A VAR second melt insures homogeneity ofthe ingot for industrial purposes; triple meltingis used for critical rotating components in jetengines.
The alternative sponge melting process uses acold hearth furnace to produce ingots to fulfillindustrial requirements, or as feedstock forsubsequent VAR melts. Here, the crushedsponge and alloying elements can also be mixedwith inexpensive recycled titanium scrap beforemelting, to reduce costs.
In cold hearth melting, the titanium mixture ismelted by either electron beams or by plasma arctorches. The metal flows across the cold hearth,where impurities sink to the bottom or areevaporated. Cold hearth melting is a preferredmethod for producing clean titanium for aero-space applications and combination cold hearth/VAR melts can eliminate inclusions and defectsthat even triple VAR melting cannot remove.
Because cold hearth melting can use a highpercentage of small low-cost scrap, it producesaffordable titanium for industrial and commercialuses.
VAR ingots and cold-hearth melted, cast slabs arepressed or rotary forged into slabs (rectangularshapes) or billets (rough round bar or variousother shapes).
Common processing techniques create millproducts — basic structural shapes with desiredproperties that maximum metal utilization. Allmill products are available in the spectrum ofalloys and grades.
Casting is an advanced technology for formingnear-net shapes. It offers greater designfreedom and significantly reduces the needfor expensive machining or fabrication to attainthe desired shape. Investment casting can beused to create large, tolerance-critical partssuch as heat shields, fan frames and missilecomponents, as well as smaller parts suchas valve bodies.
Commercial casting began in the late 1960’s andtoday the technology has matured to routinelysupply critical gas turbine engine, air frame,chemical process, medical and marine products.
Titanium powder technology may offer lowercosts in the manufacture of near-net shapes and,with the future potential of lower cost powder, itcould open a wider range of applications.
Conventional metal processing tools andprocedures can be used to form, machine andweld titanium and its workability is comparableto that of stainless steel.
The moon has a surprisingly high titaniumcontent. In fact, Apollo 15 astronautsspotted it in rock samples immediately, as
Dave Scott remarked to Jim Erwin: “Hey lookat this. This one is loaded with titanium!”
The International Titanium Association appreciatesthe support of our Members and their companiesin the production of this publication. Manyresources have been utilized in the compilationand a complete list can be found on our web siteat: www.titanium.org.
The International Titanium Association accepts noresponsibility for either the accuracy or completenessof the information contained herein and, by publishingthe same, should not be perceived as making any in-dustry recommendation. Additional information maybe available which may have a material effect on theinterpretation and use of the information provided.
Copyright © International Titanium Association, 2007.
ITA E0401 07/2007
INTERNATIONAL TITANIUM ASSOCIATION
2655 West Midway Blvd., Suite 300
Broomfield, Colorado 80020 USA
(303) 404-2221 Phone
(303) 404-9111 Fax