MATERIAL LOGAM

ISMOJO, ST.,MT

Penilaian

• Ujian Tengah Semester (UTS) = 30%

• Ujian Akhir Semester (UAS) = 40%

• Tugas-tugas = 20%

• Kuis = 10%

• Yang berhak mengikuti ujian akhir semester: kehadiran ≥ 70%

Referensi

• W.F. Smith, “Principles of Materials Science and Engineering”, McGraw-Hill, Singapore, 1990.

• S.H. Avner, ”Introduction to Physical Metallurgy”, McGraw-Hill, Tokyo, 1974.

• D.S. Clark, W.R. Varney, ”Physical Metallurgy for Engineers”, Van-Nostrand Reinhold Co., New York, 1952.

• B.J. Moniz, ”Metallurgy”, 2nd edition, ATP, Homewood, Illinois, 1994.

• Reed-Hill, Robert E., Reza Abbaschian, and Lara Abbaschian. Physical Metallurgy Principles. 4th ed. Stamfor

Materials Sciences adalah suatu aspek yang mempelajari karakteristik material secara keilmuan dan teknologi yang dapat digunakan untuk membuat material atau bahan teknik.

Materials SciencesMaterials Sciences

Metallurgical Metallurgical EngineeringEngineering

Composite Composite EngineeringEngineering

Polymer Polymer EngineeringEngineering

Materials Materials EngineeringEngineering

Ceramic Ceramic EngineeringEngineering

1. Metallurgical Engineering• Mempelajari karakteristik logam dan paduannya, merupakan ilmu tertua

yang mempelajari material teknik.• Perkembangan metalurgi selama 150 tahun terakhir membaginya menjadi

3 bagian utama, yaitu :a. Metalurgi Ekstraksi (mempelajari bagaimana mengekstraksi

dan memurnikan suatu logam dari bijihnya).b. Metalurgi Fisik (mempelajari pengaruh struktur mikro terhadap

sifat-sifat logam, memodifikasi struktur mikro).c. Metalurgi Mekanik (mempelajari teknik pembuatan dan gaya-

gaya yang bekerja untuk membentuk suatu logam menjadi produk tertentu).

2. Ceramic Engineering• Mempelajari perkembangan dan produksi suatu produk yang terbuat dari

bahan non-metalik, inorganik dengan pembakaran pada temperatur tinggi.

3. Polymer Engineering

• Mempelajari perkembangan produk yang terbuat dari bahan sintetis organik.

• Polimer terdiri atas Thermosetting dan Thermoplastic.

4. Composite Engineering

• Mempelajari penerapan gabungan material untuk memperoleh sifat-sifat yang tidak dimiliki oleh masing-masing bahan.

• Kombinasi yang dilakukan bisa logam, keramik, polimer (metal matrix composite/MMC; polymer matrix composite/PMC; ceramic matrix composite/CMC, dll).

5. Materials Engineering

• Mengevaluasi karakteristik sifat-sifat yang dimiliki oleh material. Ini berhubungan dengan penggantian material yang dapat memperbaiki kemampuan dan menurunkan harga komponen.

Spektrum pengetahuan material, Spektrum pengetahuan material, penggabungan pengetahuan penggabungan pengetahuan material dari ilmu material dan material dari ilmu material dan material teknik menjadikan material teknik menjadikan rekasayawan dapat mengubah rekasayawan dapat mengubah material menjadi produk yang material menjadi produk yang berguna bagi masyarakat.berguna bagi masyarakat.

Diagram yang menggambarkan Diagram yang menggambarkan bagaimana ilmu dan teknik material bagaimana ilmu dan teknik material terbentuk dari rangkaian pengetahuan terbentuk dari rangkaian pengetahuan dari ilmu-ilmu dasar dan berbagai dari ilmu-ilmu dasar dan berbagai disiplin ilmu pengetahuan.disiplin ilmu pengetahuan.

Flow chart pembuatan suatu komponen

Gambar diatas mengkaitkan berbagai hal yang harus diperhatikan oleh seorang perancang dalam membuat suatu komponen atau konstruksi.

9

Contoh-contoh produk :Early food containers of glass & steel use common ceramic and metal materials of the late 19th & early 20th centuries

The new containers are lightweight, will not break, and offer long shelf life for their contents

Advances in materials technology brought on new containers made of two-piece Al and steel cans and “barrier” packages made of laminated composites of plastics, aluminum, and paper.

Decorated Foil Pouches for Food and Drink • 1XXX represents the commercially

pure aluminum.

High formability, corrosion resistance and electrical conductivity

Electrical, chemical applications

• The 1XXX series would not be used where strength is a prime consideration.

• For the applications where extremely high corrosion resistance, formability and/or electrical conductivity are required (foil and strip for packaging)

1060 or 11101060 or 1110

JembatanJembatan

PipelinePipeline

DumptruckDumptruck

Pesawat Pesawat terbangterbang

Jaringan Jaringan listriklistrik

Peralatan Peralatan dapurdapur

RodagigiRodagigiKereta Kereta listriklistrik

Baut dan Baut dan murmur

ElektroElektroniknik

Pembuatan Pesawat Pembuatan Pesawat terbangterbang

Komponen Komponen mesinmesin

Komponen Komponen mesin hasil mesin hasil

corancoran

Pembuatan mobilPembuatan mobil

Komponen Komponen mesinmesin

Sudu turbin Sudu turbin

16

Patung tembaga Patung tembaga paduanpaduan

Pakaian Pakaian perangperang

Mobil masa depanMobil masa depan

Ford contour dengan bahan Ford contour dengan bahan dari aluminium ekstrusidari aluminium ekstrusi

Bronze Bronze MaskMask

Komponen produk Komponen produk pengecoranpengecoran

Chemical Physical Mechanical Manufacturing considerations

Composition

Microstructure

Phases

Grain size

Corrosion resistance

Inclusions

Melting point

Glass transition (polymers/glasses)

Magnetic

Electrical

Optical

Acoustic

Gravimetric

Color

Tensile/compressive properties

Toughness

Ductility

Fatigue

Hardness

Creep resistance

Shear strength

Available shapes

Available sizes

Available surface texture

Manufacturing tolerances

Composition

Fillers/additives

Crystallinity

Molecular weight

Flammability

Spatial configuration

Chemical resistance

Tensile/compressive properties

Heat distortion

Pressure-velocity limit

Toughness

Stress rupture resistance

Creep resistance

Manufacturing tolerances

Stability

Available sizes

Composition

Porosity

Grain size

Crystal structure

Corrosion resistance

Phases

Tensile/compressive properties

Fracture toughness

Transverse rupture

Hardness

Available shapes

Available sizes

Available surface texture

Manufacturing tolerances

Composition matrix:filler

Matrix/filler bond

Volume fraction of fillers

Reinforcement type

Chemical resistance

Tensile/compressive properties

Fracture toughness

Creep resistance

Reinforcement orientation

Available shapes

Available sizes

Manufacturing tolerances

Stability

Material Properties

Metals

Plastics

Ceramics

Composites

19

Diktator material = SOLVENT

Material terlarut = SOLUTE

Pada logam berlaku larutan padat (solid solution).

Dengan demikian solvent dan solute keduanya adalah padatan.

Pelarutan terjadi pada temperatur tinggi, dimana kedua padatan berubah menjadi cair. Untuk baja, pada temperatur tinggi, besi (Fe) dapat melarutkan banyak unsur-unsur khususnya karbon. Fe menjadi diktator. Sejumlah kecil C, S atau Mn menjadi unsur yang terlarut.

kusharjanto, metalurgi-unjani 20

Struktur partikel atom mirip dengan sistim tata surya

Secara umum struktur atom terdiri dari inti atau nucleus (proton dan neutron) yang dikelilingi oleh elektron.

Proton = partikel bermuatan positif

Neutron = netral

Elektron = bermuatan negatif

Jumlah proton = jumlah elektron

Setiap kulit pada orbit elektron mengandung sejumlah elektron, misalnya pada kulit pertama (terdekat dengan inti) = 2 elektron, kedua = 8 elektron, ketiga = 18 elektron, keempat = 32 elektron

Jika kulit terluar telah terpenuhi jumlah elektronnya, maka unsur akan menjadi stabil dan tidak akan bereaksi dengan unsur lain membentuk senyawa atau molekul. Contoh: gas inert argon dan helium digunakan sebagai gas pelindung dalam proses pengelasan, karena tidak bereaksi dengan logam untuk membentuk senyawa intermetalik yang tidak diinginkan.

Jika kulit terluar belum terpenuhi jumlah elektronnya, maka akan berikatan dengan unsur lain untuk membentuk senyawa atau molekul.

1.Ikatan kuat (primary bonding): melibatkan pembagian elektron (ikatan ion, kovalen dan logam).

2.Ikatan sekunder (secondary bonding): melibatkan tarik menarik atom-atom yang relatif lemah dan tidak ada pembagian atau pertukaran elektron (ikatan van der waals).

Salah satu dasar untuk mengklasifikasi material adalah ikatan kimia.

Dua jenis ikatan kimia:

kusharjanto, metalurgi-unjani 23

SystemEnergy

Distance between atoms

Repulsive energy

Separated atomsBond

EnergyStable

unstable

Ikatan (Ikatan (BondingBonding))Jika atom-atom mempunyai jarak yang cukup jauh, maka akan terjadi interaksi yang lemah.

Menurunnya jarak antar atom, energi-pun akan turun dan sistem menjadi lebih stabil.

Atom-atom akan mencapai jarak optimal pada level energi terendah.

Ikatan terjadi jika jarak antar atom cukup untuk menghasilkan tarik menarik.

Jika jarak atom terlalu dekat terjadi tolak menolak.

• Terjadi ketika valensi elektron meninggalkan masing-masing

atom dan digunakan bersama di antara semua atom dalam

bentuk awan elektron bebas.• Terdapat pada unsur-unsur logam yang hanya mempunyai 1,

2 atau 3 elektron dikulit terluarnya.• Melimpahnya proton, atom-atom bermuatan ion-ion positif.• Elektron-elektron yang mengambang membentuk awan-awan

elektron, sehingga elektron mudah bergerak.• Adanya elektron-elektron bebas menyebabkan konduktivitas

panas dan listriknya tinggi.

Ikatan logam (metallic Bonding)

What is a metal?

Metals

• Metals: combination of metallic elements (free electrons) good conductors of electricity and heat not transparent to visible light strong and ductile

• A metal is defined as an opaque, lustrous elemental chemical substance that is a good conductor of heat and electricity, and when polished, a good reflector of light. (ASM Definition)

The Periodic Table

Transition Metals

Metals

Metal Alloys

• Ferrous Alloys

– Classification of Steels

– Designation of Steels

• Nonferrous Alloys

– Aluminum

– Copper

– Magnesium

– Titanium

– Refractory metals

– Superalloys

– Noble metals

Metal Alloys

Classification of Ferrous Alloys Metal Alloys

Ferrous Nonferrous

Steels Cast Irons

Low Alloy

Low-carbon Medium-carbon High-carbon

High Alloy

PlainHigh

strength, low alloy

Heat treatable

Plain ToolPlain Stainless

Gray iron

Ductile iron

White iron

Malleable iron

• Based on carbon content

– Pure iron (< 0.008wt% C)

From the phase diagram, it is composed almost exclusively of the ferrite phase at room temperature.

– Steels (0.008 ~ 2.14wt% C)

In most steels the microstructure consists of both and Fe3C phases.

Carbon concentrations in commercial steels rarely exceed 1.0 wt%.

– Cast irons (2.14 ~ 6.70 wt% C)

Commercial cast irons normally contain less than 4.5wt% C

Classification of Ferrous Alloys

The iron–iron carbide phase diagram.

L + Fe3C

2.14 4.30

6.70

M

N

C

PE

O

G

F

H

Cementite Fe3C

x

x’

0.022

0.76

• The carbon content is normally less than 1.0 wt%.

• Plain carbon steels: containing only residual concentrations of impurities other than carbon and a little manganese

About 90% of all steel made is carbon steel.

• Alloy steels: more alloying elements are intentionally added in specific concentrations.

• Stainless steels

Ferrous Alloys — Steels

Standar material (materials standards)

Standar material dikembangkan oleh pemerintah, industri, baik secara nasional maupun internasional.

Standar adalah dokumen kesepakatan yang merupakan piranti/perangkat tolok ukur sifat-sifat, karakteristik atau suatu prosedur yang telah berjalan.

Standar biasanya dikembangkan oleh suatu komite yang terdiri dari para profesional dibidangnya.

Langkah pertama dalam pengembangan suatu standar adalah membuat suatu draft yang dibahas oleh sebuah komite yang nantinya akan disahkan menjadi suatu standar yang berlaku secara nasional maupun internasional.

Pengembangan proses membutuhkan waktu yang lama, tetapi dokumen akhir yang telah selesai dibahas merepresentasikan suatu konsensus dari opini komite dan memperhatikan kenyataan diindustri saat itu.

Suatu standar harus ditinjau secara berkala (minimum sekali dalam lima tahun) untuk menentukan apakah dipertahankan atau diperbaiki.

Jika suatu standar ditetapkan sudah tidak relevan lagi, maka standar tersebut harus dihapus.

Ada tiga kelas standar:

1. Spesifikasi (specification)

2. Metoda pengujian (test method)

3. Rekomendasi penggunaan (recommended practice)

Sebuah kode berisi ketiga kelas standar dan mengikat secara hukum.

1. Spesifikasi

Merupakan pernyataan bahwa suatu produk harus sesuai antara keperluan teknis dan komersial. Contohnya baja paduan dan baja tahan karat untuk baut yang bekerja pada operasi temperatur tinggi mengikuti ASTM A 193.

2. Metoda pengujian

Sekumpulan/seperangkat perintah atau cara-cara untuk mengidentifikasi, melakukan pengukuran atau mengevaluasi sifat-sifat material. Contohnya pengujian impak untuk material logam menggunakan ASTM E 23.

3. Rekomendasi penggunaan/aplikasi

Sekumpulan/seperangkat perintah atau cara-cara dalam melaksanakan satu atau lebih pengoperasian atau fungsi selain dari identifikasi, pengukuran atau mengevaluasi material. Contohnya rekomendasi penggunaan untuk persiapan permukaan baja atau material keras yang lainnya dengan menggunakan penyemprotan air sebelum dilapis atau lapis ulang mengikuti NACE RP-01-72.

4. Kode

Sekumpulan standar atau seperangkat peraturan yang harus ditaati. Contohnya ASME Boiler and Pressure Vessel Code, dimana didalamnya terdapat peraturan untuk proses perlakuan panas setelah pengelasan dari bejana tekan yang berkaitan dengan jenis dan ketebalan material.

ASTM A 193

SPECIFICATIONFOR ALLOY STEEL AND STAINLESS STEEL BOLTING MATERIAL FOR

HIGH-TEMPERATURE SERVICE

ASTM E 23

TEST METHODNOCTHED BAR IMPACT TESTING OF METALLIC MATERILAS

NACE RP-01-72

RECOMMENDED PRACTICESURFACE PREPARATION OF STEEL AND OTHER HARD MATERIALS

ASMEBoiler and Pressure Vessel Code

CODESECTION VIII, DIVISION 1, PARAGRAPH UCS-56

POST-WELD HEAT TREATMENT OF CARBON STEEL PRESSURE VESSELS

Contoh-contoh standar:

1. AISI (American Iron and Steel Institute)

2. SAE (Society of Automotive Engineers)

3. ASTM (American Society for Testing and Materials)

4. UNS (Unified Numbering System)

5. NACE (National Association of Corrosion Engineers)

6. AWS (American Welding Society)

7. AA (Aluminum Association)

8. API (American Petroleum Institute)

9. ASME (American Society of Mechanical Engineers)

Kesemuanya berada dibawah naungan ANSI (American National Standards Institute)

Organisasi-organisasi Profesional

Standar setiap negara:

Negara SingkatanAustria ONORMBelgia NBNBulgaria BDSCanada CSACzechoslovakia CSNPerancis AFNORJerman DINJepang JISInggris BSIndonesia SNIPolandia PNItalia UNIRumania STASSpanyol UNESwedia SSRusia GOSTEropa bersatu EURONORMHungaria MSZ

• A four-digit number: the first two digits indicate the alloy content; the last two, the carbon concentration

• For plain carbon steels, the first two digits are 1 and 0; alloy steels are designated by other initial two-digit combinations (e.g., 13, 41, 43)

• The third and fourth digits represent the weight percent carbon multiplied by 100

For example, a 1040 steel is a plain carbon steel containing 0.40 wt% C.

The Designation of Steels

• A four-digit number: the first two digits indicate the alloy content; the last two, the carbon concentration

The Designation of Steels

4141 40 40

Identifies major alloying element(s)

Percentage of carbon

Steel AlloysSteel Numerical Name Key Alloys

10XX, 11 XX Carbon only 13XX Manganese

23XX, 25 XX Nickel 31XX, 33XX, 303XX Nickel-Chromium

40XX Mo 41XX Cr-Mo

43XX & 47XX Ni-Cr-Mo 44XX Mn-Mo 48XX Ni-Mo

50XX, 51XX, 501XX, 521XX, 514XX, 515XX

Cr 61XX Cr-V

81XX, 86XX, 87XX, 88XX Ni-Cr-Mo 92XX Si-Mn

93XX, 98XX Ni-Cr-Mo 94XX Ni-Cr-Mo-Mn

XXBXX Boron XXLXX Lead

94XX Ni-

Sistem kodifikasi baja (lanjutan)

AISI/SAE and UNS Designation Systems and Composition Ranges for Plain Carbon Steel and Various Low-Alloy Steels

• Low-carbon steels

– Less than 0.25 wt%C

• Medium-carbon steels

– 0.25 ~ 0.60 wt%C

• High-carbon steels

– 0.60 ~ 1.4 wt%C

Classification of Steels

The iron–iron carbide phase diagram.

L + Fe3C

2.14 4.30

6.70

M

N

C

PE

O

G

F

H

Cementite Fe3C

x

x’

0.022

0.76

• Less than 0.25 wt%C

• Unresponsive to heat treatments intended to form martensite; strengthening is accomplished by cold work

• Microstructures: ferrite and pearlite

• Relatively soft and weak, but having outstanding ductility and toughness

• Typically, y = 275 MPa, UT = 415~550 MPa, and ductility = 25%EL

• Machinable, weldable, and, of all steels, are the least expensive to produce

• Applications: automobile body components, structural shapes, and sheets used in pipelines, buildings, bridges, etc.

Low-Carbon Steels

Composition of Five Plain Low-Carbon Steels

Mechanical Characteristics of Hot-Rolled Material and Typical Applications for Various

Plain Low-Carbon Steels

• 0.25 ~ 0.60 wt%C

• May be heat treated by austenitizing, quenching, and then tempering to improve their mechanical properties

• Microstructure: tempered martensite

• Stronger than low-carbon steels

• Applications: railway wheels and tracks, gears, crankshafts, and other machine parts

Medium-Carbon Steels

Typical Applications and Mechanical Property Ranges for Oil-Quenched and Tempered Plain Carbon

a Classified as high-carbon steels

• 0.60 ~ 1.4 wt%C

• Used in a hardened and tempered condition

• Hardest, strongest, and yet least ductile; especially wear resistant and capable of holding a sharp cutting edge

• Containing Cr, V, W, and Mo; these alloying elements combine with carbon to form very hard and wear-resistant carbide compounds (e.g., Cr23C6, V4C3, and WC)

• Applications: cutting tools and dies for forming and shaping materials, knives, razors, hacksaw blades, springs, and high-strength wire

High-Carbon Steels

Designations, Compositions, and Applications for Six Tool Steels

• Alloying elements: Cu, V, Ni, & Mo (total ~10wt%)

• Higher strength than low-carbon steels

• Most may be strengthened by heat treatments

• Ductile, fomable, machinable

• Tensile strength: > 480 MPa

High-Strength, Low-Alloy Steels

A Comparison of the Advantages Offered by Carbon Steel and Alloy SteelCarbon Steel Alloy Steel

Lower cost Higher strength

Greater availability Better wear

Toughness

Special high temperature

behavior

Better corrosion

resistance

Special electrical

properties 94XX Ni-

• Alloy steel is more expensive than carbon steel; it should be used only when a special property is needed.

What makes stainless steels “stainless”?

• Stainless steels are selected for their excellent resistance to corrosion.

• Stainless steels are divided into three classes: martensitic, ferritic, or austenitic

• The predominant alloying element is chromium; a concentration of at least 11 wt% Cr is required

– It permits a thin, protective surface layer of chromium oxide to form when the steel is exposed to oxygen.

– The chromium is what makes stainless steel stainless!

Stainless Steels

1) Relatively high density

2) Comparatively low electrical conductivity

3) Susceptibility to corrosion in some common environments

• Cast alloys — alloys that are so brittle that forming or shaping by appreciable deformation is not possible

• Wrought alloys — alloys that are amenable to mechanical deformation

Ferrous Alloys — Their Limitations

• Aluminum and aluminum alloys are the most widely used nonferrous metals.

• Properties

– Low density (2.7 g/cm3), as compared to 7.9 g/cm3 for steel

– High electrical and thermal conductivity

– Resistant to corrosion in some common environments

– Easily formed and thin Al foil sheet may be rolled

– Al has an FCC crystal structure; its ductility is retained even at very low temperatures

– Limitation: low melting temperature (660°C)

Aluminum and its Alloys

• Aluminum alloys: strengthened by cold working and alloying (Cu, Mg, Si, Mn, and Zn)

– Nonheat-treatable: single phase, solid solution strengthening

– Heat treatable: precipitation hardening (MgZn2)

• Applications: aircraft structural parts, beverage cans, bus bodies, and automotive parts (engine blocks, pistons, and manifolds)

– Engineering materials for transportation to effectively reduce fuel consumption

– Specific strength: the tensile strength-specific gravity ratio

Aluminum and its Alloys (Cont’d)

Aluminum Alloy Desginations

Material Number

Al (99.00% minimum and greater)

1XXX

Al alloys are grouped by major alloying elements

Copper 2XXX

Manganese 3XXX

Silicon 4XXX

Magnesium 5XXX

Magnesium and Silicon 6XXX 94XX Ni-

Aluminum’s use in vehicles is rapidly increasing due to a heightened need for fuel efficient, environmentally friendly vehicles

• Aluminum can provide a weight savings of up to 55 percent compared to an equivalent steel structure, while matching or exceeding crashworthiness standards of similarly sized steel structures.

• The Ford Motor Company now has aluminum-intensive test vehicles on the road, providing 46% weight savings in the structure, with no loss in crash protection.

Aluminum plate is used in the manufacture of aircraft and for fuel tanks in spacecraft

• Aircraft manufacturers use high-strength alloys (principally alloy 7075) to strengthen aluminum aircraft structures.

• Alloy 7075 has zinc and copper added for ultimate strength, but because of the copper it is very difficult to weld.

• 7075 has the best machinability and results in the finest finish.

Lightweight aluminum is a good material for conductor cables

• Electrical transmission lines are the largest users of aluminum rod/bar/wire products.

• In fact, this is the one market in which aluminum has virtually no competition from other metals.

• Aluminum is simply the most economical way to deliver electrical power.

Compositions, Mechanical Properties, and Typical Applications for Some Aluminum Alloys

• Unalloyed copper:

– So soft and ductile that it is difficult to machine

– Unlimited capacity to be cold worked

– Highly resistant to corrosion in diverse environments

• Copper alloys: strengthened by cold working and/or solid-solution alloying.

• Bronze and brass are two common copper alloys.

• Applications: costume jewelry, cartridge casings, automotive radiators, musical instruments, electronic packaging, and coins

Copper and its Alloys

• Bronze is an alloy of copper and tin.

– The first metal purposely alloyed by the smith

– May contain up to 25% tin

Bronze and Brass

• Brass is an alloy of copper and zinc.

– Contain 5-30% zinc

– The zinc increases the strength of the copper.

– Ductility and formability are also increased.

Bronze Mask

Cu-Zn Phase Diagram

• Properties

– Lowest density (1.7 g/cm3) of all the structural metals

– Mg has a HCP crystal structure; relatively soft and has a low elastic modulus (45 GPa)

– At room temperature difficult to deform; only small degrees of cold work may be imposed without annealing

– Most fabrication is by casting or hot working at temperatures between 200 and 350°C

– Low melting temperature (651°C)

– Relatively unstable and especially susceptible to corrosion in marine environments

• Applications: aircraft and missile application, automobiles, and in audio-video-computer-communications equipment

Magnesium and its Alloys

• Relatively new engineering materials that possess an extraordinary combination of properties

– Low density (4.5 g/cm3)

– High melting temperature (1668°C), high elastic modulus (107 GPa)

– Extremely strong: 1400 MPa tensile strength at room temperature, highly ductile and easily forged and machined

– Limitations

Chemical reactivity with other materials at elevated temperatures

Cost

• Applications: airplane structures, space vehicles, and in the petroleum and chemical industries

Titanium and its Alloys

Compositions, Mechanical Properties, and Typical Applications for Some Titanium Alloys

Alloy Type

Common Name (UNS

Numbser)

Composition (wt%)

Condition Tensile

Strength (MPa)

Yield Strength

(MPa)

Ductility (%EL)

Ti-6Al-4V (R564000)

6Al, 4V, balance Ti

Annealed 947 877 14

94XX Ni-

• Typical Applications: High-strength prosthetic implants, chemical-processing equipment, airframe structural components

• Titanium has become the leading structural metallic biomaterial and 50 years of clinical performance has proven its value.

• There are a few generic characteristics that biomaterials need to possess for applications as long-term implantable devices.

– must have the appropriate mechanical properties, taking into account the stress levels and frequencies that will be encountered and the expectations of stress transfer within the relevant part of the body

– must be sufficiently corrosion resistant, taking into account the duration of implantation and the consequences of any corrosion should it take place

– should have adequate biological safety

Titanium Biomaterials (e.g. Ti-6Al-4V)

• Superlative combinations of properties

– Nickel-based alloys

– Other alloying elements: Nb, Mo, W, Ta, Cr, and Ti

e.g. IN792: Ni-12Cr-10Co-2Mo-4W-3.5Al-4Ti-4Ta- 0.01B-0.09Zr-0.1C-0.5Hf

• Applications: aircraft turbine components

– Turbine blades and discs, high creep and oxidation resistance at elevated temperatures (1000°C)

– Must withstand exposure to severely oxidizing environments and high temperatures for reasonable time periods

– Density is an important consideration because centrifugal stresses are diminished in rotating parts when the density is reduced.

Superalloys

Modern Civil Aircraft Engines

• Turbine blades in a jet engine experience:

• Mechanical forces:

– Creep

– Fatigue

– Thermomechanical fatigue

• High temperature environment

– Oxidation

– Hot corrosion

Material Strength with Increased Temperature

Titanium Alloy

Steel

Aluminum Alloy

Nickel Alloy

Ni-based superalloys are used for turbine blades

• Modern aeroengine design constantly seeks to increase the engine operating temperature to improve overall efficiency.

• The materials for turbine blades are required to perform at higher and higher temperatures.

• The use of advanced nickel-based alloys, together with innovative cooling design

Polycrystalline turbine blade

Improvement in High-Temperature Creep Resistance of Turbine Blades

Columnar grain structure produced by a directional solidification technique

Creep resistance is further enhanced with single-crystal blades.

Thermal Barrier Coatings (TBCs)

• Demands for higher efficiency and lower emission require higher operating temperatures in both

– aircraft engines

– land-base power-generation gas turbines

• The typical melting points of the superalloys used for the turbine components range from 1230 ~ 1315°C

• The temperature in a combustion gas environment is > 1370°C

Thermal Barrier Coatings (TBCs)

• The superalloy technology alone cannot provide new metals with the improved high-temperature performance.

– Composition & microstructure evolutions

– Cooling strategy

• The key to meeting these new demanding goals lies in providing an insulating ceramic thermal barrier coating (TBC) to lower the surface temperature of the superalloy underneath

TBCs offer an increase in operating temperature greater than what superalloys achieved over 25 years

1965 1976 1985

Superalloy Development

TBC Ben

efit

167°C (300°F) Ceramic

83°C (150°F) Metal

Eq

uiv

ale

nt

Me

tal T

em

pe

ratu

re

Durham et al., 1993

TBCs comprise metal & ceramic multilayers

Thermally Grown Oxide (TGO)

(1-10m)

Ceramic Top Coat (100-400m)(Y2O3-Stabilized ZrO2)

Bond Coat (~100m)

Substrate

Cooling Air

Hot Gases

A complex interplay occurs in TBCs

• Diffusion

• Oxidation

• Phase transformation

• Elastic deformation

• Plastic deformation

• Creep deformation

• Thermal expansion

• Thermal conduction

• Radiation

• Fracture

• Fatigue

• Sintering

Understanding and improving scale-metal adhesion are critical for design of TBCs

10 µm

EB-PVDYSZ

AluminaScale

Spallation Zone

(Ni,Pt)AlBond Coat

PictureCourtesy of GEAE

• Melting temperatures range between 2468°C for niobium (Nb) and 3410°C for tungsten (W)

– Interatomic bonding is extremely strong.

– Large elastic moduli and high strength and hardness at ambient and elevated temperatures

• Applications:

– Ta and Mo are alloyed with stainless steel to improve its corrosion resistance.

– Molybdenum alloys: extrusion dies and structural parts in space vehicles

– Tungsten alloys: filaments, X-ray tubes, welding electrodes

Refractory Metals

• Expensive (precious) and superior or notable (noble) in properties

– Soft, ductile, and heat resistant

• Silver, gold, platinum, palladium, rhodium, ruthenium, iridium, and osmium

• Silver and gold may be strengthened by solid-solution alloying with copper

– Sterling silver: Ag-Cu (~7.5 wt% Cu)

• Applications:

– Jewelry, integrated circuit electrical contacts, chemical laboratory equipment (Pt), catalyst, thermo-couples

Noble Metals