PENGETAHUAN BAHAN TEKNIK
YUSRON SUGIARTO
• Bahan Teknik adalah semua unsur atau zat yang berbentuk padat, cair, atau gas yang banyak di gunakan untuk kebutuhan keperluan dunia teknik atau industri
• Padat : Logam, keramik, plastik, kaca, karet,kayu
• Cair : Pelumas, air, bensin, solar, bahan kimia lain
• Gas : Oksigen, Asitelen, hidrogen, CO2 dan lainnya
PENGETAHUAN BAHAN TEKNIK yusronsugiarto.lecture.ub.ac.id
PENGETAHUAN BAHAN TEKNIK yusronsugiarto.lecture.ub.ac.id
Flow chart Pemilihan Proses dan Material
PENGETAHUAN BAHAN TEKNIK yusronsugiarto.lecture.ub.ac.id
PENGETAHUAN BAHAN TEKNIK yusronsugiarto.lecture.ub.ac.id
• Seorang ahli teknik dituntut untuk merancang suatu produk.
• Seorang ahli teknik dituntut untuk membuat suatu produk
• Seorang ahli teknik mesin harus memilih bahan dalam pembuatan atau perbaikan.
• Tuntutan ekonomik (optimasi antara fungsi dan harga)
PENGETAHUAN BAHAN TEKNIK yusronsugiarto.lecture.ub.ac.id
PEMILIHAN BAHAN
Sifat teknis bahan yang perlu diperhatikan dalam pemilihan bahan
PENGELOMPOKAN BAHAN
BAHAN TEKNIK
LOGAM
NON-LOGAM
FERRO
NON-FERRO
yaitu merupakan logam yang
mengandung unsur besi (Fe) dalam susunan unsur dasarnya;
logam yang tidak mengandung unsur besi (Fe) dalam susunan unsur
dasarnya. Logam non-ferro
diantaranya adalah Alumunium (Al), Magnesium (Mg), Tembaga (Cu), Seng (Zn), Nickel (Ni), dan Logam Mulia.
ORGANIK
AN-ORGANIK
kayu, kertas, plastik, karet, kulit, kapas
batu, pasir, semen, keramik, gelas, grafit
PENGELOMPOKAN BAHAN
LOGAM FERRO
Bahan logam ferro mengandung karbon antara 0 sampai 4,5%, dan dibagi atas tiga golongan yaitu:
Besi dengan kadar karbon; 0 sampai 0,008%
Baja dengan kadar karbon; 0,008% sampai 2,0%
Besi cor dengan kadar karbon; 2,0 sampai 4,5%
Iron
• Pure iron rarely exists outside of the laboratory.
Iron is produced by reducing iron ore to pig iron through the use of a blast furnace. From pig iron many other types of iron and steel are produced by the addition or deletion of carbon and alloys.
The following paragraphs discuss the different
types of iron and steel that can be made from iron
ore.
PIG IRON.-
• Pig iron is composed of about 93% iron, from 3% to 5%
carbon, and various amounts of other elements. Pig iron is comparatively weak and brittle; therefore, it has a limited use and
approximately ninety percent produced is refined to
produce steel. Cast-iron pipe
and some fittings and valves
are manufactured from pig
iron.
WROUGHT IRON.-
• Wrought iron is made from pig iron with some slag mixed in during manufacture. Almost pure iron, the presence of slag enables wrought iron to resist corrosion and oxidation.
• The chemical analyses of wrought iron and mild steel are just about the same. The difference comes from the properties controlled during the manufacturing process.
• Wrought iron can be gas and arc welded, machined,
plated, and easily formed;
however, it has a low hardness and a low-fatigue strength.
CAST IRON.-
• Cast iron is any iron containing greater than 2% carbon alloy.
• Cast iron has a high-
compressive strength and good wear resistance; however, it
lacks ductility, malleability, and impact strength. Alloying it with nickel, chromium,
molybdenum, silicon, or
vanadium improves toughness, tensile strength, and hardness.
A malleable cast iron is
produced through a prolonged annealing process
INGOT IRON.-
• Ingot iron is a commercially pure iron (99.85% iron) that is easily
formed and possesses good ductility and corrosion resistance. The
chemical analysis 'and properties of this iron and the lowest carbon steel are practically the same. The lowest carbon steel, known as dead-soft, has about 0.06% more carbon than ingot iron. In iron the carbon
content is considered an impurity and in steel it is considered an
alloying element. The primary use for ingot iron is for galvanized and enameled sheet.
Steel
• Of all the different metals and materials that we use in our trade, steel is by far the most important. When steel was developed, it revolutionized the American iron industry.
With it came skyscrapers, stronger and longer bridges, and railroad tracks that did not collapse. Steel is
manufactured from pig iron by decreasing the amount of
carbon and other impurities
and adding specific amounts of
alloying elements.
Carbon Steel
• Carbon steel is a term applied to a broad range of steel that falls between the commercially pure ingot iron and the cast irons. This range of carbon steel may be classified into four groups:
• Low-Carbon Steel 0.05% to 0.30% carbon
• Medium-Carbon Steel 0.30% to 0.45% carbon
• High-Carbon Steel 0.45% to 0.75% carbon
• Very High-Carbon Steel 0.75% to 1.70% carbon
LOW-CARBON STEEL
• Steel in this classifi- cation is tough and ductile, easily
machined, formed, and welded. It does not
respond to any form of
heat treating, except
case hardening.
MEDIUM-CARBON STEEL
• These steels are strong and hard but cannot be welded or worked as
• easily as the low-
carbon steels. They are used for crane
• hooks, axles, shafts,
setscrews, and so on.
HIGH-CARBON STEEL
• Steel in these classes respond well to heat treatment and can be welded. When welding, special electrodes must be used along with preheating and stress-relieving
procedures to prevent cracks in the weld areas.
These steels are used for
dies, cutting tools, mill tools, railroad car wheels,
chisels, knives, and so on.
STAINLESS STEEL
• This type of steel is classified by the American Iron and Steel Institute (AISI) into two general series named the 200-300 series and 400 series. Each series includes several types of steel with different characteristics.
• The 200-300 series of stainless steel is known as
AUSTENITIC. This type of steel is very tough and ductile in the as"welded condition; therefore, it is ideal for welding and requires no annealing under normal atmospheric
conditions. The most well-known types of steel in this series are the 302 and 304. They are commonly called 18-8
because they are composed of 18% chromium and 8%
nickel. The chromium nickel steels are the most widely used and are normally nonmagnetic.
Alloy Steel
• Other elements (besides carbon) can be added to iron to improve mechanical property,
manufacturing, or environmental property.
• Example: sulfur, phosphorous, or lead can be added to improve machine ability.
• Generally want to use for screw machine parts or parts with high production rates!
• Examples: 11xx, 12xx and 12Lxx
Alloy Steel
• Again, elements added to steel can dissolve in iron (solid solution strengthening):
• Increase strength, hardenability, toughness, creep, high temp resistance.
• Alloy steels grouped into low, med and high-alloy steels.
• High-alloy steels would be the stainless steel groups.
• Most alloy steels you’ll use fall under the category of low alloy.
Alloy Steel
• > 1.65%Mn, > 0.60% Si, or >0.60% Cu
• Most common alloy elements :
• Chromium, nickel, molybdenum, vanadium, tungsten, cobalt, boron, and copper.
• Low alloy: Added in small percents (<5%)
• increase strength and hardenability
• High alloy: Added in large percents (>20%)
• i.e. > 10.5% Cr = stainless steel where Cr improves corrosion resistance and stability at high or low temps
Alloying Elements used in Steel
Manganese (Mn)
• combines with sulfur to prevent brittleness
• >1%
• increases hardenability
• 11% to 14%
• increases hardness
• good ductility
• high strain hardening capacity
• excellent wear resistance
• Ideal for impact resisting tools
Alloying Elements used in Steel
Sulfur (S)
• Imparts brittleness
• Improves machineability
• Okay if combined with Mn
• Some free-machining steels contain 0.08% to 0.15% S
• Examples of S alloys:
• 11xx – sulfurized (free-cutting)
Alloying Elements used in Steel
Nickel (Ni)
• Provides strength, stability and toughness, Examples of Ni alloys:
• 30xx – Nickel (0.70%), chromium (0.70%)
• 31xx – Nickel (1.25%), chromium (0.60%)
• 32xx – Nickel (1.75%), chromium (1.00%)
• 33XX – Nickel (3.50%), chromium (1.50%)
Alloying Elements used in Steel
Chromium (Cr)
• Usually < 2%
• increase hardenability and strength
• Offers corrosion resistance by forming stable oxide surface
• typically used in combination with Ni and Mo
• 30XX – Nickel (0.70%), chromium (0.70%)
• 5xxx – chromium alloys
• 6xxx – chromium-vanadium alloys
• 41xxx – chromium-molybdenum alloys
Molybdenum (Mo)
• Usually < 0.3%
• increase hardenability and strength
• Mo-carbides help increase creep resistance at elevated temps
• typical application is hot working tools
Alloying Elements used in Steel
Vanadium (V)
• Usually 0.03% to 0.25%
• increase strength
• without loss of ductility
Tungsten (W)
• helps to form stable carbides
• increases hot hardness
• used in tool steels
Alloying Elements used in Steel
Copper (Cu)
• 0.10% to 0.50%
• increase corrosion resistance
• Reduced surface quality and hot-working ability
• used in low carbon sheet steel and structural steels
Silicon (Si)
• About 2%
• increase strength without loss of ductility
• enhances magnetic properties
Alloying Elements used in Steel
Boron (B)
• for low carbon steels, can drastically increase hardenability
• improves machinablity and cold forming capacity
Aluminum (Al)
• deoxidizer
• 0.95% to 1.30%
• produce Al-nitrides during nitriding
PENGELOMPOKAN BAHAN
LOGAM FERRO
Klasifikasi Baja Karbon
PENGELOMPOKAN BAHAN
LOGAM FERRO
Klasifikasi
Besi Cor
PENGELOMPOKAN BAHAN
LOGAM NON- FERRO
Ada beberapa ciri-ciri sifat bukan logam (non-ferro), diantaranya adalah
Tahan terhadap korosi (pengkaratan) Mempunyai daya hantar listrik yang baik
Mudah dibentuk
PENGELOMPOKAN BAHAN
LOGAM NON- FERRO
TEMBAGA
Tembaga adalah suatu unsur
kimiadalam tabel periodic memiliki lambang Cu (Cuprum) dan nomor atom29.
unsur ini memiliki korosi yang lambat sekali.
PENGELOMPOKAN BAHAN
LOGAM NON- FERRO
TEMBAGA
Tembaga murni dibagi dalam tiga jenis yang didasarkan kepada cara pemurniannya.
tembaga tangguh yang dibuat dengan
mencairkan kembali tembaga hasil elektrolisa.
tembaga bebas oksigen yang dibuat dengan mendeoksidasi tembaga hasil elektrolisa
tembaga bebas oksigen hantaran tinggi yang dibuat dengan mencairkan tembaga elektrolisa dalam atmosfir hidrogen.
PENGELOMPOKAN BAHAN
LOGAM NON- FERRO
TEMBAGA
Sebagai unsur paduan pada tembaga umumnya digunakan adalah Zn, Si, Sn, Al, Ni dan lain-lainya.
Paduan antara Cu-Zn disebut brass atau kuningan paduan antara Cu-Sn disebut brons atau perunggu.
paduan yang mengandung fosfor disebut brons fosfor, Cu-Si disebut brons silikon
CU-Al disebut perunggu aluminium
PENGELOMPOKAN BAHAN
LOGAM NON- FERRO
ALUMUNIUM
Aluminium adalah unsur kimia yang mempunyai simbol Al dan nomor atom 13.
Paduan aluminium
berdasarkan pembuatan dengan klasifikasi paduan cor dan paduan tempa
berdasarkan perlakuan panas dengan
klasifikasi dapat atau tidak dapat diberlakupanaskan berdasarkan unsur-unsur paduan
PENGELOMPOKAN BAHAN
LOGAM NON- FERRO
TIMBAL (Pb)
Timbal adalah suatu unsur kimiadalam tabel periodic yang memiliki lambang Pb (Plumbum) dan nomor atom 82.
Timbal mempunyai warna biru kelabu.
Sifatnya dapat ditempa Sangat liat
Tahan korosi, air, asam.
PENGELOMPOKAN BAHAN
LOGAM NON- FERRO
TIMAH (Sn)
Timah adalah sebuah unsur kimia dalam tabel periodic yang memiliki simbol Sn (bahasa Latin: stannum) dan nomor atom 50.
Warna aluminium bening keperak-perakan, sifatnya dapat ditempa, liat dan tahan
korosi.
Timah digunakan sebagai pelapis lembaran baja lunak (pelat timah) dan untuk
pembuatan peralatan di industri pengawetan dan pelapis/ bungkus makanan
