PENGETAHUAN BAHAN TEKNIK
YUSRON SUGIARTO
PENGETAHUAN BAHAN TEKNIK
yusronsugiarto.lecture.ub.ac.id
• 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)
PEMILIHAN BAHAN
Sifat teknis bahan yang perlu diperhatikan dalam
pemilihan bahan
PENGELOMPOKAN BAHAN
FERRO
LOGAM
NON-FERRO
BAHAN TEKNIK
ORGANIK
NON-LOGAM
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.
kayu, kertas, plastik, karet,
kulit, kapas
batu, pasir, semen, keramik, gelas,
AN-ORGANIK 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 highcompressive 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 classification 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 lowcarbon 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.
berdasarkan pembuatan dengan klasifikasi
paduan cor dan paduan tempa
Paduan aluminium
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