Steel & Iron

To be reported by:
Diwata R. Bisnar
Ruth Margarette L.
Santos
Ginger A. Amonoy
Krized Noviem M.

Introduction
Composition and Structure
Steel Tensile Test
Steel Protection
Reinforcing & Structural Steel
Types of Steel & Iron
Examples of Steel Structures
O U T L I N E
Guggenheim Museum,
Bilbao, Spain

IRON vs STEEL
• Technically, iron means just that, chemically pure iron.
Without carbon, iron is very soft and ductile.
• Iron become softer upon heating.
• Steel is an alloy of iron and carbon. It contains less
than 2% of carbon.
• Adding carbon makes the iron harder.
• Steels can be forged and hardened by heat treatment.
• Iron was known to the humans from the beginning of
civilization; however steel was discovered much later.

• Steels that contains more than 2% carbon are known
as pig iron. Pig iron is obtained from iron ore by
processing it with coke in a blast furnace. This pig iron
is then further processed to reduce the carbon content
in different furnaces to obtain steels. These steels can
be then further processed to obtain alloy steels,
stainless steels by adding elements such as silicon,
manganese, chromium, nickel, etc.
IRON vs STEEL

• Iron is the 10th most abundant element in the universe
• Iron accounts for about 35% of earth’s mass, most of it is
in the inner core
• Earth crust contains about 5% of iron, the 2nd most
abundant metal (the first being aluminum)
I R O N

• The relatively low cost of iron and its high strength make
it the most-used metal in the world. The majority of iron
is in the form of steels, which are alloys of iron with
different metals and carbon.
Akashi-Kaikyo Bridge, the world’s longest suspended bridge, is made of steel.
I R O N

M A N U F A C T U R I N G O F S
T E E L
Iron Ore -----> Pig Iron
Cast Iron
Pig Iron ------> Steel
Forming of Steel

• The manufacturing of steel consists of 3 main phases
– Reducing Iron Ore to Pig Iron
– Refining Pig Iron to Steel
– Forming Steel into products
T E E L
Iron
Ore
Blast
Furnace
Pig
Iron
Basic
Oxygen
Furnace,
etc.
Steel
Blooming
Mill
Steel
Products

T E E L
Coke
Blast Furnace
Pig Iron
Pig Iron
Casting
Slag
Basic Oxygen
Furnace
Electric Arc
Furnace
Open Hearth
Furnace
Molten Steel
Iron Ore Limestone
Alloying
Agents
Continuous
Casting
Ingots
Soaking
Pits
Primary
Rolling

• Iron does not occur in nature as pure metal, but as combinations
with oxygen or sulfur, called Iron Ore. The most common are
hematite (Fe2O3), magnetite (Fe3O4), or pyrite (FeS2)
• 3 main ingredients used in reducing Iron Ore to Pig Iron are
Coke (product from Coal), Limestone, and Iron Ore
• Iron ore is converted to pig iron in the Blast Furnace
MagnetiteHematite Pyrite (Fool’s Gold)
Iron Ore Pig Iron (Step 1)

• Iron is extracted from ore by removing the oxygen,
usually by combining with carbon to produce CO2
• It takes about 5-8 hours from the loading of material
at the top till the iron is obtained at the bottom.
• The process is done continuously – the furnace
never shuts down.
• To produce 1 ton of pig iron, it takes about 1300 kg
of iron ore, 600 kg of coke, 400 kg of limestone,
7300 kg of air, 22000 kg of water, and 27x106 BTU
of heat.
• Pig iron obtained from the blast furnace cannot be
used by its own, due to its high carbon content
(about 3.5-4%). It has to be processed further to
reduce the amount of carbon and to remove other
impurities.
Iron Ore Pig Iron (Step 1)
Video of a Blast Furnace

Cast iron
• Cast iron is produced by
reheating pig iron and remove
some of the impurities. It
contains about 2-4% of carbon
• It can be cast into molds
• It is brittle and best used in
compression rather than
tension
• Common applications are
pipes and fittings.
• Cast iron is difficult to weld.

• 4 main types
– White cast iron: The carbon and iron
are in the form of iron carbide
(Fe3C).It is hard and very brittle so it
is no tused as structural components.
It may be used where high resistance
to abrasion and wear is required.
When broken, the fracture surface
appears white.
– Grey Cast Iron: The carbon is Cast Iron Pipe Fittings
Cast iron
present in the form of graphite flakes. This graphite make it softer
and machineable, but it is still very brittle. When broken, the
fracture surface appears grey. This is the most common type of
cast iron.

- Ductile Iron or Spheroidal Graphite Iron: By adding some alloying elements and
the right casting procedure, the graphite in the grey cast iron may be induced
to form into spherulites (small spheres). This reduce the brittleness.
- Malleable Iron: By applying heat treatment to the white cast iron, the nodules of
graphite may be formed. This helps increase the strength and reduce
brittleness.
Decorative Cast Iron Gate
Coalbrookdale Iron Bridge (1785), UK
Cast iron bridge
Cast iron

Pig Iron Steel (Step 2)
• Steel is an alloy of iron with some other metals, called alloying elements.
Alloying elements are added to improve properties of iron such as hardness,
elasticity, ductility, tensile strength, corrosion resistant, etc…
• Steel contains up to about 1.5% carbon
• Structural Steel contains up to about 0.25% carbon
• Types
– Mild Steel or Low Carbon Steel (C < 0.25%) this is the structural steel
– Medium Carbon Steel or just Carbon Steel (0.3% < C < 0.6%)
– High Carbon Steel (0.6% < C < 1.5%)
– Alloy Steel (Steel + Alloying elements) eg. Stainless steel
• 3 main types of furnaces used in refining pig iron to steel
– Open Hearth Furnace (Traditional)
– Basic Oxygen Furnace (Most Popular)
– Electric Arc

• Molten pig iron and recycled steel are dumped from
the top.
• Pure oxygen is blown with high pressure into the
furnace to stir things up and cause rapid burning of
materials.
• Limestone is added as a flux
• Impurities are either removed as gases (such as
CO2) or as slag.
• Alloying metals may be added to produce special
steel alloy
• Basic oxygen furnace can refine about 300 tons of
steel in under 30 minutes.Basic Oxygen Furnace
• The molten steel may be cast into a large prism called Ingot to be sent to
another factory to form into desired shapes

Molten pig iron is added to the
top of the Basic Oxygen Furnace
Steel Ingot

STEEL
• The largest producer in the world is China, followed by Japan
and USA

• Today, most of the steel is from
recycled steel. This has some
effects on the chemical
compositions of the modern steel
by having elements that were not
previously considered to be a part
of normal steel chemistry
• It is now become more difficult to
find a low-strength grade of steel.
We tend to get much higher actual
strength for the lower-strength
grade of steel.
STEEL

Forming of Steel (Step 3)
• The steel ingot goes to blooming mill where it is reheated to about 1200 C
and get passed through huge rollers to reduce the ingot to a smaller size
• It may take 20+ rollers to reduce the ingot into the desired shape and size
• Typical shapes produced are plates, rods/bars, and structural steel rolled
shapes.

STEEL COMPOSITION
Steel comprises iron and other elements such as
carbon, manganese, phosphorus, sulfur, nickel,
chromium and more.
Variations in steel compositions are responsible
for a great variety of steel grades and steel
properties.

PROPERTIES OF STEEL
• Properties of metals, in general, may be divided into 2
categories
– Structure Insensitive Properties : these are properties
that has to do with the atoms themselves, but not the
microstructure. Examples are density, elastic modulus, coefficient
of thermal expansion, specific heat.
– Structure Sensitive Properties : these are properties that
depends on the microstructure of the materials, which is greatly
affected by heating and cooling histories. Examples are yield
strength, fracture strength, ductility (elongation at failure), and
fatigue performance.

Steel Grades
Classification of various steel grades by their composition
and properties has been developed over many years by a
number of standard development organizations (SDOs)
such as European EN, US ASTM and AISI steel grades,
Japanese JIS, Chinese GB, International ISO etc.

• Hundreds of different grades and types of steel exist.
Most are divided up into three general categories: tool
steel, simple steel and stainless steel. Within each
category, different families of steel exist. The American
Iron and Steel Institute is one of the most common
standardizing organizations and uses a alphanumeric
identification system to classify steel. Converting
between different steel grades according to chemistry
or properties is possible but technical data is necessary
for more accurate conversions.
Steel Grades

• AISI steel grades (American Iron & Steel Institute) Its
development was in response to the need for a cooperative agency in
the iron and steel industry for collecting and disseminating statistics
and information, carrying on investigations, providing a forum for the
discussion of problems and generally advancing the interests of the
industry.
AISI spearheads initiatives to favorably profile the industry's reputation.
• Japanese Industrial Standards (JIS) (日本工業規格 Nippon
Kōgyō Kikaku) specifies the standards used for industrial activities
in Japan. The standardization process is coordinated by Japanese
Industrial Standards Committee and published through Japanese
Standards
• GB abbreviates Guojia Biaozhun (国家标准), which
means national standard in Chinese.

• The International Organization for
Standardization (French: Organisation internationale de
normalisation, Russian: Международная организация по
стандартизации, tr. Mezhdunarodnaya organizaciya po
standartizacii), widely known as ISO, is an international standard-
setting body composed of representatives from various
national standards organizations. Founded on February 23, 1947,
the organization promulgates worldwide proprietary industrial and
commercial standards. It has its headquarters
in Geneva, Switzerland.

Molecular Structure of Steel
Steel is a crystalline structure of iron molecules
interspersed with carbon molecules. This is properly
known as "cementite." The hardness and malleability of
steel depends not only on the carbon content, but on how
the carbon and iron molecules are arranged to one
another. Internal stresses in the steel's crystalline
structure will increase or decrease depending on the
temperature it is subjected to and the rate at which molten
steel is cooled.

Cementite
• Cementite, also known as
iron carbide, is a chemical
compound of iron and carbon,
with the formula Fe3C (or
Fe2C:Fe). By weight, it is
6.67% carbon and 93.3% iron.
It has an orthorhombic crystal
structure. It is a hard, brittle
material, normally classified as
a ceramic in its pure form,
though it is more important
in metallurgy.

Atomic Structure of Steel
Steel is a refined form of iron that has a controlled
amount of carbon added to it. It has also been
smelted with various minerals to help remove
impurities at specific temperatures. There are several
grades of steel, and other metals may be alloyed with
the steel, depending on what its eventual use will be.
The smelting of iron into steel was developed to an
efficient industrial process only in the 19th century.

STRENGTH – ability of a
structure to resist loads
without failure.

ULTIMATE TENSILE STRENGTH(UTS) -
often shortened to tensile strength (TS)
or ultimate strength
 maximum stress that a material can
withstand while being stretched or
pulled before necking, which is when
the specimen's cross-section starts to
significantly contract.

 opposite of compressive strength
 highest point of the stress-strain curve
 stress which is measured as force per
unit area

STEEL TENSILE TEST - known as tension
test
 provide information on the strength and
ductility of materials under uniaxial tensile
stresses that will be use in the same
calculations or to demonstrate that a
material complies with the requirements of
the appropriate specification

 involves taking a small sample with a fixed
cross-section area, and then pulling it with
a controlled, gradually increasing force
until the sample changes shape or breaks.

The following MATERIAL PROPERTIES can be
evaluated / determined by TENSILE TESTING:
 STRENGTH
 DUCTILITY
 ELASTICITY
 STIFFNESS
 TOUGHNESS

MATERIAL PROPERTIES:
STRENGTH - the greatest stress that the material
can withstand prior to failure.
DUCTILITY - a material property that allows it to
undergo considerable plastic deformation
under a load before failure.
ELASTICITY - a material property that allows it to
retain its original dimensions after removal of a
deforming load.

MATERIAL PROPERTIES:
STIFFNESS - a material property that allows a
material to withstand high stress without great
strain.
TOUGHNESS - is an ability to absorb energy in
the plastic range.
- or the ability to withstand occasional
stresses above the yield stress without
fracture.

 A machine which applies a tensile
force (a force applied in opposite
directions) to the specimen, and then
measures that force and also the
elongation
 creates stress-strain diagram
 Universal Testing Machine(UTM) is
the most common.

UNIVERSAL TESTING MACHINE
 known as a universal tester,
materials testing machine or
materials test frame
 tests materials in tension,
compression or bending

2 CLASSES OF TESTING
MACHINE:
1. Electromechanical
2. Hydraulic

1. Electromechanical
 uses an electric motor, gear reduction
system and one, two or four screws to
move the crosshead up or down.
 capable of a wide range of test speeds and
long crosshead displacements

ELECTROMECHANICAL
 High accuracy photoelectric encoder
 Dual testing space
 Pre-loaded ball screws, heavy bearings
and robust guidance columns
are built-in.
 Limited switch protecting
 High accuracy load cell
 Full digital servo motor with close-loop Hydraulic

2. Hydraulic
 uses either a single- or dual-acting
piston to move the crosshead up or
down.
 a cost-effective solution for
generating high force.

Marking the sample:
 A precision punch with two points exactly 2.000”
apart is used to mark the sample in the tested
region.
 These 2 points are the gauge points
 The distance between these points before the
application of the load, is called the gauge length
of the specimen

 The test is made by gripping the ends
of a suitably prepared standardized
test piece in a tensile test machine
and then applying a continually
increasing uni-axial load until such
time as failure occurs.

 “Necking” occurs as the sample
leaves the elastic deformation region
and begins to deform plastically.

 Upon completion of the test, the sample is
reassembled and final measurements for total
elongation and minimum diameter are made
using a vernier caliper.

Percentage elongation is defined as :
El% = (L f - L 0 /L o ) x100
where :
Lf = gauge length at fracture
L0 = original gauge length.

Percentage reduction in area of the
specimen is given by:
A% =(A 0 - A f /A 0 ) x 100
where :
A f = cross sectional area at site of the fracture.
A 0 = original area of cross section of the
specimen

ENGINEERING STRESS-STRAIN CURVE
 an x-y plot of stress vs. strain through the
entire range of loading of the specimen until
specimen failure.
STRESS
 Load per unit area
STRAIN
 unit the formation of the material under load

a. ULTIMATE TENSILE STRENGTH (UTS)
σmax = Pmax / A0
where:
P max = maximum load, A 0 = original cross sectional
area.
A 0 = original area of cross section of the specimen

b. YIELD POINT(YP)
- the stress at which deformation changes from
elastic to plastic behaviour
YP = Pyp / A 0
where:
P yp = load at the yield point.
A 0 = original area of cross section of the specimen

The slope of the elastic portion of the curve,
essentially a straight line, will give Young's
Modulus of Elasticity.
Young's Modulus of Elasticity
 the ratio of stress to strain below the elastic
limit.
Low modulus = flexible structure
High modulus = inflexible structure

PROOF TEST (Offset Yield Strength)
 Test required to produce a small
specified amount of plastic
deformation in the test piece.

Video of Steel
Tensile Testing

D U R A B I L I T Y
 The quality of equipment, structures, or goods of continuing to
be useful after an extended period of time and usage.
Influence of Design on Corrosion
 The design of a structure can affect the durability of any
protective coating applied to it. Detailing is important to ensure
that the protective treatment can be applied to all surfaces.
Narrow gaps, difficult to reach corners, and hidden surfaces
should be avoided wherever possible. Details that could
potentially trap moisture and debris, which would accelerate
corrosion, should also be avoided.

D U R A B I L I T Y
 Measures that can be taken include:
 Ensure weld profiles are not excessive
 Avoid using channels with toes upward
 Arrange angles with the vertical leg below the horizontal
 Avoid crevices that attract and retain water through
capillary action

C O R RO S I O N
Corrosion is a destruction of a material by
electrochemical reaction. When the steel corrodes, rust
is formed.
Steel rusts at the rate of about 0.5mm/year.
The amount of time the steel stays wet affects the rate of
corrosion.
Environmental contaminants may accelerate corrosion.
Examples are SO₂ in acid rain, and salts (from sea or
deicing salts).

C O R RO S I O N
In order for rust to occur, we need 4 elements
 Anode: The electrode where corrosion occurs
 Cathode: The other electrode needed to form a
corrosion cell
 Conductor: A metallic pathway for electrons to flow
 Electrolyte: A liquid that can support the flow of
electrons

Reactions:
Anode Side Fe → Fe²⁺ + 2e⁻
Fe²⁺ + 2(OH)⁻ → Fe(OH)₂
Ferrous Hydroxide (Black Rust)
4Fe(OH)₂ + 2H₂O + O₂ → 4Fe(OH)₃
Ferric Hydroxide (Red Rust)
Cathode Side 4e⁻ + 2H₂O + O₂ → 4(OH)⁻
C O R RO S I O N
Red rust Black rust

Corrosion of shell inside
the tank
Corrosion
in concrete

Corrosion of
rain gutter
Corrosion of
hand rail

P R E V E N T I O N O F
C O R RO S I O N
 Design the structure such that water cannot collect on the surface
or joints
 Design the structure such that inspection and maintenance can be
done easily

 Applying protective coating to seal off
the surface from moisture.
 The surface to be painted must be
dry and clean
 Periodic repainting is necessary
C O R RO S I O N
 Cathodic protection: we prevent the corrosion of steel by
making it the cathode side of the corrosion cell!
 Sacrificial Anode: this is done by connecting more anodic
metal with steel. The anode metal will corrode instead of the
steel. This anode metal must be replaced occasionally.

C O R RO S I O N
 Anodic coating : this is similar to
the sacrificial anode but, instead
of using a piece of metal, the
anode metals is coated on the
surface of the steel.
• Galvanizing: uses Zinc to
coat the surface of the steel
• Zinc-Pigmented Paint: Same
concept as galvanizing but in
the form of paint

C O R RO S I O N
 Impressed Current Cathodic Protection (ICCP): Using
external power source to make the metal cathodic
and consume the anode metal instead. Inert Anodes
such as carbon, titanium, lead, or platinum are used.
This is typically used for large structures, such as
buried pipelines, as placing sacrificial anodes at
regular intervals is impossible.

C O R RO S I O N
Video of an Impressed Current
Cathodic Protection

Examples of Protective Coating:
Anti-corrosive paint coatings

Hot Dip galvanizing
Spray galvanizing

Electroplating &
Chromium Plating
Aluminum
Spraying
Rubberizing

W E A T H E R I N G S T E E L
• Weathering steel or high strength low-alloy (HSLA) steel
(also known commercially as COR-TEN steel) is a steel alloy
with very low percentage of carbon (<0.15%) and small
amounts of chromium, copper, phosphorus, nickel, niobium,
nitrogen, vanadium, molybdenum, silicon, or zirconium
• It corrodes by forming a dense and tightly adherent oxide
barrier that seals out the atmosphere and retards further
corrosion. This is in contrast to other steels that form a
coarse, porous and flaky oxide that allows the atmosphere to
continue penetrating the steel.
• It is widely used in bridges and marine structures.
• It is not rust-proof. If water collects on the surface, it will
corrode.

S T A I N L E S S S T E E L
• Stainless steel, also known as high-alloy steels, contains 16-
28% chromium, up to 22% nickel, and some manganese. It
has very high resistance to corrosion due to the forming of a
thin, transparent coating of chromium oxide over the surface.
• It is often used as kitchen tools, laboratory equipments, etc…
For construction, stainless steel are used as cladding, water
pipes/fittings, and corrosion-resistant reinforcement for
concrete (ASTM A 955M).
• Variety of finishes are available from unpolished, brushed, to
mirror finishes.

• also known as reinforcing bar, rebar,
reinforcement steel, deformed bar or steel
bar
• commonly used as a tensioning device
in reinforced concrete and
reinforced masonry structures holding the
concrete in compression.
• usually formed from carbon steel, and is given
ridges for better mechanical anchoring into the
concrete.
R E I N F O R C I N G S T E E L

C h a r a c t e r i s t i c s
These ridges are designed to
help the bar secure itself into
the concrete better. When the
concrete is poured it flows
under and around the ridges so
that the bar in essence grips
on to the concrete when it
dries. This forms a much more
solid reinforcement than a
smooth bar would provide.
• Ridges

Concrete is strong in many ways.
However, it does not have great
tensile strength. Steel, on the other
hand does have a great deal of
tensile strength. Rebar placed into
concrete helps to increase the
overall strength of the structure,
because the tensile strength of the
rebar helps to hold the structure
together where concrete alone
would not be strong enough.
• Tensile Strength

• Carbon Steel
Rebar is made from carbon steel.
This is the most common type of
steel manufactured. Steel is made
using many different elements to
create alloys, but in carbon steel,
no other alloy material is added to
the material beyond the carbon.
Carbon steel is very strong and
may contain as much as 2 percent
carbon in the material.

• Working
Rebar can be worked with in a
number of different ways. It can be
heated and bent, a technique often
used to create a hook at the end of
the bar to reinforce an anchor
position. The material is also
suitable for welding. In situations
where even the small reduction in
strength that might occur from
welding is unacceptable, rebar is
usually wired to other bars instead.

Types and Properties of Reinforcing
Steel

Types and Properties of Reinforcing Steel
Steel Reinforcement consists of:
 bars
 wires
 welded wire fabric

The most important properties of steel are:
 Young's Modulus (Modulus of Elasticity), E
 Yield Strength, fy
 Ultimate strength, fu
 Steel Grade Designation
 Size of Diameter of the bar

Generally there are two types of steel bars
available in the market:
 Plain steel bars
 Deformed steel bars

PLAIN STEEL BARS
Plain bars are round in cross
section. They are used in concrete
for special purposes, such as
dowels at expansion joints, where
bars must slide in a metal or
paper sleeve, for contraction
joints in roads and runways, and
for column spirals. They are the
least used of the rod type of
reinforcement because they offer
only smooth, even surfaces for
bonding with concrete.

DEFORMED STEEL BARS
Deformed bars differ from the plain
bars is that they have either
indentations in them or ridges on
them, or both, in a regular pattern. The
spiral ridges, along the surface of the
deformed bar, increase its bond
strength with concrete. Other forms
used are the round and square
corrugated bars. These bars are
formed with projections around the
surface that extend into the
surrounding concrete and prevent
slippage.

Yield Stress for Steel
 probably the most useful property of
reinforced concrete design calculations is the
yield stress for steel, fy
 a typical stress strain diagram for reinforcing
steel is shown in Fig. 2a
 an idealized stress-strain diagram for
reinforcing steel is shown in Fig 2b.

Modulus of Elasticity or Young's Modulus for
Steel
 the modulus of elasticity for an reinforcing steel
varies over small range, and has been adopted
by the ACI* Code
*American Concrete Institute

Steel Grades and Strengths

Size of Diameter of the bar
*ASTM Standard-English Reinforcing Bars

Size of Diameter of the bar
*ASTM Standard-Metric Reinforcing Bars

Reinforced concrete is a mixture of concrete
and steel reinforcement. Concrete is weak in
tension and cracks easily when it shrinks or
creeps under sustained loading. It is a brittle
material. When concrete fails, it breaks
suddenly without warning.
Use in Concrete

Steel, on the other hand, is 100 times stronger in
tension than concrete; is 6 times stiffer; and will
stretch 17 times more than concrete before
failing. Steel reinforcement provides reinforced
concrete the tensile strength, stiffness, and
ductility needed to make it an efficient, durable,
versatile, and safe building material.
Use in Concrete

For reinforced concrete to work as the Designer intended,
the Inspector and Resident Engineer must ensure that
reinforcing steel placed in a structure is:
 the correct grade and type of steel;
 the correct size, shape and length;
 placed in its specified location and spaced properly
 tied and spliced together properly;
 clean and will get an adequate cover of concrete in all
directions; and
 placed in the correct quantities.

Primary and Secondary
Reinforcement
Primary reinforcement is the steel in the concrete
that helps carry the loads placed on a structure.
Without this steel, the structure would certainly
collapse.

Secondary reinforcement is the steel placed in a
structure that enhances the durability and holds the
structure together. It provides the resistance to
cracking, shrinkage, temperature changes, and
impacts necessary for a long service life of the
structure.
Primary and Secondary
Reinforcement

• one of the basic materials used in the
construction of frames for most industrial
buildings, bridges, and advanced base
structures.
• a category of steel construction material that is
produced with a particular cross section or shape,
and some specified values of strength and
chemical composition.

Kinds of Structural Steel
After iron, carbon is the most important
element in steel. The increase of carbon produces
materials with high strength and low ductility.
The techniques used for the production of steel
are high- computerized stress analysis, precision
stress analysis, and innovative jointing. The types
of structural steel sections normally used are
beams, channels, flats, and angles. The main
kinds of structural steel are generally categorized
according to the under mentioned categories of
chemical composition:

Carbon-Manganese Steels
 the major chemical ingredients
are iron, carbon, and manganese.
These are normally called mild
structural steels or carbon steels.
The strength and ductility are
high, and being economical is
therefore widely used. The
famous category amongst this
type is ASTM grade A36.
*A36 is an all-purpose carbon steel, is the most widely used structural steel for commercial
and industrial building construction. This grade has a yield stress level of 36ksi, and has
excellent welding and machining characteristics, thus is ideal for making welded and/or
bolted connections.

High-strength, low-alloy
steels:
• This is a recent development
in the steel industry. Chemical
elements are added to improve
the strength. A commonly used
type is ASTM grade A572.
*A572 is another popular grade of structural steel used in building construction. May be
bolted or welded. It is available in four minimum stress levels: 42 ksi, 50 ksi, 60 ksi and
65 ksi grades. Since A572 is stronger than A36, using it often results in lower costs
because heavier loads may be carried at longer spans by lighter beams. This translates
into cost savings because fewer footings are required and erection time can be cut down.

High-strength tempered
and quenched alloy
steels:
• These are used for structural
purposes and generally
available is ASTM grade
A514.
*A514 steels are used where a weldable,
machinable, very high strength steel is
required to save weight or meet ultimate
strength requirements. It is normally used as a
structural steel in building construction,
cranes, or other large machines supporting
high loads.

Types of Structural Steel
The three most common types of structural members
are the W-shape (wide flange), the S-shape
(American Standard I-beam), and the C-shape
(American Standard channel). These three types
are identified by the nominal depth, in inches, along
the web and the weight per foot of length, in pounds.

The W-SHAPE
• is a structural member whose
cross section forms the letter
H and is the most widely used
structural member. It is
designed so that its flanges
provide strength in a
horizontal plane, while the
web gives strength in a
vertical plane. W-shapes are
used as beams, columns, truss
members, and in other load-
bearing applications.

The S-SHAPE
• also known as American
Standard I-beam is
distinguished by its cross
section being shaped like
the letter I. S-shapes are
used less frequently than
W-shapes since the S-
shapes possess less strength
and are less adaptable than
W-shapes.

The C-SHAPE
• or the American Standard channel
has a cross section somewhat
similar to the letter C. It is
especially useful in locations where
a single flat face without
outstanding flanges on one side is
required. The C-shape is not very
efficient for a beam or column
when used alone. However,
efficient built-up members may be
constructed of channels assembled
together with other structural
shapes and connected by rivets or
welds.

General uses of structural steel
COLUMNS
• Wide flange members, as
nearly square in cross
section as possible, are
most often used for
columns. Large diameter
pipe is also used frequently
(fig. 3-10), even though
pipe columns often present
connecting difficulties
when you are attaching
other members.

Girders
• are the primary horizontal
members of a steel frame structure.
They span from column to column
and are usually connected on top of
the columns with CAP PLATES
(bearing connections), as shown in
figure 3-14. The girder is attached
to the flange of the column using
angles, with one leg extended
along the girder flange and the
other against the column. The
function of the girders is to support
the intermediate floor beams.

Beams
• are generally smaller than
girders and are usually
connected to girders as
intermediate members or to
columns. Beams are used
generally to carry floor
loads and transfer those
loads to the girders as
vertical loads.

Bar joists
• form a lightweight, long-
span system used as floor
supports and built-up
roofing supports. Bar joists
generally run in the same
direction as a beam and
may at times eliminate the
need for beams.

TRUSSES
• Steel trusses are similar to bar
joists in that they serve the
same purpose and look
somewhat alike. They are,
however, much heavier and
are fabricated almost entirely
from structural shapes,
usually angles and T-shapes.
Unlike bar joists, trusses can
be fabricated to conform to
the shape of almost any roof
system and are therefore
more versatile than bar joists.

• Purlins are generally
lightweight and channel-
shaped and are used to
span roof trusses. Purlins
receive the steel or other
type of decking, and are
installed with the legs of
the channel facing outward
or down the slope of the
roof. The purlins installed
at the ridge of a gabled
roof are referred to as
ridge struts.
PURLINS, GIRTS, AND EAVE
STRUTS

• alloy of iron and carbon
• derived from the molten
iron from the bottom
of the furnace

Types:
- named after its
white surface when
fractured, due to its
carbide impurities
which allow cracks to
pass straight through.

Types:
- too brittle for use
in many structural
components, but with
good hardness and
abrasion resistance and
relatively low cost

Types:
- named after its grey
fractured surface, which
occurs because the
graphitic flakes deflect a
passing crack and initiate
countless new cracks as
the material breaks.

Types:
- most commonly used
cast iron and the most
widely used cast
material based on
weight.
- has less tensile
strength than steel.

Types:
- has high thermal
conductivity
and specific heat
capacity
- Easy to weld

Types:
- cast as White iron
- Properties are more
like mild steel
- used for small
castings

Types:
Three basic types:
1.
•Blackheart Malleable
Iron
2.
•Whiteheart Malleable
Iron
3.
•Pearlitic malleable
iron

Types:
- nodular or spheroid graphite iron
- flexible and elastic, due to its
nodular graphite inclusions.
- used for water and sewer lines

• very runny when it is molten and
doesn't shrink much when it
solidifies
• have relatively low melting point
• excellent machinability
• resistant to deformation
• resistant to weakening by
oxidisation (rust)
• strong under compression

• It is very impure, containing
about 4% of carbon. This
carbon makes it very hard, but
also very brittle.
• Weak under tension

Cast iron is used for things like:
bridges…
The iron bridge over the River Severn at Coalbrookdale, England

Watervliet Arsenal Museum in Watervliet, New York
…buildings…

Ditherington Flax Mill
…textile mills…

Cast irons have also
a wide range of applications,
including machine and car
parts like cylinder heads,
blocks, and gearbox cases,
cookwares, pipes, etc.

Cast iron
cylinder head
Cast iron
pan
Cast iron
pipes

• the intermediate
product of melting i
ron ore with a
high-carbon fuel
such as coke, usually
with limestone as
a flux.

• has a very
high carbon content,
typically 3.5–
4.5%, which makes
it very brittle
• used to produce gray
iron
• used to produce steel

• the word "wrought" is
an archaic past tense
form of the verb "to
work,"
• iron alloy with a very
low carbon content
• tough, malleable, ductile
• easily welded.

• cannot be hardened,
due to lack of carbon.
• items produced from
wrought iron includes
rivets, nails, wire,
chains, railway
couplings, water and
steam pipes, nuts,
bolts, etc.

Carbon Steels
Alloy Steels
Stainless Steels

• Carbon steel, also called plain-carbon
steel, is steel where the main
interstitial alloying constituent is
carbon.
• Steels containing 0.2% C to 1.5%
C are known as carbon steel. They
are of three types.

Carbon steel sand casting Seamless Carbon Steel
Elbow

Sell galvanized low carbon steel wire for armored cable

Sell galvanized low carbon
steel wire for armored cable
Low Carbon
Steel
It contains
0.2% carbon.
Uses:
Sheets,
wires, pipes.

Mild steel round bar
Mild Carbon Steel
It contains 0.3%
to 0.7% carbon.
Uses:
Rails, boilers,
plates, axles,
structures.

Steel Rope, Electric
Cable, Galvanized,
High-Carbon Steel
Wire
High Carbon Steel
It contains 0.7% to
1.5% carbon.
Uses:
Surgical
instruments, razor
blades, cutlery, spring.

• Alloy steel is steel alloyed with a
variety of elements in total amounts
of between 1.0% and 50% by weight
to improve its mechanical properties.

• Some of these find uses in exotic and
highly-demanding applications, such
as in the turbine blades of jet engines,
in spacecraft, and in nuclear reactors.

A turbine blade from a jet
engine, cast as a super
alloy

•Mn-Steel
•Si-Steel
•Ni-Steel

High Manganese Steel Plate
(12 To 14% Mn)
Mn-Steel
It contains
10%-18% Mn.
Uses:
Rail tracks,
armor plate,
safe.

TENOVA - Continuous
Annealing Lines (for Si-Steel)
Si-Steel
It contains
1% to 5% Si.
Uses:
Permanent
magnet.

Ni-Steel
It contains
2% to 4% Ni.
Uses:
Gear,
shaft, cable.

• It contains 14% to 18% chromium
and 7% to 9% nickel.
• Stainless steel does not stain,
corrode, or rust as easily as ordinary
steel, but it is not stain-proof.

• also known as inox steel or inox
from French "inoxydable“.
Uses :
Car accessories, watch case,
utensils, cutlery.

Bahrain World
Trade Center,
Manama, Bahrain

Toledo Barrel Shell Space frame coal storage, Philippines, Space
frame.

Japan Tokyo
International Forum
Steel glass structures
and passageways ...

Taipei 101 –
Super structure

Specialist in steel
structure & general
contractor

Beijing (Bird’s Nest)
National Stadium,
China
Allianz Arena,
Munich, Germany

Eiffel Tower, Paris,
France
Tokyo Tower, Japan

Burj Khalifa, Dubai,
United Arab
Emirates,
currently the world’s
tallest building

The pinnacle of
New York's
Chrysler Building
is clad with type
302 stainless steel.

An art deco sculpture on the Niagara-Mohawk Power building
in Syracuse, New York.

Pipes and fittings made of stainless steel

316L stainless
steel, with an
unpolished, mill
finish.

The 630-foot (192 m) high, stainless-clad (type 304)
Gateway Arch defines St. Louis's skyline.

Bisnar, Diwata R.
Santos, Ruth Margarette L.
Amonoy, Ginger A.
Leoncio, Krized Noviem M.
Editedby:GingerA.Amonoy

Steel & Iron

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