CONSTRUCTION MATERIALS AND TESTING

CE141 – LECTURE 7 (METALS)

METALS
 CONTENT
 History  Aluminum
 Classification of Metals  Lead
 Iron  Zinc
 Steel
 Copper and Alloys
 Steel pipe, Tubing, and
 Nickel, Chromium,
Wire
Cadmium & Titanium
 Steel Fasteners
 Rivets  Clad Metals
 Structural Bolts
 Welding
 Steel Floor & Roof
Framing
 History of Metal
 Used as early as 8000 B.C.
 Early civilizations mainly used metal for
weapons, tools, and body armor
 Metal has been used for construction material
ranging from simple fasteners to main
structural members
 Classification of Metals
 Ferrous- metals containing a large percentage of iron
(Fe)
 Cast iron
 Wrought iron
 Steel
 Non-Ferrous- metals which do NOT contain iron
 Aluminum
 Lead
 Copper
 Brass
 Bronze
 Blanking- in sheet metalwork, the cutting out of a piece of metal
(using a press)
 Braking- a mechanical bending operation usually performed on
sheets and plates
 Casting- an article formed by solidification of molten metal in a
mold
 Cold drawing- drawing metal through a die without the
application of heat
 Cold-rolled- metal rolled at room temperature, below the
softening point, usually harder, smoother, and more accurately
dimensioned that hot-rolled material.
 Drawing- forcing metal to flow into a desired shape without
melting by pulling it through dies
 Embossing- creating a raised surface (design) on metal by die
pressure or by stamping or hammering on the reverse surface
 Extrusion – forcing a molten metal through a die by pressure
 Forging- heating and hammering or pressing metal into a desired
shape
Iron
 One of the most abundant metals on earth
 Commercial iron is composed of carbon,
manganese, silicon, phosphorus, and sulfur
Materials Used to Make Iron
 Iron ore
 Coke- fuel used to melt iron; derived from coal
 Limestone- used as a flux
 Flux – a material added to react chemically with
impurities and remove them from molten metal
 Pig Iron- initial molded product from a blast-furnace;
weak & brittle, but very hard
 Types of Iron
 Cast iron (and gray cast iron)- brittle metals with high
compressive strength and capacity to absorb vibration.
Lack ductility and therefore should not be hammered or
beaten. Relatively corrosion resistant. Contains 2-4 %
carbon
 Used for gratings, stair components, manhole covers,
some piping
 Types of Iron
 Wrought iron- soft, corrosion and fatigue resistant,
and easily machined. Contains < 1 % carbon
 Used for railings, grilles, fences, screens, and various
ornamental work
 Steel
 A malleable alloy of iron and carbon with substantial
quantities of manganese
 3 main methods for making steel
 Open-hearth process
 Oxygen process
 Electric furnace process
Mill Output
 Ingot- molded square or rectangular blocks of cast
metal
 Ingots are further squeezed between rollers to
produce:
 Bloom- a rectangular solid of steel formed from an
ingot as an intermediate step in creating rolled steel
structural shapes (over 36” square)
 Billet- a large cylinder or rectangular solid of metal
(smaller then 36” square)
 Slab – if the width is 2x the thickness or more
Metal Ingots
 Standard Mill Products
 Angle- a section of metal rolled, drawn, or extruded through L-
Shaped rolls or dies
 Bar- round, square, rectangular, hexagonal, or solid stock of
drawn, rolled, or extruded metal. A rod.
 Channel – a rolled, drawn, or extruded metal section having a
U shape.
 Flat- a rectangular bar whose width is greater than its thickness
 Pipe, round- a hollow, round section of metal, the size of which
is determined by the nominal inside diameter in inches
 Pipe, square- a hollow, square section of metal, the size is
determined by the nominal outside diameter in inches
 Plate- a flat piece of metal; various metals are defined as plate
by the following thickness criteria: Aluminum==1/4” or more;
Copper==.188” or more; Steel (including stainless)== 3/16” or
more
Designations of Rolled Steel Shapes
 W – wide flange
 S -- beams
 C –channels
 L – angles (may be equal or unequal legs)
 WT or MT – structural tees
Example of Designation
 W 36 x 300
 W === a wide flange beam
 36 === indicates a beam 36” deep
 300 === weight in lbs/ linear feet
 Samples of Steel Shapes

Channel Angle
Wide Flange

S-Beam
Square & Rectangular
Tee
Tubing
 Steel Wire
 Shapes are not only round, but may also include:
square, rectangular, and polygonal
 Wire is used as the starting material to form nails,
bolts, screws, rivets, and welding electrodes
 Temper- wires hardness, stiffness, and strength is
affected by the amount of carbon and alloying agents,
number of passes through dies, and the final heat
treatment
 Wire may be produced with different finishes and
coated, painted, or plated depending on its intended
use
Classification of Steel
 Four main specifications
 Method of manufacture
 Heat treatment
 Chemical composition
 Reference to a recognized standard
Stainless Steel
 To be considered stainless a steel must contain 11.5
% chromium
 There are basic series of stainless steel: 200, 300,
400, & 500 series
 Available in many finishes ranging from matte to
highly reflective (mirror)
 Structural Steel
 Consists of hot-rolled steel section, shapes, and plates
not less than 1/8” thick
 The most commonly used strength grade is 36,000
psi yield strength (ASTM 36)
 For heavily loaded members such as columns, girders,
or trusses, a high strength, low alloy steel with a yield
strength of 50,000 psi
 Steel Construction
 3 basic types:
 Wall bearing
 Skeleton framing
 Long-span
 Large industrial buildings, auditoriums, sports
arenas
 Often use steel trusses, steel arches, or rigid bents
in this type of construction
 Steel Fasteners
 3 main types of fasteners:
 Rivets
 Bolts
 Unfinished (common, machine)
 High-strength structural bolts- resist vibration
(ASTM 325 or A490 are stamped on bolt head)
 Welds
 In some application (based on code requirements)
more than one method may be used
 Welding

 A process of joining metals by applying heat and pressure,

with or without filler material, to produce an actual
union through fusion.
 There are several methods of welding used in specific
situations (shielded metal arc is the most common in
steel work).
 Welding symbols and basic joints are standardized by
AWS (American Welding Society)
 Steel Floor and Roof Framing
 Considerations for systems used:
 Span
 Load to be applied
 Depth
 Weight
 Fire resistance (code)
 Sound transmission
 Heating/Cooling system
 Appearance
 Cost/Time
 Open Web Steel Joists
 Widely used because of the long spans
 Ends of open web joists (hung from the top
chord) are extended a minimum of 4 “ in
masonry/concrete, and a minimum of 21/2 “ over
steel supports.
 Corrugated or ribbed steel decking many times
used in combination with the joists.
Ribbed Steel (Metal) Decking Forms
Metal Decking
 Aluminum
 Bauxite, the major source of aluminum, is still very
abundant in the earth (Jamaica)
 Highly resistant to weather and corrosive
environments
 Aluminum can be economically extruded to many
shapes (mouldings, edgings, window mullions)
 It is very malleable, quite ductile, non-corrosive, and
strong in proportion to its weight.
 Lead
 Important physical properties include: resistance
to corrosion, its plasticity, and its malleability
 Used for waterproofing, sound and vibration
isolation, and radiation shield.
 Can be combined with a tin alloy to plate iron or
steel (called “terneplate”)
 Use extreme care where and how lead is used
because lead vapors or dust are toxic if ingested.
 Zinc

 Is brittle and low in strength

 Major use is in galvanizing (dipping hot iron or
steel in molten zinc)
 May also be used for roofing, flashing, and
hardware
 Copper
 Resistant to corrosion, impact, and fatigue; very
ductile
 Primary use is electrical wiring, roofing, flashing, and
piping
 The oxidization of copper produces what is called a
green “patina”
 Bronze
 Originally a copper-tin alloy, but now aluminum or
silicon added to copper
 Now may be “phosphor bronze”, “aluminum
bronze” or “silicon bronze”
 Widely used for casting delicate mold impressions
(Cathedral doors)
 Brass
 Copper with zinc to form an alloy
 Used for doors, windows, railings, trim,
grilles and for finish hardware
 Nickel, Chromium, and Monel
 Chromium and nickel are used primarily as
alloying elements, however, both can take a bright
polish and do not tarnish in air, making them ideal
for use in plating.
 Monel, a nickel-copper alloy, is mostly used to
make fasteners and anchors, and has excellent
corrosion resistance.
 Clad Metals
 Combines the best qualities of 2 or more different
materials
 The intent is to create a metallurgical bond
between layers of materials
THE CONCEPT OF LIGHT Gauge STEEL CONSTRUCTION

Light Gauge Steel Framing Members

 Steel components are cold-rolled from steel sheet.
 Cold-forming increases metal strength.
 Members are essentially noncombustible equivalents
of wood light frame construction.
THE CONCEPT OF LIGHT Gauge STEEL CONSTRUCTION

C-Studs and Joists

 Used as vertical studs, and
horizontal joists, rafters, and
headers
 Standards sizes
 Depth 1-5/8 to 12 in.
 Width 1-1/4 to 2-1/2 in.
 Metal thickness 18 to 97 mils
(0.018 to 0.097 in.)
 Example designation:
600S162-54
 600: 6.00 inches deep
 S: Stud or joist
 162: 1.625 (1-5/8) inches wide
 54: 54 mils (.054 inches) metal
thickness
THE CONCEPT OF LIGHT Gauge STEEL CONSTRUCTION

Tracks
 Used at top and bottom of
wall framing and at ends of
floor framing, to hold studs
or joists
 Analogous to wall plates and
rim joists in light wood frame
construction
 Standard sizes
 Depth to match studs or joists
 Width 1-1/4 to 2 in.
 Example designation:
600T125-33
 6.00 inches deep
 Track
 1.25 in. wide
 33 mils metal thickness
LIGHT GAUGE STEEL CONSTRUCTION

Specifying Light Gauge Steel Framing

 Division 5 Metals,
Section 05 40 00—Cold-Formed
Metal Framing
 Structural, loadbearing framing
 Exterior wall framing (subject to wind
loads)
 Division 9 Finishes
Section 09 22 16—Non-
Structural Metal Framing
 Interior nonloadbearing framing
 Galvanic Action

Corrosion occurs between dissimilar metals when

sufficient moisture is present to carry an electric
current. The galvanic series, a list of metals arranged
from “least noble (anode)”, most reactive, to “most noble”
(cathode), is an indicator of corrosion susceptibility.
The farther apart the metals are on the list, the
greater the deterioration of the least noble one.
 Structural Steel Construction

• Structural Steel Construction Methods

• Structural Steel Members
• Fastening Systems
• Panel Members
Structural steel
members are
erected, braced,
and secured
together to create
a structural
framework.
In beam and
column
construction,
beams and girders
support floor and
roof loads and
distribute the
loads to the
vertical columns.
In long span
construction, long
distances are spanned
with built-up
structural steel
girders and trusses.
In wall bearing
construction,
horizontal steel
beams and joists
are supported by
other construction
materials such as
masonry.
Pre-engineered
metal buildings
consist of
prefabricated
structural steel
members
including beams,
columns, girts,
and trusses.
A variety of steel
shapes are
commonly used in
structural steel
construction.
Standard
abbreviations and
designations are
included on
erection plans to
indicate structural
steel members.
A wide variety
of structural steel
shapes are joined
together to form a
truss. Common
steel truss designs
include the
bowstring, flat,
Howe, Pratt,
scissors, and
Warren.
Steel members may
be cut to length using
an oxyacetylene
cutting torch.
Metal floor decking,
manufactured in a
variety of designs and
dimensions, is
attached to the top of
open web steel joists
to create a floor
platform.
Metal decking may be
used as bridge deck
forms. The decking
remains in place after
the shores and falsework
are removed.
METALS TESTING
Two Categories of Metal Testing

 Nondestructive
 Test performed without damaging sample
 Destructive
 Sample of material broken to determine
qualities of metal
Hardness Testing
 Most common form of nondestructive testing
 Used to determine hardness of metal
 Capacity to resist wear and deformation
 Relative measure and indicates some of the
properties
 Can be used to predict properties and
performance of the metal
 Two Types of Testing Machines
 Measure depth of penetration made by a
penetrator under known load
 Example: Rockwell, Brinell, and Vickers
hardness testers
 Measure height of rebound of small mass dropped
from known height
 Example: scleroscope
 Rockwell small needle
Hardness bezel

Tester penetrator
anvil

weights

handwheel

Copyright © The McGraw-Hill Companies, Inc.

Permission required for reproduction or display.
 Rockwell Hardness Tester
 Indicates hardness value by depth that penetrator
advances into metal under known pressure
 120º conical diamond penetrator (brale)
 1/16 or 1/8 in. steel ball used for soft
materials
 Designed by various letters and numbers
 Scales indicated by letters (A, B, C, D)
Procedure To Perform a Rockwell C
Hardness Test

1. Select proper penetrator for test material

2. Mount proper anvil for shape of test part
3. Remove scale or oxidation from surface on which test is to
be made
4. Place workpiece on anvil and apply minor load (10kg) by
turning handwheel until small needle in line with red dot
on dial
5. Adjust bezel (outer dial) to zero
6. Apply major load (150 kg)
7. After large hand stops, remove major load
8. When hand ceases to move backward, note hardness
reading on C scale
• Indicates difference in penetration of brale between minor
and major loads and indicates Rockwell C (Rc) hardness of
material
9. Release minor load and remove specimen
 Operating Principle of a Rockwell Hardness
Tester – Diamond-Cone Type

Depth to
diamond penetrator
which
penetrator
forced by
10 Kg minor Depth to which
load penetrator is
forced by
150 Kg major
Surface of load
specimen

Increment in depth due to increment in load is linear

measurement that forms basis of harness reading
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
Brinell Hardness Tester
 Operated by pressing 10-mm hardened steel ball under load
of 3000 kg into surface of specimen and measuring diameter
of impression with microscope
 Brinell Hardness Number (BHN) determined by dividing load in
kilograms applied to penetrator by area of the impression (in
square mm)
 Standard load of 500 kg used for nonferrous metals
(Impression larger so BHN lower)
 Scleroscope Hardness Tester
 Operated on principle that small, diamond-tipped hammer,
when dropped from fixed height, will rebound higher from
hard surface than from softer one
 Height of rebound converted to hardness reading
 Available in several models distinguished by how reading is
displayed
 Table 16 in appendix shows hardness conversion chart
Destructive Testing
 Metal properties relationships
 Tensile strength of metal increases as hardness
increases, and ductility decreases as hardness
increases
 Tensile strength determined on tensile testing
machine
 Maximum amount of pull material can withstand
 Also indicates elastic limit, yield point and
percentage of area reduction and percentage of
elongation of material
Tensile Testing (Inch)

 Expressed in terms of pounds per square inch

load, lb
Tensile strength 
area, in. 2
Example: Load of 10,000 lb. using .505 in.
diameter sample (0.2 in.2)
10,000
  50,000 psi
0.2
Procedure To Determine the Tensile
Strength of Steel
1. Turn sample of steel to be tested to dimensions shown
below and place on it two center-punch marks exactly 2
in. apart
2. Mount specimen in machine and make sure
jaws grip sample properly
3. Turn red hand back until it bears against black
hand on dial
4. Set pair of dividers to center-punch marks on
sample
5. Start machine and apply load to specimen
6. Observe and record readings at which there are
any changes in uniform movement of the
needle
At this point it is possible to determine elastic
limit of metal.

 Check distance between two center-punch

marks with preset dividers
 Increase load applied to specimen and check
distance between center-punch marks
 Repeat load increase and measure until distance
increases (even slightly) – the elastic limit of
metal has been reached
Extensometer may also be used to indicate
elastic limit.
7. Continue to exert pull on sample until it
"necks down" and finally breaks
8. Remove sample pieces, place broken ends
together, clamp in position
9. Measure distance between center-punch marks
to determine amount of elongation
10. Measure diameter of specimen at break to
determine reduction in diameter
Observations

 Proportional limit
 Point at which needle stops moving
uniformly and begins to slow down
 At this point, metal has reached its elastic
limit and cannot return to original size or
shape
 Yield point
 Reach just beyond proportional limit and
metal starts to stretch or yield
Observations
 Necking down
 Metal begins to show reduction in diameter
 Ultimate strength (tensile strength)
 Highest travel of needle
 Maximum pull to which metal may be
subjected before breaking
 Breaking stress
 Point at which metal broke
Tensile Testing (Metric)
 Graduated in kilograms per square centimeter
 Cross-sectional area in square centimeters
 Extensometers graduated in millimeters
 Calculations same as for inch calculations
 For conversion to Pascals use formula:

1 kg/cm2 = 980.6 Pa.

Impact Tests
 Measures toughness of metal or ability to
withstand sudden shock or impact
 Two tests: Charpy impact test or Izod test
 10-mm-square specimen
 Swinging pendulum of fixed mass raised to
standard height
 Pendulum released, swings through arc and
strikes specimen in pendulum's path
Charpy Test
 Specimen mounted in fixture and supported at both ends
with V or notch placed on side opposite direction of
pendulum's swing
 Pendulum released, knife edge strikes sample
 Difference in height of pendulum
at beginning and end indicates
amount of
energy used to
fracture specimen
 Izod Test
 Similar in principle to Charpy test
 One end of work gripped in
clamp with notched side toward
direction of
pendulum's
swing
 Amount of
energy
required to break
specimen on scale
Problem 1.0
 A steel alloy bar 100mm long with a rectangular
cross section of 10mm x 40mm is subjected to
tension with a load of 89 kN and experiences an
increase in length of 0.1mm. If the length is
entirely elastic, calculate the modulus of elasticity
of the steel alloy.
Solution
 A steel alloy bar 100mm long with a rectangular cross section
of 10mm x 40mm is subjected to tension with a load of 89 kN
and experiences an increase in length of 0.1mm. If the length
is entirely elastic, calculate the modulus of elasticity of the
steel alloy.
Problem 2.0
 A steel specimen is tested in tension. The specimen
is 1in wide by 0.50in thick in the test region. By
monitoring the load dial of the testing machine, it
was found that the specimen yielded at a load of
36kips and fractured at 48kips. (E=30x106 psi)
 A. Determine the tensile stresses at yield and at
fracture.
 B. If the original gauge length was 4in. Estimate
the gauge length when the specimen is stressed
to ½ the yield stress.
Solution
 A steel specimen is tested in tension. The specimen is 1in wide
by 0.50in thick in the test region. By monitoring the load dial
of the testing machine, it was found that the specimen yielded
at a load of 36kips and fractured at 48kips. (E=30x106 psi)
 A. Determine the tensile stresses at yield and at fracture.
 B. If the original gauge length was 4in. Estimate the gauge length
when the specimen is stressed to ½ the yield stress.
Problem 3.0
A rod with a length of 1 m and a radius of
20 mm is made of high-strength steel. The
rod is subjected to a torque T, which
produces a shear stress below the
proportional limit. If the cross section at
one end is rotated 45 degrees in relation to
the other end, and the shear modulus G of
the material is 90 GPa, what is the amount
of applied torque?
Solution
A rod with a length of 1 m and a radius of 20 mm is made of
high-strength steel. The rod is subjected to a torque T, which
produces a shear stress below the proportional limit. If the
cross section at one end is rotated 45 degrees in relation to
the other end, and the shear modulus G of the material is 90
GPa, what is the amount of applied torque?
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