Module 6
Metal Properties
and
Destructive Testing
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Eng. Ibrahim Eldesoky
ASNT NDT-LEVEL III
ASME AUTHORIZED INSPECTOR
Metal Properties
Physical properties (density)
Mechanical properties *
Alloy chemistry
Alloy heat treatment
* Mechanical properties depend on
alloy chemistry, heat treatment and
cold work.
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Destructive Testing
Failing, or destroying, a part, or a
portion thereof, to determine its
properties
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Nondestructive Testing
Does not affect the serviceability
of the part after testing is
completed
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Strength
The ability of a material
to bear an applied load
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Strength
Two common methods of expression:
Ultimate tensile strength (UTS)
Yield strength (or yield point)
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Metal Behavior Under Load
Elastic - No permanent deformation
Plastic - Permanent deformation
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Elastic
Behavior
of Steel
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Tensile Testing
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Typical Stress/Strain
Curve - Steel
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Sample Preparation
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Area of a Circular
Cross Section
Example 1
Area (circle)
= x Radius2 = R2
= x Diameter2 = D2
Sample Diameter,
Sample Radius,
4
D = 0.505 in.
R = 0.2525 in.
Area = 3.1416 x 0.25252
Area = 0.20 in2
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Alternate Calculation
Example 2 (using diameter directly)
Area =
D2
4
Area =
3.1416 x (0.505) 2
4
Area =
0.20 in2
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Calculation Shortcut
Area of Circle shortcut:
Area = 0.7854 x D2
because:
4 = 3.1416 4 = 0.7854
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Calculation of
Tensile Strength
Example 3
Load to break
Area of sample
=
=
12,500 lbs
0.20 in. 2
Tensile strength
Tensile strength
Tensile strength
=
=
=
load area
12,500 0.20
62,500 psi
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Offset Method
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Stress-Strain Diagram
High and Medium Strength Steels
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Temperature Effects
As metal temperatures increase:
Strength decreases
Hardness decreases
Ductility increases
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Ductility
The ability of a metal to deform
without breaking
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Brittle vs Ductile Failure
Brittle
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Ductile
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Ductility Terms
Percent elongation
Percent reduction of area
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Percent Elongation
Original gage length = 2.0 in.
Final gage length
= 2.6 in.
%Elongation =
final length - original length x 100
original length
%Elongation = 2.6 - 2.0 x 100 = 30%
2.0
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Percent Reduction
of Area
Original area = 0.2 in.2
Final area
= 0.1 in. 2
%Reduction of area (%RA) = ?
%RA = original area - final area x 100
original area
%RA = 0.2 - 0.1 x 100 = 50%
0.2
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Directional Properties
Both strength and ductility are
affected by the rolling direction of
the metal.
The three axes of
rolling direction are referred to as
the X, Y, and Z directions.
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Rolling Directions
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Hardness
Ability to resist indentation
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Indenter Types
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Hardness Tester
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Indentation Shapes
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Hardness Tests
Brinell
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Hardness
Tests
Rockwell
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Hardness
Tests
Microhardness
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Hardness Testing Steps
Prepare surface
Make indentation
Measure indentation
Determine hardness
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Toughness
The ability to absorb energy
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Toughness Comparison
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Toughness Testing
Impact testing
Notch toughness
Transition temperature
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Notch Toughness
Toughness in the presence of surface
notches and rapid loading
(also referred to as Impact Strength)
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Charpy Test
Prepare notched specimens (sets of 3)
Test each specimen set at a specific
temperature
Impact sample
Plot results
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Charpy Specimens
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Typical
Charpy
Testing
Machine
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Charpy Test Results
Energy absorption - Ft. lbs.
Percent shear - %
Lateral expansion - Mils
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Ductile - to - Brittle
Transition Temperature
The temperature at which a
metal fracture mode changes
from ductile to brittle
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Transition
Temperature
Determinations
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Transition
Temperature Samples
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Fatigue Strength
The strength of a metal when
exposed to repeated reversals of
cyclic stresses
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Endurance Limit
The maximum stress at which no failure
will occur, regardless of cycles
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Typical S-N Curves
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Stress Riser
A surface condition, or geometric
feature, that increases the applied
stress at the condition or geometry
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Stress Risers (Notch
Effects)
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Notch Effects on Fatigue
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Surface Finish Effects
on Fatigue
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Fatigue Testing
Prepare samples
Test series of various loads
Test to failure, record cycles
Test at maximum load vs no failure
Plot data
Determine endurance limit
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Soundness
Freedom from discontinuities
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Soundness Testing
Bend testing
Nick-break
Fillet break
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Bend Test Samples
Transverse Weld Bend Specimens
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Bend Test Samples
Longitudinal Weld Bend Specimens
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Guided Bend Test Jig
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Wrap-around
Bend Test Jig
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Bend Test Procedure
Prepare sample
Orient in jig
Bend sample (weld and HAZ in bend)
Evaluate bend to Code
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Nick Break Test
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Evaluation of NickBreak Test
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Fillet Break Test
Prepare sample
Break sample
Evaluate fracture
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Fillet Break - Sample
Fracture
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Fillet Break Specimen T-Joint
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Corrosion Testing
Evaluates metals in corrosive
environments
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Metallographic Testing
Shows structure of metal
Macroscopic - less than 10X
Microscopic - typically more
than 100X
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Photomacrograph
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Photomicrograph
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Chemical Testing
Determines Chemistry of Metals
Spectrographic
Combustion (CO, CO2 determination)
Wet chemistry (titration)
X-Ray fluorescence (XRF)
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Chemical Properties
Metals are mixtures of elements, and
are referred to as alloys
Minor changes in alloy composition can
have major effects on alloy properties
such as mechanical strength, corrosion
resistance
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Common Steel Alloys
Common Name
Ingot iron
Low C
Mild Steel
Medium C
High C
C%
.03*
.15*
.15-.30
.30-.50
.50-1.0
Typical Use
Weldability
Deep drawing
Electrodes
Structural
Machinery
Springs, dies
Excellent
Excellent
Good
Fair
Poor
* Single values are maximums
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Low Alloy Steels
High strength, low alloy
Automotive & machinery
Low temperature
Elevated temperature
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High Alloy Steels
Corrosion resistant
High temperature
High strength
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High Alloy Steels
Corrosion resistant
High temperature
High strength
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Elements in Steels - 1 of 2
C - Most important
S - Undesirable
P - Undesirable
Si - Deoxidizer
Mn - Combines with S
Cr - Hardenability,
Corrosion Resistance
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Elements in Steels - 2 of 2
Mo - Hardenability
Ni - Toughness, Ductility
Al - Deoxidizer
V - Hardenability
N - Stabilizer
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Dissolved Gases
(Embrittle steels, cause porosity)
Hydrogen
Oxygen
Nitrogen
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Aluminum Alloys
Heat treatable
Major Alloying
Element
Cu
Mg & Si
Zn
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Number
2XXX
6XXX
7XXX
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Aluminum Alloys
Non-heat treatable
Major Alloying
Element
Pure Al
Mn
Si
Mg
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Number
1XXX
3XXX
4XXX
5XXX
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Nickel Alloys
Corrosion resistant
Good low temperature properties
Good high temperature properties
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Copper Alloys
Electrical conductivity
Resistance to corrosion
Resistance to erosion
Resistance to water and salt water
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Heat Treatment - 1 of 3
Mechanical properties are often very
dependent upon heat treat condition
Many types of heat treatment
Determine heat treat condition prior to
welding on base metal or mech. testing
Consider effects of welding on heat treat
condition and mechanical properties
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Heat Treatment - 2 of 3
Heat Treatments For Steels:
Preheating
Stress Relieving
Normalizing
Annealing
Quenching and Tempering
Others
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Heat Treatment - 3 of 3
Heat Treatments For Stainless Steels:
Preheating
Stress Relieving
Solution Annealing, Water Quench
(Solution Treatment)
Quenching and Tempering
Others
More on heat treating in Module 8
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Main Content Page Layout
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The End any questions?
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