The only way to make progress is to compare your previous work to your current work. By comparing materials we can begin to understand what might cause the difference in results.
Immediately you can see from the graphs that the metals behaved very differently.
So, what we can take from these graphs are the following. The UTS alone tells us that one of these metals might be better suited for one purpose than another.
The samples were of pure aluminium, rarely the case in real world applications
As mentioned before, aluminium took the least amount of force to deform plastically. This makes it ideal for low energy manufacture, rolling and pressing at lower temperatures than other metals.
Higher plastic limit means it still takes a smaller amount of energy to deform, whilst remaining malleable- can be worked into more elaborate shapes.This material is favoured in the music industry since the material can be worked into complex shapes and retain an attractive finish.Higher UTS than aluminium
Group presentation for tensile testing a4
TENSILE TESTING LAB
• Determine dimensions
• Mark the sample with lines at 10mm intervals
• Zero instrumentation
• Set up the equipment
• Slowly increase the load, recording the results with Hounsfield
• Remove extensometer at 0.2mm extension
• Remove the sample when it fractures and record the
• Measures the change in length of an
• Two types: Contact and Non-Contact
• Contact is normally cheaper, yet still
have high precision
• Non – contact usually involves lasers
• Lindley dial gauge extensometer used in
Hounsfield Hand Operated
• Allows for a sample to be
tested under tension
• Often equipped with a
mercury force gauge and a
roll of test paper
• More expensive than the
• Greater accuracy
• Not used in Lab because of
THEORY BEHIND TENSILE TESTING
TENSILE TEST LAB
Tomos St John
Elongation, Dl (m)
The Tensile Test
Returns to it’s original size when force
Metals don’t stretch much elastically
Atoms slide over one another due to
dislocations in the structure
Sample won’t return to original size
Metals deform more plastically than
In Pa or N.mm2
E= Young’s modulus
A measure of stiffness
No unique yield point
Use PROOF STRESS
Upper Yield Stress (UYS)
Lower Yield Stress (LYS)
UYS is hard to pin point
LYS commonly used as yield point
Either measured as
% elongation to failure
% reduction in area at failure
• General information
Chemical formula: Al
Molecular weight: 26.98 gm
It is the second most malleable metal and sixth most
1000 series (Al, Si)
3000 series (Al, Mn, Cu, Mg, Si, Fe)
5000 series ( Al, Mg, Mn, Si, Fe, Zn)
8000 series (Al, Sn, Ni, Si, Fe)
Modulus of Elasticity = Stress/ Strain = 52.975 × 106 / 1088.3 × 10-6 = 48.69 GPa
Limit of Proportionality and Tensile Strength is Calculated by plotting Load, F[kN] vs
Extension, [10-6 m ] and Stress Vs Strain Graph.
All calculation results correspond with the textbook
TENSILE TESTING EXPERIMENT
Muhammad Amin Ismail
COMPOSITON AND PROPERTIES OF
Also known as Low-Carbon Steel.
• Ferum: 99.70%wt - 99.98%wt
• Carbon: 0.02%wt – 0.25%wt
• Density: 7800 – 7900 kgm-3
Modulus of Elasticity 200 – 250 GPa
Yield Strength 250 – 395 MPa
Tensile Strength 345 – 580 MPa
Elongation 26% – 47%
Hardness 107.5 – 172.5 HV
TABLE OF RESULT
Original length (mm) 50
Final Length (mm) 66
Original Area (mm2
Final Area (mm2
% Elongation 32.00
% Reduction in Area 8.15
TABLE 2: The Cross-sectional
dimensions of Mild Steel
THE RELATIONSHIP BETWEEN STRESS AND
STRAIN FOR MILD STEEL
0 200 400 600 800 1000 1200 1400 1600
Strain, ε (10-6)
FIGURE 1: Graph of Stress vs Strain.
THE RELATIONSHIP BETWEEN LOAD AND
EXTENSION FOR MILD STEEL
33FIGURE 2: Graph of Load vs Extension.
Ultimate Tensile Stress
Upper Yield Stress
Lower Yield Stress
7.0 COMPARISON SECTION
TENSILE TESTING LAB
James Alexander Douthwaite
7.1 Why do we compare?
•Allows trends to be identified and plotted.
•To determine how are results might effect real life
•To develop a standard, with which to compare others.
•It allows us to predict what might happen in later
experiments (e.g. What a combination of the materials
• The three metals behaved in very different ways.
• Aluminium was the softest, more ductile of the
• Brass behaved in a less ductile manner.
• Mild Steel was the stiffest of the three metals.
• The ultimate tensile strength (UTS) varied greatly
It is clear from the graph that....
The way these metals behaved in this test reflects
how they are used in the real world.
Everyday products take advantage of materials
chosen for their unique properties.
These days materials made to very exact
specifications by splicing the properties of two or
metals together to get the characteristics needed.
7.4 Application- Brass
• Relatively Low Density.
• Higher elastic/plastic limit than
aluminium, however still relatively
• Corrosive/tarnish resistant due to its
7.4 Application- Mild Steel
• High UTS
• Very “stiff”- ideal for a wide range
of civil applications.
• Cheap, carbon content.
ERRORS & CONCLUSION
TENSILE TESTING LAB
Incorrect data analysis
E.g. manual calculation of strain value led to results being
incorrect by a power of 10
Incorrect calibration of mercury scale on Hounsfield test
machine due to air bubble
Engineering stress and strain
Engineering stress and strain were used to make
comparison to true stress and strain values in textbooks.
Irregular data recording intervals
Small variations in stress & strain could have been
missed on force-extension graphs
e.g. UYS and LYS of mild-steel
Small room warms up after time with group of people.
Reading off small scales
Small & non-conventional scales on Force-Extension graph
axes making it hard to read accurately
Micrometer scale may be misread
Use Instron Testing Machine
Digitally plots force-extension graphs at regular intervals –
Calibration of measurement scales automatic
Repeat testing to calculate mean values
Calculate mean values from 3 samples of each metal
More accurate measurement of extension without making
contact with sample.
Wide range of uses for tensile testing:
Aerospace: Turbine blades
Packaging: Ring pulls/tight packaging
Sport: Racquet strings
Tensile test of 3 metals
Mild Steel: Highest UTS & stiffness
Brass: Most ductile
Use to industry:
Appropriate material selection based on tensile properties
Meet safety, strength, deformation constraints
Ensure manufacturing quality and consistency
Mild steel: structural material (e.g. Bridges) due to high
stiffness and strength.