Lab 1
Dr Amal Esawi
Omar Magdy Hussein
900211511
Abstract:
In this experiment, we performed a static tensile test on three rods made from different
materials. The three rods were made from Steel, Aluminum, and Cast Iron. The data presented
by the machine was the displacement and the force applied. From these two data provided, stress
and strain were calculated to evaluate each material’s strengths. Steel was the strongest material
since it had an ultimate tensile strength of 680 MPa. Aluminum was the most ductile material at
18.6%. Cast Iron had the lowest ultimate tensile strength at 220 MPa.
Table Of Contents
1. Introduction
2. Materials Used
3. Machine used
4. Procedure
5. Results
6. Analysis
7. Conclusion
Introduction:
This experiment aimed to determine how different materials would behave when
subjected to gradually increasing tension. The different materials that were being used were
Steel, Cast Iron, and Aluminum. Tension will cause each material to behave differently based on
its atomic structure. Cast Iron is a material known for being brittle; its atomic structure has no
capacity for it to slip, so it breaks before it deforms or bends. Aluminum, on the other hand, is
known for being very ductile. It is the sixth ductile material on the planet. Its atomic structure
allows the individual atoms to slip and slide past each other. This is why ductile materials start to
experience necking before they fracture, while brittle materials do not. Necking occurs when the
material has passed its elastic limit and into the plastic. Observable deformation starts to occur to
the material; its width starts to decrease in size. Brittle materials reach their fracture strength and
break. When a tensile material breaks, it experiences a cup and cone fracture.
Materials used
Machine Used
Procedure
First, we measured the diameter and the length of each rod. The Aluminum and Cast Iron were 6
mm in diameter, and the steel rod was 5.7 mm in diameter. All three rods had the same length of
32 mm.
We attached the aluminum rod first to the machine. The machine's
upper and lower arm is tied around the rod. The machine is then
activated and starts pulling at a rate of 3 mm/s. A few seconds into the
test, we can see Necking talking to the place in the center of the rod
before it breaks.
The same procedures were applied to the Cast Iron rod. However,
since Cast Iron is a brittle material, necking does not develop. It
lasted a lot less than Aluminum.
For the Steel rod, the same procedures were applied. It also experienced necking since it is a
ductile material
Results
For the aluminum rod, it had a modulus of resistance of 3.35. Its ultimate tensile strength
was 360.2 MPa, and its Fracture strength was 300 MPa. It had a ductility of 18.68%. All ductile
materials have ductility of over 5%. As you can see, there are instances where the graph
fluctuates, which may indicate that, for instance, the clamp may have lost its grip.
For the Cast Iron rod, it had a modulus of resistance of 1.13. Its ultimate tensile strength
was 220.46 MPa, and its Fracture strength was 220.46 MPa. It had a ductility of 2.025%. All
brittle materials have ductility of less than 5%.
For the Steel rod, it had a modulus of resistance of 3.33. Its ultimate tensile strength was
680.4 MPa, and its Fracture strength was 508.82 MPa. It had a ductility of 10.94%. All ductile
materials have ductility of over 5%
Analysis
The cross dimensions were used based on the ASTM Standards in Mechanical Testing,
which helps ensure that no matter where the test occurs worldwide, it would still give the same
result. The actual strain only ever matters if I look at the material’s behavior at the plastic range.
Still, most engineers would only consider the elastic region since the material is designed not to
exceed it. The diffraction between ductile and brittle materials is that ductile materials gave a
warning before they started to break. Necking was seen being formed on the road before it broke.
This is because the atomic structure of ductile material has the capacity to slip and slide past
each other. However, the atomic structure of brittle materials resists slipping and sliding. This is
why it gives no warning before it breaks.
Conclusion
In the end, we saw that aluminum was the most ductile material out of all of them. This is
because atoms can slide past each other. On the other hand, steel is the stroke with the highest
ultimate tensile strength.
References:
https://www.tutorchase.com/answers/ib/chemistry/why-are-metals-malleable-and-ductile
https://www.tutorchase.com/answers/ib/chemistry/why-are-metals-malleable-and-ductile