Characteristics of Materials of Al and Steel and 5. SEM micro-structure

1. WEAR AND TRIBOLOGY
EXPERIMENTAL LAB REPORT
SUBMITTED TO: DR.BHARATH BHUSHAN PANIGRAHI
BY
BODA OMKARESHWAR
MS16BTECH11004
Dept. Of Material Science & Metallurgical Engineering.

2. Introduction
Wear is the material removal from a surface due to interaction with another surface. Most of machines
lose their durability and reliability due to wear. Wear is the result of material removal by physical
separations due to micro fracture,by chemical dissolution or melting contact interface. Wear have several
types: abrasive, adhesive, fatigue, and corrosive and erosive.
Pin-on-disc test
The pin is that normally loaded against a rotating disc. The pin can have any shape to simulate a specific
contact, but spherical tips are often used to simplify that contact geometry. The coefficient friction is
determined by ratio of the fractional force to the loading force on the pin.
Wear test and experimental setup:
Different number of species was conducted by using a pin on disc machine (model: wear and friction
monitor TR-20) supplied by DUCOM. The pin was against the counter face of rotating disc (EN31 steel
disc) with wear track diameter 60mm. pin was loaded against the disc through a dead weight loading
system. We tested various loads of 5N, 10N and 20N with rotation velocity 300rpm. An LVDT on the
lever arms helps determine the wear at any point of time by monitoring the moment of the arm. This
movement of the arms generates a signal, which is used to determine the maximum wear the coefficient
of friction is monitored continuously as wear occurs.
Wear tests were carried out for a total sliding distance of approx... 1700m. the pin is 8mm in diameter.
Wear track cleaned with acetone.
While present the experiment the parameters such as rotation speed and time are kept constant. Before
starting test disc were cleaned with ethanol. Before start experiment.
Experiments:
1. Al pin on steel disk under different load dry conditions.
2. Al pin on steel disk under different loads in wet (lubricated) conditions.
3. Comparison of normal steel, with carburized steel and nitride steel in dry conditions.
4. Comparison of normal steel, with carburized steel and nitride steel in wet (lubricated) conditions.
5. SEM microstructure characterization of worn out samples.
Table 1: Experimental Results of Al
Sample
Condition
Load(N) RPM Time(min) Weight
before
test(g)
Weight
after
test(g)
Weight
loss(g)
Wear
(μm)
Wear
rate
(mm3
/m)
Frictional
force
Dry 5 300 14 4.2242 4.2230 0.0012 152 0.00026 0.3
Dry 10 300 14 4.2047 4.1930 0.0117 519 0.00254 1.4

3. Dry 20 300 14 4.0556 4.0319 0.0237 849 0.00516 4.2
Wet 10 300 14 4.0579 4.0513 0.0066 413 0.00143 0.1
wet 20 300 14 4.1868 4.1751 0.0117 573 0.00255 1.9
Table 2: Experimental Results of Steel
Sample
Condition
Load(N) RPM Time(min) Weight
before
test(g)
Weight
after
test(g)
Weight
loss(g)
Wear
(μm)
Wear
rate
(mm3
/m)
Frictional
force
Dry 20 300 14 11.8236 11.7102 0.1161 2057 0.00867 7.5
Wet 20 300 14 11.8321 11.7102 0.1219 1112 0.00913 3.5
Carburized
Dry
20 300 14 11.8107 11.1426 0.6681 2057 0.05006 8
Carburized
wet
20 300 14 11.8124 11.6386 0.1738 1383 0.01302 1.8
Nitrided
dry
20 300 14 11.8093 11.7868 0.225 474 0.00168 3.1
Nitrided
wet
20 300 14 11.8287 11.8077 0.021 446 0.00157 3.1

4. Results and Discussion
Al samples
(a)
(b)
(c)

5. (d)
Figure 1 graph. Wear vs Time (a) dry condition of Al (b) wet condition of Al and graph of frictional force
vs wear (c) dry condition of Al (d) wet condition of Al
Wear calculated in the micrometer. Time is calculated in seconds. The above figures shows wear behavior
of Al under different loads of 5N, 10N and 20N. It is evident from graph that as load increased wear
increases with time. Fractional force for 5N says nearly constant as the load was not very high but for
10N as the wear increases the frictional force but for 20N, the effect is opposite. The reasons for this kind
of behavior of the load on 20N sample is high, so wear also high, resulting in change contact,instead of
point contact, the surface of contact increased. Moreover, mechanism of wear in Al against is adhesion.
Under lubrication conditions, a thin layer of oil comes in between the disk and pin resulting in decrease of
coefficient of fraction between the two materials and ultimately the wear decreases. Wear wasobserved
for higher loads, to check the efficiency of the lubrication oil under high loads. This wear is happening
only because of abrasion.
(a)

6. (b)

7. (c)
(d)

8. (e)
Figure 2 SEM micrograph of (a) Dry Al 5N (b) Dry Al 10N (c) dry Al 20N (d) Wet Al 10N (e) Wet Al
20N
SteelSample
(a)
Graph of wear vs friction in wet condition of steel

9. (b)
Graph of wear vs time in dry condition of steel
(c)
Graph of wear vs time in dry condition of steel
(d)
Graph of wear vs friction in dry condition.
In the experiments the steel sample are rubbed on the disk so the wear is high. During the experiment,
samples are abrasive particles, which increased the wear. Wear behavior of the sample has been observed
under the constant load of 20N against the steel plate with angular velocity of 300rpm.
Effect of carburizing and nitrating has observed. Nitride samples are shows had better wear resistance due
to the enhanced surface property. Graph shows that surface hardened after nitrating, which increase wear
resistance. Wear rate carburized steelis higher than plain steel because the abrasive particles formed after
very hard which increased the wear rate. As the lubrication starts the wear decreases.

10. (a)
(b)
Figure 4 SEM micrograph of (a) steel under dry wear (b) carburized steel under dry wear

11. Conclusion
Here wear and frictional force are depends on the applied load and working conditions (dry or wet)
Nitriding in steelimproves surface properties.