MSE 2160/2170
Laboratory #1
A. Jominy End - Quench Test
The Jominy test measures a material’s hardenability. That is a different property
from hardness. Hardness is the resistance to indentation and is measured by a Rockwell
or similar test. Hardenability is a measure of how easy it is to make a material hard.
Hardness is related to strength, and both properties are related to how quickly the
material is cooled. Take for example the TTT curve (time-temperature-transformation
curve) for eutectoid steel ( 0.77% C).
900
Phase (austenite)
800
Equilibrium Phase Change Temperature
700
14
Pearlitestart
Pearlitefinish
600
38
400
Temperature (C)
Bainitefinish
Bainitestart
42
Unstable 
300
52
Martensitestart
57
200
Martinsitefinish
100
0.1
1
10
66
100
Time (seconds)
1000
10,000
100,000
Rockwell C Hardness
40
500
The Rockwell hardness values on the righthand scale apply to a steel that
completely transforms at the temperature on the left. For example, if you only are able to
cool the steel off to 700 C, it takes about 100 seconds before the transformation starts. It
ends at about 10,000 seconds, and the resulting steel has a hardness of 14. The
microstructure is coarse pearlite.
However, if you can cool the steel to 600 degrees, the transformation starts in
only 1 second, and is complete in 10 seconds. The resulting microstructure is still
pearlite, but it is much finer. The hardness is about Rockwell C 38.
You need to cool the steel really fast to get past the “knee” of the curve at 550 C.
If you don’t, the transformation starts in less than one second. However, if you get to 400
C quickly enough, you can delay the transformation to about 6 seconds. It finishes
transforming at about 60 seconds. The resulting microstructure is bainite, with a
Rockwell C hardness of about 42. The lower the transformation temperature, the finer
the microstructure, which leads to higher strengths and higher hardness values.
If you can cool the steel off fast enough that transformation doesn’t start, when
you get to about 220 C Martinsite starts to form. Since Martinsite formation is a
diffusionless process the amount of transformation only depends upon the temperature,
not the time. Martinsite formation is complete at about 130 C. Martinsite is very hard!
In a real sample of metal, the cooling rate is different at different positions in the
sample. That means that in areas that cooled quickly you’ll find Martinsite. In areas that
cooled more slowly, you’ll find Bainite and Pearlite.
The TTT curve on the previous page only applies to eutectoid steels (0.77% C).
Other steels will have similar curves – but they won’t be exactly the same. The
hardenability of a steel depends on its TTT curve, and on its ability to change
temperature. A steel alloy with high hardenability forms Martinsite not only on the
surface, but throughout the sample.
The Jominy end quench test is an ASTM standard test.




A steel rod is heated to a temperature where it all changes back to austenite, and
kept there long enough to come to equilibrium.
Then the sample is placed in a fixture and water is sprayed onto the end of the
sample. The cooling rate at the end is rapid, and decreases as you move down the
rod.
After the sample cools, a narrow flat is milled down the cylinder. This allows you
to measure the hardness, using the Rockwell testing machine.
The hardness is plotted versus the distance from the quenched end, producing a
hardenability curve.
1600
C
1538 C
1493 C

L
1400
C
1394 C
1200
C
1147 C

4.30% C
2.14% C
1000
C
912 C
800
C

0.76% C
600 C
400 C
Fe
1% C
2% C
3% C
4% C
Iron – Iron Carbide Phase Diagram
5% C
6% C
6.70% C
Steel alloy names indicate their composition. A steel with the designation 10xx, for
example 1040, is a plain carbon steel, with 0.40% carbon. The xx value is just the
percent carbon composition times 100. A 40xx steel has 0.2 to 0.3 % Manganese in
addition to carbon. A 4040 steel has 0.4% carbon (0.4 * 100).
Milt has two steel samples for us to test. What are they?
Sample # 1 _______________
Sample # 2 _______________
Based on the phase diagram, suggest an austenizing temperature for these steels.
Your suggestion for an austenizing temperature _______________________________
What temperature does the ASTM standard that Milt is using require? _____________
Why wouldn’t you exceed 1147 C (the eutectic temperature)?
Why can’t you just heat the sample up to the austenizing temperature, and then do the
experiment? Why does it have to heat soak?
Describe the Jominy test.
Collect the hardness data, and use it to create a hardenability curve using Excel. If you
ask nicely, Milt might even let you use his computer, so that you can create the graph
immediately after you collect the data.
Which sample is more hardenable?
B. Annealing Bobby Pins

Obtain a glass of water, at least four bobby pins, and pliers or tweezers to hold the
bobby pins in a flame without burning your fingers. Scrape off any plastic
coating from the ends of the bobby pins. Hold one bobby pin by its open end and
heat the bend red hot in the flame of a gas burner. Remove the bobby pin from
the flame and place it on a nonflammable surface to cool. After it has cooled, try
bending the bobby pin by pulling both ends apart; what do you observe?

Take a second bobby pin and also heat its bend until it is red-hot; when you
remove it from the flame, plunge it into the glass of water so that it cools quickly.
Try to bend this bobby pin; what happens?

Heat a third bobby pin red-hot and plunge it into the water, but then gently heat it
again until an iridescent blue coating forms on the surface; now slowly cool the
bobby pin. What happens this time when you try to bend it?

When you test each bobby pin, compare its response to bending to that of a fourth
bobby pin, which serves as a control.

What can you conclude about the influence of heat treatment and speed of cooling
of a metal on its properties? (Just describe the influence here)

Can you explain your observations, based on what we have learned about heat
treatments of metals? Record your explanation here. Some things to consider
are:
o What metal is a bobby pin made from?
o Is it an alloy?
o Annealing is a general term, which includes all heat treatments designed to
change properties. Tempering is a kind of annealing. See page 550 in
Askeland before jumping to conclusions.
C. Memory Metal
Memory metals are described on pages 527 to 529 of our text. “The shapememory effect is a unique property possessed by some alloys that undergo the martensitic
reaction.” (Askeland) Experiment with the samples of memory metal available to you in
the lab. Describe in your own words how they behaved, and why. You will need to do
some research beyond what is in our text book.