The document summarizes an experiment that tested the effects of heat treating on the material properties of 1050 carbon steel and 4130 alloy steel samples. Specifically, samples of each steel were annealed, air cooled, oil quenched, and water quenched. Tensile tests and hardness tests were then conducted on the treated samples. The water quenched samples exhibited the highest strength and hardness but were also the most brittle. In contrast, oil quenched samples demonstrated higher strength while maintaining better ductility than water quenched samples. The experiment provided data on how different rates of cooling during heat treatment impact the microstructure and properties of the steel alloys.

1. Material Property Effects of Heat Treating 1050 and
4130 Steel
Alejandro Cabrera
David Garcia
Amanda Gee
Kelly Inuzuka
University of the Pacific
Stockton, California
1 May 2015

2. 1
Summary:
Fundamentally, all steels are mixtures of different materials. More specifically,
alloys of iron, carbon, molybdenum, chrome, and others. Depending on the mixture and
amounts of carbon and alloys added, a steel sample may possess different material
properties such as ductility, yield strength, toughness, tensile strength, and hardness.
These properties are crucial for understanding how materials behave and what
materials to use for what applications during the design of structures or in creating new
materials. For structures designed in seismic regions the material need not only have
great strength but also ductility to be able to elastically deform under lateral loads
expected in an earthquake. If a structure has brittle materials for support, quick loading
experienced from natural disasters could cause catastrophic failure and potential loss of
life.
For this project we tested the tensile strength and hardness of two different
samples of steel, a 1050 carbon steel sample which has a carbon content percent range
of 0.37-0.44, and a 4130 alloy steel sample which has a carbon content percent range
of 0.28-.33. The data collected from the two test specimen allowed us to compare the
change in hardness and strength of each steel sample as well as allow us to compare
them with the four different quenching methods used. We also investigated the effect of
the alloy elements in the properties of the 4130 steel versus the 1050 steel sample.
The four quenchants that will be used for each steel sample will be water, air,
and oil. Annealing in the oven will also be performed. To harden steel, it is necessary to
heat the material to a temperature above the austenitizing temperature and cool it
rapidly. Each quenching method will cool down the steel at different rates until reaching

3. 2
room temperature. It is this variation in cooling rates produced by the quenchants that
will produce the change in grain sizes and microstructure of each sample which will
cause the properties to change.
Background Information:
[redacted]
Experimental Objectives:
● Make stress-strain diagrams for each material and compare the mechanical
properties of each material
● Estimate the phases/microstructures that form at different quench rates using a
TTT diagram and phase diagram
● To discover the effects alloying elements in 4130 steel
● Find toughness of both 4130 and 1050 steel

4. 3
Materials and Equipment:
Equipment in the lab included:
● MTS
● Rockwell hardness tester
● Oven
● Zetex gloves
● Tongs
● Oil
● Water
● Brick
● Bucket (x2)
● Micrometer (calipers)
● Electrical tape
● Fire extinguisher

5. 4
Materials ordered were:
Vendor
:
www.laboratorydev
icesco.com
Order
Detail
It.# Cat.# Item Quantity Unit Price
Total
Price
1 STC18 C1050 Steel - 4 1/2" length x .505" thick 6 8.75 $52.50
2 STC140
4130 Alloy Steel - 4 1/2" length x .505"
thick 6 9.25 $55.50
Vendor
: Walmart
It.# Vendor Item No. Item Quantity Price
Total
Price
1 9294287 Great Value: Vegetable Oil, 1 Gal 1 5.98 $5.98
Sub-Total $113.98
Tax: 8.90%
Total: $124.13

6. 5
Procedure:
The first step was verifying the composition and type of samples and heating up
the oven over several hours. Once the oven reached 900℃, the samples were layed out
flat with even spacing in two rows of four. The door was checked to ensure it had been
properly closed and the samples were left in the oven for 6 hours. Before removing
them, two metal buckets were filled: one with water at room temperature and the other
with oil at room temperature. The buckets were filled with sufficient material to prevent
an increase in temperature that would cause a loss of quenching ability and cracking in
the samples[1]. One 1050 sample was removed using the tongs and zetex gloves and
placed onto a brick next to the oven to allow it to air quench. Another was placed into
the water, and a third was placed into the oil. The fourth sample was left in the oven to
allow it to anneal. The 4130 samples were given the same treatments. A fire
extinguisher was on hand in case the oil caught on fire. The oven was shut off and the
oil was funneled back into the reserve before starting the hardness testing.
Once the samples had cooled, they were wiped off with paper towels, labeled,
and had the outer layer of oxidation removed with light taps. One sample was placed in
the Rockwell C hardness tester, and the machine was adjusted until the small gauge
was level. The load was then applied to the web and the gauge was tapped until the dial
stopped moving and a measurement was taken. The load was removed and the
process was repeated 10 times for each sample.
Micrometer calipers were used to measure the dimensions of the sample. The
length was measured as the distance between the edges of the filets on either side of

7. 6
the web. The thickness and width was measured at three points across each sample
and the average was used to calculate the cross-sectional area.
To prepare the MTS machine for tensile testing, the bolts on the machine were
loosened to allow changing of the height of the upper grips. The bolts were tightened
back up and a sample was held in place vertically while the lower grip was closed
around it. The position of the lower grip was adjusted using the computer so that the
upper flange could be secured into the upper grip. Before placing the samples in the
MTS to perform tensile tests, the flanges were taped with electrical tape to prevent the
brittle samples from breaking at the grips during tensile testing. The data for the
displacement and the applied load was collected with special software.
When the program for the tensile test was run, a plexiglass shield was positioned
in front of the MTS in case the grip on the samples was not secure, which could cause
them to turn into projectiles. To obtain a qualitative measure of the ductility of the
sample, pictures of the fractured samples were compared side by side.
Safety Analysis:
Potential safety hazards corresponding to our experiment were mainly physically
related. There was a chance of injuries to hands and eyes while grabbing metals out of
the oven. Injuries to eyes were also a possibility due to shards of metal breaking off
when performing the tensile testing. For this reason, we used zetex gloves when
handling hot materials and safety goggles were worn when performing tensile testing.
Tongs were used to take out the samples from the oven. A fire extinguisher was also
present when quenching in case the cooking oil caught on fire when the steel was

8. 7
quenched. As an added protection, a plexiglass shield was also used to prevent shards
of metal causing bodily injury.
Results:
Tensile Testing
❖ Annealed
[redacted]
Figure 2. Annealed 1050 vs. 4130 Tensile Test
Ultimate tensile strength is 78 Ksi for the 1050 annealed and 65 Ksi for the 4130 annealed.The proportional limit,
where the graph stops being linear is 49 Ksi for the 1050 annealed and 35 Ksi for the 4130 annealed.

9. 8
❖ Air Cooled
[redacted]
Figure 3. Air Quenched 1050 vs. 4130 Tensile Test
Ultimate tensile strength is 80 Ksi for the 1050 annealed and 98 Ksi for the 4130 annealed.The proportional limit,is
57 Ksi for the 1050 annealed and 78 Ksi for the 4130 annealed.

10. 9
❖ As Received
[redacted]
Figure 4. As Received 1050 vs. 4130 Tensile Test
Ultimate tensile strength is 67 Ksi for the 1050 annealed and 82 Ksi for the 4130 annealed.The proportional limit,is
49 Ksi for the 1050 annealed and 61 Ksi for the 4130 annealed.

11. 10
❖ Oil Quenched
[redacted]
Figure 5. Water Quenched 1050 vs. 4130 Tensile Test
Ultimate tensile strength is 175 Ksi for the 1050 annealed and 205 Ksi for the 4130 annealed.The proportional limit,
is 123 Ksi for the 1050 annealed and 140 Ksi for the 4130 annealed.

12. 11
❖ Water Quenched
[redacted]
Figure 6. Oil Quenched 1050 vs. 4130 Tensile Test
Ultimate tensile strength is 116 Ksi for the 1050 annealed and 139 Ksi for the 4130 annealed.The proportional limit,
is 82 Ksi for the 1050 annealed and 100 Ksi for the 4130 annealed.
Figure 7. Tensile testcomparison ofall 1050 samples

13. 12
Ultimate tensile strength is 78 Ksi for the 1050 annealed,80 Ksi for the 1050 air cooled,63 Ksi for 1050 as re ceived,
116 Ksi for 1050 oil quenched,and 188 Ksi for 1050 water quenched.The yield strength of 1050 annealed is 43 Ksi,
for 1050 air cooled is 67 Ksi, for 1050 as received is 42 Ksi,for 1050 oil quenched is 82 Ksi and for 1050 water
quenched is 160 Ksi.
Figure 8. Tensile testcomparison ofall 4130 samples
Ultimate tensile strength is 60 Ksi for the 4130 annealed,98 Ksi for the 4130 air cooled,75 Ksi for 4130 as received,
135 Ksi for 4130 oil quenched,and 212 Ksi for 4130 water quenched.The yield strength of 4130 annealed is 46 Ksi,
for 4130 air cooled is 75 Ksi, for 4130 as received is 55 Ksi,for 4130 oil quenched is 105 Ksi and for 4130 water
quenched is 200 Ksi.,
Hardness
[redacted]
Table 1. Rockwell C Hardness Testing for all samples. 4130 alloytypically had greater hardness than the 1050
sample. Water quenching the sample created the greatestincrease in hardness compared to the untreated
specimen. The specimen which was untreated showed the leasthardness.
Water
Quenched Air Quenched Oil Quenched Annealed No Quenching
1050 4130 1050 4130 1050 4130 1050 4130 1050 4130
Rockwell C Hardness 41.3 46.1 20.2 31.2 24.5 24.4 17.5 21.7 17.9 20.6

14. 13
Discussion:
Comparison of All 1050 Samples
When looking at the stress strain curve for all the quenching methods of the 1050 steel
(Figure 7), the water quenched and oil quenched samples had the greatest ultimate
strength and toughness. The water quenched sample behaved more brittle while the oil
quenched sample behaved more ductile. These two methods produced the fastest
cooling rate which explains the formation of martensite, thus the increase in strength yet
creation of a brittle material. The most ductile samples were the annealed and the as
received samples. This was due to the slower rate of cooling of the materials which
allowed for pearlite to form and essentially created a softer material. 1050 generally was
not as tough and had a lower ultimate tensile strength.
Comparison of All 4130 Samples
When looking at the stress strain curve for all the quenching methods of the 4130 steel
(Figure 8), the water quenched and oil quenched samples had the greatest ultimate
strength. This was the same properties seen in the oil and water quenched samples of
the 1050 steel. The most ductile samples were the annealed and the as received
samples. The data was similar to that of the 1050 steel. The fastest cooling rates
(water and oil) produced the most strength within the material but made the material
brittle. The slower cooling rates (annealing and air cooled) produced softer material
with less ultimate strength but more ductility. The 4130 samples had generally higher
strength and ultimate tensile strength compared to 1050 steel. The alloys within the
specimen increased hardness and strength in the metal when heat treated. The reason
for this is that alloys contain atoms of different sizes, which distorts the regular

15. 14
arrangements of atoms. This makes it more difficult for the layers to slide over each
other, so alloys are harder than the pure metal. This was supported through the
experimental data.
When performing the experiment, it was noted that the 4130 sample did not oxidize and
form a layer of oxide as easily as did the 1050 sample. When tensile testing the 1050
samples, at failure it was noted that a puff of oxide coming off the specimen was seen.
The reason being that the alloys (Chromium and Molybdenum) in the 4130 sample
prevent the rapid oxidation of the steel. It was also noted that the samples left in the
oven created more oxide than the other samples quenched differently. The samples
quenched in the oven should have formed less oxide since the oven should have limited
the amount of oxygen available to for the oxide to form, yet this was found to be untrue.
Although quantitative data was not taken on the amount of oxide formed on the
samples, it was observed and noted. It is believed that the oven may not be as
perfectly sealed as what was initially thought which is what lead to more oxide forming
on the samples in the oven.
Comparison of 1050 Lab Data to Published Data
Based on published data, the 1050 steel sample has an ultimate tensile strength of 190
ksi and a Rockwell C Hardness of 43. These values were similar to our experimental
values which provided an ultimate tensile strength of 180 ksi and a Rockwell C
Hardness of 41.3 [3]. This shows our experiment was accurate given the instruments
which we had at our disposal.

16. 15
Comparison of 4130 Lab Data to Published Data
Based on published data, the 4130 steel sample has an ultimate tensile strength of 81.2
ksi and a Rockwell C Hardness of 17 (for non treated 4130 steel). The experimental
data obtained was an ultimate tensile strength of 80 ksi and a Rockwell C Hardness of
20.6. This data closely matched that of the published values showing the experimental
procedure to have been relatively accurate.
Errors
There were several errors identified which could have had an affect on the
precision of the data collected. During heat treatment of the materials, it was difficult to
remove all of the samples all at once. Each specimen had to be quenched shortly after
its removal from the oven. Longer time in the oven creates inconsistencies in data.
Flaking of the material also occurred when quenched. This was the oxidation reaction
which was more prevalent in the 1050 samples than the 4130. Hardness testing was
performed on the same specimens that had to undergo tensile testing. The testing was
conducted on the web of the specimen which would lead to deformities and
imperfections in the material, making it weaker in some areas than others were the
hardness test was not performed. This would lead to a consistent error since all
specimen were hardness tested on the web. This would although lead to inaccurate
results. Deformities caused by hardness testing would ultimately decrease the strength
of the specimen during the tensile test.

17. 16
Conclusions:
A faster heat treatment results in the formation of more martensite after
quenching, thus a great increase in hardness and tensile strength[2]. However, this also
results in some increase in brittleness. Oil was predicted to form the most martensite,
which would cause the steel to be hard and brittle while the water was expected to
crack before the tests were completed. The data instead showed that water quenching
resulted in the most martensite. The annealed was expected to form pearlite which
would make the steel soft and ductile, and this was shown by the data. The rates at
which the steels were cooled determined which microstructures would form.
Alloying elements, such as molybdenum and chrome, will typically increase the
toughness, ultimate tensile strength, and hardness of the steel. The 4130 steel was
predicted to be softer, more ductile, and less tough than the 1050 steel because the
4130 contains less carbon than the 1050. The stress-strain diagrams created show that
the alloying elements made a larger difference in the properties of the material than the
carbon content.
Heat treating steels ultimately has a positive effect in terms of strength and
hardness but depending on the type of steel, ductility and toughness will change. After
a metal has been heated and quenched, it should be reheated in a process called
tempering, or drawing, to relieve the stresses caused by the previous steps. Quenching
leaves metals stressed, too brittle and hard for use. Tempering relieves the stresses,
increasing the toughness and ductility of the metal while retaining sufficient hardness
and strength. From published data we know that heat treating and tempering creates
tempered martensite which has the most optimal combination of strength and ductility.

18. 17
As an engineer, knowing what properties steels will have under specific temperatures
and conditions is important in order to provide a safe and economical design.

19. 18
References:
[1] Parkash,S. 2010, Petroleum Fuels Manufacturing Handbook: Including Specialty
Products and Sustainable Manufacturing Techniques. METAL FINISHING
QUENCHANTS, McGraw-Hill Professional, AccessEngineering, Chap. 18
[2] Brockenbrough,R. ,Merritt, F.S. 2011, Structural Steel Designer's Handbook, Fifth
Edition. PROPERTIES OF STRUCTURAL STEELS AND EFFECTS OF
STEELMAKING AND FABRICATION, McGraw-Hill Professional, 2011,
AccessEngineering Chap. 1
[3] Bernstein, I.M., 1977, Handbook of Stainless Steels. McGraw-Hill, Inc. pp.1-10
[4] Smith, W.F.,1981, Structure and Properties of Engineering Alloys. McGraw-Hill Book
Company, Chap. 4
[5] Shackleford, J.F.,2015, Introduction to Materials Science for Engineers, Eighth
Edition. Pearson Higher Education, Inc. Chap. 9-10.

20. 19
Appendix:
[redacted]
Figure 8: Final fracture results of both 1050 and 4130 steels after hardness and tensile
test. The images show the brittle and ductile fracture of both 4130 and 1050 steels
tested.