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

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

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

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

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

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

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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

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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.

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.

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.

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❖ 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.

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 test comparison of all 1050 samples

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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 test comparison of all 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 alloy typically had greater hardness than the 1050 sample. Water quenching the sample created the greatest increase in hardness compared to the untreated specimen. The specimen which was untreated showed the least hardness.

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

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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

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.

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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.

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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.

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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.

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.

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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.