Determining Mechanical Properties of 4140 Grade Steel Using Tensile Test

This paper aims to determine the mechanical properties of steel grade 4140 through the tensile test. The 4140 grade of steel is classified as a high tensile steel. The tensile test is able to put into test the capability of the steel grade 4140 to withstand loadings and how much of the load the steel grade is able to accommodate. The expected outcome will be to show the effects of the mechanical ultimate tensile strength, the changes elastic modulus, stretch, failure strain, percentage of area reduction, fracture toughness, resilience and yield point of the steel grade 4140.

Project title: Proposal of determination of the mechanical properties of 4140 grade steel using
tensile test.
Objective
The main objective of this paper is find the mechanical properties of steel grade 4140 through the
tensile test. In addition, this paper will aim at determining and obtaining data on the effect of the
speed pulling of the steel grade 4140. Different measurements and stretches will be undertaken
in this project at different loading points. The expected outcome will be to show the effects of the
mechanical ultimate tensile strength, the changes elastic modulus, stretch, failure strain,
percentage of area reduction, fracture toughness, resilience and yield point of the steel grade
4140.
Introduction and background
The measure of the mechanical properties is an important aspect for engineers. The tensile test is
one of test which is able to determine the behavior of the mechanical properties of the materials.
The test is able to show the behavior of the different grades of the materials when under load
(ASTM Committee D-20 on Plastics., ASTM Subcommittee D20.10 on Mechanical Properties.,
& ASTM International, 2015). More specifically, the mechanical properties of materials are
dictated by the external forces which are applied to the body. The ability to resist these forces is
able to form the key mechanical properties for the materials. Simply, the mechanical properties
are simply the strength of the material to resist the deformations and stresses which are imposed
into the body (Jawad & Farr, 2018). Tensile test is one of the key test which can be carried out in
order to determine the mechanical strength of the steel grades. The test is based on the reduction
or elongation of the steel area and therefore able to measure the ductility of the metal grade. The

tensile test is able to increase the gage length of the metal. After the elongation or reduction of
the gage length, the fracture of the metal specimen is measured within the gage of elongation.
The elongation or reduction measure is expressed as a percentage of the original gage length of
the metal specimen. In addition, the tensile test is also used to measure the tensile strength of the
metal specimen (Tu, 2018). In this, the test is able to express the ration of maximum load applied
to the cross-sectional area of the specimen.
The 4140 grade of steel is classified as a high tensile steel. The grade has 1% chromium
molybdenum medium which is responsible for the hardened status of the steel grade and
therefore making is one of the high tensile steel. The high chromium content is able to make the
steel grade harder which enhances the machinability of the steel (Advances in Materials
Technology for Fossil Power Plants (Conference), In Shingledecker, In Gandy, & Electric Power
Research Institute, 2014). The tensile range which is used for the manufacture of this steel grade
ranges between 850 and 1000 Mpa. From the key improvement, the steel grade 4140 has
increased machinability and have high feeds which makes it useful for the high speed
applications. The increased manufacturing strategy, the steel grade has increased mechanical
properties which help to increase the life of the steel grade. In addition, the 4140 steel grade is an
alloy, which is also known as “chrome-moly” steel. The chromium is the major alloying element
in the steel grade (Annual Conference on Experimental and Applied Mechanics, In Cloud, In
Patterson, & In Backman, 2016). The major characteristics of the steel grade is that it is tough,
ductile and wear resistant. The melting point of the steel grade stands at 27500 F. in addition, the
grade has a yield strength of between 60,000 and 105,000 psi.
The mechanical properties are important for the steel grade because they are able to determine
the use of the specific materials. In order to enhance the efficiency of performing some key task,

it is important to have the materials which have the correct mechanical properties (International
Conference on Manufacturing Engineering and Technology for Manufacturing Growth, and In
Xu, 2014). Measuring the mechanical properties is able to help in being certain that these
materials will not fail so easily when loading them. Moreover, the mechanical properties help in
coming with the best decision when determining the materials application (Branco, 2018).
Therefore, we can say the knowledge of the mechanical properties will help in decision making
of the material application purposes.
The tensile test is able to put into test the capability of the steel grade 4140 to with stand loadings
and how much of the load the steel grade is able to accommodate (Sparacino, Shenton,
University of Delaware & University of Delaware, 2016). Resisting the load failure is the main
determination which will be achieved at the end of this project. Under load, the materials have a
normal stress-strain curve which the material has to follow (Boake, 2012). This will show the
amount of the load which can be applied on certain materials and be able to accommodate it.
Each different characteristics of the grade will have the specific way of measuring it. For
instance, the engineering stress of the grade 4140 will be obtained by the division of the load
applied by the original cross-section areas of the grade.
Description and scope
In industries and work places, people are able to apply the use of the 4140 grade of steel without
even the knowledge of the correct use of the steel grade. Many will just pick the steel and use it
because they need to use the steel. With the test on the mechanical properties of the steel grade
4140, these people will be able to make decisions on the best use of the steel grade.
Underutilization of the steel grade is a common reason why it is important to be able to carry out
this test on the 4140 grade of steel. This test will be able to determine the extent at which

different characteristics will be able to fail. The failure point will provide the workers with the
knowledge on the perfect use of this steel grade.
Equipment and tools
To carry out the experiment, a Instron tensile test machine will be required. This is where the
specimen of the 4140 grade steel will be tested to determine the mechanical properties behavior.
In this machine, one end of the specimen is clumped while on the other end, the tensile force is
applied on the specimen. The electromechanical version of the machine will be use. This
machine uses an electric motor, gear reduction system and several screws to move the overhead
up and down. The speed of the motor can be varied to achieve the required crosshead speed.
In the experiment, Matlab will be applied for the analysis of the mechanical properties. This
technique will be able to have several mathematical formulas to calculate different mechanical
properties from the physically determined factors after the tensile strength test of the 4140 grade
steel. This will help to perfect formulate and understand more mechanical properties which are
related to the few achieved factors from the tensile test machine.
Constraints
One of the major constraint which is likely to be faced during the project is the measure of the
strain level. The determination of the strain level for the high tensile metals is usually high due to
their resistance on straining. The strains at the end tend to be too small for some of the machines
to be able to detect (In Silva, 2017). The measure of the strain for the high tensile metals is
usually a test and this is applicable for the 4140 grade of steel. Incorrect strain factor will lead to
wrong determination of many mechanical factors which are able to depend on the value of strain
to be determined. First the strain-stress curve will be wrong and this will mean a wrong

conclusion on the amount of the load which the grade can be able to take. To minimize the
constraint level, high precision machine will be used for this project. This will be able to ensure
that variation of up to 0.0001 of the strain factors is detected. In addition, clamping of the
specimen will be carried out to ensure that the material is tack at one position to avoid slipping.
This is another area where the specimen slips result to wrong values.
Conclusion
In conclusion, it is important to be able to determine the mechanical properties of the 4140 grade
steel. This will help in helping for the proper application of the metal grade. Due to its high
tensile capability, the metal will be placed in perfect use. In addition, the workers will have the
knowledge on the places where the steel grade 4140 is applicable and help in making the
decision to use it instead of picking any steel. The tensile test is the perfect method which can be
applied to test the loading capability of this grade. This is because the method will help to come
up with the key stress-strain curve which will help in determination of the different mechanical
characteristic of the 4140 grade. With the knowledge on the mechanical properties, proper
decision making on application and extend of loading of the 4140 grade steel can be made. This
will help in the efficiency of working with the 4140 grade since one is aware of the level at
which the grade can fail.

References
Advances in Materials Technology for Fossil Power Plants (Conference), In Shingledecker, J., In
Gandy, D., & Electric Power Research Institute. (2014). Advances in Materials Technology for
Fossil Power Plants: Proceedings from the Seventh International Conference, October 22-25,
2013 Waikoloa, Hawaii, USA. [Online]. Available from:
http://public.eblib.com/choice/publicfullrecord.aspx?p=3002482. [Accessed on 7th August 2018]
Annual Conference on Experimental and Applied Mechanics, In Cloud, G. L., In Patterson, E., &
In Backman, D. (2016). Joining technologies for composites and dissimilar materials:
Proceedings of the 2016 Annual Conference on Experimental and Applied Mechanics.
Switzerland: Springer
ASTM Committee D-20 on Plastics., ASTM Subcommittee D20.10 on Mechanical Properties.,
& ASTM International. (2015). Standard test method for tensile properties of plastics. West
Conshohocken, PA : ASTM International, March.
Boake, T. M. (2012). Understanding Steel Design: a Handbook of Steel in Architecture. Basel:
De Gruyter. [online]. Available from: http://public.eblib.com/choice/publicfullrecord.aspx?
p=1020401 [Accessed on 7th August 2018]
Branco, R. (2018). High-strength steels: New trends in production and applications. New York:
Nova Science Publishers, Incorporated.
In Silva, L. F. M. (2017). Materials design and applications. Cham, Switzerland: Springer.
[online]. Available from: http://public.eblib.com/choice/publicfullrecord.aspx?p=4822060
[Accessed on 7th August 2018]

International Conference on Manufacturing Engineering and Technology for Manufacturing
Growth, and In Xu D. (2014). Engineering solutions for intensification of production: selected,
peer reviewed papers from the 2014 2nd International Conference on Manufacturing Engineering
and Technology for Manufacturing Growth (METMG 2014), January 20-21, 2014, Miami, State
of Florida, USA. [online]. Available from: http://public.eblib.com/choice/publicfullrecord.aspx?
p=1910732 [Accessed on 7th August 2018].
Jawad, M. H., & Farr, J. R. (2018). Structural Analysis and Design of Process Equipment.
Newark: American Institute of Chemical Engineers.
Sparacino, M. G., Shenton, H. W., University of Delaware,, & University of Delaware.
(2016). The tensile performance of closed cell foam expansion joints: A study on the deleterious
effects of compression set. M.C.E. University of Delaware.
Tu, H. (2018). Numerical simulation and experimental investigation of the fracture behaviour of
an electron beam welded steel joint. Cham, Switzerland: Springer.