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A project report
On
To study the effect of heat treatment processes on the
properties of Aluminum 6063 alloy
Submitted for partial fulfillment of award of
BACHELOR OF TECHNOLOGY
Degree
In
Mechanical Engineering
By
Navneet Verma 0713340063
Bhuvneshwar Prasad Panchal 0713340029
Nikhil Kumar Singh 0713340064
Ajay Kumar 0713340003
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Name of guide
Mr. Sandeep Chauhan
MECHANICAL ENGINEERING DEPARTMENT
NOIDA INSTITUTE OF ENGINEERING & TECHNOLOGY
Greater Noida
DECLARATION
We hereby declare that this submission is our own work and that, to the best of
our knowledge and belief, it contains no material previously published or written
by another person nor material which to a substantial extent has been accepted
for the award of any other degree or diploma of the university or other institute
of higher learning, except where due acknowledgment has been made in the text.
Bhuvneshwar Prasad Panchal
Navneet Verma
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Nikhil Kumar Singh
Ajay Kumar
CERTIFICATE
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Certified that Navneet Verma, Bhuvneshwar Prasad
Panchal, Ajay Kumar, Nikhil Kumar Singh have carried
out the research work presented in this project entitled To
study the effects of heat treatment processes on the
properties of Aluminum 6063 alloy for the award of
Bachelor Of Technology Degree from Uttar Pradesh
Technical University, Lucknow under my supervision. The
project embodies result of original work and studies carried
out by Student himself and the contents of the project do not
form the basis for the award of any other degree to the
candidate or to anybody else.
Mr. Sandeep Chauhan
Sr. Lecturer
NIET, Gr.Noida
Date: June 2011
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ACKNOWLEDGEMENT
I believe that hard work is the only way to success to achieve something
worthy.
With feeling of immense gratitude and respect, I extend my deep sense of
gratitude to thank my guide Mr. SANDEEP CHAUHAN for their continuous
support throughout this work. Their incredulous guiding spirit and helping handat every step of my project has led to its successful completion.
This project was a learning experience for me. Workings in different labs
provide a real time experience of engineering. & technology being used,
currently, in manufacturing industry.
Finally I would like to thank Mr.Mahipal without their help this project would
not have been possible and their support during this period has been inspired me
to accomplish it.
Bhuvneshwar Prasad Panchal (0713340029)
Ajay Kumar (0713340003)
Navneet Verma (0713340063)
Nikhil Kumar Singh (0713340064)
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TABLE OF CONTENTS
Declaration iCertificate iiAcknowledgement iiiTable of Contents ivList of Figure vList of Table viAbstract
Chapter 1- Introduction 01-19
1.1 Introduction of Heat Treatment 01
1.1.1.Stages Of Heat Treatment And Its Purposes 03
1.2 The Objects Of Heat Treating Aluminium And Its Alloys 05
1.3. Classification Of Heat Treatment 06
1.4. Tempering 07
1.5. Annealing 071.5.1. Objectives Of Annealing 081.5.2. Stages Of Annealing 08
1.6. Normalizing 08
1.6.1. Objectives Of Normalizing 09
1.7. Hardening 091.7.1. Objectives Of Hardening 10
1.8. Heat Treatment: Capabilities And Limitations 10
1.9. Introduction Of Aluminium 11
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1.9.1. Characteristics 121.9.2. Applications 131.9.3. Aluminium Alloys 14
1.9.3.1. Aluminium Alloys In Structural Applications 151.9.3.2. Aluminium6063 Alloy 161.9.3.3. Chemical Composition Of Aluminium6063 Alloy 171.9.3.4. Physical Properties 171.9.3.5. Mechanical Properties 17
1.10. Important Mechanical Properties 18
Chapter 2- Literature Review 20-23
2.1. Literature Review 21
Chapter 3- Methodology Of Test Performed 24-29
3.1. Methodology Of Project 25
3.2. Test Performed On Aluminium 6063 Alloy 263.2.1. Tensile Test 26
3.2.1.1. Tensile Test Specimen 26
3.2.2. Izod Impact Test 27
3.2.3. Charpy Impact Test 28
3.2.4. Rockwell Hardness Test 28
Chapter 4- Results And Analysis 30-44
4.1. Test Performed 314.1.1. Tensile Test 31
4.1.2. Impact Test By Izod Method 374.1.3. Impact Test By Charpy Method 39
4.1.4. Rockwell Hardness Test 42
4.2. Microstructures Of Aluminium 6063 Alloy 44
Chapter 5- Conclusion 45
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5.1. Conclusion 46
5.2. Future Scope Of Aluminium 6063 Alloy 46
References 47Appendix 1 48
Appendix 2 50
LIST OF FIGURES
S.No. Title Page No.
Fig 4.1 Tensile Test Specimen 32
Fig 4.2 Izod Test Specimen 38
Fig 4.3 Charpy Test Specimen 40
Fig 5.1 Microstructure After Quenching 44
Fig 5.2 Microstructure After Normalizing 44
Fig 5.3 Microstructure After Annealing 44
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LIST OF TABELS
S.No. Title Page No.
4.1 Tensile Test Table Before Heat Treatment 31
4.2 Tensile Test Table After Normalizing 32
4.3 Tensile Test Table After Quenching 34
4.4 Tensile Test Table After Annealing 35
4.5 Izod Impact Test Table Before Heat Treatment 37
4.6 Izod Impact Test Table After Quenching 38
4.7 Izod Impact Test Table After Normalizing 39
4.8 Izod Impact Test Table After Annealing 39
4.9 Charpy Impact Test Table Before Heat Treatment 40
4.10 Charpy Impact Test Table After Quenching 41
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4.11 Charpy Test Table After Normalizing 41
4.12 Charpy Test Table After Annealing 42
4.13 Rockwell Hardness Test Table Before Heat Treatment 42
4.14 Rockwell Hardness Test Table After Quenching 43
4.15 Rockwell Hardness Test Table After Normalizing 43
4.16 Rockwell Hardness Test Table After Annealing 43
ABSTRACT
Heat treatment processes for aluminium are precision processes. Based on the objectives of
this research, precipitate free zones in the aluminium alloy 6063 actually give bad effect to the
mechanical properties of that alloy. The mechanical properties of the aluminium alloy should
be altering properly to improve their behavior using precipitation hardening which one of the
heat treatment types. Precipitation hardening is the most suitable heat treatment that should
use to minimize the precipitate free zones in the microstructure of the aluminium alloy 6063.
In the precipitation hardening process, the thermal and temperature condition is under control
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with high precision to ensure the transformation of the aluminium alloy structure is in good
condition and supervision limit. The samples of the material are placed in the furnace to make
a heat treating process and then quench it in the water for quenching medium. The material
testing that had been applied is based on hardness, impact and microstructure analysis. The
purpose of the hardness testing are to find out the hardness reading for all the samples that
used to look the wear resistance effect that occur after make a heat treating process to the
aluminium alloy 6063. From the impact test, the purposes are to know impact energy that
absorbed to fracture the samples of the material and then make a comparison data between
after and before heat treatment. Lastly, for microstructure analysis it is important to determine
because to look the narrow evaluation of precipitate free zones in the microstructure of
aluminium alloy after make a precipitation hardening processes. From the data and result thatalready determined, it shown the positive result based on objectives and scope of this project.
CHAPTER -1
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INTRODUCTION
1.1 INTRODUCTION OF HEAT TREATMENT
Heat treatment is a group of industrialandmetal working processesused to alter thephysical, and sometimeschemical, properties of a material. The most common application is
metallurgical. Heat treatments are also used in the manufacture of many other materials, such
as glass. Heat treatment involves the use of heating or chilling, normally to extreme
temperatures, to achieve a desired result such as hardening or softening of a material. Heat
treatment techniques include annealing, case hardening, precipitation strengthening,
tempering and quenching. It is noteworthy that while the term heat treatment applies only to
processes where the heating and cooling are done for the specific purpose of altering
properties intentionally, heating and cooling often occur incidentally during other
manufacturing processes such as hot forming or welding.
Metallic materials consist of a microstructure of small crystals called "grains" or
crystallites. The nature of the grains (i.e. grain size and composition) is one of the most
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effective factors that can determine the overall mechanical behavior of the metal. Heat
treatment provides an efficient way to manipulate the properties of the metal by controlling
rate ofdiffusion, and the rate of cooling within the microstructure.
There are two mechanisms that may change an alloy's properties during heat
treatment. The martensite transformation causes the crystals to deform intrinsically. The
diffusion mechanism causes changes in the homogeneity of the alloy.
The crystal structure consists of atoms that are grouped in a very specific arrangement,
called a lattice. In most elements, this order will rearrange itself, depending on conditions like
temperature and pressure. This rearrangement, called allotropy or polymorphism, may occur
several times, at many different temperatures for a particular metal. In alloys, thisrearrangement may cause an element that will not normally dissolve into the base metal to
suddenly become soluble, while a reversal of the allotropy will make the elements either
partially, or completely insolubles
1.1.1. STAGES OF HEAT TREATMENT AND ITS PURPOSES
The term heat treatment for aluminium alloys is frequently restricted to the specific
operations employed to increase strength & hardness of the precipitation-hardenable wrought
and cast alloys. Heat Treatment- the term heat treatment may be defined as an operation or a
combination of operations, involving the heating and cooling of a metal or an alloy in the
solid state for the purpose of obtaining certain desirable conditions or properties without
change in chemical composition. These usually are referred to as the heat treatable alloys to
distinguish them from those alloys in which no significant strengthening can be achieved by
heating and cooling. Heat treating in its broadest sense refers to any of the heating and cooling
operations are performed for the purpose of changing the mechanical properties, metallurgical
structure, or the residual stress state of the metal product .
Heat treatment applied to aluminium and its alloys are preheating or homogenizing to
reduce chemical segregation of cast structures and to improve material workability. Annealing
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to soften strain hardened and heat treated alloy components to relieve stresses and to
stabilize properties and dimensions. Precipitation (age-hardening) heat treatment to provide
hardening by precipitation of constituents from solid solution. Solution heat treatment to
improve mechanical properties by putting alloying elements into solution.
Heat treatment is a collection through may processes such as Annealing, Stress relief,
Quenching, Tempering, normalizing and ageing. All the different heat treatment process
consists the following three stages-.
1- Heating of the material.
2- Hold the temperature for a time (soaking time).
3- Cooling usually to room temperature (Normalizing).
However the temperature and time for the various processes is dependent on the material
mechanism controlling the wanted effect. The purpose of heat treatment is to achieve one or
more of the following object-
To increase the hardness of metals.
To relieve the stresses set up in the material after hot or cold working.
To improve Machinability.
To soften the metal.
To modify the structure of the material to improve its electrical and magnetic
properties.
To change the grain size.
To increase the qualities of the metal to provide better resistance to heat, corrosion and
wear.
Improve ductility and toughness.
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Pure aluminum is too soft for most structural applications and therefore is usually
alloyed with several elements to improve its corrosion resistance, inhibit grain growth and of
course to increase the strength. The optimum strengthening of aluminum is achieved by
alloying and heat treatments that promote the formation of small, hard precipitates which
interfere with the motion of dislocations. Aluminum alloys that can be heat treated to form
these precipitates are considered heat treatable alloys. Pure aluminum is not heat treatable
because no such particles can form while many heat treatable aluminum alloys are not
wieldable because welding would destroy the microstructure produced by careful heat
treatment.
Virtually all heat treatable aluminum alloys are strengthened by precipitation
hardening. Precipitation hardening involves raising the temperature of the alloy into the single
phase region so that all of the precipitates dissolve. The alloy is then rapidly quenched to form
a supersaturated solid solution and to trap excess vacancies and dislocation loops which can
later act as nucleation sites for precipitation. The precipitates can form slowly at room
temperature (natural aging) and more quickly at slightly elevated temperatures, typically
100C to 200C (artificial aging). The degree of hardening obtained depends on the size,
number and relative strength of the precipitates. These factors are determined by the
composition of the alloy and by the tempering temperature and tempering time.
Proper heat treating requires precise control over temperature, the amount of time that
an alloy remains at a certain temperature, and in the cooling rates of the particular technique.
With the exception of stress-relieving, tempering, and aging, most heat treatments
begin by heating an alloy beyond the upper transformation (A3) temperature. The alloy will
usually be held at this temperature long enough for the heat to completely penetrate the alloy,
thereby bringing it into a complete solid solution. Since a smaller grain size usually enhances
mechanical properties, such as toughness, shear strength and tensile strength, these metals are
often heated to a temperature that is just above the upper critical temperature, in order to
prevent the grains of solution from growing too large. For instance, when steel is heated
above the upper critical temperature, small grains of austenite form. These grow larger as
temperature is increased. When cooled very quickly, during a martensite transformation, the
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austenite grain size directly affects the martensitic grain size. Larger grains have large grain-
boundaries, which serve as weak spots in the structure. The grain size is usually controlled to
reduce the probability of breakage.
The diffusion transformation is very time dependent. Cooling a metal will usually
suppress the precipitation to a much lower temperature. Austenite, for example, usually only
exists above the upper critical temperature. However, if the austenite is cooled quickly
enough, the transformation may be surpressed for hundreds of degrees below the lower
critical temperature. Such austenite is highly unstable and, if given enough time, will
precipitate into various microstructures of ferrite and cementite. The cooling rate can be used
to control rate of grain growth or can even be used to produce partially martensitic
microstructures. However, the martensite transformation is time-independent. If the alloy is
cooled to the martensite transformation temperature before other microstructures can fully
form, the transformation will usually occur at just under the speed of sound.
1.2. THE OBJECTS OF HEAT TREATING ALUMINIUM ALLOYS
Speaking very generally, there are two principal purposes in view when aluminium
and its alloys are industrially heat treated. These are broadly:-
(i) Strengthening or hardening and
(ii) Annealing or softening
There are other objects in subjecting aluminium and its alloys to heat treatments and
these include the alteration of electrical or corrosion properties, the release of casting stresses
and the admission of permanent growth in , for example, pistons; these latter objects are
however of minor importance as compared with the two main objectives indicated above.
1.3. CLASSIFICATION OF HEAT TREATMENT
Various types of heat treatment processes may be classified as follows:-
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1. Tempering
a) Austempering
b) Mar tempering
c) Temperature based
i) Low temperature tempering
ii) Medium temperature tempering
iii) High temperature tempering
2. Annealing
a) Process annealing b) Full annealing
c) Spheroids annealing d) Diffusion annealing
3. Normalizing
4. Hardening
a) Case hardening (or carburizing) b) Flame hardening
c) Induction hardening d) Age hardening
e) Cyaniding e) Nitriding
1.4 TEMPERING
Tempering is a heat treatment technique for metals, alloys and glass. In steels,
tempering is done to "toughen" the metal by transforming brittle martensite orBainite into a
combination of ferrite and cementite or sometimes tempered martensite. Precipitation
hardening alloys, like many grades of aluminum and super alloys are tempered to precipitate
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intermetallic particles which strengthen the metal. Tempering is accomplished by a controlled
reheating of the work piece to a temperature below its lower critical temperature.
The brittle martensite becomes tough and ductile after it is tempered. Carbon atomswere trapped in the austenite when it was rapidly cooled, typically by oil or water quenching,
forming the martensite. The martensite becomes strong after being tempered because when
reheated, the microstructure can rearrange and the carbon atoms can diffuse out of the
distorted body-centered-tetragonal (BCT) structure. After the carbon diffuses, the result is
nearly pure ferrite with body-centered structure.
In metallurgy, there is always a trade-off between strengthand ductility. This delicate
balance highlights many of the subtleties inherent to the tempering process. Precise control of
time and temperature during the tempering process are critical to achieve a metal with well
balanced mechanical properties.
1.5. ANNEALING
Annealing, in metallurgy and materials science, is a heat treatment wherein a material
is altered, causing changes in its properties such as strength and hardness. It is a process that
produces conditions by heating to above the recrystallization temperature, maintaining a
suitable temperature, and then cooling. Annealing is used for inducing ductility, soften
material, relieve internal stresses, refine the structure by making it homogeneous, and
improve cold working properties.
In the cases ofcopper,steel,silver, andbrass, this process is performed by
substantially heating the material (generally until glowing) for a while and allowing it to cool.
Unlikeferrous metalswhich must be cooled slowly to annealcopper, silver and brass can
be cooled slowly in air or quickly by quenching in water. In this fashion the metal is softened
and prepared for further work such as shaping, stamping, or forming.
1.5.1. OBJECTIVES OF ANNEALING
To soften the aluminium so that it may be easily machined or cold worked.
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To refine the grain size & structure to improve mechanical properties like strength &
ductility.
To relieve internal stresses which may have been caused by hot & cold working or byunequal contraction in casting.
To alter electrical magnetic or other physical properties.
To remove gases trapped in the metal during initial casting.
1.5.2. STAGES OF ANNEALING
There are three stages in the annealing process, with the first being the recovery phase,
which results in softening of the metal through removal of crystaldefects (the primary type of
which is the linear defect called a dislocation) and the internal stresses which they cause.
Recovery phase covers all annealing phenomena that occur before the appearance of new
strain-free grains. The second phase is recrystallization, where new strain-free grains nucleate
and grow to replace those deformed by internal stresses. If annealing is allowed to continue
once recrystallization has been completed, grain growth will occur, in which the
microstructure starts to coarsen and may cause the metal to have less than satisfactory
mechanical properties.
1.6. NORMALIZING
Normalizing is a type of heat treatment applicable to ferrous metals only. It differs
from annealing in that the metal is heated to a higher temperature and then removed from the
furnace for air cooling. The purpose of normalizing is to remove the internal stresses induced
by heat treating, welding, casting, forg-ing, forming, or machining. Stress, if not controlled,
leads to metal failure; therefore, before hardening steel, you should normalize it first to ensure
the maximum desired results. Usually, low-carbon steels do not require normalizing;
however, if these steels are normalized, no harmful effects result. Castings are usually
annealed, rather than normalized; however, some castings require the normalizing treatment.
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Table 2-2 shows the approximate soaking periods for normalizing steel. Note that the soaking
time varies with the thickness of the metal. Normalized steels are harder and stronger than
annealed steels. In the normalized condition, steel is much tougher than in any other
structural condition. Parts subjected to impact and those that require maximum toughness
with resistance to external stress are usually normalized. In normalizing, the mass of metal
has an influence on the cooling rate and on the resulting structure. Thin pieces cool faster and
are harder after normalizing than thick ones. In annealing (furnace cooling), the hardness of
the two are about the same.
1.6.1. OBJECTIVES OF NORMALIZING
To refine the grain structure of the aluminum to improve the machaniabilty tensile
strength & structure of weld.
To remove strains caused by cold working processes like hammering rolling, bending
etc which makes the metal brittle & unreliable.
To remove dislocations caused in the internal structure of the aluminum due to hot
working.
To improve certain mechanical & electrical properties.
1.7. HARDENING
The hardening treatment for most steels consists of heating the steel to a set
temperature and then cooling it rapidly by plunging it into oil, water, or brine. Most steels
require rapid cooling (quenching) for hardening but a few can be air-cooled with thesame results. Hardening increases the hardness and strength of the steel, but makes it less
ductile. Generally, the harder the steel, the more brittle it becomes. To remove some of the
brittleness, you should temper the steel after hardening. Many nonferrous metals can be
hardened and their strength increased by controlled heating and rapid cooling. In this case, the
process is called heat treatment, rather than hardening. To harden steel, you cool the metal
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rapidly after thoroughly soaking it at a temperature slightly above its upper critical point. The
approximate soaking periods for hardening steel are listed in table 2-2. The addition of alloys
to steel decreases the cooling rate required to produce hardness. A decrease in the cooling rate
is an advantage, since it lessens the danger of cracking and warping. Pure iron, wrought iron,
and extremely low-carbon steels have very little hardening properties and are difficult to
harden by heat treatment. Cast iron has limited capabilities for hardening. When you cool cast
iron rapidly, it forms white iron, which is hard and brittle. And when you cool it slowly, it
forms gray iron, which is soft but brittle under impact. In plain carbon steel, the maximum
hardness obtained by heat treatment depends almost entirely on the carbon content of the
steel.
To perform hardening process, Al-alloy is heated to a temperature above its critical
range. It is held at this temperature for a considerable time and then allowed to cool by
quenching in water, oil, brine solution.
1.7.1. OBJECTIVES OF HARDENING
To increase the hardness of the metal so that it can resist wear.
To enable it to cut other metals i.e. to make it suitable for cutting tools.
Various factors responsible for hardness in aluminium alloy are the following:
Quenching rate
Work size
1.8. HEAT TREATMENT: CAPABILITIES AND LIMITATIONS
Heat treatments are an established, if obscure, method of disinfesting certain empty
structures and equipment. Since the anticipated phase-out of methyl bromide fumigants,
interest in this non-chemical pest management technique has been growing. Many of the
advantages, disadvantages, considerations, observations, costs and results of using heat to
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disinfest empty food processing and storage structures are situational in reality. Like
fumigation with methyl bromide, successful heat treatments depend upon trained personnel,
careful preparation, employee cooperation, good weather, etc.
Some possible advantages of a heat treatment include the following-
Perceived to be less dangerous than fumigation
Fewer regulations than associated with fumigation
Can monitor and adjust treatment easier than fumigation
More effective than fumigation of a leaky structure
More effective against pathogenic microorganisms
Some possible disadvantages of a heat treatment include the following-
Generally ineffective at penetrating commodities and debris
Significantly more expensive than a methyl bromide fumigation
Exposure period may be longer than for a methyl bromide fumigation
Strong potential for damage to equipment and structure
Less known about actual heat treatments than fumigations
1.9. INTRODUCTION OFALUMINIUM
Aluminium is a silvery white member of theboron group ofchemical elements. It has
the symbol Al and its atomic number is 13. It is not soluble in water under normal
circumstances. Aluminium is the most abundant metal in the Earth's crust, and the third most
abundant element, afteroxygenandsilicon. It makes up about 8% by weight of the Earth's
solid surface. Aluminium is too reactive chemically to occur in nature as a free metal.
Instead, it is found combined in over 270 different minerals. The chief source of aluminium
isbauxiteore.
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Aluminium is remarkable for the metal's low density and for its ability to resist
corrosion due to the phenomenon of passivation. Structural components made from
aluminium and its alloys are vital to the aerospace industry and are very important in other
areas of transportation and building. Its reactive nature makes it useful as a catalyst or
additive in chemical mixtures, including ammonium nitrate explosives, to enhance blast
power.
Despite its prevalence in the environment, aluminium salts are not known to be used
by any form of life. Also in keeping with the element's abundance, it is well toleratedby
plants in soils (in which it is a major component), and to a lesser extent, by animals as a
component of plant materials in the diet (which often contain traces of dust and soil). Soluble
aluminium salts have some demonstrated toxicity to animals if delivered in quantity by
unnatural routes, such as injection. Controversy still exists about aluminums possible long-
term toxicity to humans from larger ingested amounts.
1.9.1. CHARACTERISTICS
Aluminium is a soft, durable, lightweight, ductile and malleable metal with
appearance ranging from silvery to dull gray, depending on the surface roughness.
Aluminium is nonmagnetic and no sparking. It is also insoluble in alcohol, though it can be
soluble in water in certain forms. The yield strength of pure aluminium is 711 MPa, while
aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has
about one-third the density and stiffness of steel. It is easily machined, cast, drawn and
extruded. Corrosion resistance can be excellent due to a thin surface layer of aluminium
oxide that forms when the metal is exposed to air, effectively preventing further oxidation.
The strongest aluminium alloys are less corrosion resistant due to galvanic reactions with
alloyed copper. This corrosion resistance is also often greatly reduced when many aqueous
salts are present, particularly in the presence of dissimilar metals.
Aluminium atoms are arranged in a face-centered cubic (fcc) structure. Aluminium is
one of the few metals that retain full silvery reflectance in finely powdered form, making it an
important component of silver paints. Aluminium mirror finish has the highest reflectance of
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any metal in the 200400 nm (UV) and the 3,00010,000 nm (farIR) regions; in the 400
700 nm visible range it is slightly outperformed by tin and silverand in the 7003000 (near
IR) by silver,gold, and copper.
Aluminium is a good thermal and electrical conductor, having 62% the conductivity of
copper. Aluminium is capable of being a superconductor, with a superconducting critical
temperature of 1.2 Kelvins and a critical magnetic field of about 100 gauss (10 milliteslas).
1.9.2.APPLICATIONS
Aluminium is the most widely used non-ferrous metal. Global production of
aluminium in 2005 was 31.9 million tonnes. It exceeded that of any other metal except iron(837.5 million tonnes). Forecast for 2012 is 4245 million tons, driven by rising Chinese
output. Relatively pure aluminium is encountered only when corrosion resistance and/or
workability is more important than strength or hardness. A thin layer of aluminium can be
deposited onto a flat surface by physical vapour depositionor (very infrequently) chemical
vapour deposition or other chemical means to form optical coatings and mirrors. When so
deposited, a fresh, pure aluminium film serves as a good reflector (approximately 92%) of
visible light and an excellent reflector (as much as 98%) of medium and far infrared radiation.
Pure aluminium has a low tensile strength, but when combined with thermo-mechanical
processing, aluminium alloys display a marked improvement in mechanical properties,
especially when tempered. Aluminium alloys form vital components ofaircraft androcketsas
a result of their high strength-to-weight ratio. Aluminium readily forms alloys with many
elements such as copper, zinc,magnesium, manganeseand silicon (e.g., duralumin). Today,
almost all bulk metal materials that are referred to loosely as "aluminium", are actually alloys.
For example, the common aluminium foils and beverage cans are alloys of 92% to 99%aluminium.
Some of the many uses for aluminium metal are in:
Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles
etc.) as sheet, tube, castings etc.
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Packaging (cans, foil, etc.)
Construction (windows, doors, siding, building wire, etc.)
A wide range of household items, from cooking utensils tobaseball bats, watches.
Street lighting poles, sailing ship masts, walking poles etc. Outer shells of consumer
electronics, also cases for equipment e.g. photographic equipment.
Electrical transmission lines for power distribution
MKM steel and Alnico magnets
Super purity aluminium (SPA, 99.980% to 99.999% Al), used in electronics and CDs.
Heat sinks for electronic appliances such as transistors and CPUs.
Substrate material ofmetal-core copper clad laminates used in high brightness LED
lighting.
Powdered aluminium is used in paint, and inpyrotechnics such as solid rocket fuels
and thermite.
Aluminium can be reacted with hydrochloric acid to form hydrogen gas.
A variety of countries, including France, Italy, Poland,Finland, Romania, Israel, and
the formerYugoslavia, have issued coins struck in aluminium or aluminium-copper
alloys.[39]
Some guitar models sports aluminium diamond plates on the surface of the
instruments, usually either chrome or black. Kramer Guitars and Travis Bean are both
known for having produced guitars with necks made of aluminium, which gives the
instrument a very distinct sound.
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1.9.3. ALUMINIUM ALLOYS
Aluminium alloys are alloys in which aluminium (Al) is the predominant metal. The
typical alloying elements are copper, magnesium, manganese, silicon, and zinc. There are twoprincipal classifications, namely casting alloys and wrought alloys, both of which are further
subdivided into the categories heat-treatable and non-heat-treatable. About 85% of aluminium
is used for wrought products, for example rolled plate, foils and extrusions. Cast aluminium
alloys yield cost effective products due to the low melting point, although they generally have
lowertensile strengths than wrought alloys. The most important cast aluminium alloy system
is Al-Si, where the high levels of silicon (4.0% to 13%) contribute to give good casting
characteristics. Aluminium alloys are widely used in engineering structures and components
where light weight or corrosion resistance is required.
Alloys composed mostly of the two lightweight metals aluminium and magnesium
have been very important in aerospace manufacturing since somewhat before 1940.
Aluminium-magnesium alloys are both lighter than other aluminium alloys and much less
flammable than alloys that contain a very high percentage of magnesium.
Aluminium alloy surfaces will keep their apparent shine in a dry environment due to
the formation of a clear, protective layer ofaluminium oxide. In a wet environment, galvanic
corrosion can occur when an aluminium alloy is placed in electrical contact with other metals
with more negative corrosion potentials than aluminium.
Aluminium alloy compositions are registered with The Aluminum Association. Many
organizations publish more specific standards for the manufacture of aluminium alloy,
including the Society of Automotive Engineers standards organization, specifically its
aerospace standards subgroups, and ASTM International.
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1.9.3.1. ALUMINIUM ALLOYS IN STRUCTURAL APPLICATIONS
Aluminium alloys with a wide range of properties are used in engineering structures.
Alloy systems are classified by a number system (ANSI) or by names indicating their mainalloying constituents (DIN and ISO).
The strength and durability of aluminium alloys vary widely, not only as a result of the
components of the specific alloy, but also as a result of heat treatments and manufacturing
processes. A lack of the knowledge of these aspects has from time to time led to improperly
designed structures and gained aluminium a bad reputation. One important structural
limitation of aluminium alloys is their fatigue strength. Unlike steels, aluminium alloys have
no well-defined fatigue limit, meaning that fatigue failure eventually occurs, under even very
small cyclic loadings. This implies that engineers must assess these loads and design for a
fixed life rather than an infinite life.
Another important property of aluminium alloys is their sensitivity to heat. Workshop
procedures involving heating are complicated by the fact that aluminium, unlike steel, melts
without first glowing red. Forming operations where a blow torch is used therefore require
some expertise, since no visual signs reveal how close the material is to melting. Aluminium
alloys, like all structural alloys, also are subject to internal stresses following heating
operations such as welding and casting. The problem with aluminium alloys in this regard is
their low melting point, which make them more susceptible to distortions from thermally
induced stress relief. Controlled stress relief can be done during manufacturing by heat-
treating the parts in an oven, followed by gradual coolingin effect annealing the stresses.
The low melting point of aluminium alloys has not precluded their use in rocketry;
even for use in constructing combustion chambers where gases can reach 3500 K. The Agenaupper stage engine used a regeneratively cooled aluminium design for some parts of the
nozzle, including the thermally critical throat region.
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1.9.3.2. ALUMINIUM 6063 ALLOY
Al 6063 is an aluminium alloy, with magnesium and silicon as the alloying elements.
The standard controlling its composition is maintained by The Aluminum Association. It hasgenerally good mechanical properties and is heat treatable and weld able. It is similar to the
British aluminium alloy HE9.
6063 Aluminium alloy is mostly used in extrudedshapes for architecture, particularly
window frames, door frames, and roofs. It is typically produced with very smooth surfaces fit
foranodizing.
1.9.3.3. CHEMICAL COMPOSITION OF ALUMINIUM 6063 ALLOY
Table1.1-Chemical Composition Of Aluminium 6063 AlloyCu Si Fe Mn Mg Zn Cr Ti Al
0.10 0.20 /
0.60
0.35 0.10 0.45 /
0.90
0.10 0.10 0.10 Balance
1.9.3.4. PHYSICAL PROPERTIES OF ALUMINIUM 6063 ALLOY
Table1.2-Physical Properties Of Aluminum 6063 Alloy
Property Value
Density 2.70g/cm3
Melting point 750o
CModulus of elasticity 69.5GPa
Electrical resistivity 0.35 x 10-6 ohm
Thermal conductivity 200 W/mK
Thermal expansion 23.5 x 10-6 /K
1.9.3.5. MECHANICAL PROPERTIES
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Table1.3- Mechanical Properties
Temper O T4 T6Minimum proof stress 0.2% (MPa) 50 60 160
Minimum tensile strength (MPa) 100 130 195Shear strength(MPa) 70 110 150
Elongation (%) 22 21 14
Hardness Vickers 25 50 80
1.10. IMPORTANT MECHANICAL PROPERTIES
a) TENSILE STRENGTH:-
It is the ability of the material to resist the externally applied forces without breaking or
yielding. Tensile strength measures the force required to pull something such as rope, wire, or
a structural beam to the point where it breaks. The tensile strength of a material is the
maximum amount oftensile stress that it can take before failure, for example breaking.
b) HARDNESS:-
Hardness is the measure of how resistant solidmatteris to various kinds of permanent
shape change when a force is applied. Macroscopic hardness is generally characterized bystrong intermolecular bonds, however the behavior of solid materials under force is complex,
therefore there are different measurements of hardness: scratch hardness, indentation
hardness, and rebound hardness. Hardness is dependent on ductility, elasticity, plasticity,
strain,strength, toughness, visco-elasticity, and viscosity. Common examples of hard matter
are ceramics, concrete, certainmetals, and super hard materials, which can be contrasted with
soft matter
c) BRITTLENESS:-
A material is brittle if, when subjected to stress, it breaks without significant
deformation (strain). Brittle materials absorb relatively little energy prior to fracture, even
those of highstrength. Breaking is often accompanied by a snapping sound. Brittle materials
include mostceramicsand glasses (which do not deform plastically) and somepolymers, such
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2.1. LITERATURE REVIEW
Heat treatment processes for aluminium are precision processes. Based on the
objectives of this research, precipitate free zones in the aluminium alloy 6063 actually give
bad effect to the mechanical properties of that alloy. The mechanical properties of the
aluminium alloy should be altering properly to improve their behavior using precipitation
hardening which one of the heat treatment types. Precipitation hardening is the most suitable
heat treatment that should use to minimize the precipitate free zones in the microstructure of
the aluminium alloy 6063. In the precipitation hardening process, the thermal and temperature
condition is under control with high precision to ensure the transformation of the aluminium
alloy structure is in good condition and supervision limit. The samples of the material areplaced in the furnace to make a heat treating process and then quench it in the water for
quenching medium. The material testing that had been applied is based on hardness, impact
and microstructure analysis. The purpose of the hardness testing are to find out the hardness
reading for all the samples that used to look the wear resistance effect that occur after make a
heat treating process to the aluminium alloy 6063. From the impact test, the purposes are to
know impact energy that absorbed to fracture the samples of the material and then make a
comparison data between after and before heat treatment. Lastly, for microstructure analysis it
is important to determine because to look the narrow evaluation of precipitate free zones in
the microstructure of aluminium alloy after make a precipitation hardening processes. From
the data and result that already determined, it shown the positive result based on objectives
and scope of this project.
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The literature review of existing heat treatments indicates that heat straightening with
maximum temperature limited to 1200F is relatively similar to the process annealing heat
treatment. Heat straightening with maximum temperature limited to 1400oF is similar to the
normalizing annealing heat treatment. Both these heat treatments repair plastically deformed
microstructure by the phenomenon known as recovery and recrystallization. Normalizing
annealing is more efficient and faster than process annealing in repairing the plastically
deformed microstructure by recrystallization. Heat treatment and repair of the material
microstructure is incidental to the heat straightening repair process. The heat straightened
beam can be further heat treated to complete the repair of the material microstructure
(recrystallization etc.). The practical and economic feasibility of additional heat treatment
using electrically powered and controlled radiant heaters was evaluated and found to bereasonable.
The effects of heat treatment on the dynamic compressive properties and energy
absorption characteristics of open cell aluminium 6063 alloy produced by
infiltrating process were studied. various kinds of heat treatment were exploited such as
quenching normalising and annealing. Tensile compressive and hardness test has been
performed to define the properties of aluminium 6063 alloy. The results show that tha
hardness of the alloy increases also it softens on quenching the grain structure also define bythe tests .
The effects of solution-ageing treatment on the mechanical properties of aluminium
6063 products were studied by the method of orthogonal experiment. The mechanical
properties at different treatment conditions were analyzed. The results show that the effects of
heat treatment were obviously influenced by the original microstructure of the aluminium
60603. Higher temperature is favorable for the sufficient solution of alloy elements, but the
grains will grow up when treated at a higher temperature or soaked for a longer time. There is
a contradiction between the maximum tensile strength and elongation percentage. The surplus
phases not melted in the substrate and the solution precipitated supersaturated elements are
the main factors influencing the properties of the alloys.
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To examine the effectiveness of the treatment, simulating experiments are conducted
using a heat-treatable 6063 aluminum alloy, and the grain size, hardness property, and tensile
properties are measured and compared with those of the conventionally heat-treated sheets.
The results are summarized as follows: (1) resistance heating at a current density of about
100 A mm2 realizes heating the aluminum alloy sheet into the solution temperature range in
2 s, (2) complete achievement of rapid solution treatment by the resistance heating requires
the condition that the precipitates exist finely in the matrix, (3) the new treatment decreases
the grain size by approximately one-half but the mechanical properties are not remarkably
improved.
A systematic experimental investigation of the effect of heat-treatment technique on
the mechanical properties of 6063 aluminum alloy was carried out. Particularly, an artificial
neural network and a genetic algorithm were used to search for the optimum technique,
adapted for 6063 aluminum alloy. The results indicated strongly that an artificial neural
network combined with a genetic algorithm indeed offer a new effective means for the
optimization of materials processing technique.
A series of heat treatments were made on samples cut from bars of a 6063
heat treatable aluminum alloy that were solubilized for 4 h at 520 C, and were cooled down
to room temperature by placing one of their ends into a shallow tank of water to produce a
continuous thermal gradient along their length. Heating and cooling are carried
simultaneously for carrying out different tests. Various test are being conducted on different
equipments such as UTM machine is being used for testing compressive and tensile tests of
aluminium 6063 alloy . for hardness test Rockwell hardness test is being conducted IZOD
and Charpy tests are being conducted to find the impact strength of aluminium 6063 alloy.
These tests are performed on different temperatures for carrying out Quenching, Normalising
and Annealing processes and results are being calculated.
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CHAPTER - 3
METHODOLOGY AND TESTS
PERFORMED
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c) HARDENING: - Hardening is performed at 525oC for 3 hrs and then immediately
quenched in water.
This is applicable to the heat treatable alloys and involves a heat treatment process
whereby the alloying constituents are taken into solution and retained by rapid quenching.
Subsequent heat treatment at tower temperatures i.e. ageing or natural ageing at room
temperature allows for a controlled precipitation of the constituents thereby achieving
increased hardness and strength. Time at temperature for solution treatment depends on
the type of alloy and the furnace load. Sufficient time must be allowed to take the alloys
into solution if optimum properties are to be obtained.
5) Now we will again measure all the mechanical properties which we had checked
earlier.
6) Now compare the properties of aluminium 6063 alloy before & after heat treatment
3.2. TESTS PERFORMED ON ALUMINUM 6063 ALLOY
3.2.1. TENSILE TEST
Tensile testing, also known as tension testing, is a fundamental materials science test
in which a sample is subjected to uniaxial tension until failure. The results from the test are
commonly used to select a material for an application, forquality control, and to predict how
a material will react under other types of forces. Properties that are directly measured via a
tensile test are ultimate tensile strength, maximum elongation and reduction in area. From
these measurements the following properties can also be determined: Young's modulus,
Poisson's ratio, yield strength, and strain-hardening characteristics.
3.2.1.1. Tensile Test Specimen
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A tensile test specimen is a standardized sample cross-section. It has two shoulders
and a gage section in between. The shoulders are large so they can be readily gripped, where
as the gage section has a smaller cross-section so that the deformation and failure can occur in
this area.
The shoulders of the test specimen can be manufactured in various ways to mate to various
grips in the testing machine (see the image below). Each system has advantages and
disadvantages; for example, shoulders designed for serrated grips are easy and cheap to
manufacture, but the alignment of the specimen is dependent on the skill of the technician. On
the other hand, a pinned grip assures good alignment. Threaded shoulders and grips also
assure good alignment, but the technician must know to thread each shoulder into the grip at
least one diameter's length, otherwise the threads can strip before the specimen fractures.
In large castings and forgings it is common to add extra material, which is designed to be
removed from the casting so that test specimens can be made from it. These specimen not be
exact representation of the whole work piece because the grain structure may be different
throughout. In smaller work pieces or when critical parts of the casting must be tested, a work
piece may be sacrificed to make the test specimens. For work pieces that are machined from
bar stock, the test specimen can be made from the same piece as the bar stock.
3.2.2. IZOD IMPACT TEST:-
Izod impact strength testing is an ASTM standard method of determining impact
strength. A notched sample is generally used to determine impact strength.
The test is named after the English engineer Edwin Gilbert Izod (18761946), who
described it in his 1903 address to the British Association, subsequently published in
Engineering.
The specimen is clamped into the pendulum impact test fixture with the notched side
facing the striking edge of the pendulum. The pendulum is released and allowed to strike
through the specimen. If breakage does not occur, a heavier hammer is used until failure
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occurs. Since many materials (especially thermoplastics) exhibit lower impact strength at
reduced temperatures, it is sometimes appropriate to test materials at temperatures that
simulate the intended end use environment.
Impact is a very important phenomenon in governing the life of a structure. In the case
of aircraft, impact can take place by the bird hitting the plane while it is cruising, during take
off and landing there is impact by the debris present on the runway
An arm held at a specific height (constant potential energy) is released. The arm hits
the sample and breaks it. From the energy absorbed by the sample, its impact strength is
determined.
The dimensions of a standard specimen for ASTM D256 are 4 x 12.7 x 3.2 mm (2.5" x
0.5" x 1/8"). The most common specimen thickness is 3.2 mm (0.125"), but the width can
vary between 3.0 and 12.7 mm (0.118" and 0.500").
This test can also be used to determine the notch sensitivity.
3.2.3CHARPY IMPACT TEST:-The Charpy impact test, also known as the Charpy v-notch test, is a standardized high
strain-rate test which determines the amount ofenergy absorbed by a material during fracture.
This absorbed energy is a measure of a given material's toughness and acts as a tool to study
temperature-dependent brittle-ductile transition. It is widely applied in industry, since it is
easy to prepare and conduct and results can be obtained quickly and cheaply. But a major
disadvantage is that all results are only comparative.
The test was developed in 1905 by the French scientist Georges Charpy. It was pivotal
in understanding the fracture problems of ships during the Second World War. Today it is
used in many industries for testing building and construction materials used in the
construction of pressure vessels, bridges and to see how storms will affect materials used in
building.
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The apparatus consists of a pendulumaxe swinging at a notched sample of material.
The energy transferred to the material can be inferred by comparing the difference in the
height of the hammer before and after a big fracture.
The notch in the sample affects the results of the impact test, thus it is necessary for
the notch to be of regular dimensions and geometry. The size of the sample can also affect
results, since the dimensions determine whether or not the material is in plane strain. This
difference can greatly affect conclusions made.
The "Standard methods for Notched Bar Impact Testing of Metallic Materials" can be
found in ASTM E23, ISO 148-1 or EN 10045-1, where all the aspects of the test and
equipment used are described in detail.
3.2.4. ROCKWELL HARDNESS TEST
The Rockwell scale is a hardness scale based on the indentation hardness of a material.
The Rockwell test determines the hardness by measuring the depth of penetration of an
indenter under a large load compared to the penetration made by a preload. There are different
scales, which are denoted by a single letter, that use different loads or indenters. The result,
which is a dimensionless number, is noted by HRX where X is the scale letter.
When testing metals, indentation hardness correlates linearly with tensile strength.
This important relation permits economically important nondestructive testing of bulk metal
deliveries with lightweight, even portable equipment, such as hand-held Rockwell hardness
testers
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CHAPTER - 4
RESULTS AND ANALYSIS
4.1. TESTS PERFORMED
4.1.1. TENSILE TEST
BEFORE HEAT TREATMENT:-
a- Original dimensions:
Diameter of specimen (d1) = 10mm
Cross sectional area of specimen (A1)= 1)2 mm2 = 78.53mm2
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Gauge length of specimen (l1) = 5.65 1 = 50.0 mm
b- Final dimensions:
Diameter of specimen (d2) = mm
Cross sectional area of specimen (A2)= 2)2 mm2
Gauge length of specimen (l2) = 5.65 2
Table No.4.1- Tensile Test Table Before Heat Treatment
S.No Ultimate
load
(kN)
Extension
(l2-l1) mm
Ultimate
strength=
(MPa)
% elongation = % reduction in
area =
1 18.5 60-50=10 235.5 20 84.00
2 16.25 58-50=8 206.9 16 80.66
3 18.0 59-50=9 229.1 18 82.36
Mean diameter at breaking point = 4.2mm
1- Mean Ultimate strength = (235.5+206.6+229.1) / 3
= 223.8 MPa
2- Mean % elongation = (20+16+18) / 3
= 18 %
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3- Mean % reduction in area = (84+80.66+82.36) / 3
= 82.34 %
FFig 4.1 Tensile Test Specimen Before Heat Treatment
AFTER HEAT TREATMENT:-
i) TENSILE TEST AFTER NORMALIZING:-
Table No.4.2- Tensile Test Table After Normalizing
S.No Ultimate
load
(kN)
Extension
(l2-l1) mm
Ultimate
strength=
(MPa)
% elongation = % reduction in
area =
1 8.5 64-50=14 108.2 28 82.36
2 9 63-50=13 114.6 26 81.5
3 9.2 64-50=14 117.15 28 82.36
Area =/4(D12)
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= /4(10)2 = 78.53 mm2
Ultimate strength = 1000
(i) Ultimate strength= (8.5 x1000) / 78.53 = 108.2 MPa
(i) Ultimate strength= (9 x1000) / 78.53 = 114.6 MPa
(iii) Ultimate strength= (9.2 x1000) / 78.53 = 117.15 MPa
Mean ultimate strength = (108.2+114.6+117.15) / 3 = 113.31 MPa
Percentage elongation =
(i) % age elongation = [(64-50) / 50] x100 = 28%
(ii) % age elongation = 26%
(iii)% age elongation = 28%Mean percentage elongation = (28+26+28) / 3 = 27.33 %
Percentage reduction in area =
A1=78.53 mm2
(i) A2= /4 x (4.2)2 = 13.85 mm2
%age reduction= 82.36%
(ii) A2= /4 x (4.3)2 = 14.52 mm2
%age reduction= 81.5%
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(iii) A2= /4 x (4.2)2 = 13.85 mm2
%age reduction= 82.36%
Mean reduction in area = (82.36+81.5+82.36) / 3= 82.07%
ii) TENSILE TEST AFTER QUENCHING:-
Table No.4.3- Tensile Test Table After Quenching
S.No Ultimate
load(kN)
Extension
(l2-l1) mm
Ultimate
strength=
(MPa)
% elongation = % reduction in
area =
1 9.75 60-50=10 124.15 20 76.9
2 10 63-50=13 127.15 26 84.00
3 9.5 61-50=11 120.97 22 19.63
Area =/4(D12)
= /4(10)2 = 78.5mm2
Ultimate strength = 1000
(i) Ultimate strength= (9.75 x1000) / 78.53 = 124.15 MPa
(ii) Ultimate strength= (10 x1000) / 78.53 = 127.33 MPa
(iii) Ultimate strength= (9.5 x1000) / 78.53 = 120.97 MPa
Mean ultimate strength = (12.15 + 127.33 + 120.97) / 3 = 124.15 MPa
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Percentage elongation =
(i) % age elongation = [(60-50) / 50]x100 = 20%
(ii) % age elongation = [(63-50) / 50]x100 = 26%
(iii) % age elongation = [(61-50) / 50]x100 = 22%
Mean percentage elongation = (20+26+22) / 3 = 22.66 %
Percentage reduction in area =
A1=78.53 mm2
(i) A2= /4 x (4.8)2 = 18.095 mm2
%age reduction= [(78.53-18.0955) / 78.53] x100
= 76.9%
(ii) A2= /4 x (4)2 = 12.56 mm2
%age reduction= 84.0%
(iii) A2= /4 x (5)2 = 19.6325 mm2
%age reduction= 75.0%
Mean reduction in area = (76.9+ 84+ 75) / 3= 78.63%
iii) TENSILE TEST AFTER ANNEALING:-
Table No.4.4- Tensile Test Table After Annealing
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S.No Ultimate
load
(kN)
Extension
(l2-l1) mm
Ultimate
strength=
(MPa)
% elongation = % reduction in
area =
1 6 68-50=18 76.403 36 87.7
2 6 66-50=16 78.95 32 85.5
3 6 68-50=18 77.25 36 87.7
Area =/4(D12)
= /4(10)2
= x 25= 78.5 mm2
Ultimate strength = 1000
(i) Ultimate strength= (6 x1000) / 78.53 = 76.403 MPa
(ii) Ultimate strength= (6 x1000) / 78.53 = 78.95 MPa
(iii) Ultimate strength= (6 x1000) / 78.53 = 76.403 MPa
Mean ultimate strength = (76.403+78.95+76.403) / 3 = 77.25 MPa
Percentage elongation =
(i) % age elongation = [(68-50) / 50]x100 = 36%
(ii) % age elongation = 32%
(iii) % age elongation = 36%
Mean percentage elongation = (36+32+36) / 3 = 34.66 %
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Percentage reduction in area =
A1=78.53 mm2
(i) A2= /4 x (3.5)2 = 9.6 mm2
%age reduction= 87.7%
(ii) A2= /4 x (3.8)2 = 11.34 mm2
%age reduction= 85.5%
(iii) A2= /4 x (3.5)2 = 9.6 mm2
%age reduction= 87.7%
Mean reduction in area = (87.7+85.5