Its a project report on "A COMPARATIVE STUDY OF ALUMINIUM 6XXX SERIES ALLOY AND ALUMINIUM 7XXX SERIES ALLOY"

1. A
Project Report
on
A comparative study of aluminium 6xxx series alloy
and aluminium 7xxx series alloy
Submitted To
Department of mechanical engineering
Maulana Azad National Institute of Technology Bhopal
Under guidance: Submitted by:
Dr. Sanjay soni Abhishek Sharma(161116285)
(Assistant Professor) Harshit Chaurasiya(151116246)
Shubham Kushwaha(151116245)
Department of Mechanical Engineering, MANIT BHOPAL

2. ABSTRACT
The demands for lightweight automotive parts are soaring
tremendously in the quest for energy efficiency. Most of these parts
are produced using aluminum alloy in order to gain parts that has
lightweight, high strength and good rigidity. However, the forming
process for this aluminum alloy has to be carried out under elevated
temperatures with processes such as warm forming and heated
forming in-die quench. This work will provide reviews and intensive
lookout on the available aluminum alloy which can be used as
aluminum parts for automotive application in particular. Finally,
there was concluding remarks on the underline challenges of forming
heat-treatable aluminum alloy and subsequently highlighting the
potential work that can be applied in order to ensure a more
efficient and sustainable manufacturing agenda for heat treatable
aluminum alloy.

3. INTRODUCTION
Aluminium plays an important role for future car generation due to
its advantages and it also open up new way for multiple applications
in the automotive industry. Lightweight material such as aluminium
alloy was applied for automotive applications especially in wrought
and cast forms while aluminium sheets has the potential to be used
as vehicle components. There are a wide range of opportunities for
using aluminium in automotive powertrains, chassis and body
structures. A study showed that car bodies contributes to 20% of
total weight of the car, so a promising way to reduce car weight is to
use aluminium alloys (Carle and Blount, 1999). In contrast to steel,
aluminium has low formability, particularly, at room temperature
making it more difficult to stamp. High number of recent research
explores the methods to improve the formability of aluminium
alloys. There are two ways in manufacturing aluminium body
structure: 1) By stamping it into structure and 2) Through a
combination of many processes such as castings, extrusions and
stamping and welding as in a space frame (Cantor et al., 2008; Toros
et al., 2008).
6xxx Series
The 6xxx series are heat treatable, versatile, weldable, highly
formable, highly corrosion resistance and have moderately high
strength. Alloying elements in this series are silicon and magnesium
that will form magnesium silicate within the alloy. 6xxx series
extrusion products are the first choice for architectural and structural
applications. Aluminium alloy 6061 (AA6061) is the most widely used
alloy in this series and is often used for truck and marine ship frames.

4. Additionally, the Apple’s iPhone product uses 6xxx series alloy as
their frame and components. Recently, the demands for 6xxx series
alloys have significantly increased especially in the automotive and
construction industry. Therefore, several research works have been
undertaken whereby small copper additions were added to the
metal. The addition of copper substance to the metal indicates
improvement especially in the material properties. The addition of
copper and pre-deformation treatment of the alloys help to increase
the peak hardness and yield strength of the metal during ageing and
improve the peak hardness of the quenched alloys (Moons et al.,
year; Dutkiewicz and Litynska, 2002). Addition of copper also helps to
concentrate the precipitates and increase the volume of the
precipitates formed.
7xxx Series
Zinc is the primary alloying agent for this series and the small
addition of magnesium to the series makes it heat treatable and a
very high strength alloy. Other elements such as chromium and
copper may also be added in small quantities. The most commonly
used alloys in this series are 7050 and 7075, which are widely used in
the aircraft industry. Apple’s aluminum 2015 was made Watch from
custom that 7xxx series released alloy. In comparison in year to 6xxx
series alloy, the strength to weight ratio of 7xxx is optimum for
security crash components and the most efficient in cost per kg
saved. The main disadvantage of 7xxx series is its reduced formability
in room temperature. Henceforth, the metal had to be formed at
elevated temperature in order to improve formability. However, the
final properties of this material degrade when it is formed at
elevated temperature.

5. A recent study shows that pertinent pre-treatment condition and
deformation temperature can ensure sufficient formability for 7xxx
series alloy. Apart from that, AA7075 tubes were warm hydroformed
at a temperature of 300°C and significant improvement of
formability was achieved (Lee et al., 2004). Hui et al. (2012)
presented a paper where material characterization of AA7075-T6
material was performed.
It was discovered that the total elongation at fracture increased at
temperature between 140 and 220°C. This was due to the increase in
strain rate sensitivity, which prevents plastic strain from
concentrating in a localized neck and reduced diffuse necking.

6. LITERATURE SURVEY
When it comes to the age old question of deciding between using
6xxx aluminium alloy or 7xxx aluminium alloy for a project or task,
understanding their differences and application ranges can go a long
way and save you the trouble when looking to balance performance
with cost. For most general purpose, both alloys may be able to get
the job done but the differnces in composition, mechanical
properties and cost between both alloys can help you determine
which of the two is the best choice for your structural needs.
COMPOSITION DIFFERENCES:
When it comes to compositional differences between 6xxx and 7xxx
aluminium alloys, the differences are not visible at first glance. Sure,
both contain the same alloy agents such as magnesium, silicon,
copper,iron,zinc,titanium,manganese and chromium, but the biggest
distinction agent whats in your aluminium plate or square rod but
rather, how much is in your material.
For instance, 6xxx aluminium alloy contains less zinc than its 7xxx
counterpart, meaning that while 6xxx alloys provide superior welding
abilities and workability over other alloys , it doesn’t boast the same
high strength and stress resistance as 7xxx offers.
(7xxx series) are conspicuous amongst the commercial aluminium
alloys because of their ability to be age hardened to strengths well in
excess of the strengths that can be produced in other aluminium
alloys. Two major classes of the 7xxx alloys have been in use for
some time. The high mechanical properties have been exploited in
the aircraft industry since the Second World War. The range of high
strength aircraft alloys normally contains major alloying additions of
4.3-6.8% zinc, 2.5-3.3% magnesium, 0.5-2.0% copper, and minor
additions (less than 1%), of chromium, manganese, and zirconium.

7. The weldable alloys have a reduced alloy content; zinc is restricted to
4.0-5.0%, magnesium to 1.4-2.0%, while copper is limited to 0.2%.
Minor additions of chromium, manganese, or zirconium may still be
made. The lower alloying content of the weldable alloys results in a
reduction in the maximum strength that can be achieved,
consequently these alloys are usually referred to as the medium
strength 7xxx alloys.
In recent years there has been an increasing military interest in
reducing the weight of equipment. Light weight engineering
equipment can offer useful economies in transport, and manpower,
while light weight armoured fighting vehicles can offer increased
mobility. A comparison of the two medium-to-high strength
materials that are the main contenders for lightweight equipment,
various aluminium alloys, and various grades of steel, reveals that
the aluminium alloys have an advantage over the high strength steels
in that for equal strength a member is thicker and therefore stiffer
and more robust. The use of thicker aluminium plates results in a
considerable increase in rigidity . As a consequence a number of
purely structural stiffeners can be eliminated from designed
structures which can lead to additional savings in weight and
production man hours.
7xxx series alloys can provide superior ballistic protection under * all
modes of attack when compared to other aluminium alloys, and can
be superior to steel armour on a weight for weight basis especially
against attack by high explosive shell fragments.
The use of thicker plates and the relative ease of machining of
aluminium alloys allows the use of rabetted or stepped joints which
in turn allow easier fit up and less welding. However, the unique
attraction of the weldable medium strength 7xxx alloys is that the
weld deposit and the regions of the parent alloy affected by heat
from the welding process may naturally recover to approximately
80% of the ultimate tensile strength of the parent alloy. In other

8. aluminium alloys the heat produced during welding causes a marked
reduction in the strength of the weld zone. Despite these attractive
properties the weldable 7xxx alloys are not widely used for structural
applications, probably because of the limited knowledge concerning
the stress corrosion cracking susceptibility of these alloys. This
problem has been hard to resolve because stress corrosion cracking
involves a combination of microstructure, sustained tensile stress
and environment. Microstructures and residual tensile stresses are
strongly influenced by the semi-fabrication process and heat
treatments.

9. CONCLUSIONS
Aluminium 6xxx series alloy is highly versatile and can be used almost
for any structural component. Commercial and personal use vehicles
utilize 6xxx series alloy for truck frames and running boards,
infrastructural uses include mass transit and subway platforms,
steps, flooring, walkways and cover plates, and consumer products
such as bicycle frames and components, SCUBA tanks, fishing reels
and small utility boats all benefit from the increased weldable nature
and its ability to undergo hot forging.
Whereas Aluminium 7xxx series alloy, Beacause of its high strength-
to-weight ratio and improved strength over 6xxx alloys, 7xxx is
largely used in aerospace, marine and transportation industries
where strength and light weight properties are critical. High end
bicycle components, molding materials for the plastics and tool
industries, glider and hobby grade airframes and even numerous
military applications including assault rifle recievers and precision
rifles all benefit from the high polish and improved thermal
properties that 7xxx-series alloys provide.