2. Objective
Experimentally perform precipitation of Aluminium alloy 7075
Determine the effect of artificial ageing on hardness of Al-7075
Determine hardness of the alloy before and after the ageing process
Observe for optimum time duration of ageing of the alloy at a particular
temperature to obtain maximum strength
Compare the differences in mechanical properties, such as ductility, tensile
strength, yield strength, modulus of elasticity, and strain hardening exponent at
different aging times.
3. Aluminium 7075
● Ultimate Tensile strength : 74,000 psi - 78,000 psi
● Yield strength : 63,000 psi - 69,000 psi
● Material density : 2.810 g/cubic cm
● Specific gravity : 2.81
● Melting point : 900° F
● Modulus of Elasticity Tension : 10.4
● Modulus of Elasticity Torsion : 3.8
4. Rockwell Hardness Test
● Measures permanent depth of indentation produced by
load on the indenter
Depending upon hardness of material indenter to be used
The test axis should be within 2-degrees of perpendicular
for correct loading
We perform this test on Al-7075 samples before and after
ageing to observe the change
7. Tensile Test
All samples were subjected to tensile test to obtain
mechanical properties after the aging
From stress and strain curve obtained following
properties
Yield strength (YS)
Ultimate tensile Strength (UTS)
Ductility
Young’s Modulus (E) (YM)
8. Procedure
7075 Aluminum samples were labeled and the initial rockwell Hardness was
measured (Ten samples including two reference samples)
Samples were subjected to over aging at the 320 ºF (160 ºC) for 0,12,24,36,48
hours (Two samples at each time variant were taken for data accuracy)
Rockwell Hardness and conductivity was measured after the overaging process
Samples were then subjected to tensile test to compare the mechanical properties
differences due to aging process.
23. APPLICATIONS:
● High strength to Density ratio: Transport, Aviation, Marine, Automotive
● The strength and lightweight characteristics enhances the
applications in other fields.
● Other applications: Rock climbing equipment
Bicycle components
Inline skating frames
Hang glider airframes
● The hobby grade models typically use 7075 or the 6061 for the
chassis plates.
24. APPLICATIONS:
● Interesting Application: Manufacturing of upper and lower receivers as
well as the extension tubes for the high quality M16 Rifles in American
military.
● Desert Tactical arms, SIG sauer and French armament company use
it for their precision rifles.
● Common applications: camping knife and fork sets.
● Wide use in mold manufacture: High strength
low density
Thermal properties
Ability to highly polished
25. References
1. "Heat Treatments: Introduction." Heat Treatments: Introduction. N.p., n.d. Web. 17 Apr. 2013.
<http://www.efunda.com/processes/heat_treat/introduction/heat_treatments.cfm>.
2. "Age Hardening." Bluewater Thermal Solutions. N.p., n.d. Web. 17 Apr. 2013. <http://bluewaterthermal.com/age-hardening/>.
3. T. V. Rajan, C. P. Sharma, Ashok K. Sharma. “Heat Treatment: Principles and Techniques” 15ed. New Delhi: Prentice-Hall, 2006. 336-8.
http://books.google.com/books?id=A2QG3UssqKUC&pg=PA336&lpg=PA336&dq=gp+II+zone&source=bl&ots=Gmso2xnIks&sig=dsRTDlPIE0
tyo2qF4YhpUGNLIsU&hl=en&sa=X&ei=tzJ_UaSRFOLtiwKqooDgAQ&ved=0CDoQ6AEwAQ#v=onepage&q=gp%20II%20zone&f=false
4. Effect of Ageing on Microstructure and Mechanical Properties of Bulk, Cryolled and Room temperature rolled Al 7075 Alloy by Sushantha Kumar
Panigrahi, R Jayaganthan; 2011.
5. "Rockwell Hardness Test Method | Newage Testing Instruments." Rockwell Hardness Test Method | Newage Testing Instruments. N.p., n.d. Web.
29 Nov. 2015.
6. "Rockwell Hardness Testing." Rockwell Hardness Testing. N.p., n.d. Web. 29 Nov. 2015.
7. "WWW.BUEHLER.COM." An ITW Company. N.p., n.d. Web. 29 Nov. 2015.
