International Journal of Engineering, Science and Mathematics Vol. 7 Issue 4, April 2018, ISSN: 2320-0294 Impact Factor: 6.765 Journal Homepage: http://www.ijesm.co.in , Email: ijesmj@gmail.com Double-Blind Peer Reviewed Refereed Open Access International Journal - Included in the International Serial Directories Indexed & Listed at: Ulrich's Periodicals Directory ©, U.S.A., Open J-Gage as well as in Caďell’s DireĐtories of Puďlishing Opportunities, U.S.A 86 International Journal of Engineering, Science and Mathematics http://www.ijesm.co.in , Email: ijesmj@gmail.com Direct Effects of Process Parameters on the Mechanical Properties of the Friction Stir Welding of Aluminium Alloys A319 and AA6063 Mr. Sadaruddin Ansari Mr. Amit Kumar Dept. of Mechanical Engineering Dept. of Mechanical Engineering NIT, Meerut NIT, Meerut Abstract- Aluminium is a soft, lightweight metal recognized in dull silvery white appearance. It is the second most plentiful element on the earth. Aluminium has become an important metal in the 19th century owing to its light weight and corrosive resistant properties. Dissimilar Al alloy welds are important in structural, automotive and aerospace applications and need attention as it substitutes the conventional welding techniques with low cost and high efficiency one like friction stir welding (Priya et al 2010). This paper focuses on the friction stir welding of wrought aluminium alloys 6063 and cast aluminium alloy A319 that are extremely highly used in the structural and automotive industries. This paper presents a study of the effect of FSW process parameters on the desired responses using the design of experimental approach. It analyse the relationships of various FSW process parameters selected for study and their effect on weld characteristics like ultimate tensile strength, yield strength, percentage elongation and hardness on the development of mathematical models. Response Surface Methodology (RSM) is used to develop regression equations relating to response characteristics and process parameters. Results of the models are presented in graphical form for better understanding. Validation of the mathematical modeling of FSW tool probe geometry effects on the aluminum alloy weld is presented using analysis of variance (ANOVA) regression models. Keywords- A319 and AA6063 alloys, FSW, welding procedure, FSW process quality, mechanical properties Introduction- Aluminium is the second most malleable element (after gold) and it is the sixth most ductile element. It is three times lighter than steel and yet it offers high strength in its alloy form. It is lower in density (2.7 gm/cm3), low in melting temperature (Tm-660°C) and face cubic crystal (fcc) structure which makes aluminium components to be produced and fabricated more easily and with less cost. Pure aluminium is soft and has low tensile strength of 40-50 MPa in annealed condition. It is strengthened by making it undergoing several processes like alloying, cold working and heat treatment. Aluminium is alloyed with numerous other elements to improve its formability, thermal conductivity, high strength and corrosion resistance. The number series ranges from 1xxx - 9xxx series for wrought aluminium alloys and 1xx.x - 9xxx for cast aluminum alloys. These series are classified according to the major alloying elements that are added to the aluminium. Wrought and cast aluminium alloys are subdivided under heat treatable and non heat treatable aluminium alloys.1xxx, 3xxx, 4xxx, 5xxx series of wrought aluminium alloys and 1xx, 2xx are grouped under non heat treatable aluminium alloys. 2xxx, 6xxx, 7xxx of wrought aluminium alloys and 3xx, 4xx of cast aluminium alloys are grouped under heat treatable aluminium alloys (Polmear 1995). Heat treatable aluminium alloys are thermally treated or mechanically treated to achieve improvement in the desired properties such as strength and hardness etc. 6xxx series constitute under group of wrought aluminium alloys with silicon (Si) and magnesium (Mg) as the major alloying element. These Al-Si-Mg alloys are heat treatable and have