Page 37 - Zmist-n2-2015

Ô³çèêî-õ³ì³÷íà ìåõàí³êà ìàòåð³àë³â. – 2015. – ¹ 2. – Physicochemical Mechanics of Materials

OPTIMIZATION OF FRICTION STIR WELDING PARAMETERS
FOR MAGNESIUM ALLOY AZ91D USING TAGUCHI DESIGN

1 2
R. SENTHILRAJA , A. NAVEEN SAIT
1
Department of Mechanical Engineering, Jayaram College of Engineering & Technology,
Tiruchirappalli, India;
2
Department of Mechanical Engineering, Chendhuran College of Engineering & Technology,
Pudukkottai, India
Friction stir welding of magnesium alloy, AZ91D casting materials has been welded and
their tensile strength is investigated. Evaluation of FSW process parameters such as tool
rotational speed, welding speed and axial force on tensile strength was carried out using
Taguchi parametric design and optimization approach. Optimized process parameters are
established using ANOVA technique and the percentage contribution of process
parameters are also determined.
Keywords: magnesium alloy, Taguchi, ANOVA, friction stir welding, tensile strength.
Friction stir welding (FSW) is a metal joining process in which heat is generated
by friction between the tool and the workpiece to produce solid state welding [1]. A
recent report reveals that the tensile strength of aluminium and magnesium materials at
the joints is lower than that of the base material except during elongation. Hence
determination of the optimum values of welding parameters such as welding speed,
rotational speed helps in increasing the tensile strength at the weld joints [2]. Won-Bae
Lee et al. analyzed the joint characteristics of friction stir welded AZ91D magnesium
alloy of 4 mm thickness plate. The microstructure analysis reveals that the grain size
decreases with increase in welding speed at the stir zone [3]. An attempt was made by
Elangovan and Balasubramanian to understand the influences of rotational speed and
pin profile of the tool on the friction stir processed (FSP) zone formation in AA2219
aluminium alloy [4]. The AZ31B magnesium alloy was successfully joined without
any macro level defects by using this process. The optimum tool rotational speed,
welding speed, and axial force are 1600 rpm, 0.67 m/s and 3 kN respectively. It is also
reported that the tensile properties are higher when compared with other joining process
[5]. Many researchers evaluated the tensile strength to determine the optimum welding
parameters, namely rotational speed and welding speed. However, the axial force was
seldom considered while determining the optimum process parameters. Taguchi tech-
nique and ANOVA technique are considered to be a robust effective tool for carrying
out experimental work and further processing the experimental data for optimization [6].
The objective of this work is to establish the optimum friction stir welding
parameters of AZ91D magnesium alloy. The main parameters to be considered for
optimization are rotational speed, welding speed and axial force. Optimization of
process parameters is done with the help of ANOVA technique.
Experimental details. Materials and processes. The experiments were carried
out using 6 mm thick plates of AZ91D magnesium alloys. The chemical composition
of AZ91D Mg alloy (mass.%): 9.1 Al; 0.0027 Ni; 0.001 Cu; 0.65 Zn; Bal. Mg and mecha-
nical properties: tensile strength – 293 MPa; yield strength – 222.7 MPa; elongation – 13%.

Corresponding author: A. NAVEEN SAIT, e-mail: naveensait@yahoo.co.in

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