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International Journal of Engineering and Innovative Technology (IJEIT) Volume 2, Issue 11, May 2013
Application of Taguchi Methods and ANOVA in
GTAW Process Parameters Optimization for
Aluminium Alloy 7039
Anoop C A, Pawan Kumar
Department of Mechanical Engineering, NIT Calicut (Kerala), India VRDE, Defence Research and Development Organization, Ahmednagar (MS), India Vainarman et al.  reported that the use of pulsed arc
welding in place of conventional GTAW increases the output
by 200–400%, reduces consumption of argon by three to ten
times, and also reduces the cost of 1 m weld deposition by
three to five times. The aim of pulsing is mainly to achieve maximum penetration without excessive heat build-up, by
using the high current pulses to penetrate deeply and then
allowing the weld pool to dissipate some of the heat during
relatively longer arc period at a low current. The increased numbers of variables in the pulsed GTAW process also
support the possibility of increased control of the
solidification process. Arc pulsation is responsible for the grain refinement, lesser risk of cracking, reduction in width of HAZ (heat affected zone) and less distortion. A. Kumar et al  developed a method to use Taguchi method to optimize
the magnetic arc oscillation welding process parameters of
non-heat treatable aluminum alloy 5456 welds for increasing
the mechanical properties. P. K. Giridharan  et al
developed optimization of pulsed GTAW process parameters
to obtain optimum bead geometry using the developed
models. M. Balasubramanian  et al used traditional Hooke
and Jeeve’s algorithm for optimizing process parameters to obtain maximum impact toughness properties in the pulsed
GTA welding of titanium alloy. In this paper, AA7039
samples were welded by pulsed GTAW process and testing
was carried out on various machines or equipments. The
setting of the pulsed GTAW process parameters were
determined by using Taguchi’s experimental design method.
Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA), are employed to find the
optimal levels and to analyze the effect of the GTAW process parameters on properties of welds like microhardness, ASTM
grain size number and HAZ width. Confirmation test with the
optimal levels of welding parameters was carried out in order to illustrate the effectiveness of Taguchi’s optimization
Abstract— Aluminium alloy 7039 is an Al-Mg-Zn alloy
employed in aircraft, automobiles, infantry combat vehicles and high speed trains due to their low density, high specific strength and excellent corrosion resistance. Pulsed Gas Tungsten Arc
Welding is used in this study for welding AA7039. The influence of the various GTAW process parameters, i.e. Pulse Current, Base current and Pulse Frequency on welds were studied for properties of weld like microhardness, ASTM grain size number and heat
affected zone (HAZ) width. The settings of the process parameters were determined by using Taguchi’s experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA), and regression analyses are
employed to find the optimal process parameter levels and to analyze the effect of these parameters on the weld properties. Confirmation test with the optimal levels of welding parameters was carried out in order to illustrate the effectiveness of the Taguchi optimization method.
Index Terms— AA7039, GTAW, Microhardness, Taguchi
optimization methods, ANOVA.
Aluminium alloys find wide applications in aerospace,
automobiles, railway vehicles, bridges and high speed ships
due to its light weight and higher strength to weight ratio . A demand for lighter and stronger aluminium armor for
protection against high explosive shell fragments led to the introduction of aluminium alloy 7039. It is heat treatable and weldable...
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