Application of Box Benkhen Design in the Investigation of GTA Welded Bead Profile Characteristics on AA6061 Using Alternating Shielding Gases

Abstract

The present investigation is aimed to study the effect of alternate supply of the shielding gas in different alternating frequencies in comparison with the conventional method of GTA welding with pure argon gas. The three sets combination is used as 1.0–0.0, 0.5–0.5 and 0.75–0.25 s to supply alternative shielding gas argon and helium respectively. The influence of alternating shielding gases on the bead profile characteristics like depth and area of penetration is studied. Bead-on-plate welding is performed on a 6 mm thickness AA6061 aluminium alloy at different combinations of input parameters like welding current (I), welding speed (S) and alternating frequency of helium gas (T). Box behnken design is used to find the combinations of input parameters with three levels of each parameter. Response surface methodology is used to establish a mathematical model which is used to predict the weld bead characteristics like depth and area of penetration. The influence of process parameters on the weld bead characteristics is investigated using the developed model. Bead characteristics are strongly influenced by alternating frequency of helium shielding gas followed by welding current, welding speed. Surface plot and contour graph are developed from the results of regression equation, which are utilized in the optimization of process parameters to maximize the weld bead characteristics. From this investigation, it is found that the bead-on-plate welding done with welding current of 190 A, welding speed of 236.66 mm/min and alternating frequency of helium gas of 0.5 s exhibited maximum depth and area of penetration of 4.95 mm and 31.88 mm2 respectively.