OPTIMIZATION OF ASPECT RATIO OF TIG WELDING ON MILD STEEL

ABSTRACT

The rise in the failure of mechanical components, some of which are attributable to poor weld joints has given rise to research study on the optimization of aspect ratio and weld joint strengths. The quality of welds is highly dependent on the right combination of input process parameters. Irrespective of the welding process, the need for the right combination of input process parameters cannot be over emphasized. To achieve a desired weld quality, the weld features such bead geometry and the mechanical properties were examined and related to the weld input parameters.                                                        

In this study, central composite design matrix was employed using Design Expert 7.01 software to optimize the aspect ratio and tensile strength of mild steel welded joint. A total of 20 sets of experiments were produced; the weld specimen was mild steel plate measuring 60 mm × 40 mm × 10 mm. TIG welding machine with 100% Argon Shielding Gas was used for this experiment and at the end of the experiment, an optimum weld aspect ratio of 0.815 and optimal tensile strength of 497.555N/mm2 was achieved using current of 120amp, voltage of 27 volt and gas flow rate of 17 L/min. This value of 0.646 is expected to contain the minimum adequate molten metal just enough to make the desired bead penetration to form good aspect ratio at a minimum cost with appropriate weld quality and productivity. This would help minimize the formation of cracks after weld.