Selection of optimum process parameters for penetration depth improvement of welded mild steel joints

Abstract

High and low heat input degrade weld and weaken bond of fabrications respectively resulting in poor mechanical properties and high failure rate. However, good penetration depth is important factor for quality weld of materials. The research examined various welds by central composite design and then analyzed by response surface methodology. The experiments were achieved using prepared 100 samples of mild steel welded plates measuring 6mm x 40mm x 80mm. The investigation was performed 20 times using 5 samples for each run and then the hardness was measured and analyzed. The results obtained show that the penetration depth terminating at the weld root favoured a high quality weld. The model produced numerical optimal solution of current 120amps, voltage 20volts and gas flow rate 12l/min will produce a welded structure having a penetration depth 5.510mm at a desirability value 95.7%.