TITLE:
Development of a Predictive Model to Improve the Hardness of Mild Steel Welded Joint
AUTHORS:
O. O. Ogbeide, L. M. Ebhota
KEYWORDS:
RSM, TIG, Mild Steel, Contour Plot
JOURNAL NAME:
Engineering,
Vol.13 No.4,
April
30,
2021
ABSTRACT: Structural integrity of weldment is greatly influenced by its process parameters and usually, it is expected for a welded joint to be stronger than its parent metal, but in actual fact, most failures occur at the welded joints and it is mostly due to poor combination of process parameters or inexperience of the welder. This poor combination leads to poor hardness exhibited at the welded joint. The aim of this study is to predict and improve the hardness of mild steel welded zone using the tungsten inert gas (TIG) welding process. Response Surface Methodology (RSM) was employed to analyze the welded response. 200 pieces of mild steel coupons measuring 27.5 × 10 × 10 mm were prepared and used for the experiment, the experiment was performed 20 times, using 5 specimens for each run, after which the hardness was measured and results analyzed respectively. The study produced eighteen (18) optimum results with the best selected to produce a material hardness of 299.269 N/mm2 with desirability of 95.6%, resulting from current of 120 amp, voltages of 20 and gas flow rate of 12 L/min.