Effect of preheating techniques on bead geometry and microhardness of weldment developed through the submerged arc welding process

Abstract In this work, the feasibility and effects of preheating techniques on bead geometry and micro-hardness of weldment developed by bead on plate submerged arc welding (SAW) process on mild steel plate were evaluated. The two preheating methods were introduced using muffle furnace and metal inert gas (MIG) welding in such a parametric combination that in both the cases surface temperature of the plate was nearly 100 °C, prior to SAW process. For obtaining the most favorable process parameters combinations, the design of the experiment was adopted by using Taguchi’s L16 orthogonal array. Bead configuration including penetration, bead width, heat affected zone (HAZ) and reinforcement are the key attributes of welding in product design and manufacturing perspective. Muffle furnace preheating produced comprehensive better weldment compared to the preheating by MIG, though preheating through MIG welding was having the extra advantage of additional metal deposition. Microhardness has not significantly affected by preheating techniques, rather depends on cooling rate as well as heat input. Grey based Taguchi approach was used to optimize the process parameters to obtain better weldment.