Modeling and Optimizing the Hardness of the Melted Zone in Submerged Arc Welding Process using Taguchi Method

Welding, as one of the most useful method for permanent joint of components, is of great importance in industry. Among the wide variety of welding processes, submerged arc welding, given its particular characteristics, is commonly used in industries. The distinguishing advantages of this method are high penetration and sedimentation rate as well as alloy development during welding by creating a cover of desired combinations of elements on the surface of work piece, which improve mechanical, corrosive, fricative and other properties. In this process, the proper selection of input parameters is necessary for high productivity and cost-effectiveness. One of the important characteristic of weld quality, which is influenced by welding parameters, is the hardness of the melted zone (HMZ). In this paper, experiments were conducted by Taguchi experimental design and Minitab 14 statistical software, and the interaction of input parameters was not taken into account. Current intensity, arc voltage, welding speed, nozzle distance from the work piece and thickness of magnesium oxide nanoparticles were considered as the input parameter and the HMZ was assumed as the response. After collecting data, the signal to noise ratio (S/N) was calculated to obtain optimal levels for all input parameters. Then, using analysis of variance (ANOVA), the significance level of (P) for each input parameter was determined and validated for the hardness of the melted area. The results show that current intensity, welding speed, arc voltage, nozzle distance from work piece and thickness of magnesium oxide nanoparticles had respectively the highest impact on the hardness of melted zone.