Parametric Optimization And Comparative Study Of Ductile Cast Iron (DCI) 500/7 Grade Material By Using Shielded Metal Arc Welding (SMAW)

Abstract

Welding is a vital manufacturing technique used to join two or more materials—primarily metals or thermoplastics—by applying heat, pressure, or a combination of both. In this study, the Shielded Metal Arc Welding (SMAW) process was employed to perform parametric optimization on ductile cast iron (DCI) grade 500/7. A total of 18 welded plates were fabricated using two different electrodes, following the L9 orthogonal array (OA) design. These samples were evaluated through both (Destructive Testing) DT—including hardness, impact, and tensile tests—and (Non-Destructive Testing) (NDT) methods such as (Dye Penetrant Testing) DPT, (Magnetic Particle Testing) MPT, (Radiographic Testing) RT, and visual inspection. The study focused on three key input parameters: welding current (100, 110, and 120 Ampere), preheat temperature (250°C, 300°C, and 350°C), and interpass temperature (100°C, 200°C, and 300°C). Corresponding output responses measured included hardness (BHN), impact strength (J), and tensile strength (MPa). A multi-objective optimization was performed using the Taguchi method combined with Grey Relational Analysis (GRA). Results indicated that the B-540 electrode outperformed B-850, delivering superior mechanical properties under the tested conditions. The electrode A-540 shows the more stability and better result as compared to B-850 electrodes. The Interpass temperature shows the dominant parameter for A-540 electrode whereas the Pre heat temperature plays an influential parameter for the electrode B-850. The experiment number 7 gives the best result for the A-540 electrodes satting the current at 120 ampere, preheat temperature at 250°C and Interpass temperature at 300°C. The experiment number 2  states the input parameters as current at 100 ampere, preheat at 300 °C and Interpass temperature at 200 °C  for the electrode B -850.