EFFECTS OF WELDING POLARITIES ON THE MECHANICAL PROPERTIES OF ARC WELDED MILD STEEL JOINTS

Welding polarity is a major parameter in arc welding because it affects heat distribution, penetration, and weld-bead formation and welded joint mechanical properties. Mild steel is widely used in engineering, construction, agricultural machinery, and fabrication, making reliable weld quality essential. This study on the effects of direct current electrode-positive (DCEP) and direct current electrode negative (DCEN) on the mechanical and physical characteristics of arc welded mild steel joints. Mild steel specimens were prepared and welded under controlled conditions using the two polarity configurations, while other major welding parameters were kept as consistently as possible. Welded joints were evaluated using tensile strength, hardness, and impact toughness tests. Weld penetration, bead characteristics HAZ behavior were also examined. The results showed that DCEP produced better overall performance than DCEN under the experimental conditions. The mean tensile strength increased from 435.0 MPa for DCEN to 471.7 MPa for DCEP, whereas the mean impact energy increased from 40.7 J to 47.0 J. Similarly, weld-metal hardness increased from approximately 168 to 186 HV, and weld penetration improved from 2.8 mm to 3.6 mm. The findings indicate that DCEP enhanced fusion and provided a more favorable combination of tensile strength, hardness, and impact toughness, although it produced a wide HAZ. Therefore, DCEP is recommended for mild-steel arc-welding applications requiring improved penetration and mechanical performance. Proper control of welding current, voltage, travel speed, electrode characteristics, and joint preparation is also recommended for consistent weld quality. Overall, the welding polarity significantly influences the physical and mechanical properties of mild-steel welded joints, with DCEP providing the most favorable overall performance.