Effect of welding parameters on microstructure and mechanical properties of GMAW welded S275 steel welded zone

This study investigates the effect of welding parameters on the microstructural evolution and mechanical properties, such as tensile strength and hardness, in mild steel plates welded using gas metal arc welding (GMAW). The welding parameters examined include welding current, arc voltage, and gas flow rate, with ER K-71 T filler wire as the consumable material. Results indicate that a higher welding current and reduced gas flow rate result in a maximum tensile strength of approximately 533 MPa. However, discrepancies were noted in the microhardness data across different zones, with the heat-affected zone (HAZ) exhibiting a hardness of 115.8 HV, while the weld zone and base metal showed values of 76.7 HV and 112.9 HV, respectively. Microstructural analysis revealed the presence of bainite and ferrite with a tempered martensitic structure in the welded area, demonstrating that the combination of welding parameters plays a critical role in controlling phase transformations and mechanical behavior. It is essential to reconcile the observed hardness values with the conclusions drawn to ensure accurate interpretation of the data.