Influence of GTAW and SMAW Techniques on the Mechanical Behavior of S275JR Low Carbon Manganese Steel Welded Joints

In the present study, the weldability of S275JR low carbon manganese steel using gas tungsten arc welding (GTAW) and shielded metal arc welding (SMAW) at respective heat inputs of 321.18 and 304.63 J/mm, was investigated. The welded joints’ microstructural evolution and mechanical properties were assessed through optical microscopy, hardness, and tensile testing. The weld metal microstructure comprises various structures such as ferrite and pearlite. The hardness distribution revealed higher values in the heat-affected zone (HAZ) of GTAW joints (270 HV), compared to SMAW joints (257 HV). Results show that SMAW joints exhibited higher ultimate tensile strength (532 MPa) and joint efficiency (98.8%) compared to GTAW joints, which achieved an ultimate tensile strength 502 MPa and a joint efficiency of 93.2%. Both joints fractured at the HAZ during tensile testing, indicating its critical influence on the welded joint performance. It is recommended that various ranges of heat inputs be employed during welding the S275JR via GTAW and SMAW techniques to control and optimize welding parameters.