Investigation of Weldability of 2205 and P355GH Steels Using Robotic MAG Welding

Sheets of P355GH pressure vessel steel and AISI 2205 duplex stainless steel were successfully joined using metal active gas (MAG) welding at varying speeds. ER 309L Si filler wire, applied in accordance with AWS A5.9 standards, and a 90% Ar + 5% CO₂ + 5% O₂ shielding gas were employed. Non-destructive inspections, including visual, magnetic particle, and ultrasonic testing, confirmed defect-free welds. Mechanical testing demonstrated reliable performance: tensile specimens fractured in the P355GH base metal with strengths of ~ 551–555 MPa, while bend tests showed no cracks up to 180°. Charpy impact tests indicated maximum toughness in the AISI 2205 HAZ (~ 90 J), followed by the P355GH HAZ (~ 70 J) and weld metal (~ 55 J), with toughness decreasing at higher welding speeds due to reduced heat input. Hardness peaked in the AISI 2205 HAZ (~ 285 HV), followed by the weld metal (~ 250 HV) and P355GH (~ 210 HV), with higher speeds yielding increased hardness. Microstructural and fractographic analyses revealed dendritic solidification, grain coarsening near fusion boundaries, and fracture modes ranging from brittle in P355GH HAZ to predominantly ductile in the weld metal. EDS confirmed compositional transitions consistent with filler and base alloys. These results verify the industrial applicability and mechanical reliability of robotic MAG welding for dissimilar P355GH–AISI 2205 joints.