Weld overlaying of corrosion-resistant filler metals on A516 G-70 carbon steel

This study explores the application of weld overlays on A516 G-70 steel using different filler metals, including ER 2594 super duplex stainless steel, ER 2209 duplex stainless steel, and ER 316L austenitic stainless steel. The aim of the overlaying process was to enhance the corrosion resistance and erosion performance of the base alloy. Pulsed current gas tungsten arc welding was employed as the overlaying technique. Detailed microstructural assessments were performed using optical microscopy and field emission scanning electron microscopy, supplemented by energy dispersive X-ray spectroscopy. The ratio of ferrite to austenite was evaluated through X-ray diffraction analysis and measurements using a ferrite scope. Results indicated that increasing the heat input reduced the ferrite phase in the ER 2594 and ER 2209 overlays. To assess corrosion behavior, Tafel polarization and electrochemical impedance spectroscopy tests were carried out on both the substrate and the overlay materials. Among the overlays, ER 2594 produced under moderate heat input showed the best corrosion resistance, with a notably low corrosion current (i_corr = 6.6 nA/cm²) and higher impedance (Z) compared to other overlays. Furthermore, erosion performance was evaluated using a slurry test with water containing 5 wt% sand particles at a flow rate of 10 m/s, with an impact angle of 30°, and varying duration. The ER 2594 overlay proved substantially lower mass loss, indicating superior erosion resistance compared to both the base and other cladding alternatives. Based on the findings, the ER 2594 considered as the most suitable overlay filler for the A516 base material.