Phase Balance Control of Duplex Stainless Steel Overlay with Buffer Layer

ER304 and ER309L were deposited with cold metal transfer welding process on Q345 low-alloy steel substrates as buffer layer for duplex stainless steel ER2209 overlay respectively to improve phase balance. An ER2209 overlay was deposited without buffer layer for comparison. The overlays were examined with optical metallographic microscope, and ferrite contents in the overlays were measured. Tafel curve of the overlays were measured. The results show that the ferrite content in the directly deposited ER2209 overlay is only 32.76%, deviating from the phase balance range, due to dilution effect of the substrate and the repeated heating effect of multi-passes welding. With ER304 or ER309L as a buffer layer, the ferrite content in the ER2209 overlay increases significantly to 48.78% and 44.00%, respectively, ensuring phase balance. Corrosion resistance of the ER2209 overlays increases with both ER304 and ER309L as a buffer layer.