Acidic Corrosion Behavior of Slag-free Self-shielded Flux-cored Arc Welding Overlay

The corrosion resistance of slag-free self-shielded flux-cored welding overlays with different ferrotitanium (Fe-Ti) additions in 3.5 wt.% NaCl + 0.01 mol/L HCI acidic solution was investigated. The corrosion occurs in the matrix rather than M-7(C, B)(3), M-3(C, B) and TiC in the microstructure of all the welding overlays. The corrosion resistance of hypereutectic welding overlay is decreased when the Fe-Ti addition is increased from 0 wt.% to 12 wt.%. The corrosion resistance of the welding overlay is the lowest since the overlay is a eutectic structure at the Fe-Ti addition of 12 wt.%. The eutectic structure increases the interface of corrosion reaction, which accelerates the corrosion rate and increases the corrosion current. With the Fe-Ti addition increasing from 12 wt.% to 24 wt.%, the corrosion resistance of the welding overlays with hypoeutectic structure is gradually increased, owing to the increase of the proportion of TiC and chromium content in the matrix.