Effect of Ti-based inclusions and acicular ferrite on the corrosion performance of multipass weld metals

This paper reports the effect of Ti-based inclusions and acicular ferrite on the corrosion performance of carbon steel multipass weld metals. The weld metals containing Ti-based inclusions have been prepared by addition of different quantities of titanium oxide nanoparticles to the electrode coating, which was dispersed using the ultrasonication process. After welding, the relationship between microstructure and corrosion performance of the weld metals was studied through full metallographic, potentiodynamic polarization and electrochemical impedance spectroscopy methods. It was observed that the use of titanium oxide nanoparticles in the coated electrodes grain refined the weld metals, which is attributed to the beneficial role of nanostructured inclusions as heterogeneous nucleation sites of acicular ferrite. It was also deduced from the corrosion tests of the weld samples that increasing the Ti-based inclusion content and grain refinement can deteriorate the corrosion resistance of the weld metals.