Effect of Welding on The Corrosion Behaviour of a Highly Alloyed Austenitic Stainless Steel UNS N06027 in Polluted Phosphoric Acid Media

摘要

The objective of this work is to study the effect of welding on the corrosion resistance of the austeniticstainless steel Alloy 59 (UNS N06027) as well as the galvanic corrosion generated by the base/weldpair estimated from the polarisation curves according to the mixed potential theory. The materials havebeen exposed to polluted phosphoric acid at several temperatures. The microstructure of the sampleswas studied by SEM and EDX analysis. The results show that the welding process shifts the corrosionpotential values to more anodic potentials. The corrosion current densities and the passive currentdensities also increased by the effect of welding. This effect is aggravated with the increase intemperature. Open circuit potential values were located in the passive zone of the potentiodynamiccurves, which means that the materials passivated spontaneously.The galvanic corrosion of the pair isnot severe in the studied conditions. The ratio between the galvanic current density of the pair and thecorrosion current density of the uncoupled anode is less than 5, which implies compatibility of themembers in the couple.