Welded gr. 91 steel is widely used for structural components in the energy production field, where it suffers from
selective corrosion near welded joints. In this work, Gr. 91 plates were welded using a gas tungsten arc welding
technique and subjected to two different post-welding heat treatments (tempering or normalising plus tempering).
Localised corrosion measurements performed with a microcell, coupled with microstructural characterisations, showed that corrosion was very active in the heat-affected zone (HAZ) in the as-welded condition and was
worsened by the tempering treatment. In contrast, after a normalising treatment, the electrochemical behaviour
of the welded joint was uniform.
