The effect of titanium on pitting corrosion resistance of welded supermartensitic stainless steel

This study evaluated the effect of Ti in the supermartensitic stainless steel (SMSS) on the pitting corrosion in welded joints using gas tungsten arc welding. In the welded SMSS sample, there was martensite grain coarsening in the heat-affected zone (HAZ), and d-ferrite formation at the interface between the base metal and HAZ regions. The presence of Ti in the SMSS prevented grain coarsening and promoted the formation of retained austenite in the HAZ regions. The values of the pitting potentials of SMSS + Ti and SSMS using a cell-pen (designed to reveal the behaviour of localised microstructure in a narrow area) were 0.347 and 0.286 V in the non-welded condition, and 0.374 and 0.183 V in the welded condition, respectively. The corresponding values using the conventional cell were 0.349 and 0.257 V in the non-welded condition and 0.230 and 0.089 V in the welded condition, respectively.