Influence of Grain Boundary Characteristic Distribution on Corrosion Behavior of 316L Stainless Steel Welded Joint

Using electron backscatter diffraction (EBSD), orientation imaging microscopy (OIM) and X-ray residual stress analysis technique, electrochemical test and immersion corrosion test were used to study the special grain boundary distribution and distribution of weld and base material of 316L stainless steel welded joint and surface residual stress distribution, and the influence of solution temperature on its corrosion resistance. The results showed that the proportion of low coincidence site lattice (CSL) grain boundaries in the weld of 316L stainless steel welded joints was 45% lower than that of the base metal. The critical pitting potentials of the weld and base metal were 0.26 V and 0.40 V, respectively. In 4% FeCl₃ solution, the corrosion rate of the weld was about twice that of the base metal, and those corrosion rates increased with the increase of solution temperature. Low CSL grain boundary and high residual tensile stress were the reasons for the preferential corrosion of welds.