Micro Morphology of 316L Stainless Steel after Long-Term Service in Supercritical Water Oxidation System

Scanning electron microscopy (SEM) was used to observe the micro morphology of the base metal and weld of a 316L stainless steel pipe serviced in supercritical water oxidation (SCWO) system for a long time, and the corrosion mechanism was analyzed. The results indicated that the inner wall of the stainless steel pipe was jagged with uneven edges, which was caused by large surface roughness and long-term erosion corrosion of the medium in pipe. There were several intergranular corrosion cracks in the outer wall, which was mainly related to chromium. The corrosion of the weld was more serious than that of the base material, obvious thinning phenomenon was shown on in the inner wall with the maximum amount of thinning up to 0.2 mm.