Chromium-depleted mechanism: Supersaturated solid solution carbon disperses toward grain boundaries.

Chromium, which is close to the boundary, forms chromium carbide CR23C16 or (Fe, Cr) C6 and precipitates at grain boundaries. Since carbon disperses much faster than chromium, chromium does not have to be added to the grain boundary from the grain to the grain boundary, so that it is adjacent to the grain boundary. The mass fraction of Cr in the periphery of the grain is less than 12%, which is the so-called "chromium-depleted" phenomenon. I. Corrosion resistance of welded joints of γ-SS (a) Corrosion resistance of joints 1. Intergranular corrosion, representative 18- 8 In steel welded joints, intergranular corrosion occurs in three locations, including corrosion in the weld zone, corrosion in the sensitized zone, and corrosion in the fusion zone.