Definition - What does Grain Dropping mean?
Grain dropping refers to a physical occurrence when small intermolecular component materials of a metallic object dislodge from the metal's surface along the intergranular crystalline boundaries due to corrosion.
Corrosionpedia explains Grain Dropping
Grain dropping is most readily observed in cases of deterioration of the metal's intermolecular boundaries. This deterioration is caused by the erosion of cross-sectional surface thickness due to the propagation of cracks.
Stainless steel is particularly prone to grain dropping due to intergranular corrosion. This is heightened at high temperatures ranging from 425°C to 870°C (797°F to 1600°F). At these temperatures, chromium carbide is formed at the grain boundary and chromium is depleted, which causes the loss of hardness and corrosion resistance.
Grain dropping causes the loss of entire grains and structural damage, and is difficult to remediate once it has begun due to its self-propagating mechanism.