Distribution characteristics of inclusions along with the surface sliver defect on the exposed panel of automobile: A quantitative electrolysis method

The specific distribution characteristics of inclusions along with the sliver defect were analyzed in detail to explain the formation mechanism of the sliver defect on the automobile exposed panel surface. A quantitative electrolysis method was used to compare and evaluate the three-dimensional morphology, size, composition, quantity, and distribution of inclusions in the defect and non-defect zone of automobile exposed panel. The Al2O3 inclusions were observed to be aggregated or chain-like shape along with the sliver defect of about 3–10 µm. The aggregation sections of the Al2O3 inclusions are distributed discretely along the rolling direction, with a spacing of 3–7 mm, a length of 6–7 mm, and a width of about 3 mm. The inclusion area part is 0.04%–0.16% with an average value of 0.08%, the inclusion number density is 40 mm−2 and the inclusion average spacing is 25.13 µm. The inclusion spacing is approximately 40–160 µm, with an average value of 68.76 µm in chain-like inclusion parts. The average area fraction and number density of inclusions in the non-defect region were reduced to about 0.002% and 1–2 mm−2, respectively, with the inclusion spacing of 400 µm and the size of Al2O3 being 1–3 µm.