GB/T 30789.8-2015 "Paints and varnishes — Evaluation of degradation of coatings — Designation of quantity and size of defects, and of intensity of uniform changes in appearance — Part 8: Assessment of degree of delamination and corrosion around a scribe or other artificial defect" specifies the method for evaluating the degree of coating delamination and corrosion around a scribe or other artificial defect on painted test panels or workpieces under corrosive environments, excluding the assessment of pitting and pitting depth. The evaluation is conducted promptly after testing or after conditioning. The delamination grade is determined by removing the disbonded coating using a blade, compressed air, or adhesive tape, while the corrosion grade can be assessed directly or after removing the coating. Measurements should be taken with a ruler with a minimum scale of 0.5 mm, and the grades are calculated accordingly. This standard provides a basis for evaluating the aging performance of coatings.