GB/T 39130-2020 applies to galvanized, zinc-iron alloy, zinc-aluminum alloy, and aluminum-zinc alloy coated steel sheets (strips) with thicknesses ranging from 0.1 mm to 3.0 mm, standardizing test methods for assessing coating adhesion. The standard defines terminology, specifies sample requirements, outlines bending test procedures, and details the content of test reports. It primarily employs 180° bending tests and V-bend tests, utilizing testing equipment such as bending test machines and adhesive tape. By controlling parameters like indenter diameter and bending angle, and combining evaluation methods such as visual inspection and tape adhesion, the standard determines whether cracks, peeling, or other issues occur in the zinc layer, thereby accurately assessing the bonding strength between the coating and the substrate.