The national technical standard for color-coated steel sheets is primarily defined by GB/T 12754-2019, "Color-coated steel sheets and strips," which applies to color-coated products used in sectors such as construction and home appliances. The standard specifies the following requirements:
Substrate Material: Must consist of cold-rolled steel sheets, hot-dip galvanized steel sheets, or aluminum-zinc alloy-coated steel sheets. For galvanized substrates, the minimum coating weight (total for both sides) must be at least 90 g/m² (in accordance with GB/T 2518).
Coating Performance:
Salt Spray Resistance: ≥ 500 hours (with corrosion width from the scribe line not exceeding 2 mm on either side).
Adhesion: Must achieve a rating of 0 (no detachment) when tested using the cross-cut (grid) method.
Hardness: Pencil hardness must be ≥ HB (as per GB/T 6739).
Dimensional Tolerances: The allowable deviation for thickness is ±0.05 mm, and for width, it is ±2 mm (standard sheet widths range from 1000 mm to 1250 mm).