1. Coating thickness specification requirements
The thickness of the galvanized layer on the surface of the steel plate has an important impact on the quality and performance of the steel plate. Generally speaking, the thickness of the galvanized layer of cold-rolled steel plate should be greater than or equal to 6μm, and the thickness of the galvanized layer of hot-rolled steel plate should be greater than or equal to 4.5μm. The surface of galvanized steel sheet should be flat and free of wrinkles, crimps, cracks and other defects.
2. Specification requirements for surface flatness
Surface flatness is also an important indicator to measure the quality of galvanized steel sheets. Standards such as ISO, JIS and ASTM stipulate that the height of the steel plate surface protrusion should not exceed 30% of the surface flatness tolerance. The surface flatness tolerance should be in accordance with the standard specifications of the corresponding country.
3. Adhesion specification requirements
The adhesion of the steel plate surface has an important impact on the corrosion resistance and service life of the steel plate. Relevant standards and specifications at home and abroad require that the surface of the steel plate should be evaluated by the method of uninterruptible burner test or cutting test, and the test results should meet the provisions of the corresponding standards.
Fourth, industry standards and quality testing methods
For the quality control of galvanized steel sheets, the current industry standards mainly include GB/T 2518-2008 "Continuous Hot-dip Galvanized Steel Sheets and Steel Strips", GB/T 1479-2017 "Technical Conditions for Hot-dip Galvanized Steel", etc. At the same time, through a series of quality inspection methods, including thickness measurement, surface flatness measurement, adhesion testing, etc., effective quality control can also be carried out on galvanized steel sheets.
