Q:How to judge the quality of the zinc layer of galvanized coil?
A:Observe whether the zinc layer on the surface is smooth and continuous, and whether there are defects such as missing plating (exposed steel plate substrate), zinc particles (protruding particles in the plating), and air knife stripes (uneven thickness of the plating due to uneven airflow).
Galvanized coil with patterns: The patterns should be uniform and consistent, without large areas of missing patterns or abnormally dense areas.
Galvanized coil without patterns: The surface should be flat and delicate, without obvious crystal particles or bumps.
Q:How to detect the appearance of galvanized coils?
A:Substrate defects
Check for scratches, roller marks, holes, edge waves (uneven edges), wrinkles, etc. left over from the rolling of the substrate, which may affect subsequent processing and corrosion resistance.
Edge quality
The edges of the coil should be neat, free of burrs, cracks or delamination, otherwise it may cause tearing or coating shedding during processing.
Check for "edge waves" (wavy deformation of the edge) or "middle waves" (wavy deformation of the middle area), which are usually related to the rolling process and affect flatness.
Q:How to detect the coating thickness of galvanized coil?
A:Thickness gauge measurement: Use a magnetic thickness gauge (applicable to iron-based coatings) to directly measure the coating thickness. Different standards have clear requirements for coating thickness.
Weighing method calculation: Cut a sample of a certain area, remove the coating and weigh it, and calculate the coating thickness by the weight difference (applicable to precise laboratory testing).
Q:How to detect the substrate material of galvanized coil?
A:Confirm whether the substrate is a cold-rolled coil or a hot-rolled coil, check the material grade (such as DC51D+Z, SGCC, etc.) and chemical composition (carbon, manganese, silicon, etc. content). Poor-quality substrates may have insufficient strength or cracking due to excessive impurities.
Check whether the chemical composition and mechanical property data (such as yield strength, tensile strength, elongation) in the warranty or test report meet the standards.
Q:What is the simple identification process?
A:Visual inspection: observe surface flatness, defects, and edge quality.
Thickness and adhesion: Use a thickness gauge to quickly detect the thickness of the coating, and preliminarily judge the adhesion through a bending test.
Verify the logo: Confirm whether the manufacturer, brand, implementation standard and other information are complete and consistent.
On-demand testing: Select corrosion resistance or mechanical properties testing according to the usage scenario.