The thickness of the color zinc passivation film is 8-15μm, the salt spray test is more than 72 hours, and the appearance is rainbow-colored. When trivalent chromium passivation is used, the environmental protection performance is excellent.
Surface treatment: The thickness of the color zinc passivation film is 8-15μm, the salt spray test is more than 72 hours, and the appearance is rainbow-colored. When trivalent chromium passivation is used, the environmental protection performance is excellent.
Performance improvement: The corrosion resistance is 3 times higher than that of electrogalvanizing, and it is suitable for outdoor buildings (such as awnings, sunshades) and bathroom equipment installation. The shear strength of M5 specification in stainless steel plate is ≥35kN.
Application scenarios: outdoor billboard installation, aluminum alloy door and window fixing, ship interior decoration, etc., which need to take into account both corrosion resistance and aesthetics.
Type | Surface treatment | Salt spray test | Hardness range | Corrosion resistance | Environmental protection | Typical application scenarios |
Electro-galvanized hexagonal head | Silvery white | 24-48 hours | HV560-750 | General | No hexavalent chromium | Indoor steel structure, ordinary mechanical connection |
Colored zinc-plated hexagonal head | Rainbow color | More than 72 hours | HV580-720 3 | Good | Trivalent chromium environmental protection | Outdoor photovoltaic bracket, port equipment |
Black zinc-plated hexagonal head | Black | More than 96 hours | HV600-700 | Excellent | Trivalent chromium environmental protection | Automobile chassis, high-temperature equipment |
Electro-galvanized cross countersunk head | Silvery white | 24-48 hours | HV580-720 | General | No hexavalent chromium Indoor decoration, furniture manufacturing | Colored zinc-plated cross countersunk head |
Rainbow color | More than | 72 hours | HV580-720 | Good | Trivalent chromium environmental protection | Outdoor awnings, bathroom equipment |
Environmental factors: For outdoor or high humidity environments, color zinc plating or black zinc plating is preferred; for indoor dry environments, electroplating zinc can be selected.
Load requirements: For high-load scenarios (such as bridges and heavy machinery), black zinc-plated hexagonal drill tail screws must be selected. Specifications above M8 must be tested for torque according to GB/T 3098.11.
Environmental requirements: Electroplating zinc (chromium-free) is recommended for the medical and food industries; trivalent chromium passivated color zinc plating or black zinc plating can be selected for ordinary industrial projects.
Electric drill speed control: 3.5mm diameter drill tail screws are recommended to be 1800-2500 rpm, and 5.5mm diameter drill tail screws are recommended to be 1000-1800 rpm.
Torque control: The torque of the M4 specification is about 24-28kg・cm, and the M6 specification is about 61-70kg・cm. Avoid deformation of the substrate due to excessive tightening.