1.What is the core definition and production process of SECC?
Substrate Preparation: Low-carbon cold-rolled steel sheets (such as SPCC, corresponding to the Chinese designation DC01/DC03) are used. Multiple cold-rolling steps are used to convert the hot-rolled steel sheets into substrates with uniform thickness (typically 0.3-2.0mm) and a smooth surface, ensuring subsequent coating adhesion and forming accuracy.
Electrolytic Degreasing/Pickling: Removes oil and scale from the substrate surface to prevent impurities from affecting the adhesion of the zinc coating, serving as a pretreatment for galvanizing.
Electrolytic Galvanizing: The pretreated cold-rolled substrate is placed in an electrolyte containing zinc ions. Electrolysis deposits zinc ions uniformly on the substrate surface, forming a zinc coating with controllable thickness (typically 5-20μm, adjustable as needed). Compared to hot-dip galvanizing (SGCC), electrolytic galvanizing produces a thinner, more uniform coating with less surface roughness. Post-treatment: After galvanizing, "passivation treatment" (such as chromate passivation or chromium-free passivation) and "oiling" are required to further improve corrosion resistance (the passivation layer can prevent white rust on the zinc layer) and improve lubricity during processing (oiling reduces stamping scratches).
2.How does SECC's excellent corrosion resistance manifest itself?
The zinc coating significantly improves the steel's corrosion resistance through both "sacrificial anodic protection" (preferential corrosion of zinc) and "physical isolation" (isolating air and moisture). Unpassivated SECC steel withstands neutral salt spray for approximately 48-96 hours, but passivated steel can withstand 120-240 hours, significantly exceeding the performance of uncoated cold-rolled steel (SPCC).
3.How is SECC's high precision and smooth surface demonstrated?
Based on the characteristics of cold-rolled substrates, SECC has an extremely small thickness tolerance (±0.02mm), a flat plate shape (no wave deformation), and a high uniformity of the electrolytic zinc coating (coating thickness deviation ≤10%). The surface is smooth and flawless, and no additional polishing is required to meet appearance requirements (such as home appliance panels and electronic housings).
4.What is the cold formability of SECC?
The cold-rolled base material has a low carbon content (typically C ≤ 0.15%) and good plasticity. Combined with a thin, tough zinc coating, SECC can withstand complex cold processing, such as:
Deep drawing (e.g., grooves and protrusions in electronic device casings);
Bending (minimum bend radius up to 0.5 times the plate thickness without plating loss);
Punching and shearing (processed edges are free of noticeable burrs and the plating is less susceptible to cracking).
5.What are the main application areas of SECC?
Electronics and Electrical Appliances:
Consumer Electronics: Laptop cases, mobile phone mid-frame brackets, tablet back panels;
Home Appliances: Air conditioner indoor unit housings, washing machine control panels, microwave oven inner brackets, refrigerator drawer rails;
Electronic Components: Circuit board brackets, transformer housings, connector housings.
Automotive:
Automotive Interiors: Instrument panel brackets, door trim panels, air conditioner vent components;
Automotive Electronics: Car navigation housings, charging station housings (requires rust resistance and precise dimensions).
Other Precision Industries:
Office Equipment: Printer bodies, copier internal components;
Medical Devices: Small medical device housings (such as blood glucose meters and blood pressure monitors, which must be smooth and easy to clean).