Galvanised steel coils play a key role in a wide range of industries, providing protection against corrosion and adding durability to a wide range of applications. Galvanised steel coil is produced by galvanising SPCC (cold-rolled steel coil). SPCC is an affordable and readily available steel coil known for its excellent workability, which makes it a preferred choice for various forming processes such as bending and squeezing. However, SPCC has a high susceptibility to rust and usually requires some form of surface treatment.
There are many grades available. SECC (electro-galvanised steel coil) and SGCC (hot-dip galvanised steel coil) are two popular choices with different characteristics and applications.
SPCC(Steel Coil Cold Commercial)
SPCC Steel coil - Cold rolled steel coil for general use, which is equivalent to the Chinese Q195-215A grades or St12 in German Standard. S here is for steel, and P is for plate; C is for cold and the last C is for commercial quality.
SGCC (Hot-dip Galvanized Steel Coil)
SGCC adopts the hot-dip galvanizing process, immersing the steel sheet in molten zinc to form a layer of zinc-iron alloy. This process gives the steel sheet stronger corrosion resistance.
SECC (Electrolytic Galvanized Steel Coil)
SECC is an electrogalvanized cold-rolled steel sheet. A layer of zinc is formed on its surface through the electrolytic galvanizing process. This layer of zinc not only improves the steel sheet's corrosion resistance but also extends its service life.
Differences between SPCC, SGCC and SECC
SPCC is the most common cold-rolled steel coil. It is not galvanized and its surface is usually black and rough.
Processing Method: The manufacturing process of SPCC is relatively simple and the cost is low, suitable for large-scale production.
SGCC(Hot-Dip Galvanization): Hot-dip galvanization involves immersing steel coils in molten zinc after heating. This process creates a thick plating layer and forms an alloy layer between the zinc and the base metal, resulting in exceptional durability and long-term corrosion resistance. It's essential to note that the high temperatures involved can sometimes lead to heat-induced distortion, posing challenges in certain applications.
SECC(Electro-Galvanization): Electro-galvanization employs an electric current to deposit dissolved zinc onto the surface of the material to be plated. This method offers uniform coating thickness and decorative properties, making it a preferred choice for various applications. Unlike hot-dip galvanization, electro-galvanized materials typically undergo chromate treatment to enhance corrosion resistance and prevent white powdery corrosion formation.
Performance Comparison
Corrosion Resistance
Both SECC and SGCC have good corrosion resistance due to galvanizing treatment. Among them, SGCC has slightly stronger corrosion resistance because the hot-dip galvanized layer is thicker and more uniform.
SPCC has poor corrosion resistance and requires additional anti-corrosion treatment during use.
Strength and Toughness
SGCC has excellent strength and toughness, suitable for manufacturing components that bear large loads.
SECC also has good strength and toughness, meeting the needs of most home appliances.
SPCC has relatively low strength and toughness but is suitable for manufacturing some thin materials.
Appearance and Surface Quality
The surface of SECC is smooth and bright, suitable for products with high appearance requirements.
The surface of SGCC forms spangle and has high brightness but has a unique visual effect.
The surface of SPCC is usually black and rough, requiring further surface treatment to achieve an ideal appearance.
Application Areas
Home appliance manufacturing
Automobile manufacturing
Construction industry applications
SECC: Due to its smooth surface and excellent corrosion resistance, SECC steel coil is widely used in the manufacturing of home appliances, such as the outer shells of refrigerators, washing machines, and air conditioners, as well as electronic product shells and chassis.
SGCC: With its high strength, high toughness, and good corrosion resistance, SGCC steel coil is applied in various fields such as home appliances, low-voltage electrical appliances, building decoration, and vehicle manufacturing, such as security doors, guardrails, and conveyor belts.
SPCC: Due to its low cost, SPCC steel coil is mainly used to manufacture products with low requirements for corrosion resistance, such as cans, underbodies, steel pipes, and tabletops.
SECC is a steel that has undergone electrolytic zinc plating applied to SPCC (cold-rolled steel coil), while SGCC is a steel that has undergone hot-dip galvanising applied to SPCC. Both materials are suitable for applications such as electrical enclosures and building materials because they are corrosion resistant and easy to work .
