1.What is the difference between chemical composition and mechanical properties basis?
Galvanized Coil: The base is low-carbon steel with a zinc coating.
High Strength: Typically stronger than aluminum alloys.
High Hardness: More wear-resistant, but also causes greater wear on tools and dies during processing.
High Elastic Modulus: Approximately 200 GPa, which means significant springback during bending, requiring precise die design to compensate.
Aluminum Alloy Coil: Common types include 1000 series (pure aluminum), 3000 series (Al-Mn), and 5000 series (Al-Mg).
Low Strength: However, the specific strength (strength/density) is high.
Low Hardness: Soft and easily scratched, but with low processing resistance.
Low Elastic Modulus: Approximately 70 GPa, which means less springback during bending, making it easier to achieve precise bend angles.
2.Comparison of cutting and punching processes, what are the results?
Aluminum alloy: Clearly superior. Due to its lower strength and hardness, less force and energy are required for shearing and blanking. Wear on dies and cutting tools is also significantly reduced, resulting in longer tool life and higher processing efficiency.
Galvanized coil: Requires larger punching and shearing machines. The hard zinc layer and steel substrate accelerate wear on die cutting edges.
3.How do bending and forming processes compare?
Aluminum alloy: Also superior. Its reduced springback makes it easier for operators to control the bend angle and formed shape. Aluminum alloy also makes it easier to achieve the desired curve for complex roll forming.
Galvanized coil: The biggest challenge is springback. Operators must be experienced and compensate for springback by "overbending" to achieve an accurate 90-degree angle. This requires more time for adjustment.
4.What are the comparison effects between deep drawing and stretching?
Aluminum alloys generally perform better. Many aluminum alloys (such as 3003 and 5052) have excellent ductility, making them well-suited for deep drawing and forming complex parts (such as pots and cans).
Galvanized coils: While the low-carbon steel substrate itself is also highly ductile, they are prone to Lüders bands (also known as slip lines), irregular strain lines on the surface that degrade appearance. This is to be avoided in parts requiring stringent surface finishes.
5.How do the welding processes compare?
Galvanized coil: Clearly superior. Galvanized steel welding processes are highly mature, allowing for standard MAG welding and resistance spot welding. These techniques are readily available and easy to use.
Aluminum alloy: It presents significant challenges.
The dense aluminum oxide film on the surface (melting point approximately 2050°C) is much higher than the aluminum substrate (melting point approximately 660°C), requiring high power or specialized welding techniques (such as AC TIG welding) to break it.
A high-purity shielding gas (such as argon) is required.
High thermal conductivity leads to rapid heat dissipation, making incomplete penetration defects more likely to occur.
The high coefficient of thermal expansion results in significant weld distortion.