Choosing the right screw material based on the application environment is crucial, requiring a comprehensive consideration of corrosion risk, stress requirements, temperature conditions, and cost budget. The durability and safety of materials vary significantly under different environments; choosing the right material can effectively prevent loosening, breakage, or corrosion.
1. Humid or Outdoor Environments: Stainless Steel Preferred
In rainy, humid, or salt spray environments (such as coastal areas, bridges, and ships), stainless steel screws (such as 304 and 316) are the first choice.
304 Stainless Steel: Highly corrosion-resistant, suitable for general outdoor facilities, building curtain walls, streetlights, etc.
316 Stainless Steel: Contains molybdenum, offering stronger resistance to chloride corrosion, suitable for high-salt spray marine environments or chemical equipment.
If the budget is limited, galvanized carbon steel screws can be used, but their rust-resistant lifespan is shorter, requiring regular maintenance.
2. High-Temperature or Engine Compartment Environments: Heat-Resistant Stainless Steel or Alloy Steel
In high-temperature areas such as engine compartments and exhaust systems, ordinary carbon steel is prone to oxidation and failure.
Stainless steel (e.g., 309, 310): Resistant to high-temperature oxidation, can operate stably in environments above 600°C.
Alloy steel (e.g., 40Cr, 35CrMo): High strength, can withstand high temperatures and high stress after heat treatment, commonly used in engine mounting components and suspension systems.
Avoid using aluminum alloy or plastic screws, as they are prone to deformation at high temperatures.
3. High-stress or critical structural parts: High-strength alloy steel. Chassis, suspension, transmission systems, etc., bear enormous vibrations and loads.
8.8 grade and above alloy steel screws: High tensile strength, can withstand dynamic loads, standard equipment in automobiles and heavy machinery.
Surface treatment often uses Dacromet or hot-dip galvanizing to balance rust prevention and high strength requirements.
4. Lightweight application scenarios: Aluminum alloy or titanium alloy. Suitable for weight-sensitive fields such as aerospace, racing, and high-end bicycles.
Aluminum alloy screws (such as 7075): Lightweight and corrosion-resistant, but with lower strength than steel screws, making them unsuitable for high-load applications.
Titanium alloy screws: With strength approaching that of steel, but weighing only 60% of steel, they offer excellent corrosion resistance, but are very expensive and are often used in high-end modifications or precision instruments.
