The material of a screw directly affects its strength, corrosion resistance, and applicable environment.
Carbon steel: Low cost, high strength (4.8-12.9 grade), but prone to rust; suitable for general machinery.
Stainless steel (e.g., 304/316): Corrosion resistant, medium strength (A2-70/A4-80), suitable for humid or chemical environments.
Alloy steel (e.g., 35CrMo): High strength (10.9-12.9 grade), high temperature resistant; used in heavy-duty or high-temperature applications.
Copper/aluminum: Good electrical conductivity, low strength; used in electronic or magnetic field shielding applications.
The choice of screw material directly affects its mechanical properties and environmental adaptability. Taking carbon steel screws as an example (such as the 4.8 grade galvanized screws sold in the store), their tensile strength can reach 400MPa, suitable for conventional mechanical assembly; while stainless steel screws (such as 304 material), although slightly lower in strength (tensile strength about 700MPa), can resist acid and alkali corrosion due to the passivation film formed by chromium, making them suitable for food equipment or coastal environments.
For extreme working conditions, such as mining machinery (refer to the store's M820 expansion screws), 10.9 grade alloy steel must be selected, and the hardness must reach HRC32-39 through quenching and tempering processes, while a galvanized layer is used for corrosion protection. Special scenarios require attention: electronic equipment requires copper/aluminum screws to prevent electromagnetic interference, while bridge engineering (such as the store's M58 standard screws) requires 4.8 grade carbon steel with Dacromet coating to resist salt spray corrosion.
All fasteners in our store are manufactured according to ISO/GB standards, and the material parameters are clearly marked. For example, the carbon content of the M18*80 American standard screw with a performance grade of 8.8 is strictly controlled between 0.25% and 0.55% to ensure a balance between load-bearing capacity and toughness.
