Metal Fasteners
Date:2026-08-20
Metal fasteners are standard mechanical parts used to achieve detachable fastening connections between mechanical components. Their performance and quality directly affect the safety and lifespan of the entire equipment.
1. Main Classifications
Based on function, standard fasteners can be mainly divided into twelve categories. The most common categories include:
Bolts, Studs, and Screws: These are the most common threaded fasteners. Bolts are usually used with nuts for through-hole connections; studs are screwed into the connected parts at one end and fitted with a nut at the other; screws can be directly screwed into the threaded holes of the connected parts.
Nuts: Used in conjunction with bolts and studs, hexagonal nuts are the most widely used.
Washers: Primarily used to protect the supporting surfaces of the connected parts; spring washers also have an anti-loosening function.
Pin and Rivet: Pins are used for positioning or connection; rivets are used to achieve permanent connections.
2. Materials and Performance
The selection of materials and performance grades of metal fasteners determine their application range.
Common materials: Carbon steel and low-carbon steel are the most commonly used; stainless steel is used in applications requiring high corrosion resistance; titanium alloys, due to their lightweight and high strength, are frequently used in the aerospace, medical, and food industries. For extreme high-temperature environments, refractory metals such as molybdenum and niobium, with melting points exceeding 2400°C, are also used.
Performance grade: The performance grade of a bolt is a key indicator of its strength, such as grades 8.8, 10.9, and 12.9. The numbers in the performance grade have specific meanings. Taking grade 4.6 as an example: the first digit "4" represents a nominal tensile strength of 400 MPa; the second digit "0.6" represents the yield strength ratio (yield strength/tensile strength), therefore its yield strength is 400 × 0.6 = 240 MPa. In high-end fields such as high-speed rail and aerospace, high-strength fasteners of grade 10.9 and above are typically required.
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