ASTM A325 is a standard specification for high-strength, heat-treated, alloy steel bolts used in structural steel connections. These bolts are designed for use in structural connections in buildings, bridges, and other structures. They come in two types, Type 1 and Type 3, and are made from a medium carbon steel and are heat-treated to achieve a minimum tensile strength of 120 ksi and 105 ksi for heavy hex structural bolts. Type 1 is a medium carbon, carbon boron, or medium carbon alloy steel and is intended for general structural use. Type 3 is made of weathering steel and is intended for use in unpainted applications. The standard also includes requirements for chemical composition, mechanical properties, and testing procedures.
The standard dimensions for A325 bolts include:
- Nominal size (diameter): from 1/2 inch to 1-1/2 inches
- Threads: Unified National Coarse (UNC) or Unified National Fine (UNF)
- Thread Length: The minimum thread length is equal to the nominal diameter plus 1 inch.
- Head: Heavy Hex Head
- Length: The length of the bolt is measured from the underhead bearing surface to the extreme end of the bolt.
Additional dimensions such as thread length, head and body diameter, fillet radius, and minimum and maximum body length are also included in the ASTM A325 specification. It is important to note that the manufacturer must provide the dimensional information, and it should be verified by the user.