ASTM A325 is an ASTM International standard for heavy hex structural bolts, titled Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength.
It defines mechanical properties for bolts that range from 1⁄2 to 1+1⁄2 inches (13 to 38 mm) in diameter.
[3] To minimize confusion, bolt head markings are unchanged and the designation A325 is retained as a grade name within the new standard.
The standard states that the bolts must be tightened to at least 70% of the tensile yield strength.
[citation needed] For a higher strength version of this type of bolt, see ASTM A490.