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A490 bolts are specifically engineered for steel-to-steel structural connections and heavy-duty structural applications. Designed with shorter thread lengths than conventional hex bolts, they effectively keep threads excluded from the joint shear planes in critical structural connections.
Unlike standard A325 fasteners, A490 bolts are manufactured from alloy steel (as opposed to medium carbon steel), providing superior mechanical strength with a guaranteed minimum 150 ksi tensile strength. Available specifications cover 1/2″ through 1 1/2″ diameter, extending up to 12″ in length for selected profiles.
The main difference lies in the material and tensile capability. ASTM A490 bolts are forged from alloy steel providing a higher minimum tensile strength of 150 ksi, compared to ASTM A325 bolts made from medium carbon steel offering 120 ksi.
A490 bolts feature shorter thread lengths to guarantee that the full, unthreaded shank aligns across the joint shear plane, preventing threads from entering connection interfaces and maximizing shear strength.
Standard diameters for ASTM A490 bolts range from 1/2″ up to 1 1/2″, with available lengths up to 12″ depending on the specific diameter and structural requirements.
Standard ASTM A490 bolts are usually supplied in plain/black finishes due to the risk of hydrogen embrittlement associated with standard acid pickling and hot-dip galvanizing, although alternative protective coatings may be applied in accordance with relevant structural coating standards.
They are ideal for heavy steel-to-steel framing, bridge constructions, high-rise buildings, and industrial structural joints where maximum load-bearing performance and tensile resistance are critical.
