ASTM A325 covers high strength structural bolts used in structural steel connections. A325s have a heavy hex head, a full body diameter, and are normally short in overall length since they are connecting steel to steel. Unlike other ASTM grades, A325 is specific not only in the chemical and mechanical requirements, but also in the allowed configuration. These bolts range in diameter from 1/2″ through 1-1/2″ and are manufactured from a medium-carbon or medium-carbon alloy steel that is quenched and tempered to develop the desired mechanical properties.