Threaded rod

A threaded rod, also known as a stud, is a relatively long rod that is threaded on both ends; the thread may extend along the complete length of the rod. They are designed to be used in tension. Threaded rod in bar stock form is often called all-thread.

Studs

Studs may have a drive slot in one end to facilitate installing the stud.

Types

For studs that are not completely threaded, there are two types of studs: full-bodied studs, and undercut studs. Full-bodied studs have a shank equal to the major diameter of the thread. Undercut studs have a shank equal to the pitch diameter of the screw thread. Undercut studs are designed to better distribute axial stresses. In a full-bodied stud the stresses are greater in the threads than in the shank.

Undercut studs (rolled thread) are also stronger because the metal is "rolled" up to the major diameter, not removed. This preserves the grain of the steel, and in some cases even enhances it. Full bodied studs (cut thread) are weaker because metal is removed to create the thread, disturbing the grain of the steel.