Scope:

The “Grade” of the fasteners implies tensile strength and intended purpose. Grade A studs, bolts, and threaded rod with a tensile strength of about 60 ksi are fit for general use; Grade B bolts, studs, and threaded rods having tensile strengths of 60-100 ksi are intended for flanged couplings in plumbing systems with cast iron flanges and Grade C are replaced by specification Gr. 36.

Procedure:

The open-hearth and basic oxygen produce steel for bolts and studs. Bolts are made by forging the hot or cold and machining bar stock. Stress relief annealing is required for cold-headed fasteners with non-hex head designs. Threads on bolts and studs are rolled or chopped, then zinc-coated, hot-dipped, and mechanically deposited.

Specimen:

Bolt and stud threads must be of the Coarse Thread Series and have a Class 2A tolerance.

Data:

When estimated as follows, the carbon equivalent (CE) did not exceed 0.55 in the heat analysis:

CE = %C+ % Mn/ 6 + % Cu/ 40 + % Nl/ 20 + % Cr/ 10 − % Mo/ 50 − % V/ 10

Conclusion:

ASTM A307 – 21 determines the chemical and mechanical criteria for three classes, i.e., Grades A, B, and C, of carbon steel bolts and studs of specified sizes. This protocol does not cover machine screws, thread cutting, mechanical expansion anchors, and other similar externally threaded fasteners.