This specification deals with the highest quality of round carbon steel spring wire, uniform in quality and temper, intended especially for the manufacture of valve springs and other springs requiring high-fatigue properties. The steel wire shall be subjected to continuous casting, hardening, and tempering to produce the desired mechanical properties. The steel shall conform to the chemical requirements for carbon, manganese, phosphorus, sulfur, and silicon. Mechanical properties shall be determined by the tension test, wrap test, twist test, and special surface inspection. The material as represented by tension test specimens shall conform to the tensile requirements for tensile strength and reduction of area. Metallurgical characterization of steel shall include decarburization, surface condition, and microstructure.

1.1 This specification covers the highest quality of round carbon steel spring wire, uniform in quality and temper, intended especially for the manufacture of valve springs and other springs requiring high-fatigue properties.

1.2 The values stated in either SI (metric) units or inch-pound units are to be regarded separately as standard. The values stated in each system are not exact equivalents; therefore, each system must be used independent of the other.