Cold Drawn or Hot Rolled alloy steel bars are typically annealed or heat treated (quenched and tempered), depending on end use. Heat treating is employed to attain required mechanical properties, typically at the expense of machinability. Heat treated bars are often stress relieved in order to have more precise control of these mechanical properties.
Alloy has the ability to increase a steel’s hardenability (the depth of hardness that a steel can achieve) through heat treating. Alloying elements do not make the steel inherently any harder; instead they increase the depth to which the steel will harden, enhancing mechanical properties often through the full cross-section of the steel.
This makes it possible to obtain desired mechanical properties in larger sections and use less severe quenching means. This depth of hardness is determined by the alloy elements and type of heat treating used. Other characteristics of alloy steel bars are high strength, fatigue resistance, wear resistance, and toughness.