This specification covers wrought iron-silicon (Fe-Si) relay steels that are generally used in the manufacture of electromechanical devices, such as relays and solenoids, requiring higher electrical resistivity, higher permeability, and lower coercivity and residual magnetism than provided by either carbon steels or soft magnetic low-carbon irons. Available forms and conditions are forging billet, hot-rolled product, cold-finished bars, strip, and wire. These steels are not the same as the flat-rolled non-oriented or grain oriented iron-silicon electrical steels covered by ASTM Specifications A 677, A 683 and A 876. The steels covered in this specification have nominal silicon contents of 1.1, 2.3 and 4.0 % Si. Both the 1.1 and 2.3 % Si types are also available in an enhanced machinability composition. Along with chemical composition, steels produced to this specification must meet a specified maximum value of coercive field strength when heat treated according to this specification. Appendices are given containing typical magnetic, physical and mechanical properties and heat treatment.

1.1 This specification covers wrought iron-silicon (Fe-Si) steels that are generally used in the manufacture of electromechanical devices, such as relays and solenoids, requiring higher electrical resistivity, higher permeability, and lower coercivity and residual magnetism than provided by either carbon steels or soft magnetic low-carbon irons. The steels covered in this specification are:

1.2 This specification covers steels in the form and condition required for fabrication into parts. The fabricated parts typically require a final heat treatment to obtain the desired magnetic performance. The term mill annealed as used in this specification applies to a heat treatment, typically applied by the producer, intended to improve formability. The mill anneal does not provide the optimum magnetic performance and is not intended to replace the need for the finish annealing of parts.

1.3 This specification covers steels in the form of forging billets, hot-rolled bar and strip, cold-finished bar, wire, and cold-rolled strip in thicknesses up to 0.250 in. (6.35 mm).

1.4 This specification does not cover electrical sheet steels used in transformer and motor laminations.

1.5 This specification does not cover powder metallurgy materials capable of being processed into magnetic core components having similar silicon contents.

1.6 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.