Standard Specification for Iron-Silicon Relay Steels

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:

Steel Type Nominal Composition 1 1.1 % Si-Fe 1F 1.1 % Si-Fe Free Machining 2 2.3 % Si-Fe 2F 2.3 % Si-Fe Free Machining 3 4.0 % Si-Fe

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 either customary (absolute (or practical) cgs-emu and inch-pound) units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with this specification.