ASTM International Standard Specification for Iron-Nickel and Iron-Nickel-Cobalt Alloys for Low Thermal Expansion Applications ASTM F1684-06(2016)

This specification covers the requirements and corresponding test methods for two iron-nickel alloys and one iron-nickel-cobalt alloy, for low thermal expansion applications. The two iron-nickel alloys, which both contain nominally 36 % nickel and 64 % iron, are the conventional alloy designated as UNS No. K93603 and the free-machining alloy designated as UNS No. K93050. On the other hand, the iron-nickel-cobalt alloy contains nominally 32 % nickel, 5 % cobalt and 63 % iron, and is designated as UNS No. K93500. UNS No. K93603 and UNS No. K93500 shall be in the forms of wire, rod, bar, strip, sheet plate, and tubing, while UNS No. K93050 shall be for bar products only. When test, the alloys shall comply to specified requirements for chemical composition, surface finish, temper, grain size, hardness, tensile strength, thermal expansion, transformation, and dimensions.