1.1 ,This specification covers two iron-nickel alloys and one iron-nickel-cobalt alloy, for low thermal expansion applications. The two iron-nickel alloys, both containing nominally 36 ,% nickel and 64 ,% iron, with the conventional alloy designated by UNS No. K93603, and the free-machining alloy designated as UNS No. K93050. The iron-nickel-cobalt alloy, containing nominally 32 ,% nickel, 5 ,% cobalt and 63 ,% iron, is designated by UNS No. K93500. This specification defines the following product forms for UNS No. K93603 and UNS No. K93500: wire, rod, bar, strip, sheet plate, and tubing. The free-machining alloy, UNS No. K93050, is defined for bar products only. Unless otherwise indicated, all articles apply to all three alloys.