LEAD SWITCH WIRE ROD, LEAD SWITCH LEAD PIECE, AND LEAD SWITCH

摘要

A lead switch wire rod used as a raw material for a lead piece to be provided in a lead switch, wherein: the wire rod is configured from a ferrous alloy containing Fe and 0 mass% to less than 10 mass% of Ni, the total amount contained of the Fe and Ni being 10 mass% to less than 20 mass% and the balance being obtained from Co and impurities; said ferrous alloy has a cubic crystal structure; the Curie temperature is at least 900°C; specific resistance at ordinary temperature is not more than 15 µΩ∙cm; the ratio of the thermal expansion coefficient of the glass tube provided on the lead switch with respect to the thermal expansion coefficient of the lead switch wire rod is at least 90%; and the wire diameter is not more than 1 mm.