PURPOSE: To improve the service life of an electrode in the spot welding for a surface treated steel sheet or an Al alloy sheet used in the automobile industry or the like by forming it of a Cu allay contg. a specified amt. of Fe.
CONSTITUTION: This copper allay for a resistance welding electrode contains, by weight, 4.5 to 20% Fe and the balance Cu and contains oxygen in the ratio of ≤5 O2/Fe. In this allay, precipitated Fe is oxidized on the surface of an electrode by heat treatment and welding heat to prevent its reaction with the material to be welded, and even in the case the oxide is dropped off in the process of welding, Fe on the surface of the electrode is oxidized by welding heat, and it has a reproducing function. In the case the content of Fe is less than 4.5%, it is used only for its precipitation hardening, and the effect of its reproducing function is made insufficient because the amt. of Fe oxide to be formed is very small; and in the case it exceeds 20%, the heat conductivity and electric conductivity characteristic of Cu are deteriorated. This allay is manufactured by subjecting a material to melting and casting or subjecting rapidly solidified powder to HIP, thereafter subjecting it to hot extruding or executing allaying by laser-electron beams by an electrode tip.
ORIMO HISAO
OKITA TOMIHARU
FURUKAWA ALUMINIUM