PURPOSE: To improve feedability and to reduce the wear of an electrifying chip at welding time as well by composing the flux cored wire for welding so that the ratio of the mean hardness at the vicinity of the surface of the outmost outer sheath to the mean hardness of the inner sheath comes within specified range.
CONSTITUTION: The flux core wire for welding is composed so that the ratio of the mean hardness (P1) near the surface of the outmost outer sheath 1 to the mean hardness (P2) of the inner sheath 2 may satisfy the relation of 0.3<P1/P2<0.95. The hardness of the outer sheath 1 and inner sheath 2 is adjusted by combining by variously varying the chemical composition, working rate and heat treatment conditions of a using strip steel. The feedability is thus improved, the wear of an electrifying chip at welding time is reduced as well and the continuous welding for long time can be executed.
SHINOKURA TSUTOMU
SUGAYA YUJI
TANO MASAMI
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