WIRE FOR WELDING HAVING EXCELLENT FEEDING PROPERTY

摘要

PURPOSE:To improve the feeding property of a wire by controlling the ratio between the average thickness of an intergranular oxide layer of a wire surface layer and average crystal grain size within a specific range in the stage of intermediate annealing. CONSTITUTION:The same charge samples of the wire subjected to the intermediate annealing are drawn randomly from plural points and the intergranular oxide layers viewed from the cross section are measured. The average value thereof is determined. The value A of the ratio between the thickness of the average intergranular oxide layers and the average crystal grain size is controlled in a >=0.4-<=1.8 range. The intergranular oxidation arises over the entire surface of the crystal boundaries when the value A exceeds 1.8 and therefore the intergranular oxide part has the more tendency to exfoliation in the stage of drawing. Oil film breakage arises during the wire feeding when the value A is <0.4. The value A is therefore controlled within the above-mentioned range and the wire feeding property is improved by making combination use of lubricating oil coating.