MANUFACTURE OF SEAMLESS TUBE AND ROLLING STOCK THEREFOR
Document Type and Number:
Japanese Patent JP3305604
PROBLEM TO BE SOLVED: To prevent generation of inside surface scratch of steel tube and to manufacture seamless tube with excellent inside surface skin by manufacturing a rolling stock for seamless tube of specified shape and then piercing rolling the rolling stock under Mannessman method.
SOLUTION: The seamless tube is manufactured by utilizing rolling stock for seamless tube satisfying an inequality in which the radius of round bar is rO, the distance from the center to the defective part is r1, and the radius of product after piercing rolling is R and the inside radius is r, and by piercing the rolling stock for seamless tube under Mannesman method. The rolling stock for seamless tube is made of continuous casting material for chrome bearing comprising, by weight, 0.15-1.10% C, 0.15-0.70% Si, ≤1.10% Mn, 0.50-1.60% Cr, ≤1.00% Mo, ≤8ppm O and the balance Fe with inevitable impure elements.
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