| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for deciding the quantity of reducing powder in elongating a steel tube by which scale loss is reduced and the efficiency of descaling is improved. SOLUTION: When a hollow tube stock after piercing is elongated, the quantity of the reducing powder which is supplied onto the inside surface of the hollow tube stock is decided based on the elongation ratio of elongating. It is preferable to decide the quantity of the reducing powder so as to satisfy the undermentioned equation (1). Va>=5×EL+10... equation (1). Where, Va is the quantity of the reducing powder per unit area of the inside surface of the hollow tube stock (g/m2), and EL is the elongation ratio (unit: dimensionless number).
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