MANUFACTURE OF SEAMLESS STEEL PIPE AND MANUFACTURING EQUIPMENT TRAIN FOR EXECUTING THE SAME METHOD

Japanese Patent JP3458485

B2

PURPOSE: To provide a manufacturing method of a seamless steel pipe of excellent performance at high productivity with inexpensive equipment and manufacturing equipment train therefor.
CONSTITUTION: A round billet is directly manufactured by use of a round-shaped casting mold by continuous casting, this round billet is soaked to a prescribed temp. in a heating furnace 3 while its temp. is over the transformation temp. Ar1, piercing and rolling are executed at a strain rate of 5 ≤50/sec with a piercer 5 and, then, elongation and rolling for sizing are executed at an average strain rate of ≥0.01/sec and at the finishing temp. of 800-1000°C by imparting the working ratio of ≥10% with the rolling mills of both continuous elongator and finishing mill which are directly connected in series on the same line. In the transporting route 4 on the outlet side of the finishing mill, recrystalization treatment is given in which either of slow cooling at a cooling rate under air-cooling and keeping the billet at the finishing temp. for a prescribed time, soaking/keeping it at the prescribed temp. for the prescribed time or temp. rising/heating/keeping is executed and, successively, direct quenching and tempering are on-line executed. To execute this method, respective equipment and device are arranged in direct connection.

Kunio Kondo
Yasutaka Okada
Seiji Tanimoto

JP25508894A

October 20, 2003

October 20, 1994

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SUMITOMO METAL INDUSTRIES,LTD.

B21B19/04; B21B1/00; B21B45/00; C21D8/10; C21D9/08; (IPC1-7): B21B19/04; B21B1/00; B21B45/00; C21D8/10; C21D9/08

JP1228603A
JP58135708A

Mikiji Sugioka (2 outside)

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