PURPOSE: To produce a seamless steel tube having fine-grained structure and excellent in toughness by controlling steel components and hot rolling conditions, respectively.
CONSTITUTION: A billet of a steel which has a composition consisting of 0.05-0.2% C, 0.01-2.5% Si, 0.15-1.5% Mn, 0.005-0.1% Al, 0.005-0.1% Ti, 0.005-0.1% Nb, and the balance essentially Fe or further containing one or ≥2 kinds among Cr, Mo, Ni, V, rare earth elements, Ca, Co, and Cu and is heated up to ≥1200°C is subjected to hot piercing rolling, by which a tube stock is manufactured. Subsequently, the tube stock whose temp. is lowered to a temp. between Ar3 and Ar1 is heated up to a temp. of 900-1000°C higher than the above temp., finish-rolled at ≥(Ar3+50°C) finishing temp., and air-cooled, by which the high toughness seamless steel tube can be produced.
ASAHI HITOSHI
UENO MASAKATSU
SATO HISAMI
JPH0250916A | 1990-02-20 | |||
JPH01234521A | 1989-09-19 | |||
JPS62149814A | 1987-07-03 | |||
JPS5819432A | 1983-02-04 | |||
JPS59182920A | 1984-10-17 |
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