| 摘要 |
<p>A method of producing seamless steel pipes of excellent performance efficiently by an on-line system, and seamless steel pipe manufacturing equipment in which the apparatuses used from a casting step to a heat treatment step are provided on-line. In this method, the following steps (1-6) are carried out continuously in order. 1) Round billets are manufactured by a continuous casting machine (1). 2) The billets temporarily cooled to a temperature not more than Ar1 transformation point are heated again and soaked in a heating furnace (3). 3) The soaked billets are bore-rolled by a piercer (5) at a rate of strain of not more than 200/sec to obtain raw pipes. 4) The raw pipes are rolled by a rolling mill (M), in which a mandrel mill (7) and a sizer (8) are arranged closely to each other, at an average rate of strain of not less than 0.01/sec, a reduction ratio of not less than 40 % and a finishing temperature of 800°-1050 °C, whereby seamless steel pipes are manufactured. 5) These seamless steel pipes are cooled by a cooling unit (9) at a cooling rate of not less than 80 °C/min to a temperature not higher than Ar3 transformation point. 6) The cooled seamless steel pipes are heated again at 850°-1000 °C for 10 sec to 30 min, quenched and then tempered.</p> |
