| 摘要 |
PURPOSE:To obtain the title steel pipe for a thermal well capable of controlling the creeping rate in the following temp. range by hot-rolling high-temp. steel having a specified composition into a pipe at a roll finishing temp. higher than the Ar3 point, quenching the pipe, and subsequently tempering the pipe at a temp. higher than a specified temp. and lower than the Ac1 point. CONSTITUTION:The high-temp. steel contg., by weight, 0.08-0.35% C, 0.05-0.5% Si, 0.3-2.0% Mn, 0.01-0.1% Al, and >=1 kind among 0.05-0.50% Mo, 0.01-0.1% Nb, and 0.01-0.1% V is treated as follows. Namely, the steel is rolled into a pipe at a roll finishing temp. higher than the Ar3 point, then the pipe is directly quench-hardened from the high temp. to a temp. higher than the Ar3 point, or the pipe is reheated to the temp. and then quench-hardened. The steel is subsequently tempered at the temp. between 500 deg.C and the Ac1 point to improve the creep characteristic, and the desired steel pipe for a thermal well having a low creeping rate is obtained at a low cost.
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