| 摘要 |
<p>A seamless steel tube is manufactured from a high alloy steel containing at least 5% of Cr while effectively preventing mandrel bar withdrawal troubles after elongation rolling of a material being rolled. A seamless steel tube of a high alloy steel containing at least 5% of Cr is manufactured by subjecting a material being rolled 3 to elongation rolling using a retained mandrel mill 1 in which the speed of a mandrel bar 2 in the axial direction is maintained constant while the speed of movement Vb of the mandrel bar 2, the speed Vi of the material being rolled 3 on the inlet side of the retained mandrel mill 1, and the speed Ve of the material being rolled 3 on the exit side of the retained mandrel mill 1 satisfy the relationship: 0.15 ‰ Vb/{Vi + Ve)/2} ‰ 0.70 by controlling the speed of movement Vb of the mandrel bar 2.</p> |
