| 摘要 |
<p>A process for reducing a raw steel pipe obtained by a solid phase bonding pipe manufacturing method or a welding pipe manufacturing method is carried out by heating the steel pipe to a temperature in excess of 100 °C and lower than 800 °C before it is reduced, restricting the temperature of the steel pipe during a rolling operation to a level in a specific range, controlling the temperature difference of the steel pipe in the circumferential direction thereof at the inlet side of a reducing mill to be in a specific range, and also controlling the temperature of the steel pipe between the stands of the reducing mill. This enables the steel pipe to be reduced with a low load with the work hardening effect minimized without deteriorating the properties of the surface thereof, and the dimensional precision of the product pipe to be maintained at a high level.</p> |
