| 摘要 |
<p>When a steel raw material of a round section is subjected to rolling at 3 or more passes to form a steel product of round section, the rolling is conducted by using a pair of upper and lower flat rolls at first pass, using a pair of upper and lower same or different caliber rolls at second or more passes until just before a last pass, and using a pair of upper and lower round caliber rolls at the last pass, under a condition that an area reduction in the first pass is within a range of less than a total area reduction from the raw material to the product. In this case, it is preferable that the area reduction in the first pass is not less than 50% of a total area reduction in the second or more passes.</p> |
