| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for effectively preventing falling-down mark in a pipe material of high alloy steel. <P>SOLUTION: In the diameter-reducing rolling method of a seamless steel pipe using a stretch reducer having a plurality of 3-roll rolling stands which are serially disposed, a roll having an edge release amount x satisfying the following expression (1) relative to a stand having a diameter reduction rate per unit stand of Y. 0.80Y-4.44≤x≤1.22Y-6.81...(1) where Y denotes the diameter reduction rate per unit stand (%), and x denotes edge release amount (mm). <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
