| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a high-frequency induction heating stress relaxation method, capable of relaxing residual stress at a welded joint part of a small-diameter thin-walled pipe. <P>SOLUTION: In the high-frequency induction heating stress relaxation method for relaxing residual stress at an inner surface of the welded joint part 4, the inner surface of the welded joint part 4 of the small-diameter thin-walled pipes 2, 3 is cooled with water while being heated by a high-frequency induction coil 6 from an outer surface of the pipe. When performing high-frequency induction heating, the heating depth S of the high-frequency induction heating is adjusted to a range of t/6 to t/2, and the distance D between the weld center and the end of the high-frequency induction coil is adjusted to equal to or larger than a value defined by the formula: 1.35×(R×t)<SP>1/2</SP>, where R is the neutral radius and t is the sheet thickness of the pipes 2, 3. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
