| 摘要 |
<p>PURPOSE:To prevent the occurrence of a defective part by forming a cladding part by welding on the surface of a base tube wall separated from a weld zone, displacing the tube wall by its shrinkage force and giving the residual stress in the compression direction to the inside of a base tube in the vicinity of the weld zone. CONSTITUTION:When the cladding part 21 is formed by superimposition of weld beads on the surface of the base tube wall separated from the weld zone W, the tube wall right under the cladding part 21 is pressed inwards in the radial direction in accordance with heat shrinkage of the cladding part 21 and the residual stress in the compression direction is given to the inside of the base pipe 9 by extending this displacement to the inside of the base tube 9 in the vicinity of the weld zone W. Accordingly, the occurrence of the defective part in the vicinity of the weld zone W of the inside of the base tube 9 can be prevented and further, workability at the time of carrying out improving work of the residual stress can be improved.</p> |
