| 摘要 |
PROBLEM TO BE SOLVED: To provide a forge-welded tube which is not broken from a joined part even when subjected to severe plastic deformation such as flaring work by solving the following problems: the strength in the joined part of the forge-welded tube is not improved satisfactorily and the joined part is broken in many cases by flaring work even when controlling the depth of a short-deep line on the side of the outer surface, the depth of the short-deep line on the side of the inner surface and inclusions in the joined part so as to fall within a specific range according to a conventional technique. SOLUTION: In the forge-welded tube excellent in the workability, the flat height ratio (H) by a flattening test in which the joined part 9 of the forge-welded tube 8 is set to be the neighborhood of one end in the crushing direction is not more than the limit flat height ratio (HL2) which is defined by expression: HL2=-6.0×R2+6.56, using the ratio (R2) of the maximum thickness in the joined part to the wall thickness of the tube. COPYRIGHT: (C)2010,JPO&INPIT |
