| 摘要 |
<p>The copper pipe or tube stub (1) has an even thickness, smaller than that of the aluminium pipe stub (4) thereto it is to be welded, and an outer diameter substantially equal to that of the aluminium pipe stub, an increased thickness zone (2) being provided inside the end portion of the copper pipe stub (1), which is formed by butt upsetting and creeping of the metal material, the stub portion adjoining the increased thickness zone being work-hardened in such a way as to allow for the pipe stub to resist against the mechanical stresses occurring during the welding operations.</p> |
