| 摘要 |
A weldment, such as the wall of a pressure vessel, is formed from segments, each of which includes a steel substrate, a protective layer of tantalum which is exposed to the interior of the vessel and an intervening layer of copper which lies between and is bonded to the substrate and the protective layer. The substrate and the two layers which form the cladding are explosively bonded together and the bonding procedure may leave the protective layer with small domes or embossments and pockets of trapped gas behind the embossments. The two segments are welded together edge-to-edge at their substrates, with their protective and intervening layers aligned. If one were to follow the traditional procedure, one would place a tantalum batten strip over the protective layers along the opposed edges so as to cover the edges, and then weld the batten strip to the protective layer along the edges of the strip. But any weld which passed over a pocket would open the pocket, causing the trapped gas to burst out and carry molten copper from the intervening layer with it, and of course the copper would contaminate the weld, leaving it less capable of resisting chemical attack. This problem is alleviated by venting the pockets over which the batten strip passes with small holes and driving their embossments down. The batten strip overlies the holes so corrosive substances will not pass through the protective layer.
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