| 摘要 |
A process for welding mechanically and/or thermally treated alloy pipes to achieve the full tensile capacity of the unwelded base alloy across the welded pipe joint is disclosed. The process comprises welding the pipes together at the beveled pipe ends to form a cap of weld metal. The weld metal cap overlaps that portion of the heat-affected zone which is created in the base alloy adjacent to the bevel of each pipe during welding. To further increase the tensile capacity of the welded joint, a low-heat buffer bead layer can be deposited on the outer surface of each pipe proximate the outer edge of each bevel, prior to depositing the weld metal between the bevels. The buffer bead layers serve to reduce the thickness of that portion of the heat-affected zone which is formed in the base alloy under each toe of the weld metal cap (upon formation of the weld metal cap) to a level having no significant reduction in the overall tensile capacity of the welded joint. In both instances, the weld metal cap is used to reinforce the base alloy over that portion of the heat-affected zone formed generally adjacent to the bevel of each pipe, thereby ensuring that the plane of weld joint failure is located predominantly in the region of the base alloy which has not suffered loss of strength due to welding heat, rather than in the weaker heat-affected zone or in the weaker weld metal itself. The resulting welded pipe joint will have a tensile capacity which is at least substantially equal to the tensile capacity of the unwelded base alloy.
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