A low heat input dual DC pulse compound arc welding method for thin-walled metal pipes

Abstract

The invention discloses a low-heat-input double-DC (Direct Current) pulse hybrid electric arc welding device and a welding method. The low-heat-input double-DC pulse hybrid electric arc welding device comprises a first DC pulse power, a second DC pulse power, a main welding gun and an auxiliary welding gun, wherein the two electrodes of the first DC pulse power are separately connected with the main welding gun and a workpiece; and the two electrodes of the second DC pulse power are separately connected with the auxiliary welding gun and the workpiece. During welding, the main welding gun and the auxiliary welding gun are separately arranged along the welding direction front and back; and a preset phase difference is maintained between the first DC pulse power and the second DC pulse power, so that when the electric arc of the main welding gun is at a peak value period, the electric arc of the auxiliary welding gun is at a basic value pilot arc period. When the main electric arc is at the peak value period, the auxiliary electric arc is at the basic value pilot arc period, and when the auxiliary electric arc is at the peak value period, the main electric arc is at the basic value pilot arc period, so that a sufficient fusion depth is generated by the main electric arc; the auxiliary electric arc can adjust and control the metal flowing of a weld pool, and can prolong the existence time of the weld pool; and unnecessary welding heat input is reduced.

Description

technical field [0001] The invention belongs to the field of welding, and in particular relates to a low heat input dual direct current pulse composite arc welding device and a welding method. Background technique [0002] DC TIG welding is one of the main welding methods used in the production process of thin-walled steel pipes. It is a key technology for steel pipe production, which determines the efficiency and quality of steel pipe production. However, limited by the shortcomings of TIG welding itself, such as low deposition rate and shallow penetration, it is difficult for ordinary TIG welding to achieve high-speed welding. At the same time, a large number of actual production and theoretical studies have shown that with the synchronous increase of welding current and welding speed, the welding process gradually becomes unstable, and forming defects such as undercuts and hump welds are prone to occur, seriously affecting welding quality. Therefore, the welding speed ha...

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Problems solved by technology

[0004] However, the DC double TIG arc welding process has a large heat input during the welding process and the arrangement of the two arcs makes the weld seam and the metal in the heat-affected zone stay at high temperature for a long time, causing the grain growth of the welded joint to be more serious, which will cause the joint decline in mechanical properties

For example, for ferritic stainless steel pipes, the severe growth of the grains in the weld seam and the heat-affected zone will not only reduce the mechanical properties of the weld seam, but also cause a decline in its corrosion resistance.

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