7-series high-strength aluminum alloy variable polarity plasma arc welding method

Abstract

The invention relates to a 7-series high-strength aluminum alloy variable polarity plasma arc welding method. The method aims at solving the problem that in the prior art, the welding quality is poor. The vertical welding process is adopted, 7-series high-strength aluminum alloy workpieces are fixed through clamps after being vertically placed, a variable polarity plasma welding gun provided with an automatic wire feed device is horizontally placed on one side of the workpieces, the gun head of the welding gun right faces a welding seam between the two workpieces to conduct variable polarity plasma arc welding, the current selection range of the positive polarity and the negative polarity of the variable polarity plasma arc welding is between 190 A and 260 A, and the current selection range of the negative polarity is between 240 A and 300 A. A variable polarity plasma arc welding power supply serves as a power supply of the plasma welding gun. The 7-series high-strength aluminum alloy variable polarity plasma arc welding method has the advantages that 7-series high-strength aluminum alloy with a thickness ranging from 6 mm to 12 mm can be welded, it can be ensured that the reasonable temperature gradient section is formed between a liquid molten pool and solid metal in the welding process, the stable hole punching effect can be obtained, hole punching molten pool force and the heat balance can be ensured, the defects of welding hot cracks, pores and the like can be overcome, the appearance of the welding seam is uniform and neat, the welding deformation is small, and the welding efficiency is high.

Description

technical field [0001] The invention relates to an aluminum alloy welding method, in particular to a 7-series high-strength aluminum alloy variable polarity plasma arc welding method. Background technique [0002] As a new type of structural material, the 7-series high-strength aluminum alloy is widely used in the aerospace field due to its excellent properties such as high strength, light weight, high toughness, and corrosion resistance. However, its welding performance is poor, and it is easy to produce defects such as large weldment deformation, thermal stress, pores and liquefaction cracks when welding is carried out by traditional fusion welding methods. The 7-series high-strength aluminum alloy has poor fluidity of the molten metal due to the high content of Zn and Mg elements. During the welding process, it is necessary to ensure that a reasonable temperature gradient range is formed between the liquid molten pool and the solid metal. The average welding current is t...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the above-mentioned defects of the prior art, and provide a method that can solve the problems of poor stability of the plasma arc and sensitivity to changes in welding parameters caused by the large number of variable polarity plasma arc welding process parameters in the welding process, and can ensure the heat and energy required for forming the perforation. A reasonable temperature gradient range is formed between the liquid molten pool and the solid metal to obtain a stable perforated molten pool and avoid defects such as thermal cracks and pores when welding aluminum alloys. The 7-series high-strength aluminum alloy variable polarity plasma arc welding method

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