Active agent for 2219 aluminum alloy variable-polarity TIG welding and using method thereof

Abstract

The invention discloses an active agent for 2219 aluminum alloy variable-polarity TIG welding and a using method thereof. The active agent comprises active agent powder, and the active agent powder iscomposed of the following components of, in percentage by mass, 50-78% of AlF3 powder, 10-25% of ZnF2 powder, 0.2-11% of LiF powder, 10-17% of NOCOLOK brazing flux powder and 0.3-8% of K2SiF6 powder.The using method of the active agent comprises the following steps of preparing the active agent powder, preparing a paste or cream active agent, carrying out surface treatment on a 2219 aluminum alloy workpiece, applying the active agent and welding. The active agent disclosed by the invention can remarkably reduce generation of weld pores when the 2219 aluminum alloy workpiece is subjected to variable-polarity TIG welding, so that weld penetration is increased by 1.6 times or above, formation of a welding line is good, and the tensile strength of joint of the welding line is obviously improved.

Description

technical field [0001] The invention relates to the technical field of aluminum alloy welding, in particular to an activator for 2219 aluminum alloy variable polarity TIG welding and a use method thereof. Background technique [0002] The 2219 aluminum alloy belongs to the Al-Cu-Mn series of high-strength hard aluminum alloys that can be strengthened by heat treatment and can be strengthened by deformation. The mass percentage of the main element Cu in the composition is very high, w(Cu) is between 5.8% and 6.8%, grain refiners such as Ti, Zr, V are added to the alloy, and the solidus temperature is relatively high , so that the 2219 aluminum alloy has the advantages of low thermal crack tendency and high fracture toughness. The welding process requirements are relatively simplified, which greatly improves the structural performance of the tank made of 2219 aluminum alloy. It is the main structure of the new generation of low-temperature launch vehicle tanks in my country. The...

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Problems solved by technology

The three main methods of welding 2219 aluminum alloy tank structure are friction stir welding (FSW), variable polarity plasma arc welding (VPPAW) and variable polarity argon arc welding (VPTIG), among which friction stir welding (FSW) is a high High-efficiency, low-energy, and low-cost solid-phase joining method, suitable for welding high-strength aluminum alloys that are difficult to weld by conventional fusion welding processes, eliminating the root cause of pores-melting crystallization, but the process is complicated and equipment investment is large; polarity change Plasma arc welding (VPPAW) is a process specially developed for automatic welding of aluminum and aluminum alloys that combines plasma arc and variable polarity power supply technology. It has excellent ability to remove weld pores, and its process flexibility is better than that of friction stir welding. However, the main disadvantage of VPPAW is that the equipment and process are relatively complicated; variable polarity argon arc welding (VPTIG) is the main welding process for the manufacture of new launch vehicle tanks in China, including manual welding and automatic welding, and is suitable for tank bottoms and barrel sections. For the welding of main structural welds such as ring seams and fork-shaped ring longitudinal seams, variable polarity TIG welding is used in the manufacturing plan of the welding structure of the 5m diameter storage tank of the Long March 5 launch vehicle that is under development. Permanent TIG welded joints still have quality problems such as high porosity incidence and dense porosity near the fusion line

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