MIG (metal inert-gas) welding method for aluminum alloy thick plates in high-speed trains

Abstract

The invention discloses an MIG (metal inert-gas) welding method for aluminum alloy thick plates in high-speed trains. The method using ER5356 welding wires and 99.9% protective argon gas for multiple welding includes the steps: 1, preheating a work piece before welding at the temperature of 70-90 DEG C; 2, treating the surface of the work piece to be welded, removing oil stain and dust on the surface of the work piece to be welded with organic solvent, and clearing surface oxide film from the work piece to be welded by mechanical means; 3, controlling welding wire energy to range from 7.0KJ / cm to 9.0KJ / cm, ambient humidity to be not larger than 70%, and interlayer temperature to be between 70 DEG C and 90 DEG C; 4, checking the weld defect, checking the weld after each single welding, removing checked weld pores with wire brushes or air chippers, and performing next welding then. The method has the advantages that welds form well, welding deformation is little, welded joints are high in strength, MIG welding quality of the aluminum alloy thick plates in high-speed trains is improved effectively, and welding quality stability is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of welding. More specifically, the present invention relates to a MIG welding method of aluminum alloy thick plates for high-speed trains. Background technique [0002] With the rapid development of the high-speed railway industry in recent years, the welding of aluminum alloys for rail vehicles has become a new research hotspot. Aluminum alloy is the key material for the manufacture of high-speed EMUs. The welding quality of aluminum alloy is the basis for determining the long-term safe operation of high-speed trains, and is of great significance for improving the operating life of high-speed trains. As a key process in the manufacture of high-speed train bodies, aluminum alloy welding plays a very important role. How to improve the welding quality of aluminum alloy has become the key in the manufacture of aluminum alloy car body. Aluminum alloy thin-wall welded structures are light in weight, corrosion-...

AI Technical Summary

Problems solved by technology

The surface of aluminum oxide film is easy to absorb moisture. When welding, it hinders the fusion of basic metals, and it is easy to form defects such as pores, slag inclusions, and lack of fusion, resulting in a decrease in weld performance.

(2) easy to produce pores

(3) Weld deformation and crack formation tend to be large

(4) Burning loss of evaporation of alloying elements

Second, there are more welding pores

Pores will not only reduce the compactness of the weld, reduce the load-bearing area of ​​the joint, but also reduce the strength and plasticity of the joint, especially the cold bending angle and impact toughness, which must be prevented.

Third, it is prone to unfused phenomenon

Due to the existence of these defects, the overall quality of the aluminum alloy car body of the high-speed train is affected, and it constitutes a hidden danger to the safety of the high-speed train, which must be overcome with all efforts