Metal inert gas (MIG) welding method of aluminum alloy thin plate for high speed train

Abstract

The invention discloses a metal inert gas (MIG) welding method of an aluminum alloy thin plate for a high speed train. The method is characterized in that an ER5356 welding wire and 99.9% argon protective gas are selected to conduct single pass welding. The method includes the following steps: 1) surface machining of a workpiece to be welded; 2) MIG welding; 3) welding gap defect checking. The step 1) includes that the workpiece to be welded is not preheated, an organic solvent is directly adopted to remove grease dirt and dust on the surface of the workpiece to be welded, and a mechanical method is adopted to remove an oxidation film on the surface of the workpiece in a washing mode. The step 2) includes that weld heat input is controlled between 4.0KJ/cm and 5.0KJ/cm during MIG welding, and environment humidity is controlled to be smaller than or equal to 70%. The step 3) includes that pore defects of a welded workpiece are removed through a steel wire brush or an air chipper. The method has the advantage that thin plate aluminum alloy welding connector pore welding hot crack number can be greatly reduced, welding gap forming is good, welding deformation is small, welding connector strength is higher, the MIG welding quality of the aluminum alloy thin plate for the high speed train is effectively improved, and welding quality stability is ensured.

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 sheets 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-resist...

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