Surface preprocessing method for laser welding of aluminum alloy

Abstract

The invention provides a surface preprocessing method for laser welding of an aluminum alloy. The method is characterized by comprising the steps of 1) performing surface texturing treatment on an area, to be welded, of the aluminum alloy through short-pulse laser with energy density of I1, thus forming a regular ripple microstructure; and increasing the surface roughness of the area, to be welded, of the aluminum alloy, wherein the I1 is more than the burning loss threshold Ia of the aluminum alloy; 2) cleaning the surface of the area, to be welded, of the aluminum alloy through the short-pulse laser with the energy density of I2; removing polluting matters on the surface of the microstructure of the area, to be welded, of the aluminum alloy through the short-pulse laser with energy density of I2 so as to remove pollutants on the surface of the microstructure of the area, to be welded, of the aluminum alloy; and increasing the surface cleanness of the area, to be welded, of the aluminum alloy, wherein the I2 is more than the washing threshold Ic of the aluminum alloy and is less than the burning loss threshold Ia of the aluminum alloy; and 3) starting to weld the aluminum alloy within 30min. With the adoption of the method, two major problems that the reflectivity of the aluminum alloy surface to to laser is high, and a surface oxide film is hard to remove, can be synchronously solved; and the forming quality of a weld joint of the aluminum alloy is obviously improved.

Description

technical field [0001] The invention belongs to the technical field of laser surface treatment, in particular to a surface pretreatment method for aluminum alloy laser welding. Background technique [0002] Laser welding has the advantages of small heat-affected zone, fast welding speed, good welding quality, strong welding flexibility, and easy automation. It has been widely used in aviation, aerospace, automobiles, high-speed trains and other fields. However, there are the following difficulties in laser welding aluminum alloy: the surface of aluminum alloy has a high reflectivity, which leads to low utilization rate of laser energy, and even burns the optical fiber and laser; the surface of aluminum alloy is very easy to generate Al with high melting point 2 o 3 film, leading to poor welding stability and causing defects such as hydrogen pores and inclusions in the weld. Therefore, the surface of aluminum alloy must be pretreated before laser welding, and different from...

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Problems solved by technology

[0006] The object of the present invention is to provide a surface pretreatment method for laser welding of aluminum alloys, which can simultaneously solve the two problems of high laser reflectivity on the surface of aluminum alloys and difficult removal of surface oxide films, and can significantly improve the formation of aluminum alloy welds. quality

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