Method for improving fusion depth in laser welding process of aluminum alloy

Abstract

The invention relates to a method for improving a fusion depth in a laser welding process of an aluminum alloy, comprising the following steps of: firstly, cleaning a welded part of a welded aluminum alloy and carrying out sand spraying treatment on the welded part; mixing metal power zinc powder or magnesium powder with a micron-grade granularity by using acetone to form diluted paste and spraying on the surface of the aluminum alloy subjected to the sand spraying treatment, wherein the thickness is 1-20 microns; utilizing plasma spraying to spray aluminum powder on the surface coated by the zinc powder or the magnesium powder, wherein the thickness of an aluminum powder coating is 10-100 microns; and carrying out laser welding or smelting on the surface obtained by the method. In a process of laser welding or smelting, when a laser bundle is irradiated to the coating sprayed with the aluminum powder, on one hand, the absorption rate of laser is greatly improved due to diffuse reflection effect of a rough sprayed surface; and on the other hand, the absorption of energy is accelerated due to that the surface area of the sprayed aluminum powder is increased; the zinc powder or the magnesium powder at the lower side is accelerated to be heated to rapidly form steam by the heat absorbed by a spraying layer due to the non-density of the spraying layer, so that the absorption to laser energy is further improved, a keyhole effect is formed and the better fusion depth is obtained.

Description

technical field [0001] The invention relates to a method for improving laser welding of aluminum alloys. Background technique [0002] Due to its good physical, chemical and mechanical properties, aluminum alloys are increasingly used in various industrial products, especially in the aerospace, electronics and automotive industries. However, the welding of aluminum alloys used to be a relatively difficult problem. It was not until the popularization of AC tungsten argon arc welding that the problem of welding ordinary aluminum alloys was relatively solved. Laser welding is a new welding technology developed in recent decades. It has the advantages of less heat input, concentrated energy density, and small deformation of the heat-affected zone. It can be used for welding precision parts. At present, laser welding is more and more popular in industrial production Many applications. However, there are also many disadvantages and problems when laser welding is used for aluminu...

AI Technical Summary

Problems solved by technology

However, when laser welding is used for aluminum alloys, there are also many shortcomings and problems

The most serious problem is that due to the high initial reflectivity of aluminum and aluminum alloys to the laser, the welding process is unstable during laser welding. Due to the high reflectivity, most of the energy is reflected and cannot be absorbed by the aluminum matrix.

Typical aluminum alloys have a wavelength of 10.6 μm for CO 2 The laser reflectivity is as high as 97%, and for YAG lasers, the reflectivity has also reached more than 80%. At the same time, due to the high thermal conductivity of the aluminum alloy itself (the thermal conductivity of most aluminum alloys is three times that of ordinary carbon steel), this This situation makes laser welding difficult, and it cannot be melted and formed in many cases. Typical CO 2 When the power of the laser beam is 3Kw, it scans the smooth aluminum alloy surface, and even cannot form a molten pool, and the reflected laser still has a high power. If the reflection direction is not well controlled, it will damage the setting and even threaten the personal safety of the operator.

Therefore, the high reflectivity and high thermal conductivity of aluminum alloys to lasers limit the wide application of aluminum alloy laser welding to a large extent.

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