At the beginning aluminum alloy laser welding, there is a high reflection phenomenon, seriously affect the material absorption of laser energy. Wavelength is short, the material absorption of light better, therefore, Fiber laser is much better than CO2 laser in absorption of aluminum alloy as the energy density is more concentrated with fiber laser. Once the material begins to absorb light energy, the reflectivity of the liquid metal towards the light drops drastically and the absorbtion increases super fast.
Using wobble laser welding, can significantly improve the porosity, because of the stirring light beam forms a relatively large keyhole, improves the stability of the keyhole, favors escape of the gas; compared to normal laser beam welding, molten pool temperature gradient the smaller, lower liquid metal solidification rate, prolong the bubble escape time, reduce the porosity and improves the stability of wire feeding, stable welding quality advantage.
In the aerospace manufacturing industry, the application of new materials is increasing, and it also promotes the development of corresponding new welding methods. Wobble Laser welding of aluminum-lithium alloys is one of them.
The development trend of modern aircraft structural materials is: vigorously develop high-strength, high-specific modulus, corrosion-resistant, high-tolerance, low-temperature multi-functional structural materials to achieve structural weight reduction; improve materials and structural preparation techniques, reduce manufacturing costs and maintenance costs . Modern body materials are still dominated by aluminum alloys, the amount of steel tends to decrease, and the amount of titanium alloys increases significantly. Aeroengine main materials are aluminum alloys, titanium alloys, high temperature alloys and various types of high temperature composite materials. Aluminum-lithium alloys are the most rapidly developing field in aviation metal materials in the past decade.
Industrial production of aluminum-lithium alloys refers to aluminum alloys containing 1% to 3% of Li with Li as the main strengthening element. The purpose of adding Li to the alloy is to increase the elastic modulus of the alloy and decrease the density of the alloy (density is 5% to 12% lower than that of the general aluminum alloy, and the elastic modulus is 5% to 8% higher). Al-Li alloy has low density, high specific strength, high specific stiffness, excellent low temperature performance, good corrosion resistance and excellent superplastic forming properties; its strength, fracture toughness, yield strength, fatigue properties are all with temperature. Reduced and increased; it has good superplasticity, can be made into complex shapes, difficult to form parts, reduce labor intensity and reduce the weight of the structure. Using it to replace the conventional aluminum alloy can reduce the mass of the components by 15% and increase the stiffness by 15% to 20%. It is considered as an ideal structural material in the aerospace industry. In this field, aluminum-lithium alloys have replaced conventional high-strength aluminum alloys on many components.