Study on microstructures and mechanical properties of super narrow gap joints of thick and high strength aluminum alloy plates welded by fiber laser

Abstract

The welding of thick high strength aluminum alloy plate was exceedingly difficult. Traditional arc welding was prone to softening the welded joints and involves multilayer; meanwhile, multi-pass welding may cause great residual welding stress, and deformation resulted in dampening the wide expansion of the welding structure of thick high strength aluminum alloy plates. Therefore, it was urgent to develop advanced materials and welding technologies to enhance the comprehensive mechanical properties of welded joints. Fiber laser boasted the advantages such as perfect monochromaticity and high quality light beam. In order to decrease the thermal loss of the welding heat source on the matrix, small power fiber laser and super narrow gap groove were applied for the effective welding of the 20-mm thick 7A52 aluminum alloy. The welding adopted multilayer and single pass welding with the groove width no wider than 4 mm. The weld was composed of four layers and the size was no wider than 4.5 mm, which was basically consistent with the widths of the whole. The parent metal was welded with 5183 alloy and 5E06 alloy. Fiber optical microscope, scanning electron microscope (SEM), transmission electron microscope (TEM), and tensile testing machine were employed to investigate the influence of Er-Zr microalloying aluminum alloy welding wires upon the microstructure and mechanical properties of the welded joints.

Design of welding parameters for laser welding of thick-walled structures made of aluminum alloy

“…In modeling and numerical simulation, the influence of the laser beam on the material during the fusion welding process can be defined by means of different heat source models [7][8][9][10][11][12][13][14]. Understanding thermal phenomena and the heat transfer during the welding process is crucial for the analysis of microstructure, mechanical properties, and a quality of the weld joints [15][16][17][18]. Based on the results of numerical simulation, it is possible to predict the process of development of weld joints under different welding conditions and parameters.…”

Weld characteristics of narrow gap oscillating laser welding of dissimilar aluminum alloys with hot wire

“…6xxx Al-Mg-Si alloys have excellent processing workability, weldability and corrosion resistance [1] , while 2xxx Al-Cu alloys have the advantages of high strength and good fatigue properties [2] , both of which are widely used in aerospace, military and high-speed rail [3][4][5] . Recently, with the increase of load capacity and strength of the equipment, the usage of thick dissimilar aluminum alloys has increased significantly [6] . In order to meet the welding demand, a large heat input must be used to increase the penetration depth.…”

Study on the burning loss of magnesium in fiber laser welding of an Al-Mg alloy by optical emission spectroscopy

“…Compared to conventional welding processes, laser welding process shows important advantages due to high power density, low heat input, low welding distortion, and high aspect ratio. Therefore, laser welding of aluminum alloy is an immediate area of research focus all around the world [3][4][5][6]. Owing to high heat conduction coefficient, low viscosity, high linear expansion coefficient, high reflectivity of the metal, and low boiling point of the alloying elements, there are various welding defects, including porosity, undercut and joint softening during laser welding of aluminum alloy [7,8].…”