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Study on Welding Procedure of 2024 Aluminum Alloy with Moderate Thickness and Numerical Simulation

Author: ZhangLiang
Tutor: WangShaoGang
School: Nanjing University of Aeronautics and Astronautics
Course: Materials Processing Engineering
Keywords: 2024 aluminum alloy Welding process Mechanical Properties Microstructure Numerical Simulation
CLC: TG457.14
Type: Master's thesis
Year: 2010
Downloads: 288
Quote: 1
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Abstract


2024 aluminum alloy is heat treatment to strengthen aluminum alloy, widely used in the aircraft skin, spar and other structural parts of a larger force, and with the development of high-tech, its range of applications is still growing. However, due to such special welding material, prone to thermal cracking, porosity and other welding defects in the welding process, the strength of welded joints obtained coefficient is often lower, subject to certain restrictions on its application in the actual production. Select the appropriate welding method and process parameters in order to obtain the quality of welded joints to meet the actual requirements, usually based on the structure and size of the weldment. In this paper, using the gas tungsten arc welding (TIG), melting TIG welding (MIG) and vacuum electron beam welding (EBW) three different welding of different thickness 2024 aluminum alloy plate welded joint performance and The microstructure and properties of welded joints obtained research and theoretical analysis of the system, and its related welding parameters to optimize the weld surface forming a good and excellent joint quality of welded joints. Meanwhile, based on ANSYS software using double ellipsoid heat source model MIG and EBW welding temperature field conducted a simulation analysis, and through APDL secondary development language to achieve the welding process moving heat source of the load and uninstall, analysis of different welding processes joints The distribution characteristics of temperature field, the results can provide theoretical guidance for the optimization of the welding process. The results show that, compared to the welded joints obtained by the method of three welding strength and the strength of the base material itself decline, which have different degrees of the EBW joint strength is the highest, followed by MIG joint strength, while TIG lowest joint strength, but Under normal circumstances, the strength of the EBW, and MIG welding head are able to meet the actual engineering structures application requirements. Joint microstructure observations show that in three different welding under the process conditions, the joint weld metal, the microstructure of the weld in the electron beam welding process to render fine equiaxed grain eutectics distributed more uniformly, and The microstructure of the weld in the gas tungsten arc welding and melting polar argon welding technology showed the shaft dendrite morphology, grain size is significantly larger than the grain size of the electron beam welding; three welding the heat-affected zone of the connector is substantially the the coarse columnar dendritic morphology, but significantly smaller vacuum electron beam welding head HAZ columnar grain size compared to the other two welded joints. Scan of the tensile fracture of the welded joints can be clearly observed in the fracture surface morphology of the TIG welding head to the river pattern and tear ridge, was typical cleavage fracture characteristics; MIG welding and EBW welding head The fracture surface of a large number of dimples, and in part of the bottom of the dimples can clearly see that there are many of the small particles, the outside of the dimple torn edges obvious, showing ductile fracture characteristics. XRD analysis of the weld joint, and the results show that the the three joint weld District α-Al phase based TIG welding head welds found to exist the θ (CuAl2) strengthening phase and elemental Si phase; MIG welding head welds in the distribution of θ (CuAl2) and Mg2Si strengthening phase θ (CuAl2); distribution of electron beam welding head welds and S (Al2CuMg), strengthening and TEM microscopic analysis further confirmed strengthening the joints phase main phase θ (CuAl2). The thickness 8mm 2024 aluminum alloy MIG and EBW welding temperature field simulation analysis using ANSYS software, the calculation results show that, using double ellipsoid heat source model simulation results closer to the actual welding process, verify the establishment of the heat source model reliability. Analysis of the results of the simulation, and compared to the actual weld pool morphology consistent. Welding parameters on the temperature field analysis shows that the smaller the welding speed, the higher the peak temperature of the high temperature region of the temperature field range and the same measurement point; welding, the greater the power, the higher the peak temperature of the same measurement point. Comprehensive Test results show that melting using TIG welding and vacuum electron beam welding method can achieve high-quality plate 2024 aluminum connection.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > Welding of a variety of metal materials and components > Welding of metallic materials > Aluminum
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