Abstract
In this study, a 3D coupled thermo-mechanical finite element model is developed to predict and analyze the defect formation during friction stir welding based on coupled Eulerian Lagrangian method. The model is validated by comparing the estimated welding temperature, processed zone shape and void size with those obtained experimentally. The results compared indicate that the simulated temperature and the data measured are in good agreement with each other. In addition, the model can predict the plasticized zone shape and the presence of a void in the weld quite accurately. However, the void size is overestimated. The effects of welding parameters and tool pin profile are also analyzed. The results reveal that welding at low welding speed or high tool rotational speed could produce a smaller void. Moreover, compared to a smooth tool pin, a featured tool pin can enhance plastic flow in the weld and achieve defect-free weldment. The results are helpful for the optimization of the welding process and the design of welding tools.
Highlights
Friction stir welding (FSW) is a novel solid-state joining technique invented by the welding institute (TWI) in 1991 [1]
The results showed that the cooling rate plays a significant role in defect formation, and a higher cooling rate leads to faulty deposition of material behind the tool pin
According to the coupled Eulerian Lagrangian (CEL) method, in the present study, the workpiece was modeled under Eulerian framework, while the FSW tool was modeled as a Lagrangian body
Summary
[15,16] used a commercial CFD code, FLUENT, to develop a 3D model to understand the temperature distribution and material flow around a complex threaded tool during friction stir welding of Al7075 aluminum alloy. Buffa G. et al [24] developed a thermo-mechanical coupled, rigid-visco-plastic, three-dimensional finite-element model to study the effect of tool geometry on the material flow pattern and the grain size distribution in the welded joints. A 3D coupled thermo-mechanical finite element model is developed to simulate the FSW process based on coupled Eulerian Lagrangian (CEL) method. The proposed CEL model has a number of advantages over the previous numerical models: it can predict the material flow as well as defect formation during the FSW process explicitly. Of the joint was prepared to characterize the macrostructure by optical microscopy
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