Experimental and numerical analysis of friction stir additive manufacturing of 2024 aluminium alloy

With the rapid development of industrial manufacturing, additive manufacturing has attracted extensive attention in the industry since it possesses a high material utilization rate. Friction stir additive manufacturing (FSAM) is a novel solid-phase additive manufacturing method which possesses the advantage of achieving excellent mechanical properties of FSAM of aluminium alloy components. The formation characteristic of the additive zone and thermal processes in FSAM significantly determine the mechanical properties of the FSAM components. However, there is still a lack of quantitative analysis of the thermal processes in FSAM of AA2024-T4 aluminium alloy. Thus, a finite element model (FEM) of FSAM was proposed, and the element birth-death technology was employed to capture the addition of an additive layer during the FSAM process. The evolu-tion of the thermal field in FSAM was quantitatively studied by the model. The formation characteristics and mechanical properties of the additive components were analyzed. It indicates that the volume of the additive zone increases with an increase in the tool rotation speed, while it decreases with an increase in the transverse speed during FSAM. The height and width of the hook structure decrease with an increase in the transverse speed. The tensile strength of the FSAM component first increases with the increase in the transverse speed and reaches its maximum value at the transverse speed of 90 mm/min, while further increases in the transverse speed reduce the tensile strength. The peak temperature of the first layer is the highest during the whole FSAM process. While the peak temperate of subsequent additive layers is about 475 celcius, which is lower than the first layer and remains almost constant. The maximum value of the thermal cycle decreases with an increase in the tool's transverse speed. While the high-temperature residence time increases with a decrease in the tool transverse speed. The model is validated by comparing the predicted heat-affected zone with the experimentally measured ones. It lays a solid foundation for optimizing the friction stir additive manufacturing process to improve manufacturing efficiency and enhance the performance of the built components.

Automated summary

Friction stir additive manufacturing (FSAM) is a novel solid-phase additive manufacturing method. A finite element model (FEM) of FSAM was proposed to quantitatively study the thermal processes and mechanical properties of FSAM components. The results show that the volume of the additive zone in FSAM increases with the tool rotation speed and decreases with the transverse speed. The height and width of the hook structure decrease with the transverse speed. The tensile strength of FSAM components initially increases with the transverse speed and reaches its maximum at 90 mm/min, then decreases. The maximum value of the thermal cycle decreases with the transverse speed, while the high-temperature residence time increases with the decrease in transverse speed.