Study on the influence of scanning spacing and speed on tensile properties of 3D-printed aluminum alloy using three-dimensional digital image correlation method

To investigate the influence of different printing parameters on the tensile properties of 3D printed aluminum alloy materials, a three-dimensional digital speckle deformation strain measurement system (3D-DIC) system and a universal testing machine were used to measure and analyze the mechanical properties, including tensile strength, elongation at break, and stress–strain curves, of the material under different scanning spacings and scanning speeds. The strain field and displacement field at the necking region of the specimens were obtained, and the microstructure of the fracture surface was characterized using scanning electron microscopy (SEM). The experimental results show that when the scanning spacing is 0.08 and 0.12 mm, the tensile strength first increases and then decreases with increasing scanning speed. When the scanning spacing is 0.05 mm, the tensile strength increases monotonically with increasing scanning speed. The elongation at fracture decreases with increasing scanning speed and scanning spacing. With increasing scanning spacing and scanning speed, the strain field shows a transition from dispersed distribution to localized concentration and finally to discretization, accompanied by a progressive increase in strain concentration and a gradual decrease in deformation uniformity. Variations in printing parameters lead to distinct microstructural features, which are directly reflected in the macroscopic mechanical properties of the material.

In response to the urgent demand for lightweight, high-performance 3D printed aluminum alloy components in the aerospace and automotive industries, and considering the key influence of scanning spacing and scanning speed on the mechanical properties of components fabricated via selective laser melting (SLM), this study addresses the limited understanding of the synergistic effects of these parameters and the lack of correlation between full field strain evolution and mechanical performance. By systematically exploring the effects of printing parameters on the macroscopic mechanical properties and microstructural characteristics of the materials, this study provides theoretical support for the optimization of 3D printed aluminum alloy processing and contributes to the improvement of the comprehensive performance of fabricated components.

Flat dog bone–shaped tensile specimens were prepared from AlSi10Mg aluminum alloy powder using SLM. Nine parameter combinations were designed by varying the scanning spacing (0.05, 0.08, and 0.1, 2 mm) and scanning speed (1000, 1500, and 2000 mm/s) while keeping the layer thickness fixed at 0.04 mm and the laser power of 250 W. A 3D-DIC system and a SANS CMT5505 electronic universal testing machine were used simultaneously to collect macroscopic mechanical parameters such as stress–strain curve, tensile strength, elongation at break, and three-dimensional displacement and strain field data at the necking region of the specimen under uniaxial tensile loading at room temperature (tensile speed: 1 mm/min). Fracture surfaces were also examined using SEM to analyze microstructural characteristics and defect distributions of the surface microstructure. The results show that when the scanning spacing is 0.08 and 0.12 mm, the tensile strength first increases and then decreases with increasing scanning speed. By contrast, when the scanning spacing is 0.05 mm, the tensile strength increases continuously with scanning speed. The elongation at break decreases with increasing scanning spacing and scanning speed, with the weakening of plasticity owing to high scanning speed being more significant at larger spacings. As scanning spacing and scanning speed increase, the strain field distribution transitions from dispersed to localized and then to discretized, accompanied by increased strain concentration and reduced deformation uniformity. SEM observations show that the fracture surface corresponding to the optimal parameter combination (0.08 mm spacing and 1500 mm/s scanning speed) is dominated by uniform, moderately ductile dimples with minimal defects, whereas specimens fabricated with large spacing and high scanning speed exhibit a high density of lack-of-diffusion defects and significant brittle fracture characteristics.

The scanning spacing and scanning speed in 3D printed AlSi10Mg aluminum alloy exhibit a significant interactive effect on macroscopic mechanical properties by regulating melt pool behavior, microstructure uniformity, and defect distribution during the SLM process. The optimal process parameter combination is a scanning spacing of 0.08 mm and a scanning speed of 1500 mm/s, which enables a balanced optimization of tensile strength and plasticity. By contrast, a scanning spacing of 0.12 mm and a scanning speed of 2000 mm/s should be avoided owing to performance degradation caused by insufficient fusion. Furthermore, 3D-DIC technology enables accurate full-field characterization of the deformation behavior of the entire field, providing a reliable approach for elucidating the correlation mechanisms between printing parameters, microstructure, and macroscopic performance. These results provide an important basis for process optimization and performance control of 3D printed aluminum alloy components.