Microstructure and constitutive model for flow behavior of AlSi10Mg by Selective Laser Melting

Abstract

This work is devoted to investigate the flow behavior and microstructure evolution of AlSi10Mg by additive manufacturing in hot deformation. Tensile test is carried out under different temperatures, i.e. 200 ∘ C, 250 ∘ C, 300 ∘ C, 350 ∘ C and 400 ∘ C, with various strain rates of 0.004/s, 0.002/s and 0.0004/s. Theoretically, the modified Arrhenius-type model of additive manufacturing materials at high temperature is established. Experimentally, scanning electron microscope and optical microscope are used to analyze the mechanism of hot deformation. It is found that at 200 ∘ C both the dendritic eutectic Si and acicular eutectic Si precipitate, forming cellular structure and strengthening phases. And then, the acicular eutectic Si is partially dissolved into Al matrix, but there is no obvious growth of dendritic Si at 300 ∘ C. With the temperature increasing, the cellular structure and melt pool boundary gradually disappear. For 400 ∘ C temperature, like homogenization process, the precipitation of saturated solid solution forms the dispersed phase, and the stress-strain curve shows a weak hardening. Meanwhile, the statistical result shows that that the constitutive model agrees well with the experimental results at high temperature. This study may provide guidance for the improvement of additive manufacturing material properties by post-treatment. • The modified Arrhenius-type equation of AlSi10Mg is theoretically established. • Microscope images show that the micropores may decrease as the temperature rises. • The melt pool, heat affected zone and remelt zone are weakened under hot deformation. • The precipitates are spheroidized under hot deformation at 400 ∘ C. • Evolution of AlSi10Mg: saturation precipitate and dispersion strengthened stage.