Abstract
? 2022 Elsevier B.V.The effect of Si content on the quench sensitivity of the Al-Si-Mg alloys was investigated by conducting the age hardening test of the alloys with different cooling rates after solution heat treatment. The quench sensitivity increases with increasing Si content in the range of 2–12%. The microstructure shows that, apart from the solute loss to the dynamic precipitates with low hardening ability, the decrease in the dislocation density induced by the thermal stress at a low cooling rate contributes to enhanced quench sensitivity by lowering the density of heterogeneous nucleation sites for precipitates. The quench sensitivity map is constructed, it relates the decrease in the peak hardness to the average cooling rate and the strain energy stored in the aluminum matrix due to the mismatch of thermal expansion under the assumption of pure elastic deformation. The effect of the microstructure characteristics, including the size, fraction and shape of Si on the quench sensitivity can be accounted for by the latter parameter.
NSTL
Elsevier