Effect of solid solution on microstructure and mechanical properties of 6451 Al alloy

The effects of the solid solution on the microstructure and mechanical properties of 6451 Al alloy sheets were investigated by using conductivity and tensile tests， combined with OM and SEM observations. The results show that when the solid solution temperature is 560 ℃， recrystallization occurs in the sheet at 3 s of solution treatment. When the solution time is extended to 5 s， the Mg2Si particles are slowly dissolved. When the time is extended to 7 s， the equiaxial grains are formed after the complete recrystallization， a large amount of Mg2Si particles are dissolved， and the strength of the sheet is rapidly increased. With the further extension of the solution time， the growth rate of the strength of the T4P-stated sheet slows down obviously， and the increment of the yield strength after baking is basically unchanged. After the solution time of 30 s， there is no obvious change in the grain size. When the solution time is increased to 60 s， the Mg2Si particle is completely dissolved， and the yield and tensile strengths of the T4P-stated sheet are improved to 125 MPa and 247 MPa， respectively， with a better elongation of 30%. The functional relationship model between the yield strength and solid solution variation of the T4P-stated sheet based on classical diffusion theory is established according to the research results.