EFFECT OF AGING ON TENSILE PROPERTIES OF CAST AL ALLOY

摘要

The phase formation and phase evolution during solution heat treatment and age hardening of an Al-6.63Si-3.23Cu-0.3Mg-0.58Fe-0.55Zn casting alloy were predicted qualitatively and quantitatively based on the computational thermodynamics (CALPHAD) method.Tensile test results demonstrated that a temperature of 190 deg C is an effective aging temperature for this alloy; peak properties were achieved in only about 4.5 h. T6 aging at 5 h is far from peak strengthening. The strength after aging for 4.5 h at 190 deg C is significantly higher than that resulting from the T6 treatment in the same amount of time. However, the higher strength comes at the expense of a loss in ductility. Aging at 230 deg C also yielded promising results; peak aging was reached in only 1 h. The strength under this treatment was also significantly higher than the strength with typical T6 aging, though the strength was slightly less than the peak strength at 190 deg C. The ductility measured after aging at this temperature was comparable with the ductility after aging at 190 deg C. This work shows that for maximum strengthening, either 190 or 230 deg C could be used as aging temperatures to reduce the artificial aging time of the alloy.