Study on the pre-aging process of Al-6.4Zn-2.4Mg-2.05Cu-0.12Zr alloy thick plate by three-stage aging heat treatment
The effect of pre-aging process on the microstructure and properties of Al-6.4 Zn-2.4Mg-2.05Cu-0.12Zr thick plate during three-stage aging heat treatment was studied with DSC,TEM,hardness tester,etc.The results show that after solution stretching and natural aging(NA),the precipitates are mainly in the GP zone,with continuous chain dis-tribution at grain boundaries and a material hardness of about 162 HV.An analysis was con-ducted on the effects of different pre-aging temperatures ranging from 80 to 140℃on grain boundaries and intragranular precipitates in the naturally aged plate.The results indicate that with the increase of pre-aging temperature,the size of precipitates inside grains and at grain boundaries grows simultaneously.Pre-aged at 120 ℃ for 24 hours,the intragranular precipi-tated phase is mainly composed of the η'phase,and the hardness reaches highest(189 HV).Pre-aged at 140℃for 24 hours,more η phases precipitate and leads to a decrease in hardness.The optimal pre-aging process is determined to be 120 ℃ for 24 hours based on comprehensive structure and performance of the plates.It has been verified in the laboratory and industrial production,and the processed plates have reached the same performance level of similar alloy products abroad.
万方数据
维普
