热处理对热等静压态TC4合金及其降温多道次变形微观组织的影响

Effect of Heat Treatment on Microstructure of Hot Isostatic Pressed TC4 Alloy and Its Multi-Pass Deformation

采用Gleeble-1500D热模拟试验机,在应变速率0.001~5s^-1的条件下对热等静压态(HIPed)TC4合金进行降温多道次热压缩实验,总变形量为70%。HIPed TC4合金采用935℃+60 min+水冷(WQ)固溶处理,分别在520℃+4/6h+水冷/空冷(WQ/AC)和560℃+4/6 h+水冷/空冷(WQ/AC)下进行时效处理;降温多道次变形后HIPed TC4合金分别在945℃+60 min+WQ进行固溶处理和560℃+6 h+WQ进行时效处理。结果表明:HIPed TC4试样组织随着时效温度的升高,板条状次生α相含量减少;而随着时效时间变长,等轴α相逐渐增多,组织主要以次生条状的α相与等轴α为主。降温多道次变形试样,在应变速率为0.1 s^-1时,合金经过950→850℃降温多道次变形后再通过固溶-时效处理,获得了较为理想的三态组织。

The multi-pass thermal compression experiments of hot isostatic pressed(HIPed)TC4 titanium alloy were carried out on the Gleeble-1500D thermal simulator at strain rate of 0.001~5 s^-1,and the total deformation was 70%.The HIPed TC4 titanium alloy was treated by solution treatment of 935℃+60 min+water quenching,and then by aging treatment of 520℃+4/6 h+water quenching/air cooling and 560℃+4/6 h+water quenching/air cooling.After multi-pass deformation,the samples were treated by solution treatment at 945℃+60 min+water quenching and aging treatment at 560℃+6 h+water quenching.The results show that the content of secondaryαphase of HIPed TC4 titanium alloy decreases with the increase of aging temperature,while the equiaxedαphase increases in amount with the increase of aging time,and the microstructure mainly consists of secondary stripαphase and equiaxedαphase.Meanwhile,the ideal tri-modal microstructure(equiaxedαphase+secondary stripαphase+βtransformation phase)of HIPed TC4 titanium alloy can be obtained by solution and aging treatment during multi-pass deformation at the deformation temperature from 950℃to 850℃and strain rate of 0.1 s^-1.