-1。建立了U720Li合金在這2種保溫時(shí)間下的熱加工圖。通過分析熱加工圖各區(qū)域?qū)?yīng)的變形組織，明確了保溫5 min的最佳熱加工條件為1090~1110 ℃/1~10 s-1和1146~1180 ℃/1~10 s-1，而保溫10 min的最佳熱加工條件為1080~1090 ℃/1~10 s-1和1153~1160 ℃/ 1~10 s-1?？梢娺m當(dāng)縮短變形前保溫時(shí)間可擴(kuò)大該合金的安全加工窗口。在未發(fā)生開裂的情況下，動(dòng)態(tài)再結(jié)晶（DRX）晶粒隨變形溫度和保溫時(shí)間的增加而逐漸增大，但隨應(yīng)變速率的增加先減小后增大。當(dāng)變形溫度低于1100 ℃，主要DRX機(jī)制為顆粒誘導(dǎo)連續(xù)DRX。當(dāng)變形溫度高于1130 ℃，主要DRX機(jī)制轉(zhuǎn)變?yōu)椴贿B續(xù)DRX。;To improve the hot workability of hard-deformed superalloy U720Li, the effect of holding time before deformation (5 and 10 min) on hot deformation behavior was investigated by hot compression tests. Results show that the flow stress increases with increase in strain rate, while decreases with increase in deformation temperature and holding time. Based on the obtained Arrhenius-type constitutive models, the calculated peak stresses are in good agreement with experimental values, indicating that this model can accurately predict the hot deformation behavior of U720Li alloy, and the deformation activation energies for the holding time of 5 and 10 min were calculated to be 992.006 and 850.996 kJ·mol-1, respectively. Moreover, processing maps of U720Li alloy with these two holding durations were constructed. Through observation of deformation microstructures in each domain of the processing maps, the optimal hot working conditions for the holding time of 5 min are determined to be 1090?1110 °C/ 1?10 s-1 and 1146?1180 °C/1?10 s-1, and the optimal hot working conditions for the holding time of 10 min are 1080?1090 °C/1?10 s-1 and 1153?1160 °C/1?10 s-1, indicating that the safe processing window can be obviously enlarged by shortening the holding time reasonably. In the absence of cracking, the dynamic recrystallization (DRX) grain size increases gradually with increasing the deformation temperature and holding time, but it first decreases and then increases with the increase in strain rate. When the deformation temperature is below 1100 °C, the DRX mechanism is mainly the particle-induced continuous DRX. As the temperature is raised to above 1130 °C, the main DRX mechanism changes to discontinuous DRX."/>