TC11钛合金等轴组织热变形行为与组织演变

Hot Deformation Behavior and Microstructure Evolution of TC11 Titanium Alloy with Equiaxed Structure

采用等温恒应变速率压缩试验研究了TC11钛合金等轴组织两相区980～800℃，应变速率0．001～0．1s^-1，变形程度50％条件下的变形行为，分析了变形参数对应力-应变曲线、微观组织演变机制和规律的影响，建立了该合金两相区变形的热加工图，并采用EBSD技术测试了热变形组织的晶界特征。结果表明：（1）980℃变形，B相是主要变形相，0．001—0．1s。之间的功率耗散效率值在动态回复和再结晶范围内；α相经历了变形促进下的溶解（高应变速率）和聚集粗化（低应变速率）的过程，即α晶粒尺寸和相含量随着应变速率的加快明显减小。（2）950～900℃变形，0．001～0．01s^-1之间的功率耗散效率值在超塑性变形范围内；变形主要是软基体的B相和界面的变形行为；变形过程中，α晶粒尺寸和相含量基本不变。（3）850～800℃变形，α相是主要变形相，发生了连续动态再结晶过程；β相起晶界协调变形的作用。

Hot deformation behavior of TC11 alloy with equiaxed structure was investigated in the twophase region over the range of 980 -800 %, strain rate of 0. 001 -0.1 s^-1, and maximum deformation of 50% by means of isothermal and constant strain rate tests. The effects of thermal-mechanical parameters on stress-strain curves and microstructure evolution were analyzed. And hot processing maps were established. EBSD technique was used for testing grain boundary characteristic of deformation structures. The results in- dicated that： （1） 15 phase was the main deformation phase, and power dissipation efficiency indicated that dynamic recovery and recrystallization occurred in 0. 001 - 0.1 s^-1. Meanwhile α phase experienced solution （high strain rate ）and coarsening （low strain rate） promoted by deformation at 980℃. During the process, ct grain size and its amount decreased with strain rate increasing. （ 2 ） Super-plastic deformation indicated by power dissipation efficiency occurred at 950 -900℃, 0. 001 -0.01 s^-1. And the deformation concentrated on soft β phase, interface and grain boundary layers. （3） The deformation mechanism at 850 -800℃ was continuous dynamic recrystallization of α phase which was the main deforming phase, and β was the deformation coordinate phase.