不同原始组织TC6钛合金高温变形 微结构演化及其力学性能  

Microstructure Evolution and Mechanical Properties of TC6 Alloy with Different Original Microstructures during High Temperature Deformation

作　　者：孙坤[1] 徐媛[1] 叶青[1] 钟卫[1] 

机构地区：[1]楚雄师范学院,云南楚雄675000

出　　处：《稀有金属材料与工程》2012年第3期406-412,共7页Rare Metal Materials and Engineering

基　　金：云南省应用基础研究计划项目(2011FZ185);楚雄师范学院学术骨干资助项目(09YJGG02);楚雄师范学院院级重点资助项目(10YJZD04)

摘　　要：采用gleeble-1500热模拟试验机和Hopkinson压杆,对具有4种典型组织的TC6钛合金分别进行了高温准静态压缩和室温动态压缩试验,结合TEM观察,研究了不同原始组织的TC6钛合金高温变形微结构演化及其力学性能。结果表明:具有4种典型组织的TC6钛合金高温变形时随温度升高微结构的演化可分为等轴型组织演化和网篮型组织演化,前者演化过程为:等轴α相的拉长变形—动态再结晶—动态再结晶晶粒长大—α/β相变;后者演化过程为:板条状α相弯曲变形—板条状α相断裂—动态再结晶—动态再结晶晶粒长大—α/β相变,板条状α相变成短棒状。位错活动及动态再结晶是控制4种组织的TC6合金在高温变形过程中组织演化和力学性能的重要因素;网篮组织晶界众多,位错运动障碍较多,在高温下具有较其余3种组织更高的流变应力;等轴组织α相晶粒较大,位错运动障碍较少,其流变应力在4种组织中最低;双态组织、固溶时效组织的流变应力介于等轴组织与网篮组织之间。4种组织的TC6钛合金的室温动态力学性能均对应变率较敏感。4种组织的TC6钛合金在室温及应变率为2500～4000s-1动态压缩条件下,塑性由大到小依次为:等轴组织、双态组织、固溶时效组织和网篮组织,流变应力由大到小依次为:固溶时效组织、双态组织、网篮组织和等轴组织。High temperature quasi-static compression test and RT dynamic compression tests on TC6 titanium alloy samples with 4 kinds of original microstructures were carried out using the gleeble-1500-type thermal simulation testing machine and Hopkinson bar. Effects of different original microstructures on their microstructure evolution in high temperature deformation, thermal distortion behavior and mechanical properties of TC6 alloy were studied, by combining the corresponding transmission electron microscope （TEM） analysis and the stress-strain curves. Results show that there exist two types of microstructure evolution for the 4 kinds of microstructures of TC6 alloy in the hot deformation. One type is equiaxed-type microstructure evolution, whose process is elongation of equiaxed a phase--dynamic recrystallization--growth of dynamic recrystallized grain--phase transformation of α/β. The other is lamellar-type microstructure evolution, whose process involves bending of lath-shaped a phase--breakdown of the lath-shaped a phase--dynamic recrystallization-- growth of dynamic recrystallized grain--phase transformation of α/β and lath-shaped a phase becoming short-bar a phase. Dislocation movement and dynamic recrystallization are important factors that control microstructure evolution and mechanical properties of TC6 alloy during high temperature deformation. Lamellar structure shows the highest flow stress among the 4 kinds of microstructures due to its large quantity of grain boundaries which obstruct the dislocation movement. The equiaxed structure displays the lowest flow stress in the 4 kinds of microstructures owing to its larger grain size which involve lesser obstacles to movement of dislocation. The flow stresses of the binary and the solution and aging structure are between that of lamellar structure and that of the equiaxed structure because of their mixed construction of equiaxed grains and acerose grains. The room temperature dynamic mechanical properties of the TC6 alloy with 4 kinds of microstructures

关 键 词：TC6钛合金:高温变形 微观结构演化 力学性能 

分 类 号：TG146.23[一般工业技术—材料科学与工程] TG115.53[金属学及工艺—金属材料]