TA15钛合金的动态热压缩行为及其机理研究

Study on the Dynamic Hot Compression Behavior and Deformation Mechanism of TA15 Titanium Alloy

为了研究TA15(Ti-6Al-2Zr-1Mo-1V)钛合金的动态热变形行为,采用圆柱试样在Gleeble-1500热模拟机上进行了恒应变速率压缩变形试验(变形温度550～1000℃,变形速率0.01～1 s-1),计算了材料的变形激活能Q并观察了热变形组织.结果表明,材料的流动应力随着变形温度的升高而降低,随应变速率的提高而增大.材料的流变行为表现为加工硬化(550～600℃)、动态再结晶(650～900℃)、动态回复(950～1000℃)三种类型.材料在(α+β)相区的热变形激活能为517kJ/mol,β相区为205kJ/mol.流动应力曲线、变形激活能以及变形组织分析表明,在α+β相区动态再结晶是材料的主要软化机制,而在β相区软化机制则以动态回复为主.随着变形速率的降低,在(α+β)双相区动态再结晶进行得更加充分,而在β相区则动态回复的亚晶趋于长大.

To study the dynamic hot deformation behavior of TA15 （Ti-6Al-2Zr-1 Mo-1 V） alloy, the hot compression experiments adopting cylindrical specimens at constant strain rates were executed on Gleeble-1500 simulator（ deformation temperatures of 550 - 1000 ℃and strain rates of 0.01 - 1 s^-1 ） , the deformation activation energy Q was calculated and the hot deformation microstructure was observed. The results show that the flow stress decreases with deformation temperature rising and increases with strain rate growing. The flow deformation behavior could be divided into three types of working hardening （550 - 600℃ ） , dynamic recrystallization （650 -900℃ ） and dynamic recovery（950 - 1000℃ ）. The calculated deformation activation energy is 517kJ/mol in （α ＋ β） phase regionand 205kJ/mol in β phase region. The flow stress curves, deformation activation energy and deformation microstructure reveal that the main softening mechanism is dynamic recrystallization in （ α ＋ β） field and dynamic recovery in β field. As the strain rate declines the dynamic recrystallization proceeds more adequately in （ α ＋ β） region and the subgrain of dynamic recovery has the tendency to grow in β region.