β-T51Z合金的热变形行为与组织演变研究

Study on hot deformation behavior and microstructure evolution of β-T51Z alloy

摘要:

针对亚稳β-T51Z(51.1Zr-40.2Ti-4.5Al-4.2V)合金,采用Gleeble-3500试验机进行热模拟实验,利用EBSD和TEM分析了变形温度和应变速率对合金热变形行为的影响及其组织演变规律。结果表明：T51Z合金在热变形时,其流变应力曲线呈现典型的单峰动态再结晶特征,其应力增幅随着变形温度的降低或应变速率的增加逐渐增加。基于峰值应力建立了合金热变形本构方程,计算得出热变形激活能为159.57 kJ/mol,该合金在热压缩过程中的变形机制主要与位错的交滑移有关。变形温度和应变速率对合金形变组织影响较大,整个热变形过程都存在动态回复,随着变形温度的升高或应变速率的降低,合金动态再结晶分数逐渐增大。在800°C/10 s-1变形条件下,合金容易形成绝热剪切带,宏/微观变形不均匀现象严重。

Abstract:

The hot deformation behavior and microstructure evolution of metastable β-T51Z alloy during hot compression deformation was sdudied through EBSD and TEM by thermal simulation compression at Gleeble-3500 thermal-mechanical simulator under different deformed temperatures and strain rates.The results show that the compressing curves in hot deformation have a typical characteristic of single-peak dynamic recrystallization,and the degrees of increased stress increase gradually with decrease of deformed temperatures or increase of strain rates. Based on the peak stress,the constitutive equation of thermal deformation of alloy is established, and the activation energy Q is 159.57 kJ/mol,the deformed mechanism of alloy during hot compression is mainly related to the cross slip of dislocation.The deformed temperature and strain rate have a great influence on the deformation microstructure.Dynamic recovery exists throughout hot deformation process,with increase of deformed temperatures or decrease of strain rates, the fractions of dynamic recrystallization increase gradually. When deformed temperature is 800°C and strain rate is 10 s-1,the adiabatic shear band is easily formed and the macro/micro deformation is not uniform.