Ti-6.5Al-3.5Mo-1.5Zr-0.3Si合金β加工动态再结晶行为研究

Dynamic Recrystallization of β Phase of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy

摘要:

利用Thermecmastor-Z热模拟试验机，在变形温度1020~1080 ℃和应变速率0.001~70 s-1范围内对原始等轴组织的Ti-6.5Al-3.5Mo-1.5Zr-0.3Si合金进行等温恒应变速率压缩实验，分析高温流动行为，构建基于动态材料模型的功率耗散图，并结合微观组织观察对其β加工的动态再结晶行为进行研究。结果表明，Ti-6.5Al-3.5Mo-1.5Zr-0.3Si合金在β单相区变形时，不同温度和应变速率下的流动应力曲线均呈稳态流动特征，但仅根据流动应力曲线并不能确定是否发生动态再结晶。根据功率耗散图分析和微观组织观察可知，Ti-6.5Al-3.5Mo-1.5Zr-0.3Si合金β加工易发生动态再结晶的热力参数范围为：变形温度1020～1080 ℃，应变速率0.01～0.1 s-1，此区域功率耗散功率η值都大于0.4，为实际β加工时优化的热力参数范围；应变速率过高或过低，均不易发生动态再结晶

Abstract:

An isothermal and constant strain rate compression test is carried out for the Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy with an equiaxed α+β microstructure in the temperature range of 1020~1080 ℃ and the strain rate range of 0.001~70 s-1. A power dissipation map is developed on the basis of flow stress data and by using the principles of dynamic material model. The results show that the steady state flow characteristics exist during hot compression deformation for the Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy in the temperature range 1020~1080 ℃. The dynamic recrystallization regime was identified in the power dissipation map and the microstructure examination was performed for validation. In the β phase field, the dynamic recrystallization occured in the temperature range of 1020~1080 ℃ and the strain rate range of 0.01~0.1 s-1 with the efficiency of power dissipation η mostly larger than 0.4, which is the optimum β forging processing parameters. It is proved that the power dissipation map based on dynamic material model is an effective method for successful β-forging and microstructure control