两种不同初始组织BT25y钛合金的温度敏感性对比

Comparison on temperature sensitivities for BT25y titanium alloy with two different initial microstructures

基于热模拟压缩试验研究了初始片层组织/初始等轴组织BT25y钛合金的温度敏感性。结果表明:变形温度对两种不同初始组织BT25y钛合金的流动应力均具有显著影响,两相区低温变形时初始片层组织BT25y钛合金的流动应力明显大于初始等轴组织,初始片层组织主要的软化机制为动态球化,初始等轴组织发生α相的动态再结晶,两种不同初始组织在β单相区变形时均发生β相的动态再结晶。温度敏感性分析显示:初始片层组织BT25y钛合金的温度敏感性指数s随变形温度和应变速率的升高而减弱,在低温(850~880℃)、低应变速率(0.001~0.01 s^(-1))变形时表现出最大的温度敏感性;初始等轴组织BT25y钛合金的s值随变形温度的升高整体上呈减小趋势,随应变速率的变化情况则受控于变形温度。

The temperature sensitivities of BT25y titanium alloys with initial lamellar microstructure and initial equiaxed microstructures were studied by thermal simulation compression test.The results show that the deformation temperature has a significant effect on the flow stresses of BT25y titanium alloys with two kinds of initial microstructures,and the flow stress of BT25y titanium alloy with initial lamellar microstructure is obviously greater than that of BT25y titanium alloy with initial equiaxed microstructure at low deformation temperature in two-phase region.The main softening mechanism in initial lamellar microstructure is dynamic globularization,the dynamic recrystallization ofαphase occurs in initial equiaxed microstructure,and the dynamic recrystallization ofβphase occurs in both initial microstructures when deforming inβphase region.Temperature sensitivity analysis shows that the temperature sensitivity exponent s of BT25y titanium alloy with initial lamellar microstructure decreases with the increasing of deformation temperature and strain rate and achieves the maximum value when deforming at the low temperature of 850-880℃and the small strain rate of 0.001-0.01 s^(-1),and the s value of BT25y titanium alloy with initial equiaxed microstructure decreases generally with the increasing of deformation temperature,while the change condition with the strain rate is controlled by the deformation temperature.