Ti55531合金高温变形特性分析及其本构方程的建立

Study of the High Temperature Deformation Behavior and Establishment of the Constitutive Equation for Ti55531 Alloy

为了探究Ti55531合金的可旋压性能,采用热模拟压缩试验,研究了全β相固溶态Ti55531合金在α+β相区、β相区及相变点Tβ共7个温度点及0.01、0.1、1 s-13个应变速率下的单向热压缩变形特性。结果表明:Ti55531合金流变应力随应变速率的增大和变形温度的降低而增大;流变应力随应变的增加而增大,出现峰值后逐渐趋于平稳。650~800℃是该合金合理的旋压温度范围。在650~800℃,0.01、0.1、1 s^(-1)变形条件下,该合金的最大径向旋压力小于所用设备的最大径向推力,可以结合实际工件尺寸精度及表面质量等方面的要求调整变形速率。Ti55531合金的高温变形特性可用Sellar和Mc Tegart提出的双曲正弦模型来描述。结合旋压工艺参数,获得全β相固溶态Ti55531合金在α+β两相区变形的本构方程,为后续有限元数值模拟分析及热旋工艺制定提供理论基础及试验依据。

To explore the spinning characteristics of Ti55531 alloy with all β solution state, this work determined the compression characteristics of the Ti55531 alloy in the α＋β phase region, β -phase region and the Tβ （a total of 7 temperature points）, strain rates of 0. 01, 0. 1 and 1 s-1 by using thermal simulation compression experiment. The results show that, the flow stress of Ti55531 alloy increases with increasing strain rate and decreasing deformation temperature, and it also increases with increasing strain and is becoming stabilized after reaching a peak. The range of reasonable spinning temperature for Ti55531 alloy is 650 - 800 ℃. The maximum radial pressure of the alloy is less than the maximum radial thrust of spinning machine at temperature of 650 - 800 ℃ with strain rates of 0. 01, 0. 1 and 1 s-1, so the deformation rate can be adjusted according to the actual workpiece dimensional accuracy and surface quality, etc. Combination of Sellars and McTegart hyperbolic sine model and spinning parameters is adopted to obtain constitutive equation of Ti55531 alloy in theα＋β phase region deformation, which provides theoretical and test basis for finite element numerical simulation analysis and process test of hot spinning.