热变形中TC18钛合金本构关系及第二类再结晶全图研究

Constitutive Relation and Secondary Recrystallization Maps of the TC18 Titanium Alloy During Hot Deformation

分别反映金属流变应力特征和组织-变形关系的本构关系和第二类再结晶全图是TC18钛合金热加工工艺制定的关键数据。在Gleeble-3800热模拟试验机上,对TC18钛合金进行系列热压缩变形,其中,变形温度为790~900℃,应变速率为0.01~10s^-1,应变量为0.1~0.5。通过拟合Arrhenius式中α,n,Q,ln A与ε的六次多项式,建立了材料高温热压缩本构方程,热压缩流变应力预测值与实验值吻合良好;通过组织观察及α晶粒尺寸测算绘制出其各应变速率下的第二类再结晶全图。

The constitutive equation and the secondary recrystallization maps,which reflect the flow stress characteristics and microstructure-deformation relationship of the material,respectively,are the key data for the TC18 titanium alloy during the hot deformation.In the present paper,the hot compression deformation was carried on Gleeble-3800 under the conditions that the deformation temperatures were 790~900℃,the strain rates 0.01~10 s^-1 and the strains 0.1~0.5.By fitting the 6th polynomials ofεandα,n,Q,ln A in the Arrhenius formula,TC18 titanium alloy’s constitutive equation of hot compression was established.The predicted values of flow stress of the hot compression are in good agreement with the measured values;the secondary recrystallization maps of each strain rate were d rawn by observing the microstructure and measuringαgrains’sizes.