热成形TA32钛合金薄壁件的形状控制与性能优化

Shape controlling and property optimization of TA32 titanium alloy thin-walled part prepared by hot forming

为了优化TA32钛合金薄壁件的热成形工艺,对其热流动行为、显微组织演变和断口形貌进行研究。根据实验数据建立一套基于合金显微组织的本构方程,描述高温流动应力与相体积分数、位错密度、晶粒尺寸和损伤演化之间的关系。将本构模型嵌入ABAQUS6.14中模拟典型薄壁件的热成形过程,预测不同工艺参数下成形件的等效应变、位错密度、损伤分布以及成形缺陷。在变形温度为800℃、加载速度为5mm/s的条件下,采用改进形状尺寸后的毛坯成功模拟出无起皱和破裂缺陷的合格零件,且其最大损伤值仅为18.3%。通过显微硬度实验验证本构模型和有限元模拟的准确性,表明基于物理内变量的有限元模型能够有效地优化TA32钛合金复杂零件的热成形过程。

The hot flow behaviors,microstructure evolution and fractographs were studied to optimize the hot forming process of the TA32 titanium alloy thin-walled part.A set of microstructure-based constitutive equations were developed based on the experimental data,which described the relationships among the hot flow stresses and the evolution of phase volume fraction,dislocation density,grain size and damage.The constitutive model was imported into ABAQUS 6.14 to simulate the hot forming process for a typical thin-walled part.The effective strain,dislocation density and damage distribution as well as forming defects of formed parts under different process parameters were predicted.A qualified part without wrinkling and fracture defects was produced at a loading speed of 5 mm/s at 800℃ by the modified blank shape,where the maximum damage value was only 18.3%.The accuracy of constitutive model and finite element(FE)simulation was verified by the microhardness tests,which indicates that the FE model based on physical internal-state variables can well optimize the hot forming process of TA32 titanium alloy complex parts.