退火纯钛板压缩力学性能的各向异性

Anisotropy of compressive mechanical properties of annealed pure titanium sheet

沿退火纯钛板材轧向(RD 0°)、横向(RD 90°)以及轧制平面内与轧向成45°(RD 45°)等3个方向取圆柱形试样,采用Instron电子拉伸机和分离式Hopkinson压杆,进行准静态和动态压缩实验,获得不同应变率下的应力-应变曲线,计算3个方向的应变率强化效应。研究结果表明:退火纯钛板准静态和动态压缩力学性能均表现出明显的各向异性,其中RD 90°方向屈服强度最大,RD 45°方向次之,RD 0°方向屈服强度最小;在较小的应变程度下流变应力也具有同样的规律。不同方向上的应变率强化效应也存在显著差异:RD 0°方向最强,RD 45°方向次之,RD 90°方向最弱;基于纯钛{0001}-1 1 20-基面和{1 010}-1 210-棱柱面滑移微观塑性变形机制,结合晶体塑性变形理论,考虑多晶板材晶体取向分布,定性解释了退火纯钛板压缩力学性能各向异性。

The quasi-static and dynamic compressive mechanical properties of annealed pure titanium sheet were investigated by means of Instron apparatus and Split Hopkinson pressure bar technology.Cylindrical specimens cut with the cylinder axes along the sheet’s rolling direction（RD 0°）,transverse direction（RD 90°） and 45° direction from rolling direction（RD 45°） lying in the rolling plane were compressed at different strain rates.The results show that both the yield strength and flow stress for the RD 90° direction sample are the maximum at low strain degree,while those for the RD 0° direction are the minimum.The strain rate hardening effects of annealed pure titanium sheet for three different directions also exhibit pronounced anisotropy.The effect for RD 0° direction is the strongest while that for the RD 90° direction is the weakest.Taking into account of crystal orientation distribution of polycrystalline pure titanium sheet,the mechanical anisotropy of titanium sheet can be explained qualitatively based on the {0001} -1 1 20- basal slip and {1 010}-1 210- prismatic slip and the microscopic crystal plasticity theory.