Ti-55531合金棒材力学性能各向异性的机制研究

Mechanism of Mechanical Property Anisotropy in Ti-55531 Alloy Bars

摘要:

针对Ti-55531合金大规格棒材室温力学性能的各向异性，尤其是塑性各向异性较大的问题进行研究，采用室温拉伸和断裂韧性测试，并结合OM、SEM及EBSD等微观表征手段，对棒材初始组织、断口形貌及裂纹扩展路径等进行系统表征与分析，揭示了Ti-55531合金棒材力学性能各向异性的原因，研究表明：由于β相的<110>织构导致不同加载方向{101}<111>滑移系的Schmid因子不同，出现屈服强度差异；Ti-55531合金的拉伸塑性与断裂韧性存在明显关联，表明室温塑性的各向异性与裂纹扩展阶段密切相关，并受合金组织特征的影响；Ti-55531合金室温塑性的各向异性主要取决于β晶粒的形貌，并受β相取向织构和等轴α_p分布等因素的影响。

Abstract:

The anisotropy of the room temperature (RT) tensile properties, especially plasticity, of Ti-55531 alloy bars was investigated. RT tensile and fracture toughness tests were conducted, as well as OM, SEM, and EBSD characterization. The raw structure, fracture morphology, and crack propagation path were analyzed to reveal the reasons for the anisotropy of the tensile properties of Ti-55531 alloy bars. The results show that due to the <110> texture of the β phase, the Schmid factors for {101}<111> slip systems with different loading directions are different, leading to anisotropy in yield strength; the tensile plasticity is correlated with fracture toughness of Ti-55531 alloy, indicating that the anisotropy of RT plasticity mainly depends on the crack propagation stage and is influenced by the relevant structural characteristics; the anisotropy of RT plasticity Ti-55531 alloy mainly depends on the morphological texture of β grains, and is affected by the orientation texture of β phase and distribution of equiaxed α_P.