新型TB9钛合金屈服强度的应变率效应

TB9钛合金具有良好的力学性能，被广泛应用于航空航天领域，其材料强度随服役过程中应力作用的加载速率变化而发生改变。本文采用三次真空自耗熔炼工艺制备TB9钛合金材料，并对其开展了室温拉伸和压缩试验，研究了该材料在应变率0.0005-0.1 s-1范围内的力学性能及其变形行为，讨论了应变率对该材料压缩和拉伸屈服强度的影响。结果表明：应变率由0.0005 s-1升高至0.1 s-1时，TB9钛合金材料的平均压缩屈服强度由955.96 MPa升高至1 090.94 MPa，平均拉伸屈服强度由971.01 MPa升高至1 096.31 MPa，压缩屈服强度应变率敏感系数为0.02273，拉伸屈服强度应变率敏感系数为0.02110；随着应变率的增大，TB9钛合金拉伸试件断面韧窝尺寸及深度均会变小，这是由于应变率大时，瞬间局部能量增加，裂纹萌生和扩展速度加快所致。此外，本文采用线性函数拟合了TB9钛合金材料室温下屈服强度增强因子与自然对数应变率之间的关系，可用于预测TB9钛合金在工程应用中的力学行为。

Study on Strain Rate Effect of Yield Strength of New TB9 Titanium Alloy

TB9 titanium alloy has good mechanical properties and is widely used in the aerospace field. Its material strength changes with the loading rate of stress during service. In this paper, TB9 titanium alloy was prepared by three times vacuum consumable melting process. The mechanical properties and deformation behavior of TB9 under different strain rates of 0.0005-0.1 s-1 were studied by tensile and compression tests at room temperature. The effects of strain rate on the compressive and tensile yield strength of TB9 titanium alloy were discussed. The results show that the compressive and tensile yield strength of TB9 titanium alloy increase with the increase of strain rate. When the strain rate increases from 0.0005 s-1 to 0.1 s-1, the average compressive yield strength increases from 955.96 MPa to 1 090.94 MPa, the average tensile yield strength increases from 971.01 MPa to 1 096.31 MPa, the compressive yield strength strain rate sensitivity coefficient is 0.02273 and the tensile yield strength strain rate sensitivity coefficient is 0.02110; with the increase of strain rate, the dimple size and depth of TB9 titanium alloy tensile specimen will decrease, which is due to the increase of instantaneous local energy and the acceleration of crack initiation and propagation when the strain rate is high. In addition, the linear function is used to fit the relationship between the yield strength enhancement factor and the logarithm of strain rate of TB9 titanium alloy at room temperature, which can be easily used to predict the mechanical behaviors in engineering applications.