This investigation presents the response of Ti-6Al-2Sn-4Zr-2Mo, manufactured using powder bed fusion with electron beam (PBF-EB), under combined tension-torsion loading. Combined loading experiments were conducted quasi statically, at a strain rate of 10^-3 s^-1, and dynamically at strain rates ranging between 500 s^-1 and 2000 s^-1. Quasi static experiments were carried out using a universal electro-mechanical testing machine. Dynamic experiments were performed using a bespoke Hopkinson Tension-Torsion bar apparatus capable of generating stress pulses characterised by different proportions of tensile and torsional loading. The dynamic response of the material was analysed across a wide spectrum of stress states, including uniaxial tension, shear, and various combinations of tension and shear. A novel specimen geometry, consisting of four equally spaced ligaments arranged circumferentially around the axis of the sample is introduced.The quasi static and dynamic failure envelopes of PBF-EB and traditionally manufactured Ti-6Al-2Sn-4Zr-2Mo are presented in the shear versus direct stress space and compared for the first time. The ultimate stress loci of the PBF-EB processed material are approximated employing the Drucker-Prager and Mohr-Coulomb criteria to evaluate their rate sensitivity and assess the accuracy of existing failure models. The results delineate an evident influence of the strain rate and a moderate tension-compression asymmetry of the failure envelopes. The influence of manufacturing defects, stress state, and loading rate on deformation and failure mechanisms is assessed by analysing the failure surfaces of tested samples by means of scanning electron micrographs.

中文翻译：

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传统和粉末床熔融与电子束制造的 Ti-6Al-2Sn-4Zr-2Mo 在低应变率和高应变率下的多轴响应

本研究介绍了使用粉末床与电子束熔融 （PBF-EB） 制造的 Ti-6Al-2Sn-4Zr-2Mo 在联合拉伸-扭转载荷下的响应。以 ^10-3 s-1 的应变速率准静态进行联合加载实验，并以 500 ^s-1 和 2000 ^s-1 之间的应变速率进行动态加载实验。使用通用机电试验机进行准静态实验。使用定制的霍普金森拉伸扭杆装置进行动态实验，该装置能够产生以不同比例的拉伸和扭转载荷为特征的应力脉冲。分析了材料在各种应力状态下的动态响应，包括单轴拉伸、剪切以及拉伸和剪切的各种组合。介绍了一种新的标本几何形状，由四条等距韧带组成，这些韧带围绕样品的轴线圆周排列。PBF-EB 和传统制造的 Ti-6Al-2Sn-4Zr-2Mo 的准静态和动态破坏包络线在剪切与直接应力空间中提出，并首次进行了比较。使用 Drucker-Prager 和 Mohr-Coulomb 准则对 PBF-EB 加工材料的极限应力位点进行近似计算，以评估它们的速率敏感性并评估现有失效模型的准确性。结果描述了应变率的明显影响和破坏包络线的适度拉伸-压缩不对称性。通过扫描电子显微镜照片分析测试样品的失效表面，评估制造缺陷、应力状态和加载速率对变形和失效机制的影响。