Abstract The material fracture behavior and associated mechanism is known to be affected by the stress state and strain rate. Using a recently developed rectangular hat-shaped specimen, the fracture behavior of Ti6Al4V was investigated with a stress triaxiality varying from −0.31 to 0.50 at strain rates ranging from quasi-static to 104 /s. The fracture mechanisms of Ti6Al4V under these conditions were studied at micro-scale through observations of cross-sectional microstructure and quantitative analysis of fracture surface morphology. It was found that λ, a parameter defining the percentage of equiaxed dimples on the fracture surface, shows a close correlation with the observed fracture mechanism. Therefore, a λ based criterion based has been introduced in this work to quantitatively describe the transition of fracture mechanisms. It was observed that the embrittlement of Ti6Al4V was promoted by a higher strain rate or a larger positive stress triaxiality, as expected. However, the stress triaxiality appeared to play a more dominant role. At sufficiently high negative or positive stress triaxiality values, the effect of strain rate on fracture mechanism became negligible.

中文翻译：

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Ti6Al4V 断裂机制在很宽的应力三轴度和应变率范围内转变的定量分析

摘要 已知材料的断裂行为和相关机制受应力状态和应变率的影响。使用最近开发的矩形帽形试样，研究了 Ti6Al4V 的断裂行为，应力三轴度从 -0.31 到 0.50，应变速率从准静态到 104 /s。通过观察横截面微观结构和定量分析断口形貌，在微观尺度上研究了 Ti6Al4V 在这些条件下的断裂机制。发现 λ，一个定义断裂表面等轴凹坑百分比的参数，显示出与观察到的断裂机制密切相关。因此，在这项工作中引入了基于 λ 的准则来定量描述断裂机制的转变。正如预期的那样，观察到更高的应变率或更大的正应力三轴度促进了 Ti6Al4V 的脆化。然而，应力三轴性似乎起着更重要的作用。在足够高的负应力或正应力三轴度值下，应变率对断裂机制的影响变得可以忽略不计。