增材制造（AM），又被称为3D打印，是一种通过计算机辅助设计（CAD）

采用“分层制造，逐层叠加”的加工方式加工材料及其构件的独特的加工方式。与材料传统“减材制造”的加工工艺不同，AM工艺可以直接从原料制备所需的构件，具有快速成形、结构可控等优点，可以大大节省加工过程所需的原料和时间。已有的研究表明增材制造合金的准静态力学性能往往优于传统铸造工艺加工成形的合金，但是其动态力学性能则研究较少，在航空航天、国防工业等领域内，材料往往会承受冲击载荷，限制了AM合金在这些领域内的应用。因此，充分掌握AM合金的动态力学性能对拓宽AM合金的应用场景至关重要。

Ti6Al4V合金（TC4）作为目前应用最为广泛的钛合金之一，具有密度低、比强度高、优越的生物兼容性、高耐腐蚀性、高耐磨性等优点，被公认为最受欢迎的钛合金，广泛应用于生物医疗、国防工业以及航空航天等领域。然而由于钛合金的热导率小，传统加工工艺制造的钛合金很容易出现加工硬化现象，加工难度较大，极大限制了锻造Ti6Al4V合金的应用前景。因此，研究增材制造Ti6Al4V合金的动态力学性能与变形机理对于增材制造合金的应用有重要意义。

本文选取增材制造Ti6Al4V合金与锻造Ti6Al4V合金为研究对象，系统研究了两种合金的准静态力学性能、动态力学性能及变形机理，并给出了两种合金材料的动态本构方程和高压状态方程，取得的主要创新成果如下：

（1）通过设置不同温度、不同应变率实验，研究了两种不同工艺的合金材料在室温、低温和高温下的准静态压缩力学性能，研究表明两种合金材料都具有良好的强度塑性组合，在液氮温度下的屈服应力都有了显著的提升，在高温环境下的屈服应力都有显著的降低，表明两种合金材料都具有显著的热软化效应，AM合金的高温力学性能明显优于锻造合金。

（2）通过设置多组不同应变率的动态压缩试验，研究了两种合金材料的动态压缩力学性能，研究发现两种合金材料有着近似的动态力学性能，相比准静态压缩时的屈服应力均有了显著的提升（约70%），表明两种合金均有着显著的应变率硬化效应。使用准静态压缩和动态压缩的实验结果，分别拟合了两种合金的Johnson-Cook动态本构模型，并使用不同温度的高温准静态压缩实验和不同应变率下的动态压缩实验对该本构方程进行验证，验证结果表明拟合给出的动态本构方程与实际应力应变曲线误差较小，能够准确描述两种合金材料的动态变形行为。

（3）利用一级轻气炮系统，分别对两种合金进行了四组不同碰撞应力的平板撞击实验，研究了两种合金材料的冲击压缩（ε >10⁵s^-1）行为，研究结果表明，两种合金材料都具有很高的冲击弹性极限HEL：锻造合金为2.56GPa、AM合金为2.78GPa。使用最小二乘法拟合给出了两种合金材料的Hugoniot状态方程参数，发现两种合金材料的状态方程仅在零压声速c0 中存在4%左右的差异。

（4）使用OM、XRD、EBSD和TEM等表征手段，对两种合金冲击变形前后的相结构和微观形貌进行表征，发现变形前锻造合金与AM合金均为α+β相，但是锻造合金为等轴晶而AM合金为独特的片层组织。XRD分析表明两种合金相结构稳定，都有着很高的冲击相变阈值（>7.9GPa），通过EBSD和TEM表征分析得到两种合金的塑性变形机制均由位错主控。

Additive manufacturing (AM), also known as 3D printing, is a unique processing method that processes materials and their components through computer-aided design (CAD) using the "layered manufacturing, layer-by-layer superposition" processing method. Different from the traditional "subtractive manufacturing" processing technology of materials, the AM process can directly prepare the required components from raw materials. It has the advantages of rapid prototyping and controllable structure, which can greatly save the raw materials and time required for the processing process. Existing studies have shown that the quasi-static mechanical properties of additive manufacturing alloys are often better than alloys processed by traditional casting processes, but their dynamic mechanical properties are less studied, which limits the impact of AM alloys in aerospace, defense industries and other fields. Therefore, it is very important to fully grasp the dynamic mechanical properties of AM alloys to broaden the application scenarios of AM alloys.

As one of the most widely used titanium alloys at present, Ti6Al4V alloy (TC4) has the advantages of low density, high specific strength, high corrosion resistance, high wear resistance, excellent biocompatibility, etc., and is recognized as the most popular titanium alloy. Alloys are widely used in aerospace, automotive and medical fields. However, due to the low thermal conductivity of titanium alloys, titanium alloys manufactured by traditional processing techniques are prone to work hardening, and the processing is difficult, which greatly limits the forging of Ti6Al4V alloys. Therefore, it is of great significance to study the dynamic mechanical properties and deformation mechanism of additively manufactured Ti6Al4V alloys for the application of additively manufactured alloys.

In this paper, additively manufactured Ti6Al4V alloy and forged Ti6Al4V alloy are selected as the research objects, and the quasi-static mechanical properties, dynamic mechanical properties and deformation mechanism of the two alloys are systematically studied, and the dynamic constitutive equation and high-pressure state equation of the two alloy materials are given. and deformation mechanism, the main innovative achievements are as follows:

(1) By setting different temperatures and different strain rates, the quasi-static compressive mechanical properties of two alloy materials with different processes at room temperature, low temperature and high temperature were studied. The research shows that the two alloy materials have a good combination of strength and plasticity , the yield strain at liquid nitrogen temperature has been significantly improved, and the yield stress at high temperature environment has been significantly reduced, indicating that both alloy materials have a significant thermal softening effect, and the high temperature mechanical properties of AM alloy are significantly better than forged alloys.

(2) By setting multiple groups of dynamic compression tests with different strain rates, the dynamic compression mechanical properties of the two alloy materials were studied. It was found that the two alloy materials have similar dynamic mechanical properties, and the yield stress of the two alloy materials has significantly increased (about 70%) compared with the quasi-static compression, indicating that both alloys have a significant strain rate hardening effect. Using the experimental results of quasi-static compression and dynamic compression, the Johnson-Cook dynamic constitutive models of the two alloys were fitted respectively, and the constitutive models were determined using high-temperature quasi-static compression experiments at different temperatures and dynamic compression experiments at different strain rates. The verification results show that the error between the dynamic constitutive equation given by the fitting and the actual stress-strain curve is small, and the dynamic deformation behavior of the two alloy materials can be accurately described.

(3) Using the first-stage light gas cannon system, four groups of plate impact experiments with different impact stresses were carried out on the two alloys, and the impact compression (ε >10⁵s^-1) behavior of the two alloy materials was studied. The results showed that the two alloys All alloy materials have high impact elastic limit HEL: 2.56GPa for forged alloy and 2.78GPa for AM alloy. The parameters of the Hugoniot equation of state of the two alloy materials are fitted by the least square method, and it is found that the difference of the state equation of the two alloy materials is only about 4% in the zero-pressure sound velocity c0 .

(4) Using OM, XRD, EBSD and TEM to characterize the phase structure and micro-morphology of the two alloys before and after impact deformation, it was found that both the forged alloy and the AM alloy were in the α+β phase before deformation, but the forged alloy was equiaxed Crystal and AM alloys are unique lamellar structures. XRD analysis shows that the phase structure of the two alloys is stable, and both have a high impact phase transformation threshold (>7.9GPa). The plastic deformation mechanism of the two alloys is mainly controlled by dislocations through EBSD and TEM characterization analysis.