装甲铝合金厚板分层开裂机理及控制技术研究

Delamination fracture along the thickness direction of armor aluminum alloy is one of the main problems that threaten the safe service of armor vehicles, so it has important theoretical significance and engineering application value to carry out the research on the mechanism and control technology of delamination fracture of armor aluminum alloy thick plates. In the past, the research was mostly focused on the damage evolution under the load along rolling direction. In this project, the heterogeneous distributions of the residual stress and microstructure along the thickness direction of thick plate are taken full consideration to do research on the mechanism and control technology of damage evolution of armor aluminum alloy thick plates. First, based on the crystal plasticity theory, a crystal plasticity finite element model for the meso-damage evolution of armor aluminum alloy under typical working conditions is created to simulate the effects of microstructure on the delamination fracture of thick plate. At the same time, the experiments about the effects of rolling process on the grain size and distribution, crystallographic orientation and the heterogeneous distribution of microstructure along thickness direction are done. The influence mechanism of microstructure on the delamination fracture of the armor aluminum alloy thick plate is revealed. Second，the thermo-mechanical coupling finite element model of residual stress analysis is established to simulate the distribution of the residual stress in the thick plate and its effect on the delamination fracture. Combined with the mechanical properties’ experiments along thickness direction, the influence mechanism of residual stress on the delamination fracture of the armor aluminum alloy thick plate is revealed. Based on the above study, the rolling-solid solution processes for effective control of residual stress and uniform microstructure are explored, and it can provide the basic theory and technical support to control the delamination fracture of armor body and guarantee the quality of armor vehicles.

装甲铝合金板厚方向分层开裂是威胁装甲车辆安全服役的主要问题，因此开展其开裂机理与控制技术研究具有重要的理论意义和工程应用价值。以往研究多集中在轧向加载时板材的失效分析，本项目充分考虑板厚方向残余应力和微观组织分布不均，开展装甲铝合金板厚方向的损伤演化机理及控制技术研究。首先，以晶体塑性理论为基础，构建典型工况下装甲铝合金细观损伤演化的晶体有限元模型，模拟微观组织对厚板分层开裂的影响。同时，实验研究轧制工艺对晶粒尺寸及分布、晶体取向、厚度方向组织不均的影响，揭示微观组织对装甲铝合金厚板分层开裂的影响机理。其次，建立残余应力分析的热力耦合有限元模型，模拟厚板淬火残余应力分布及其对分层开裂的影响，结合厚度方向的力学性能实验，揭示残余应力对铝合金厚板分层开裂的影响机理。在此基础上，探明微观组织均匀、残余应力可控的轧制-固溶淬火工艺，为控制车体开裂、保证装甲车辆质量提供理论依据和技术支持。

装甲铝合金板厚方向分层开裂是威胁装甲车辆安全服役的主要问题，开展其开裂机理与控制技术研究是解决开裂问题的有效途径。以往研究多集中在轧向加载时板材的失效分析，本项目充分考虑板厚的微观组织分布不均，开展2519A装甲铝合金板厚方向的损伤演化机理及控制技术研究。（1）揭示了难溶第二相、晶粒结构、析出相等对铝合金板厚方向力学性能及分层开裂的影响机理：沿轧向链状分布的难溶第二相和厚度方向微观组织不均使厚板容易发生分层开裂，厚向受载时裂纹穿过的晶界面积远大于轧向受载时的晶界面积，厚向受载时更容易发生沿晶断裂。（2）随着固溶温度的升高，合金中难溶第二相的数量及尺寸都减少，微观组织沿板厚方向的不均匀分布得到改善，从而提高了合金的力学性能和抗断裂能力。（3）探明了轧制预变形工艺对合金板厚方向微观组织及力学性能的影响规律：预变形的增加，细化了合金的晶粒，减少粗大第二相的数量，促进了θ′相析出，进而提高了合金的力学性能和抗分层开裂的能力，11%轧制预变形时合金的力学性能最佳。（4）揭示了T9I6时效处理对合金板厚方向微观组织及力学性能的影响机理：T9I6时效处理能促进θ′相析出，增加合金θ′相体积分数，使θ′相分布更均匀，同时T9I6时效处理降低了合金板厚方向微观组织及力学性能的不均匀性，从而提高了合金板厚方向的力学性能和疲劳性能。相关研究为控制车体开裂、保证装甲车辆质量提供理论依据和技术支持，项目在国内外重要刊物上发表论文21篇，其中SCI、EI论文14篇，授权国家发明专利5项，培养了1名博士研究生、4名硕士研究生。