金属结构材料塑性变形微观组织历史敏感特性和材料最优轨迹

Microstructures evolutions exhibit higher and higher sensitivity to processing history during the deformation of metallic materials with the cleanliness and alloying extent increase. This kind of sensitive characteristic is considered as one of the main reasons for fluctuations of microstructures and properties within forgings. Thus, the knowledge on sensitive characteristics to processing history is significant for microstructure control in plastic deformation, especially to metallic materials with high cleanliness and high alloying extent. And it is a key scientific problem how to implement a stable and reliable control on microstructures and properties on basis of the knowledge. In this investigation, by taking the Ni-base superalloy as the research object, the state space method is applied to model microstructures evolution which is taken as the dynamic system during plastic deformation. Using the proposed model, characterization and analysis methods for sensitivity to processing history are proposed. Laws of dynamic responses between the microstructure evolution and the processing history are explored, basing on which the history-sensitive graphs are drawn. Then the objective functional is set up in which the term with regard to history sensitivity is included. And then the optimization algorithm of material optimal trajectories is set up. The research results are expected to lay a foundation and provide technical support for implementation of stable and reliable control on microstructures and properties for metallic materials of new generation with high cleanliness and high alloying.

随着金属材料纯净度和合金化程度不断提高，材料的组织性能表现出越来越强烈的历史敏感特性，成为此类材料组织性能波动的主要因素之一。深刻了解并阐明金属材料塑性变形微观组织历史敏感特性，实现高纯净度/高合金化金属结构材料锻件组织性能的稳定可靠控制是塑性加工领域亟待解决的关键科学问题。本项目拟选择高合金化的镍基高温合金为研究对象，采用材料轨迹（变形参数随时间的变化曲线）表征塑性加工历史，完成以下研究内容：建立材料微观组织演化的状态空间模型，提出材料历史敏感性数学表征及试验分析方法；揭示微观组织与加工历史的动态响应规律，绘制历史敏感性图；构建包含历史敏感性函数项的目标泛函，建立能够反映历史敏感性的材料最优轨迹求解方法。本研究对塑性加工过程的组织控制具有重要意义，可为实现高纯净度/高合金化金属结构材料锻件组织性能的稳定可靠控制奠定理论基础和提供技术支持。

航空航天等领域用难变形材料，塑性加工过程对历史敏感性较强，成为此类材料组织性能波动的主要因素之一。本项目选择高合金化的镍基高温合金GH4169和GH706合金为研究对象，采用材料轨迹（变形参数随时间的变化曲线）表征塑性加工历史，完成了如下研究内容：建立了典型材料GH4169合金与GH706合金的微观组织演化的状态空间模型，并给出了材料历史敏感性数学表征及试验分析方法；针对GH4169合金，为了揭示微观组织与加工历史的动态响应规律，根据锥形样压缩实验所得微观组织结果，绘制了不同历史敏感性图；构建了包含历史敏感性函数项的目标泛函，建立了能够反映历史敏感性的材料最优轨迹求解方法，并编写了Fortran程序。利用所推导得到的空间状态模型及目标泛函，对某盘类件的加载速度轨迹进行了设计，得到的盘件微观组织均匀性良好，证实了本项目所得到的空间状态模型及目标泛函的合理性。进一步说明了本研究对塑性加工过程的组织控制具有重要意义，为实现高纯净度/高合金化金属结构材料锻件组织性能的稳定可靠控制奠定理论基础和提供技术支持。