基于组织演化与缺陷分布耦合表征的合金热裂敏感性评估方法研究

Hot tear is the familiar casting defect and it can split the continuity of castings markedly. Hot tear great influence on casting service performance and safety. A comprehensive representation method on discontinuity defects and microstructure was introduced in this research. The influence rules of defects and microstructure distribution on the material heterogeneous and mechanical anisotropy under high solid fraction situation. A three-dimension imaging algorithm and multi-scale iteration algorithm will be developed to build the heterogeneous material model. Furthermore, the solidification stress couple analysis under multi-scale will be executed here, and a casting hot tear tendency couple assessment method will be built base on above studies. Due to the variable of casting shape and local solidification condition, the experimental study and numerical simulation method will be used in this research. The inference rules of coupled microstructure characteristic and casting defects to the hot tear tendency in casting material will be studied in detail. Under different pouring technology and alloy composition, the sensitive rules between hot tear tendency to the microstructure and porosity characteristic will be studied. A kind of assessment method of hot tear tendency will be built based on the upper study which includes the microstructure predicting, the casting defects predicting and thermal stress analysis. This research has important theoretical significance and extensive application value to improved casting design security and quality of castings.

热裂纹是铸造过程中的常见缺陷，它显著的割裂了材料基体的连续性并降低其局部强度，严重地影响了铸件服役的安全性。本课题基于对铸件中非连续性缺陷及微观组织的综合表征，系统地研究高固相率下缺陷及组织的分布特征对材料非均质性及力学各向异性的影响规律，研发空间三维映射及多尺度迭代等算法，建立非均质材料力学性能模型，并在此基础上开展凝固应力多尺度耦合分析，构建铸件热裂倾向性的多尺度耦合评估方法。针对铸件形态及局部凝固条件的多样性，采用实验与数值模拟研究相结合的方法，系统地研究缺陷及组织的分布特征与热裂尺寸效应的耦合对铸件热裂倾向的影响规律，并在此基础上探讨不同浇注工艺及合金成分条件下热裂倾向性对组织及缺陷特征的敏感性规律，从而建立集成微观组织预测、缺陷预测和铸造热应力分析的热裂倾向性评估方法，对提高设计的可靠性及铸件质量具有重要的理论意义和应用价值。

热裂是一种严重的铸造缺陷缺陷，它显著的割裂了材料基体的连续性并降低其局部强度，降低了铸件材料的局部机械性能，严重地影响了铸件服役的安全性。本课题采用多尺度数值三维重构技术，基于空间点素重组算法获取了铸件材料中缩孔、缩松、夹渣和气孔缺陷的分布特征和几何特征，并采用材料缺陷特征空间映射算法建立了包含缺陷的非均质材料模型，基于对铸件中非连续性缺陷及微观组织的综合表征，系统地研究高固相率下缺陷及组织的分布特征对材料非均质性及力学各向异性的影响规律，研发空间三维映射及多尺度迭代等算法，建立非均质材料力学性能模型，并在此基础上开展凝固应力多尺度耦合分析，构建铸件热裂倾向性的多尺度耦合评估方法。凝固过程参数（固相率、缩松孔隙率及晶体微观形态）等都在热裂评估过程中予以考虑。针对铸件形态及局部凝固条件的多样性，采用实验与数值模拟研究相结合的方法，系统地研究缺陷及组织的分布特征与热裂尺寸效应的耦合对铸件热裂倾向的影响规律，并在此基础上探讨不同浇注工艺及合金成分条件下热裂倾向性对组织及缺陷特征的敏感性规律，从而建立集成微观组织预测、缺陷预测和铸造热应力分析的热裂倾向性评估方法，对提高设计的可靠性及铸件质量具有重要的理论意义和应用价值。