球墨铸铁微观组织模拟仿真

【作者】 唐瑞春；

【导师】 舒信福；

【作者基本信息】 昆明理工大学 ， 材料加工工程， 2004， 硕士

【摘要】 球墨铸铁件作为重要的工程材料，在当今的很多国家的铸件产量中有较大的比例并且生产技术也达到了一定的水平。但由于铸造过程中的复杂性使得球墨铸铁件的质量仍然存在着很多的问题。为了更好地控制其生产质量，本文根据生产实际及当前的关于球型石墨、晶体方面的形成、生长理论，结合先进的计算机技术，对金属凝固过程的微观组织进行了计算机模拟仿真，也称为凝固过程微观模拟，这个名称是相对于凝固过程宏观模拟而言的，具体是指在晶粒尺度上对金属凝固过程进行模拟仿真。本文根据热力学、凝固原理等理论，建立了凝固过程中热传递、溶质传递和石墨球、奥氏体的形核、生长进行模拟，以能量最小原理为基础，考虑体积自由能和界面能的定量影响，建立了晶粒生长概率模型。根据所建立的模型，采用了Microsoft Visual C++6． 0开发平台开发了相应的三维模拟计算程序和二维动态显示程序。针对微观模拟计算量大的特点，本文采用了局部区域模拟法，并相应地解决了整体区域和局部区域之间的数据映射、局部区域的边界处理、局部区域模拟结果的放大显示等问题。该方法通过仅对关键的局部区域模拟而有效地节省了计算量。针对球墨铸铁(成分为：碳含量为3． 7％、硅含量为3． 3％、锰含量小于0． 4％)在砂型中的凝固过程，进行了实验对比研究。使用编写的模拟仿真软件对实验过程中的微观组织进行了模拟，并把模拟的计算结果与实验结果进行了对比，二者基本吻合。更多还原

【Abstract】 Spheroidal graphite cast iron , As important engineering material ,its production has been increasing in many countries and its production technology has been established . However , there sre still many problems on casting quality because it is difficult for engineers to see and understand what is really happening during casting solidification . In order to more control the quality of the spheroidal graphite cast iron ,in this paper ,according to the practice, the present theory of formation, growing of spheroidal graphite and crystal, and advanced compute technology , Microsructure formation during metal solidification are simulated , which is also called Micro-Modelling . It is ralative to Macro-Modelling during solidification. To be specific , it means the simulation of solidification process at the scale of grain.According to the thermodynamics and solidification theory in this paper , the mathematical and physical model , which coupled heat transfer , solute transfer , nucleation of graphite and austenite , the growth of praphite and austenite was developed . Simulating the grain nucleation and growth of austenite by using Monte Carlo (MC) method . MC method is based on the law of the lowest energy and the effects of bulk free energy and interfacial energy are taken into account here . Accoring to the model which have been developed , the program of 3-dimensional calculation simulation and 2-dimensional image display is developed by using Microsoft Visual C++ 6.0 .Local Area Simulation (LAS) is developed to reduce the amount of calculation of Micro-Modelling by only choosing local area to simulate . TheLAS method includes three parts : mapping the simulation data belonging to Macro-scope onto the local area , dealing with the boundary of the local area and magnifying the graphical results of the local area..Experimental study on the solidification process of the spheroidal graphite cast iron (the chemical composion: C3.7%,Si3.3%, Mn <0.4 % ) in sand is compared to the models of this dissertation . Microsrueture during solidification are simulated by software which was programmed. The results of simulation are compared to the experimental results . It shows that the models used to Micro-Modelling can meet the targets .更多还原