灰铸铁凝固数值模拟的形核率模型建立.pdfVIP

学兔兔 Feb．2010 VOI．59 NO．2 ·165· 灰铸铁凝固数值模拟的形核率模型建立 张 宁，郑洪亮，陈 凯，田学雷 (山东大学材料液固结构演变与加工教育部重点实验室，山东济南250061) 摘要：设计并浇注了一系列阶梯形灰铸铁件，采用金相显微镜研究了各铸件不同位置的共晶团数量，分析了影响灰铸 铁共晶形核的主要因素，探求了灰铸铁的共晶形核规律。研究表明，过冷度和碳当量对灰铸铁共晶形核起主要作用。 随着过冷度的增大，灰铸铁共晶形核率增大。随着碳当量接近共晶成分，灰铸铁共晶形核率也增大。在总结灰铸铁形 核理论并结合试验所得数据的基础上，采用统计学方法分别得出有关亚共晶灰铸铁和过共晶灰铸铁的形核率公式，为 凝固过程数值模拟的动力学计算提供准确模型。 关键词：灰铸铁；形核率；凝固过程数值模拟 中图分类号：TG249 文献标识码：A 文章编号：1001—4977(2010)02—0165—04 Nucleation Model for NumericaI Simulation of Solidification of Gray Iron ZHANG Ning，ZHENG Hong—liang，CHEN Kai，TIAN Xue．1ei (Key Laboratory for Liquid—Solid StructuraI Evolution and Processing of Materials。Ministry of Education，Shandong University，Ji。nan 250061，Shandong，China) Abstract~A series of stepped castings were designed and poured，and metallographic microscope was employed to determine the number of eutectic cells．The factors that influence nucleation and the regularity of nucleation rate were studied．1t iS revealed that the carbon equivalent and the degree of undercooling mainly determine the nucleation rate．The eutectic celI increases as the degree of undercooling rises．The number of eutectic cells increases as the carbon equivalent IS close to the eutectic composition．On the basis of theories and experiment results，a regression modeI of nucleation of hypoeutectic cast iron and hypereutectIc cast iron was obtained，which could be the more accurate modeI for dynamical analysis used in solidification simulation． Key WOrds：gray iron；nucleation；solidification simulation 灰铸铁具有良好的充型能力、加工性、耐磨性、 成分、过冷度对形核率的影响，以求建立能够精确模 耐热性、吸震性和成本低廉等特点，在铸造生产中占 拟灰铸铁凝固过程，准确预测灰铸