冷冻砂型对铸铁合金凝固行为及组织性能影响规律研究  

Effect of frozen sand mold on solidification behavior and microstructure of cast iron

作　　者：戴宇峰 单忠德 杨浩秦 罗磊 梁校 DAI Yufeng;SHAN Zhongde;YANG Haoqin;LUO Lei;LIANG Xiao(School of Materials Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 210006,Jiangsu,China;School of Mechanical and Electrical Engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 210006,Jiangsu,China;National Key Laboratory of Structural Mechanics and Control of Aerospace Machinery,Nanjing 210006,Jiangsu,China)

机构地区：[1]南京航空航天大学材料科学与技术学院,江苏南京210006 [2]南京航空航天大学机电学院,江苏南京210006 [3]航空航天机械结构力学与控制全国重点实验室,江苏南京210006

出　　处：《金属加工（热加工）》2024年第9期112-118,共7页MW Metal Forming

基　　金：国家重点研发计划(2021YFB3401200);江苏省基础研究计划(自然科学基金)青年基金(BK20230885)。

摘　　要：采用冷冻砂型铸造铸铁合金,界面换热系数是反映冷冻砂型与铸铁合金换热程度的重要参数,对于分析铸铁合金组织性能具有重要意义。研究测定了合金的界面接触温度随时间的变化规律,在此基础上分析了界面换热特征,获得了界面换热系数随初始界面温度变化的函数式,同时分析了冷冻砂型中铸件凝固的铸态微观组织及力学性能。结果表明:界面换热系数随着冷冻砂型初始温度的增加而降低,随含水率的减少而升高。当含水率为6%(质量分数,下同)时,在-35℃、-30℃、-25℃初始冷冻温度条件下,铸型铸件界面换热系数峰值分别是195663W/(m^(2)·K)、147933W/(m^(2)·K)、120836W/(m^(2)·K);当含水率为5%时,在-35℃、-30℃、-25℃初始冷冻温度条件下,铸型铸件界面换热系数峰值分别是209257W/(m^(2)·K)、176878W/(m^(2)·K)、134472W/(m^(2)·K)。相同含水率下初始冷冻温度越低,珠光体晶粒越细,石墨化程度越高,抗拉强度也越高。The interfacial heat transfer coefficient of cast iron is an important parameter to reflect the heat transfer degree between the frozen sand cast iron alloy and cast iron alloy,which is of great significance for the analysis of microstructure properties of cast iron alloy.In this study,the change rule of the interfacial contact temperature of the alloy with time was measured.Based on this,the characteristics of the interfacial heat transfer were analyzed,and the function of the interfacial heat transfer coefficient changing with the initial interfacial temperature was obtained.Meanwhile,the as-cast microstructure and mechanical properties of the castings solidified in the frozen sand mold were analyzed.The results show that the interfacial heat transfer coefficient decreases with the increase of the initial temperature of the frozen sand mold,and increases with the decrease of water content.At the initial freezing temperature of-35℃,-30℃and-25℃with moisture content of 6wt.%,the peaks of interface heat transfer coefficients of cast castes are 195663W/(m^(2)·K),147933W/(m^(2)·K)and 120836W/(m^(2)·K).At the initial freezing temperature of-35℃,-30℃and-25℃with moisture content of 5wt.%,the peaks of interface heat transfer coefficients of cast castes are 209257W/(m^(2)·K),176878W/(m^(2)·K)and 134472W/(m^(2)·K).Under the same moisture content,the lower the initial freezing temperature,the finer the pearlite grain,the higher the graphitization degree and the higher the tensile strength.

关 键 词：冷冻砂型 铸铁合金 界面换热系数 初始温度 含水率 

分 类 号：TG25[金属学及工艺—铸造]