反向挤压铸造大型轮毂杂质元素偏析行为研究  

Segregation Behavior of Impurity Elements in Large Wheel Hub by Reverse Squeeze Casting

作　　者：邢书明[1] 王永生[2] 刘鑫 侯景路 Xing Shuming;Wang Yongsheng;Liu Xin;Hou Jinglu(School of Mechanical and Electronic Control Engineering,Beijing Jiaotong University;Hot Processing Branch,Beijing North Vehicle Group Co.,Ltd.;Tianjin Jinhuitong Bicycle Co.,Ltd.)

机构地区：[1]北京交通大学机械与电子控制工程学院,北京100044 [2]北京北方车辆集团有限公司热加工分厂 [3]天津金汇通自行车有限公司

出　　处：《特种铸造及有色合金》2021年第3期265-269,共5页Special Casting & Nonferrous Alloys

基　　金：国家自然科学基金资助项目(51275031);天津市重点研发计划资助项目。

摘　　要：杂质元素的偏析是导致大型关键结构件异常失效破坏的重要因素。针对反向挤压铸造A356.2铝合金大型轮毂,研究了P、Ca、Zn、Pb、Cu、Fe、Zr、Mn等杂质元素的偏析程度、偏析位置和偏析类型。结果表明,挤压铸造过程中持压凝固阶段的流变行为对杂质元素的偏析会产生重要影响。发现了3种偏析:沿流变补缩通道分布的"通道偏析"、在变形死区的"零流变偏析"以及Ca和Cu的"密度偏析"。这些杂质元素的偏析程度依偏情况为:Zn、Pb、P是严重偏析元素,偏析比高于0.3,偏析级别达4级;Ca属于偏析较重的元素,偏析比为0.2~0.3,偏析级别为3级;Fe、Cu、Mn、Zr等杂质元素都属于偏析较轻的元素,偏析比为0.1~0.2,偏析级别为1~2级。各杂质元素的偏析位置受凝固顺序、流变状态和空间位置所控制,凸模(压头)下方的中心位置(零流变区)和反向充填的局部热节位置是k0<1杂质元素的集聚区,反向充填的最远位置反而是杂质元素贫乏的位置。The segregation of impurity elements is known as an important factor leading to abnormal failure of large-scale key structural parts.The segregation degree,segregation position and segregation type of impurity elements such as P,Ca,Zn,Pb,Cu,Fe,Zr and Mn were analyzed for A356.2 aluminum alloy wheel hub by reverse squeeze casting.The results reveal that the rheological behavior of squeeze casting has an important influence on the segregation of impurity elements.Three kinds of interesting segregation are presented as follows:the"channel segregation"along the rheological feeding channel,the"zero rheological segregation"in the non-deformation zone,and the"specific gravity segregation"of calcium and copper.The degree of segregation of these impurity elements can be divided into four grades according to the segregation ratio from low to high.Zinc,plumbum and phosphorus belong to serious segregation elements with the segregation ratio higher than 0.3,which reaches grade 4,while calcium belongs to the heavy segregation element with the segregation ratio of 0.2~0.3,which is grade 3.Meanwhile,the impurity elements such as iron,copper,manganese,zirconium are all light segregation elements with the segregation ratio of 0.1~0.2,which is grade 1 or grade 2.The segregation position of impurity elements is controlled by solidification sequence,rheological state and spatial position.The central position(zero rheological zone)under punch or indenter and local hot spot positions of reverse filling are the accumulation area of k0<1 impurity elements.On the contrary,the farthest position of reverse filling is poor in impurity elements.

关 键 词：铝合金 轮毂 挤压铸造 杂质元素 偏析 

分 类 号：H142.3[语言文字—汉语] TG292[金属学及工艺—铸造]