数字化无模冷冻铸造成形方法研究  

Research on Forming Method of Digital Patternless Freezing Casting

作　　者：单忠德 杨浩秦 刘丰 王怡飞 Shan Zhongde;Yang Haoqin;Liu Feng;Wang Yifei(State Key Laboratory of Advanced Forming Technology and Equipment,China Academy of Machinery Science and Technology Group Co.,Ltd,Beijing 100044,China)

机构地区：[1]机械科学研究总院集团有限公司先进成形技术与装备国家重点实验室,北京100044

出　　处：《稀有金属材料与工程》2020年第12期4321-4328,共8页Rare Metal Materials and Engineering

基　　金：国家杰出青年科学基金(51525503)。

摘　　要：提出了一种数字化无模冷冻铸造成形方法。其原理是用纯水做砂型铸造用粘接剂,预混适量水分的型砂颗粒通过低温冻结后形成冷冻砂坯,然后进行基于减材制造成形原理的冷冻砂型切削的新技术。揭示了包覆型砂颗粒的水膜通过低温相变后冻结成冰晶粘接桥的微观形貌演化规律,发现冷冻砂型的强度是由冰晶颗粒和型砂颗粒的界面结合作用产生的,并且随着冷冻温度降低,砂型抗拉强度显著增加。同时系统地开展了A356铝合金在冷冻砂型中的凝固成形机理研究,包括冷冻砂型中铸件凝固的铸态微观组织、成分分布及力学行为。结果表明:随着凝固速率提高,组织中初生α-Al相的二次枝晶臂间距(SDAS)显著减小,晶粒明显细化,Si元素在基体中的溶解度增大。试件抗拉强度、塑性值和微观硬度值均显著升高,金属构件尺寸精度可达CT8级。A digital patternless freezing casting method was proposed,in which pure water is used as the binder for sand mold casting,sand particles premixed with a proper amount of moisture are frozen at low temperature to form a frozen sand blank,and then the frozen sand mold cutting is carried out based on the principle of material reduction manufacturing and forming.The morphology evolu tion law of the water film of coating sand particles was revealed,which freezes into ice crystal bonding bridge after low-temperature phase transformation.It is found that the strength of frozen sand mold is produced by the interfacial bonding between ice crystal particles and sand particles,and the tensile strength of sand mold increases significantly with the decrease of freezing temperature.In a ddition,the solidification forming mechanism of A356 aluminum alloy in the frozen sand mold was studied,including th e as-cast microstructure,composition distribution and mechanical behavior of the frozen sand mold casting.The results show that with the increase of solidification rate,the secondary dendrite arm spacing(SDAS)of primaryα-Al phase in the microstructure is significantly reduced,the grains are obviously refined,and the solubility of Si element in the matrix is increased.The tensile strength,elongation and microhardness of t he test piece are significantly increased,and the dimensional accuracy of the metal component can reach CT8 grade.

关 键 词：无模成形 冷冻铸造 微观组织 绿色铸造 

分 类 号：TG21[金属学及工艺—铸造] TG146.21[一般工业技术—材料科学与工程]