铸铁模消失模铸造过程数值模拟及组织性能研究

运用View cast对所设计的铸铁模消失模铸造工艺进行数值模拟,预测工艺方案所产生的缩孔、缩松的大小和位置。模拟结果显示,铸件实现了顺序凝固,无明显缩孔、缩松缺陷。此外,铸件设置加强肋保证了铸铁模在使用过程中不会因冷热交变产生挠曲变形。利用消失模铸造生产的铸铁模组织以针状铁素体和珠光体为主,加热至500℃、700℃,试样组织和硬度没有明显变化,加热至900℃时发生了铁素体向奥氏体转变,冷却后生成均匀分布的珠光体以及细小的铁素体。氧化实验分析发现,温度对试样的氧化速率有较大影响,主要是因为不同温度下试样表面生成不同的氧化膜,使试样的氧化速率有较大的差异。

Numerical Simulation, Microstructure and Mechanical Properties of the Lost Foam Casting Process for Casting Mould

The simulation software View cast was used to predict the sizes and positions of the shrinkage in the casting-pattern produced by lost foam casting.The result showed that the sequence solidification was achieved in the casting process;no defect was observed which are satisfied with the technical requirements.Reinforcing rib was de-signed to ensure that the cast iron mould was not deformed in the process of the cold and heat.The microstructure of the material which was observed under the optical microscope was mainly based on acicular ferrite and pearlite.When heated to 500 ℃ and 700 ℃,there was no obvious changes of the hardness and organization.While heated to 900 ℃, ferrite austenite transformation,and the uniform distribution of pearlite after cooling,at the same time,the samples had significant decrease in hardness.It can be learned from the analysis of oxidation experiments that the temperatures have great influence on the oxidation rate of sample,and reason for this phenomenon is that different thickness of oxide films were formed under different temperatures,as a result,the oxidation rate of the samples treated under dif-ferent temperatures is different.