复杂不锈钢叶轮熔模铸造工艺的优化

Optimization of Investment Casting Process for Stainless Steel Impeller with Complicated Geometry

不锈钢叶轮的形状复杂且壁薄,使熔模铸造不锈钢叶轮铸件出现缩孔缩松及浇不足等缺陷。这些缺陷与铸件的充型和凝固过程密切相关。本文使用ProCast软件数值模拟研究叶轮的充型及凝固过程,并将结果与实验进行了比较。结果表明:浇注温度为1550℃、浇注速度为0.75 m/s有利于叶轮铸件的充填,可避免浇不足缺陷。适当的铸造温度和铸造速度仍无法避免在叶轮铸件内产生缩孔缩松缺陷。根据叶轮铸件的结构特点,采用在叶轮铸件中空处施加冷铁的方式可以消除铸件中的缩孔缩松缺陷,当冷铁高度为叶轮铸件内部高度的1/3时,去除缩松缩孔缺陷的效果最明显。

Due to the complicated geometry and thin wall of the stainless steel impeller, during the investment casting process, some casting defects such as shrinkage porosity and filling shortage are usually produced, which have a close relationship with the filling and solidification process. So, the software Pro Cast was used to study the filling and solidification process of impeller and the numerical simulation results were compared with the experimental results in this paper. The following results can be acquired：1. when the pouring temperature is 1550℃ and the casting speed is 0.75 m/s, the investment casting impeller can be filled to avoid the filling shortage defect; 2. although the appropriate pouring temperature and casting speed can avoid the filling shortage defect, but it can not avoid the shrinkage porosity defects in the impeller casting; 3. to pre-place certain cold iron in the middle of the impeller casting mold according to its structural characteristics can eliminate the shrinkage porosity defects. When the height of the pre-placed cold iron is 1/3 of the height of the inner cavity of impeller mold, the effectiveness in elimination the defects in the castings is the best thereby a high quality impeller can be acquired.