Zhou Bing, Qiu Zhiyan, Chen Keping, Xu Chun, Wang Zhanyong
School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, China.
Materials (Basel). 2022 Apr 21;15(9):3009. doi: 10.3390/ma15093009.
In order to solve the problem of insufficient convective heat transfer of uniaxial stirred melt, the temperature field and shear rate of melt under planetary stirring were studied based on CFD simulation. The microstructure and properties of this technology were also experimentally studied. The results show that compared with the uniaxial stirring semi-solid technology, the convective heat transfer ability of aluminum alloy, semi-solid slurry in planetary stirring mode is stronger. In addition, its temperature field can be reduced to the semi-solid range faster and more evenly, which is conducive to a large number of nucleation and improves the nucleation rate. The temperature difference of the whole melt is small, so the preferred direction growth and uniform growth of dendrites are avoided, and the morphology is improved. Properly increasing the revolution and rotation speed of the stirring shaft can refine the grains of semi-solid aluminum alloy parts, improve the grain morphology, and improve the tensile strength. The planetary stirring semi-solid process is very suitable for rheological high-pressure casting.
为了解决单轴搅拌熔体对流换热不足的问题，基于CFD模拟研究了行星搅拌下熔体的温度场和剪切速率。还对该工艺的微观组织和性能进行了实验研究。结果表明，与单轴搅拌半固态工艺相比，行星搅拌方式下铝合金半固态浆料的对流换热能力更强。此外，其温度场能更快、更均匀地降至半固态范围，有利于大量形核并提高形核率。整个熔体的温差小，避免了枝晶的择优生长和均匀生长，改善了形态。适当提高搅拌轴的公转和自转速度可细化半固态铝合金零件的晶粒，改善晶粒形态，提高抗拉强度。行星搅拌半固态工艺非常适合流变高压铸造。
