6061合金电磁半连续铸锭与二次加热组织研究

用电磁半连续铸造技术制备6061合金半固态坯料,并在不同的保温温度和保温时间下进行二次加热实验,观察铸锭及二次加热坯料的微观组织,研究保温温度和保温时间对二次加热淬火组织的影响.结果表明:6061合金可以通过电磁半连续铸造获得具有细小、均匀、非枝晶组织的铸锭;二次加热过程中,随着保温温度的升高,组织转变速度加快;保温温度过高,淬火组织粗大,对成形件性能不利;随着保温时间的增加,初生α-Al不断球化,淬火组织也越圆整,但晶粒长大明显;在610~630℃下保温10~15 min,所得淬火组织均匀,晶粒细小,是理想的成形组织.

Research on Cast and Reheated Microstructures of 6061 Alloy by Electromagnetic Semi-continuous Casting

The semi-solid billet of 6061 alloy was prepared by electromagnetic semi-continuous casting technology and the reheating experiments were carried out.The influence of holding temperature and time on quenching microstructures after reheating was studied by observing the microstructures of ingot and reheated billets.The results showed that 6061 ingot with fine and uniform equiaxed grain structure can be obtained by electromagnetic semi-continuous casting.The microstructure evolution is accelerated with the increase of holding temperature during reheating.Too high holding temperature is not good to the property of formed parts because of the coarse grain of quenching microstructure.The quenching microstructure turns out to be more spherical because the α-Al spheroidizes continuously with the increase of holding time,but the grain size increases obviously.The fine and uniform grain structure can be obtained by reheating at 610～630 ℃ for 10～15 min.