Reheating Technology and Microstructure Evolution of Semi-solid LY12 Alloy

The semi-solid billets of LY12 alloy fabricated by cooling-slope-tube with shearing process were reheated.The effects of reheating temperature and holding time on the semi-solid microstructure were investigated during reheating.The results show that the eutectic phase dissolves and diffuses toward primary phase.The globe rate of primary phase increases with the increase of remelting temperature or holding time.When the holding temperature is much higher or the holding time is much longer,the samples are susceptible to deformation.The optimum microstructure with the grain diameter of 55～65 μm and liquid fraction of 43%～45% can be obtained when the reheating temperature is 610～615 ℃ and holding time is 10～15 min.The samples are susceptible to serious deformation above 620 ℃.