LY12合金半固态二次加热工艺及组织演变

Reheating Technology and Microstructure Evolution of Semi-solid LY12 Alloy

研究了倾斜式冷却剪切技术制备的LY12铝合金半固态坯料在二次加热时加热温度和保温时间对其组织的影响。研究表明,二次加热可使团块状相逐渐演变成球状相;随保温温度及保温时间的增大,初生相的生长和球化速度变快;保温温度过高或保温时间过长,试样易发生变形;二次加热最佳工艺为610～615℃保温10～15min,此时晶粒大小为55～65μm,液相率为43%～45%;高于620℃时,试样在重熔过程中易发生严重变形。

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 ℃.