AZ61合金半固态二次加热工艺及组织演变

研究了应力诱发熔体激活法(SIMA)制备的AZ61镁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,二次加热初期半固态组织首先熔合合并,随着保温时间延长,晶粒逐渐长大和球化,液相份数增加;保温温度越高,晶粒长大和球化速度加快。在592℃加热、保温20min~40min,可以获得均匀、圆整的半固态组织,晶粒大小为80μm~90μm,液相率为40%~42%。高于597℃时,试样重熔过程中易发生严重变形。

Reheating technology and microstructural evolution of semi-solid AZ61 magnesium alloy during reheating in semi-solid state

The semi-solid billets of AZ61 magnesium alloy fabricated by strain-induced melt activation(SIMA) process were reheated.The effects of reheating temperature and holding time on the semi-solid microstructure were investigated during reheating.The results showed that the semi-solid microstructure grew up firstly through coalescence in the early stage of the whole reheating process.The mean diameter of grains increased with the prolongation of isothermal holding time,with grains sphericized and liquid fraction increased.In the meantime,the higher the holding temperature was,the faster the grains grew up and sphericized.The optimum microstructure with mean diameter of grains 80～90μm and liquid fraction 40%～42% can be obtained,when the reheating temperature was near 592℃ and holding time 20～40min.The samples were susceptible to serious deformation above 597℃.