双向弱电磁搅拌+等温保温处理制备半固态A356合金浆料的研究*

Research on Semisolid A356 Alloy Slurry Fabricated by Two-Way Slightly Electromagnetic Stirring and Isothermal Holding

摘要:

结合弱电磁搅拌和熔体等温保温技术,提出了一种复合浆料制备新工艺：双向弱电磁搅拌+等温保温处理。研究了铝熔体双向弱电磁搅拌后等温温度580~610℃、等温保温时间3~15min对凝固组织形貌演化规律的影响。结果表明,在不同的等温保温参数作用下,随着温度升高、时间延长,初生相尺寸逐渐细化球化,但等温温度和等温时间存在阈值。超过阈值,初生相反而粗化。经过对比初生相形貌可知,在等温温度600℃、等温时间7min条件下初生相的尺寸细化和球化程度达到最佳,平均等积圆直径为29.4μm,形状因子0.86。因此,该温度和时间是半固态A356铝合金在复合工艺条件下,匹配合理的熔体等温处理工艺参数。通过该新型复合工艺可制备出品质合格的半固态铝合金浆料。

Abstract:

A new technology combined with slightly electromagnetic stirring and melt isothermal holding technology was formed: Two-way slightly electromagnetic stirring and isothermal holding. The effects of the isothermal holding temperature from 580℃ to 610 ℃and the isothermal holding time from 3min to 15min on the evolution of solidification microstructure were researched. The results indicated that under different isothermal heat treatment parameters, as the temperature increased and time prolonged, the size of the primary grains was gradually refined and spheroidized. However, the threshold value of the isothermal holding temperature and time could be found, so the grains became coarsened. Above the threshold value, by comparing the microstructure of the grain, it was found that the proper parameters were the isothermal holding temperature of 600℃and the isothermal holding time under 7min, at this conditions, the average equal-area circle diameter and average shape factor of the primary phase were 29.4μm and 0.86, respectively. Therefore, the proper temperature and time was the semisolid A356 aluminum alloy in the composite process to match the reasonable melt isothermal holding process parameters. The qualified semisolid aluminum alloy slurry could be prepared by the new composite process.