冷却斜管工艺对A357合金凝固组织的影响
Effects of Cooling Sloped Pipe Process on Solidification Microstructure of A357 Alloy
韩坤年, 张 兴, 段望春
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作者单位：甘肃省机械科学研究院, 甘肃 兰州 730030
中文关键字：冷却斜管； A357合金； 半固态； 组织细化
英文关键字：cooling sloped pipe; A357 alloy; semi-solid; microstructure refinement
中文摘要：采用冷却斜管工艺以及在金属铸型中预放热电偶的方法，考察了A357合金在不同浇注温度下，经不同长度的斜管处理后，合金液的最高温度以及凝固组织的变化。结果表明：对A357合金进行冷却剪切处理，可有效的细化、球化凝固组织；浇注温度，斜管长度都会影响A357合金最终的凝固组织，随着浇注温度的降低以及斜管长度的增加，A357合金凝固组织中粗大的枝晶向玫瑰晶以及细小的球状晶转变；浇注温度在660 ℃时，经300、450、600 mm斜管处理后，进入铸型的合金液处于半固态区间，而在690、720 ℃浇注时，经斜管处理后的合金液仍为液态。
英文摘要： Cooling sloped pipe process and pre-set thermocouple in the metal mold were applied. The maximum temperature of casting alloy melt as well as the changes of solidification structure were investigated at different pouring temperature and different lengths of pipe. The results show that cooling sloped pipe process can effectively refine and spheroidize the solidification structure of A357 alloy. Pouring temperature and pipe length affect the final solidification structure of the alloy, with pouring temperature decreasing as well as pipe length increasing, the solidification of the alloy transforms from thick dendrite to rose as well as small spherical crystal; the casting alloy melt is in semi-solid liquid range when pouring at 660 ℃ after treated by 300 mm, 450 mm, 600 mm sloped pipe, while pouring at 690 ℃ and 720 ℃, the alloy melt through sloped pipe process is still liquid.