铸铁件生产中值得关注的一项新工艺-铸件凝固后的“控制冷却”

A New Type Technology Meriting Attention in Production of Iron Castings -Engineered Cooling of Castings after Solidifying

石墨铸铁件，也即含游离石墨的铸铁件，在浇注并凝固后的冷却条件对其性能具有重要的影响。铸件凝固后的控制冷却是一项新技术，其应用效果主要有：铸件不必进行消除应力退火，生产灰铸铁件不必加入Cu、Sn 等元素，生产ADI铸铁件不进行等温退火即可获得奥铁体基体等。日本一家公司对大型柴油机缸体铸件凝固后进行了控制冷却，所取得的效果为：（1）铸件凝固后的平均冷却速率从5.7℃／h提高到16.0℃／h；（2）铸件冷却至500℃需要的时间由46 h 缩短至18 h；（3）铸件无需进行消除应力退火。目前，美国等国家正在致力于石墨铸铁件凝固后的控制冷却技术的试验研究，但要在实际生产中应用这一技术，还有一些具体问题有待解决。

Cooling condition of graphitiferous iron castings （i.e., iron castings containing free graphite） after pouring and solidifying will have signiifcant inlfuence on their properties. The engineered cooling of castings after solidifying is a novel technology. The results got from the use of this cooling technology are that： （a） the castings have no need of stress relieving, （b） production of gray iron castings has no need of additions of copper and tin, （c） ADI castings with ausferrite matrix may be produced without the use of isothermal annealing, etc. In one corporation of Japan, the engineered cooling technology has been applied to a type of large-sized diesel cylinder after solidifying, and the results are as follows： （a） average cooling rate of the casting after solidifying was increased from 5.7℃/h to 16.0℃/h; （b） time required to cool the casting to 500℃ was shortened from 46 h to 18 h; （c） the casting had no need of stress relieving. At present, US and other countries are devoting oneself to study on the engineered cooling for the graphitiferous iron castings after solidifying, some specific problems, however, have yet to be solved, otherwise it is impossible for this cooling technology to be used in actual production.