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六十年代以来,在利用磁场控制结晶方面已提出了不少研究报告及专利[1—10〕,其中有一些已在生产上应用。利用磁场控制合金结晶过程的实质是靠磁场感应液体合金,使之运动或静止,以使铸件形成所要求的晶体组织。利用旋转磁场控制合金的结晶过程,使铸锭得到细小的等轴晶,效果显著,已在半连续铸锭上试验成功。 但是许多资料只介绍旋转磁场可以细化晶粒的一面,而对铸锭中有时出现的柱状晶区,未作任何说明。我们的实践表明,旋转磁场是控制晶粒细化的有利手段,但是在一定条件下仍然能产生柱状晶,甚至对于某些合金会引起微观组织的粗化。 本工作的目的是进一步研究在旋转磁场作用下合金结晶过程的一些基本规律,以便更好地利用这一方法。
Since the 1960s, many research reports and patents [1-10] have been proposed in the field of controlling the crystallization using magnetic fields, some of which have been applied in production. The use of magnetic field control alloy crystallization process is essentially magnetic field-sensitive liquid alloy, so that the movement or stationary, so that the casting to form the required crystal structure. The use of rotating magnetic field control alloy crystallization process, so that the ingot to obtain a small equiaxed crystal, the effect is remarkable, has been successfully tested on semi-continuous ingot. However, a lot of information only describes the rotating magnetic field to refine the crystal grain side, but there is no explanation for the columnar crystal grain sometimes appearing in the ingot. Our practice shows that the rotating magnetic field is a useful tool to control the grain refinement, but it can still produce columnar crystals under certain conditions, even for some alloys, causing the microstructure to coarsen. The purpose of this work is to further study some basic rules of the crystallization process of alloys under the action of rotating magnetic field in order to make better use of this method.