对"均衡凝固技术"几个基本问题的讨论--球墨铸铁缩松、缩孔问题探讨(三)

就球铁件缩松、缩孔问题对“均衡凝固技术”几个基本问题进行讨论。指出作为该理论的基础的缩胀叠加图不完全符合实际情况；石墨化膨胀提前不利于消除缩松、缩孔。对薄小件缩松倾向大的原因、冒口是否应当靠近和离开铸件热节、是否可以早于铸件热节凝同、冷铁能否使膨胀提前，以及顶注的优点等问题提出不同的看法。认为按比例进行的均衡凝同不可能实现，而且依靠膨胀提前达到的均衡凝同对防止缩松、缩孔不利。

A Discussion on Several Basic Problems of "Proportional Solidification Technology"--An Approach to Shrinkage Problems of Nodular Iron (Ⅲ)

With respect to shrinkage problems of nodular iron, a discussion on several basic problemsof the "Proportional Solidification Technology" was held. It was pointed out that, as the basis of this theory, the contraction-expansion superposition graph doesn't conform to reality comprehensively; advanced graphitization expansion is unfavorable to shrinkage prevention. Different viewpoints were proposed on the reasons why castings with thin section and of small size are more easy to suffer from shrinkage defect? whether should the feeder be kept close to and also away from the hot spot of casting? whether could the feeder be earlier solidify than the hot spot of casting? Could the expansion be advanced by chills? what is the virtue of top pouring? It was considered that it is impossible to realize proportional solidification, and that the proportional solidification realized by advancing expansion is unfavorable to shrinkage prevention.