球墨铸铁的收缩分为液态收缩、凝固收缩和固态收缩三部分。其中凝固收缩和凝固的方式影响球铁的缩松倾向。球墨铸铁是以体积凝固方式凝固的。在球铁中,球状石墨在奥氏体包围下长大。当共晶团长大互相接触后,石墨球继续长大的体积膨胀力大部分作用在相邻的共晶团上,趋向于把它们挤得更开,使期间的孔洞增大。在最后凝固的部位,由于共晶团互相 Nodular cast iron shrinkage is divided into liquid shrinkage, solidification shrinkage and solid-state shrinkage of three parts. Among them, the way of solidification shrinkage and solidification affects the tendency of ductile iron. Ductile iron is solidified by volume solidification. In ductile iron, spherical graphite grew up surrounded by austenite. When eutectic groups grow up and come into contact with each other, the bulk expansion force that the graphite balls continue to grow mostly acts on the adjacent eutectic groups, tending to squeeze them more apart and increase the porosity during this period. In the final solidified parts, due to eutectic groups with each other