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球铁有较大的共晶石墨化膨胀,这个膨胀对铸件的尺寸精度、内在的及外观的质量均有影响。过去对此的研究着重在膨胀量上,现今的研究则致力于膨胀力上,因为由后者研究其影响更为直接而且精确。最大共晶膨胀力是指试样的膨胀完全受到抑制时测得的膨胀力。在本研究中利用耐火砖的高刚度和低的导热性,以其做成铸型,并设计了与现在一般采用的不同的测试装置,不仅可测出球铁的最大共晶膨张力,而且还可在其他条件相同的情况下,比较铸型刚度不同的共晶膨胀力。这为目前其他测试方法所不及。本试验的数据用最小二乘原理整理,借助电子计算机的运算和控制绘图,较精确地绘出了铸型刚度(阻力)和共晶膨胀力之间的关系曲线,并对曲线进行了讨论。在本试验的给定成分下得出的最大共晶膨胀力约为166.7kg/cm~2。
Ductile iron has a larger eutectic graphitization expansion, the expansion of the casting dimensional accuracy, intrinsic and appearance of quality have an impact. In the past, the research on this has focused on the amount of expansion. Nowadays, the study focuses on the expansion force, which is more direct and accurate. The maximum eutectic expansion force is the swelling force measured when the expansion of the sample is completely suppressed. In this study, the high rigidity and low thermal conductivity of refractory bricks were used to make castings and a test apparatus different from that commonly used today was designed to measure not only the maximum eutectic expansion of ductile iron, but also But also in other conditions under the same circumstances, the mold stiffness of different eutectic expansion force. This is beyond the reach of other test methods. The data of this experiment are sorted by the least squares principle. With the help of the calculation and control drawing of the computer, the curve of the relationship between the stiffness (resistance) and eutectic expansion force of the mold is plotted more accurately. The maximum eutectic expansion force obtained for a given composition of this test is about 166.7 kg / cm ~ 2.