In the early 1960 s, with the purpose to exploit and utilize the rich rare earth resource of their country, Chinese foundrymen,
including the foundry technicians of Wuxi Diesel Engine Works (WDEW), had made efforts in research of rare earth nodular iron. As a result, it was found that the nodularizing effect of the rare earth is relatively weak, and the nodularity of the rare earth nodular iron is inferior to that of the magnesium nodular iron, however the former iron has obviously less
dross and shrinkage than the latter iron. This result caused the attempt to use both the rare earth and magnesium as nodularizer to conduct nodularizing treatment that led to the birth of the rare earth magnesium nodular iron and solved the quality problems in nodular iron production at that time in China caused by reasons in both aspects of raw materials and technology, so it had played and is still playing a significant effect in nodular iron development of China. Investigation showed that, compared with magnesium nodular iron crankshafts, the
RE-Mg nodular iron crankshafts have much less dross and shrinkage defects, and obviously higher fatigue strength and wear resistance. Therefore it was popularized quickly nationwide in China. Not long after that, it was again WDEW which had successfully developed the pour-over nodularizing treatment process ('sandwich' process) with RE-Mg-Si-Fe alloy as nodularizing agent to replace the before-used nodularizing process with the rare earth and magnesium being plunged into molten iron under pressure in a sealed ladle which was not very safe and caused severe temperature decrease, as well as further applied the RE-Mg nodular iron to connecting rods, heavy section crankshafts and heavy cylinder blocks with weight up to 20 t. In addition, in the beginning of 1965, WDEW also succeeded in development of the isothermally quenched RE Mg nodular iron camshafts and putthem into mass production. The rare earth can be used to neutralize the anti-nodularizing effect of some trace elements and some gasses in the molten iron, and some trace elements are also needed to neutralize the nodular graphite distorting effect of the rare earth. The critical CE value of RE-Mg nodular iron to cause graphite floatation is 4.55 %, almost the same as that of Mg nodular iron. When using rare earth elements in nodular iron, it is necessary to pay attention to ensure their content to be proper in order to make full use of their advantages and avoid their unfavourable effects.