The research on the chemical composition of nodular cast iron provides a reliable basis for the composition design of the experiment. Therefore, the chemical composition range of nodular cast iron experiment is designed. See Table 1.
| Element name | C | Si | Mn | P | S | Re | Mg | Cu | Bi |
| Element content | 3.6-4.0 | 1.8-2.3 | <0.4 | <0.04 | <0.02 | 0.02-0.03 | 0.02-0.04 | 0-0.5 | 0-0.006 |
Smelting experiment includes batching calculation and production process design. Proportioning calculation is to calculate the proportion of each furnace charge during smelting according to the designed chemical composition and the chemical composition of raw materials. The production process design of nodular cast iron is to formulate the best production process parameters according to the actual production conditions.
The raw materials used in the experiment of nodular cast iron mainly include raw pig iron, scrap steel, ferrosilicon, high-efficiency spheroidizing agent, composite inoculant, pure secret, electrolytic copper, etc. the chemical composition is shown in Table 2.
| Raw material | C | Si | Mn | P | S | Ca | Re | Mg | Ba | Bi | Cu |
| Pig iron | 4.27 | 0.45 | 0.124 | 0.031 | 0.0163 | – | – | – | – | – | – |
| Steel scrap | 0.30 | 0.30 | 0.40 | – | – | – | – | – | – | – | – |
| High efficiency spheroidizing agent | – | 44-46 | – | – | – | 2.98 | 2.85 | 8.25 | – | 0.1 | – |
| Compound inoculant | – | 60-65 | – | – | – | 1 | trace | trace | 3-5 | – | – |
| Ferrosilicon | – | 75 | – | – | – | – | – | – | – | – | – |
| Pure bismuth | – | – | – | – | – | – | – | – | – | 99.99 | – |
| Electrolytic copper | – | – | – | – | – | – | – | – | – | – | 99 |
In order to fully grasp the actual production situation and ensure the success of the experiment, in the early stage of the experiment, the chemical composition of molten iron, the amount of spheroidizing agent and inoculant, and the influence of copper and tin on the mechanical properties of nodular iron were studied respectively according to the mechanical properties of the obtained samples. Considering the cost factor, in the early stage of the experiment of nodular cast iron, each furnace of molten iron was calculated according to 250 kg, a total of 8 furnaces, one casting was poured in one furnace, and the furnace number was A1-A8.
In the later stage of ductile iron experiment, the production of simulated castings is carried out according to the best production process parameters determined in the early stage, and the technical verification and trial are further carried out through the simulated ductile iron. In the later stage of the experiment, each furnace of molten iron is proportioned according to 5 tons, a total of 2 furnaces, and 2 pieces are poured in one furnace, numbered B1-B4 according to the pouring sequence.