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Synthetic ductile iron production process
Pubdate date:2019-10-17Views:0
Synthetic nodular cast iron is made of scrap steel, pig iron, recycled material and recarburizing agent. It melts molten iron with certain composition through complex physical and chemical reactions under high temperature conditions, and spheroidizes and inoculates to obtain ductile iron. Production Process. Compared with the traditional ductile iron production process, it has the advantages of low production cost, low energy consumption and high product quality.

Its production process:

1, ingredients:

Scrap steel (70%), spheroidal pig iron (30%), recarburizer, spheroidizing agent and inoculant are used as charge, and are smelted by medium frequency furnace and cast into pieces.

2, smelting:

According to the ingredients, the feeding to the intermediate frequency furnace should strictly follow the following sequence: pig iron - 1/3 scrap - 1/2 recarburizer - 1/3 scrap - 1/2 recarburizer - 1/3 scrap. When the power transmission starts to be smelted and smelted to 1400 to 1430 ° C, the slag is sampled for spectral analysis. If the composition meets the requirements of the molten iron composition, the temperature is raised to 1450~1470 °C, and the spheroidization is carried out. If the ingredients do not meet the requirements, the ingredients are adjusted proportionally until the requirements are met, and the temperature is raised to the spheroidization temperature of the process.

3, spheroidizing process:

1) Bake the iron bag to dark red.

2) Preheat the inoculant with a total amount of iron content of 1.4% to 1.5% and a particle size of 10~25mm to 150~200°C, and put it on one side of the dam bag. The 75SiFe inoculant with a particle size of 15% to 0.3% and a particle size of 15~20mm is flattened and compacted, and its surface is covered with perlite. Finally, a ferrite plate similar in shape to the side of the dam is added to the ferrosilicon to achieve good spheroidization.

3) When the molten iron is about 1/3, it will start to adopt the flow. The operation method is to make a tooling, and the inoculant is uniformly added to the spheroidizing bag with the molten iron flow from the stove in the form of a chute, the molten iron is finished, and the inoculant is also added at the same time. The inoculant uses 3~5mm ferrosilicon particles, and the amount used is 0.4%~0.6% of the amount of molten iron.

4) After the reaction is completed, the molten iron in the ladle is calmed and the slag is repeatedly slag. Before casting the casting, the total amount of the 75SiFe inoculant with a particle size of 0.1%~0.15% and the smaller particle size is placed on the liquid surface and repeatedly stirred. , for instant gestation.

4, pouring:

Cast the molten iron into pieces as required.

5, heat treatment process:

In order to avoid the use of a continuous annealing process for heat treatment of ductile iron castings, problems such as unstable product quality have arisen. A more suitable segment annealing heat treatment process, namely high temperature graphitization and low temperature tissue transformation two-stage annealing, to eliminate white mouth, reduce hardness and improve cutting performance.
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