In the process of using the carburizer, many factories tend to pay attention to the carburizing effect of the carburizer. In "synthetic cast iron" hot metal, carburizer is one of the main sources of graphite nucleation, which is often overlooked. In fact, the addition of carburizer is not simply "increasing C", but in order to increase its graphite nucleation nucleus, so that it can obtain better matrix structure and mechanical properties. In production practice, not all carburizers can achieve this effect.
The production of qualified carburants requires strict selection of materials and then high temperature graphitization.
In this process, impurities such as sulfur, gas (nitrogen, hydrogen, oxygen), ash, volatiles, and water are not only reduced, but also improved in purity. The appearance of nitrogen pores is more effectively avoided. At the same time, it also changes the carbon atoms from the original disordered and disordered arrangement to the ordered layered arrangement, so that most carbon atoms can become a better graphitization driving force.
This process is called graphitization. The surface of the carburizer that has not been graphitized at high temperature is covered with a thin layer of viscous ash, so there is basically no direct dissolution in the hot metal, and the carbon can only gradually diffuse and dissolve in the hot metal over time. The dissolution time of the carburizer increased, and the absorption amount of the carburizer decreased.
Only graphitized carburizer can quickly dissolve carbon atoms in hot metal, when the hot metal solidifies, under the action of a strong nucleation driving force, adsorbed on the nucleation nucleus generated by the gestation, and grow into graphite. If the selected carburizer is not graphitized at high temperature, the graphitization driving ability of carbon atoms will be greatly reduced, and the graphitization ability will be weakened.
Even if the same amount of carbon can be achieved, the quality of the product is completely different.
There are many kinds of carburizing agents, and there are many materials that can be used as cast iron carburizing agents. The production process of the carburizer is also different, the quality is very different, and the price difference is also very large. Casting product geometry and quality requirements, the correct choice of carburizer.