Different types of castings have different requirements for the technical indicators of recarburizers

In the foundry industry, different types of castings have different requirements for the technical indicators of recarburizers, and these requirements are crucial for ensuring the quality of castings.

Gray iron castings are a common type of casting. For gray iron castings, the carbon content of the recarburizer is usually required to be between 90% - 99%. A higher carbon content helps to promote graphitization, enabling the casting to have good mechanical properties. The sulfur content should be strictly controlled below 0.5%, as sulfur can reduce the graphitization ability, increase the chill tendency of the casting, and affect its machining and service performance. The volatile matter should be less than 1%. Excessive volatile matter will generate gas during the melting process, leading to defects such as blowholes in the casting. The particle size of the recarburizer is generally appropriate between 0.5 - 5mm. A suitable particle size can ensure that the recarburizer is evenly dispersed in the molten iron, improving the carburizing effect.

Ductile iron castings have more stringent requirements for recarburizers. Its carbon content needs to reach over 95% to ensure that there is enough carbon participating in the reaction during the nodularizing treatment to form good spherical graphite. The sulfur content must be less than 0.05%, as sulfur is a strong anti - nodularizing element that will interfere with the nodularizing process, reducing the number of graphite nodules and deteriorating their shape. The volatile matter should be less than 0.5% to reduce the impact of gas generation on the nodularizing effect. The particle size ranges from 1 - 10mm, which can better meet the carburizing requirements during the melting process of ductile iron.

The recarburizer used for steel castings usually requires a carbon content of over 98% to meet the high - carbon content requirements of molten steel. The sulfur content requirement is extremely strict, needing to be less than 0.03%, because sulfur can reduce the toughness and fatigue resistance of steel. The particle size is generally between 0.2 - 5mm, facilitating rapid dissolution and diffusion in the molten steel.

In conclusion, different types of castings have different regulations on the technical indicators such as carbon content, sulfur content, volatile matter, and particle size of recarburizers according to their own characteristics and quality requirements. Selecting a suitable recarburizer and strictly controlling its technical indicators are the keys to producing high - quality castings.