Introduction
Continuous casting is one of the most important process in steelmaking industry. It became an important manufacturing process due to its high productivity, good quality and lower cost. In this process, liquid steel is poured into an open-topped casting mould and is allowed to solidify. This process have several important advantages, including reduced need for ingot molds, higher production rates, improved product quality and cost savings.
However, the process of continuous casting is not without flaws. These defects can have a significant impact on the quality of the final product. This article will discuss what these defects are and how they can affect the quality of the rolling stock.
Defects of Continuous Casting
The most common defects of continuous casting are slivers, stringer, hanging skin, pigtails, center-line segregation and macro-segregation. Slivers are strings of metal which are formed due to inadequate penetration of the steel in the mold. This can lead to poor surface quality and weak areas in the structure of the material. Stringers occur when a steel strand passes over the top of the mould, leaving a small trail of metal which is neither solid nor homogeneous. Hanging skin is a result of the acceleration of the liquid as it passes through the mold, leaving behind a thin, unprotected layer of metal which can easily be broken off. Pigtails are related to slivers but are of a much smaller size, typically less than a millimeter long. Center-line segregation occurs when there is an unequal distribution of alloying elements between the center and edges of the steel strand. This can result in material with a nonuniform composition and structure. Finally, macro-segregation is a result of rapid cooling, leaving behind large and non-homogenous lumps of material which can lead to non-uniform structures.
Impact on Rolling Stock
The effects of defects from continuous casting can have a significant impact on the quality of rolling stock. Slivers and hang skin can both result in weak areas in the material and poor surface quality, which can lead to higher rates of failure during use. Stringer and center-line segregation can both have an effect on the final product, as they can result in non-uniform composition, structure and hardness. This can reduce the strength and performance of the metal, leading to a lower quality product. Pigtails and macro-segregation can lead to areas of the steel which are structurally weak and can be easily fractured, leading to failure during operation.
Conclusion
In conclusion, the defects of continuous casting can have a significant impact on the quality of the final product. Slivers, stringers, hang skin, pigtails, center-line segregation and macro-segregation can all have an effect on the rolling stock, as they can lead to weakened areas, non-uniform composition and hardness, as well as increased risk of failure during operation. It is therefore important to identify and address any defects during the process of continuous casting in order to ensure the best quality of the product.
