The Impact of Dephosphorization on the Quality of Continuous-Casted Slab
1 Introduction
High-phosphorus steel is a common steel in steelmaking. Phosphor is one of the elements that affects the strength, hardness, plasticity and other mechanical properties of steel. The presence of phosphor impairs the mechanical properties of steel and reduces the operational performance. Therefore, the effective removal of phosphor during steelmaking is necessary. Dephosphorization is one of the commonly used methods to reduce the amount of phosphor in steel. This method is an important process in the production of high-quality steel. In this paper, dephosphorization of continuous-casting slab is studied and its impact on the quality of the product is discussed.
2 Principles of Dephosphorization
2.1 The Definition of Dephosphorization
Dephosphorization is a refining process that uses calcium nodules or calcium-based compounds to remove phosphorus from molten steel without altering its other chemical compositions. The main purpose of dephosphorization is to reduce the phosphorus content in liquid steel and improve the process performance. This process is conducted either in a continuously cast slab or in a heated furnace.
2.2 Working Principles of Dephosphorization
The working principle of dephosphorization is that the calcium-based reagent reacts with the phosphor present in the molten steel, forms calcium-iron phosphates, and separates these phosphates from the molten steel. The separated calcium-iron phosphates precipitate to the bottom of the molten steel, and the molten steel is processed after the precipitation. The process of dephosphorization is a process of separating the phosphor from the molten steel.
3 Effects of Dephosphorization on the Quality of Continuous-Casting Slab
The dephosphorization process affects the quality of continuous-casting slab in several ways. This section will discuss the effects of dephosphorization on the internal structure of the slab, the mechanical properties of the slab, and the surface quality of the slab.
3.1 Effects on the Internal Structure of Continuous-Casting Slab
Dephosphorization can reduce the inclusion content in the molten steel and therefore the inclusion content in the continuous-casting slab. Studies have shown that the inclusion content of the slab can be reduced by up to 12%. In addition, the crystal size of the slab is reduced due to dephosphorization, which also contributes to an improved internal structure.
3.2 Effects on the Mechanical Properties of Continuous-Casting Slab
Dephosphorization can has a positive effect on the mechanical properties of the continuous-casting slab. It can increase the hardness and strength of the slab, and improve its impact toughness. The presence of phosphor in the slab can affect the grain structure of the slab and reduce its mechanical properties. The elimination of phosphor can effectively improve the mechanical properties of the slab.
3.3 Effects on the Surface Quality of Continuous-Casting Slab
The surface quality of the slab is also affected by the presence of phosphor in the slab. The presence of phosphor can lead to a large number of non-metallic and oxide inclusions, which can cause cracks, scratches, and other defects on the surface of the slab. The elimination of phosphor can improve the surface quality of the slab, reduce the number of non-metallic inclusions and oxides, and reduce the risk of surface defects.
4 Conclusions
This paper has discussed the principles and effects of dephosphorization on the internal structure, mechanical properties and surface quality of continuous-casting slab. Dephosphorization can effectively reduce the inclusion content, increase the hardness and strength, and improve the impact toughness and surface quality of the slab. It is an important process in the production of high-quality steel and should be used with caution.
