内容
Continuous casting is a major process used in the production of steel. An important measure of the quality of the final product is the presence or absence of casting defects. The purpose of this report is to identify and evaluate the most common defects found in continuous casting and how they can be addressed.
Modern continuous casting involves the process of Steelmaking, where molten metal is poured through a bottom patched mold that is then vibrated and cooled by a pressurized liquid. Once solidified, the strand is cut at the pre-determined length and sent to the hot rolling mill. The desired shape and properties of the final product depend on the process followed during the continuous casting process.
Unfortunately, the continuous casting process is not without its flaws. When these defects are present, the product is less desirable, failure of the cast may result, and repair costs may be incurred. The most common continuous casting defects have been categorized into three major classes: surface defects, dimensional defects, and metallurgical defects.
Surface defects occur when non-metallic particles are trapped in the casting, commonly known as inclusions. The most common of these particles are oxides and sulfides, which create voids that weaken the integrity of the final product. Inclusive flaws can be addressed by controlling the ladle adjustment, tap and slag characteristics during the melting process, and by controlling the pouring temperature.
Dimensional defects are a result of improper cooling, conditions of solidification, or improper formation of the strand. Examples of this type of defect include shrinkage defects, misruns, warpages, and poor centerline temperature. Control of the cooling environment and surface treatments have proven effective in reducing these defects.
Metallurgical defects, on the other hand, are caused by a poor chemical composition of the metal or improper melting and alloying processes. These include deformation, segregation, crescents, overheating, and surface oxidation. An accurate analysis of the chemical composition of the molten steel can help identify and rectify these issues.
In conclusion, recognizing and evaluating the common defects found in continuous casting is a critical part of the success of the process. By following proper protocols, improving ladle adjustment, tap and slag characteristics during the melting process, and by controlling the cooling environment and surface treatments, it is possible to reduce the occurrence of these casting defects.
