Defects in Continuous Cast Steels Dec11

Defects in Continuous Cast Steels...

Defects in Continuous Cast Steels Continuous casting (CC) is the process which converts liquid steel into a solid product mainly in the form of slab (either thick or thin), bloom or billets. It is one of progressive steel making technologies which produces a cast product of a desired cross section in indefinite length. The CC process requires strict observance of operating procedures,  technological norms, and advanced production and control techniques. Despite these measures, the occurrence of defects in the CC product cannot be fully ruled out. The formation and the type of defects depends on the status of CC machine equipment, the cast product shape and size, the steel grade, the technological conditions of casting such as casting temperature and speed, the mould oscillation and cooling, the quality and properties of the casting powder etc. A defect in a CC product can be defined as a deviation in the appearance, shape, dimension, macrostructure, and/or chemical properties when compared with the specifications given in the technical standards or any other normative documents in force. Defects are detected after casting in the CC product through visual inspection of their surface at the cooling beds, by checking the surface quality again by visual inspection on the inspection beds, or by checking the chemical analysis and the macrostructure of the test samples in the laboratories. The defects in CC products generated during the solidification and cooling process lead to loss or diversion of prime material for further processing or sale. To prevent these losses, it is necessary to analyze the causes of the occurrence of defects for taking preventive action by adopting preventive metallurgical technologies and constructive solutions. Also it is necessary to segregate and remove defective product from the prime material. A defect is not always the...