Three Dimensional Finite-element Analysis And Taper Design Of Continuous Casting Mould Of Steels

Today, over96.95%of the steels are produced via continuous casting in our country. Continuous casting machine has become the workhorse in steel industry. The mould is one of the most important equipments in continuous casting machine. The qualities of the billets produced by continuous casting largely depend on the solidification and shrinkage processes of molten steel in the mould. However, the shape and taper of the inner cavity will influence the heat transfer between the billet and mould directly. So, the shape and taper of the inner cavity need to be designed suitably, which need to understand the temperature and stress field in the billet first. But the results are difficult to be acquired through experimental in view of the economical and technical reasons. With the development of computer, it is an effective way to optimize and design the mould by simulation. It is an important assignment for simulation of continuous casting process to optimize and design the continuous casting craft and the mould by using less labor and resources for higher properties of the billet.The petal-like inner cavity mould provides for the billet to be shaped, and hence for cooling to be regulated, during travel of the billet through the shaping portion of the mould. With the development of the simulation technology, a three dimensional thermal-stress couple model was build to simulate the solidification and the shrinkage of the billet in the mould based on the ANSYSTM. A dynamic-loaded boundary condition was used to simulate the movement of the billet in mould with considering the ferrostatic pressure. So based on the secondary development for ANSYSTM, the solidification and shrinkage of the molten steel in mould are simulated.The results indicate that three kinds of billet (37Mn5V, ST45EQ and X42) have lower temperature (which respectively is1073oC、1097oC、104oC) in the petal-center than that in the petal-edge at the exit of the petal-like mould, and the shrinkage is larger in the petal-center than the petal-edge. The shrinkage of the billet with considering ferrostatic pressure is smaller than that without considering ferrostatic pressure. The difference value has a maximum (0.15mm) at490mm below meniscus. There exists tensile stress in mushy area and compression stress in solid phase area; moreover, tensile stress reach maximum at almost solidification front; compression stress reach maximum at billet shell surface. At the exit, shrinkage of the two kinds of square billets (B72LX and ER73S6) is0.251mm and0.058mm respectively in the surface center.1.188mm and1.913mm in the angle and1.146mm and1.865mm in the deflective angle.Based on the analysis of the simulation results, according to the shrinkage of the five grades steel, the tapers of the moulds of the five grades steel were designed. There are four stages of the taper for steel37Mn5V and st45eq, and the petal disappears at360mm above the mould exit for this two grades steel. There are two stages for steel x42, and the petal disappears at500mm above the mould exit. Besides, the tapers of the angel and surface center of the square billet are designed respectively. The taper changes smooth between the angel and surface center of the square mould.