Analysis of thermomechanical behavior of mold for continuous casting of steel in function of the copper alloy
Tutor / director / evaluatorRiera Colom, María Dolores
Document typeMaster thesis
Rights accessRestricted access - author's decision
The mold is one of the most important components of the continuous casting machine since the mold controls the shape and initial solidification of the steel product, where quality is either created or lost. During casting, the mold is submitted to heat flux from liquid steel on one side whereas the other side is water cooled, leading to the generation of large temperature gradients. It is also submitted to other stresses such as ferrostatic pressure and clamping forces. Casting can last several dozens of hours whereas the cooling step of the mold, when liquid steel is not poured anymore into the mold, can last only a few minutes. Maintaining a reliable, crack-free mold within close dimensional tolerances is crucial to safety and productivity. In order to withdraw the right amount of heat and to prevent mold distortion, mold is generally made of copper alloys that have the thermal and mechanical properties required for this function. The two copper alloys most widely used for casting mold are Cu-Ag and Cu-Cr-Zr. They present a wide range of thermal and mechanical properties due to the different treatments to which they can be submitted. The present master thesis aims to study the influence of thermomechanical properties of copper alloys on continuous casting mold behavior during casting and cooling, and more precisely on mold for continuous casting of steel slabs using realistic finite element models of heat transfer and stress. After realizing a literature review of the most widely used copper alloys, three finite elements models were developed in order to study the influence of three copper alloy grades on mold thermomechanical behavior. The three finite elements models were a 2D simplistic transverse section of the mold model, a 2D transverse section of the mold model that includes bolts and the backup plate and a 3D quarter mold model. Simulations of casting and cooling step were performed with ABAQUS 6.10® for the two most widely used copper alloys and a copper alloy that was previously submitted to a heat treatment. Simulations results show that the two copper alloys most widely used lead to similar mold behavior. Besides, the material submitted to a heat treatment does not lead to a critical behavior but can lead to a necessity of more frequent re-machining of the mold.
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