Papers by Keyword: Soft Reduction

Abstract: The paper compares the internal structure of two continuously cast slabs with a section of 300 × 2600 mm from a tube steel of the strength class K60, one of which is molded with a soft reduction, and the other is without external influence. A comparative analysis of the structure of two templates showed that the location of areas with an increased metal pickle ness in the axial part of the templates varies. On the template from a slab cast without reduction, this section is below the geometric center of the work-piece in thickness, at a distance of 49.2% from the underside, that is, the "lower" asymmetry of the slab structure is observed. On the template from the slab cast off with soft reduction, the area with an increased pickle-ness is located above the middle of the work-piece: at a distance of 51.7% of the side of the large radius, an "upper" asymmetry of the slab structure is formed. Consequently, as a result of the external action on the cast work-piece, the location of the axial sponginess, relative to the geometric centre of the slab, is changed by moving from the lower to the upper half of the work-piece. The metal of the axial part of the reduced slab has a denser structure, the degree of development of axial looseness in the metallographic evaluation is reduced by an average of 0.5 points. The work shows the change in the content of chemical elements along the thickness of slabs. In the reduced metal, the maximum value of the degree of zonal inhomogeneity of the most impurities is higher than in the metal without external influence. This is explained by the fact that, as a result of reduction, the zone of location of the axial chemical heterogeneity in the slab becomes smaller in width.

Abstract: In this paper, a two-dimensional non-steady-state heat transfer model has been established for the working conditions of thick slab in a steel plant in China, a modification has been made on the basis of the nailing experimental results, the slab solidification difference of practice and prediction by field heat tracing model has been analyzed. The results show that the actual solidification end point of slab is more close to meniscus than prediction, the distance difference is 0.592m, the better soft reduction zone is from 0.2 to 0.9, which the level of central segregation can be reduced from the class B 1.0 to C 1.0.

Abstract: Numerical and physical simulation on model samples can provide data for various aspects of metal forming, without resorting to time-consuming and costly full-scale tests. This paper presents examples of modeling of the deformation of a slab with a liquid core. The use of soft reduction can enhance the homogeneity of the structure, which improves the quality of cast billets. Mathematical modeling is described here where the fluid layer is taken into account by the influence of boundary conditions in the crust in the form of ferrostatic pressure, which allows calculation of the intensity of deformation, total deformation and strain. It also provides a novel method for studying the process of soft reduction. It is based on a physical model of the slab consisting of a closed solid shell made of a calibrated lead shot and the Wood's alloy. To simulate the liquid molten metal, the interior of the shell is filled with gelatin. This approach can be applied to further studies on deformation processes and the penetration of deformation into complex metallic systems.

Abstract: To clarify the efficiency of internal reduction during continuous casting bloom when the technology of soft reduction is applied, a thermal-mechanical coupled FEM model was developed to investigate the internal reduction efficiency. Basing on the model developed in this article, the area variation of the mushy zone under soft reduction could be calculated. A new calculation method of internal reduction efficiency through the area variation of mushy zone was proposed. The variation trend of internal reduction efficiency as a function of soft reduction amount, calculated by two different methods, was introduced.

Abstract: Soft reduction has been proved to be the best way to minimize center segregation and eliminate center porosity. Aiming at determining optimum soft reduction parameter for variation steel grades and different process conditions, a thermal-mechanical coupled FEM(Finite Element Method) model was developed to analyze the deformation behavior of the given bloom under the operation of soft reduction technology. The mechanical strain / stress of the bloom cross-section, especially the stain /stress around the solidification front, under the application of soft reduction are obtained. Considering the high temperature mechanical properties of the given steel grade GCr15 (with chromium content of 1.40~1.65 percent and carbon content of 0.95~1.05 percent) and strain/stress distribution in the section thoroughly, the proper soft reduction parameter are determined.

Abstract: Based on practical production technology, using some methods like segregation index analysis, the research is focused on the relationship between the maximum segregation index of carbon, phosphorus, sulfur in superwide slab and rolling reduction, reduction ratio, reduction rate of superwide slab caster. During the process of soft reduction, the theory that the minimum of the maximum segregation index corresponds to the technological parameters like optimal rolling reduction, optimal reduction ratio, optimal reduction rate of the superwide slab caster can be provided as a theoretical basis for the production of superwide slab.

Abstract: A two dimensions (2D) multiphase solidification model is used to study the liquid core solidification in the influence of deformation during soft reduction of continuous casting (CC). The transient transport equations (mass, momentum and enthalpy) for each phase of a thin steel slab CC are solved. Four different cases including of density-temperature function and deformation reduction factor on this CC are simulated. The solidification ending point position of liquid core, temperature, velocity and fracture of liquid and solid phases are compared. Understandings to the deformation and liquid core formation mechanism on soft reduction solidification process of CC are improved.