Stiffness Analysis and Experimental Verification of Segment Frame of Continuous Casting Machine

To verify the stiffness, the natural vibration and the reliability of the continuous casting machine in the configuration of dynamic soft reduction. Firstly, the three-dimensional model of the segment frame was established and the finite element simulation of the structure was carried out. Then, the deviation of the roll gap in the working process of the caster was measured by analog loading test. The results show that the stiffness of the segment frame of the continuous casting machine meets the requirements. Using dynamic soft reduction can improve the centerline segregation of casting slab in the process of continuous casting, which is of important practical significance in the production practice.

Study on Prediction of Reduction Position Based on Solidification and Heat Transfer Model

As one of the important parameters of dynamic soft reduction technology, reduction position seriously affects the using effect of this technology to decrease center segregation and porosity of continuous casting slabs. According to the actual production conditions, a two-dimensional solidification and heat transfer model was established. In order to obtain more accurate model, the heat transfer coefficient was amending by the pin shooting technique in measuring shell thickness. The laws of the effect of casting speed, superheat degree and specific water flow on reduction position were analyzed respectively and reduction positions were predicted in different working conditions based on the model. The experimental results show that the center segregation and porosity decreased obviously when it produces at the reduction position predicted by the model.

Application of the Dynamic Soft-Reduction Technology on the No.4 Slab Continuous Caster of Bayi Steel

The revamping & upgrading work has been done smoothly for the old soft-reduction system of the No.4 slab continuous caster in Bayi steel, as a result, all the segments (include both arc segments and level segments ) now have the dynamic soft-reduction function, which have been put into the industrial application successfully. Through the production practice, we can see that, after the revamping project, the dynamic soft-reduction function could be applied normally both in the arc segments and in the level segments for the No.4 slab caster, the whole soft-reduction process has been conducted steady and smoothly, the precision of roll gap control is good, the L2 model always makes an exact trace for the casting process and has the advanced algorithm, the L1 program has the reasonable control function and the reliable execution. When the soft-reduction action was executed in the unbending segment (Seg.7), there was no internal crack taking place for all the slabs, and the internal quality of slab such as center segregation was improved obviously, which had shown the metallurgical effect of the dynamic soft-reduction technology fully.

Effect of the Non-Equilibrium Solidus Temperature on Length of Soft Reduction Zone

Solidus temperature is one of the important key parameters to describe the non-equilibrium solidification states. However, the study of the non-equilibrium solidus is not enough presently. In present work, the key Influence factors on solidus temperature have been discussed, and it can be calculated by a mathematical model for solute microsegregation during the solidification. The calculated solidus can be agree with the recommended values by some dynamic soft reduction model. It is shown clearly the thermal analysis with non-equilibrium solidus was consistent with the pin shooting experiments. And the effect of the non-equilibrium solidus temperature on solid fraction and the length of soft reduction zone at the solidifying front has been studied sufficiently. Dynamic soft reduction metallurgical effect with the non-equilibrium solidus has been agreed by carbon segregation index and Macroetched experiment.

The Industrial Application of Dynamic Soft-Reduction Technology on the No.1 Slab Continuous Caster in No.2 Steelmaking Plant of Xinyu Steel

Through the one-month intense industrial test, the CISDI packaged soft-reduction technology of slab continuous casting has been put into practice to the No.1 slab caster of the No.2 steelmaking plant in Xinyu steel, China. The whole system has many advantages, such as the advanced algorithm and idea, the reasonable platform structure and the improved control function, which has been running stably and reliably. During the test process, a new calibrating method of roll gap has been adopted, which resulted in the perfect precision of gap control and the rational pressure feedback of hydraulic cylinder. By comparison of the macrographs of slab samples for the various steel grades, definitely, it can be concluded that, the application of the dynamic soft-reduction function will improve the internal quality of slab obviously, which has notable metallurgical effects on the center segregation defect of slab.

Study of Heat Transfer of Steel Solidification Process

Because the dynamic soft reduction of continuous casting process is based on the computation of the solidification end point, using model to simulating the steel solidificating process is more and more interesting. Especially, the influence of the heat flux to the solidification end point is needed to research thoroughly. In this paper the heat transfer model for the simulation of the solidification of steel droplet is established. The simulation reveals that the steel droplet (the radium is 7.2 mm) is solidified quickly in 4.3 seconds on water cooling copper plate, and in 3 seconds there is half of the droplet is frozen to solid. If there are materials resisting heat transfer inserted between cooling plate and liquid steel, the solidification end position would be moved to the deeper place below the shell in obvious extent, and the influence of heat flux to the ratio of mushy zone is weaker than that to solidification end point position.