Study On Solidification Heat Transfer And Dynamic Soft Reduction Process For Slab Continuous Casting

In the continuous casting process, the Thermal-Mechnical behavior of casting slab has a significant impact on the final product quality. Therefore, the research of temperature distribution and soft reduction gradient of slab has an important practical significance in practical production process. In this paper, the research of secondary cooling and dynamic soft reduction key process parameters of slab was carried out, based on slab caster of steel making plant located in southwest of our country. The main content and conclusions in the paper are as follows:(1) Behavior of solidification heat transfer of slab was analyzed in continuous casting process, and build slab cross-section two-dimensional solidification heat transfer slice moving model. Changes of thermal physical parameters and forced vection boundary conditions caused by liquid steel were taken into consideration in the solidification heat transfer model.(2) Simulation study of slab temperature field in continuous casting process. Analysis of X80, P510, SAPH440 slab cross-section temperature and shell thickness distribution, and explore the influence of solidification heat transfer result of variation of casting speed and cross-section. Simulation results show that slab surface centre line of temperature rose at air cooling zone, and the temperature rising degree goes up with increasing of casting speed. For ever increase of 0.2m/min of casting speed, solidification end move backward from 4m to 4.4m and disappearing position of liquidus move back from2.6m to 3m. Variation of slab cross-section has no impact of solidification end location.(3) Simulation study on process parameters of slab soft reduction gradient, soft reduction rate and soft reduction zone and so on. Through analysis of theoretical model of soft reduction gradient and combining production technical and high temperature mechanical performance parameters, Finite Element Method has been used to simulate and calculate the soft reduction process, and we obtain various parameters under different casting speed, grades, and slab cross-sections. The conclusions we have drawed are as follows:? Soft reduction rate and gradient of slab decreased along with the strand directin; Average soft reduction gradient represents approximate linear decreasing relationship with casting speed, for X80 and P510 the average soft reduction gradient lowers 0.04mm/m while SPAH440 lowers 0.02m/min when the castig speed increases 0.2m/min? Soft reduction zone is closely related with casting speed, and reduction zone represents linear relationship with casting speed, the casting speed going up from 1.0m/min to 1.4m/min length of reduction zone increasing from 0.2m to 0.25m when the casting speed ever goes up 0.2m/min.? Steel grade changes caused little impact to soft reduction rate and gradient, and the range of soft reduction gradient variation of the three studied grades are all from 0.25mm/m to 0.33mm/m.? Changes of slab width caused little impact to distribution of center line solid fraction of slab, and curves of distribution of center line solid fraction of different width slab along with strand direction are very close. Soft reduction gradient had little effect with changes of slab width, the range of variation of soft reduction gradient is less than 5% when the width change 30%; Average of soft reduction gradient of slab represents linear relationship with width of slab, while slab width changes 20% the average soft reduction gradient changes 2%.