Study On Flow Field And Temperature Field In CSP Mold

Compact Strip Production(CSP) casting is one of the thin slab casting process,andthe mold is core of this process.With the unique funnel-shaped structure of mold, thisprocess greatly differents from the ordinary slab.The mold has a narrowcavity,simultaneously the initial shell will be extrusion and deformed by mold copper incasting process.And under the condition of high casting speed, the free surface may besevere fluctuation、uncovered and involving liquid slag,thereby causing the bondbreakout phenomenon.Additionally,uneven growth of shell is the main reason for stressconcentration in Weaknesses of solidified shell, causing cracks Breakout possibly. Theseare the major factors that influence the casting anterograde.So it is important to studythe flow and heat transfer behavior of molten steel in mold,and it is also the key factorto ensure casting anterograde and improve slab quality.In this paper,the object of study is the CSP mold of a domestic steel,and thephysical modeling and numerical simulation have been used to study the molten steelflow pattern and heat transfer behavior in mold systematically. The study shows that:1) The molten steel flow pattern in mold are two upper refluxes and two downrefluxes,and in considering the case of solidified shell,there are small whirlpoolsexisting near the corner of the mold,which may increase the possibility that liquid slagis involved in the place between the shell and the mold copper.2) Level fluctuation hascyclical intense phenomenon,and the cycle is around25s. The level fluctuation near theSEN is very small,and the position(1/4position) in the middle of SEN and narrow sideis bigger,and the largest appears at the narrow. Simultaneously the level fluctuation atthe narrow is affected by casting speed and insertion depth of SEN greatly,and the levelfluctuation near the SEN affected relatively small.3) When the casting speed is4.0m/min,the slag phenomenon began to appear; and when the casting speed is4.5m/min,the free surface may be exposed.4) Along the casting direction,thetemperature on shell surface has a law that the temperture decreases first and increasesthen.And in the upper part of the mold, the transverse temperature is uniform relativelyand it is not uniform in the lower part of the mold,at which exist two places where thetemperature gradient is higher.5) The thickness of the solidified shell is uneven at moldexit,where1/4position is thinner(about11mm)、the two other places are thick(about15mm).With increasing casting speed,the temperature gradient on shell surface decreases and the shell grow more evenly.With increasing the insertion depth of SEN,the average temperature on shell surface decreases and the thickness of the solidifiedshell near SEN and narrow increase, at the same time the thickness of1/4position isalmost unchanged,which cause more uneven of the thickness of the solidified shell.6)Through a comprehensive analysis of physical and numerical simulation results,itsuggests that the right process parameters:casting speed4.0m/min、insertion depth ofSEN300mm and casting speed4.3m/min、insertion depth of SEN340mm,which canguarantee no slag、surface exposed phenomenons and make solidified shell growuniformly.By studying the flow field、temperature field and growth pattern of solidified shellin CSP mold,the law has been clarified that process parameters affect the flow field andtemperature field,and the results provide a theoretical basis for ensuring castinganterograde and improving slab quality.