Research On Melting Behavior Of The Ca Cored-wire And Refining Process Optimization Of Molten Steel In Ladle

Calcium treatment process can turn Al₂O₃ inclusions into calcium aluminate,so that the inclusions are more likely to coagulate and remove,thus improving the cleanliness of the steel.While the effect of calcium treatment is not ideal,yield of calcium still remains to improve.Q235 steel produced by a domestic CSP plant was studied in this artical,submerged nozzle and the inclusions of Q235 treated by SiCa cored wire was investigated and analyzed,modification effect calcium treatment in Q235 was analyzed by Thermodynamics&Kinetics,melting behaviour of SiCa cored wire in 1873K steel,flow field characteristic,diffusion characteristic of Ca and inclusions in steel was caculated by FLUENT,the gastification behaviour of Ca in steel,the influence of the size,structure,alloy on Ca treatment process was resolved,and scheme of argon blowing parameters and wire-feeding parameter was put forword.The main conclusions are as follows:?1?The nodule and evolution of inclusions was studied.The results are as follows.The modification path that inclusions transfered by Ca treatment can be summarized as follows:Al₂O₃?MgO·Al₂O₃?Al₂O₃·xCaO?·yMgO?+?CaS??Al₂O₃·xCaO?·yMgO?.The nodules were mainly composed of unmodified Al₂O₃,MgO·Al₂O₃ and insufficiency modified calcium aluminate,calcium treatment effect was not ideal.Improving the yield of calcium and optimizing steel flow field characteristics can improve thecalciumtreatment process.?2?Melting and gastification behaviour of calcium and SiCa cored wire was simulated,and analyzed,designing scheme of cored wire size is studied.The results are as follows:Cored wire rapidly heats up when feeding into the molten steel,the SiCa alloy has been melted while the steel sheet is not melted,the SiCa alloy liquid enters the steel when the steel sheet is completely melted.The melting time of SiCa cored wire with 0.74mm thickness of steel and 4.28mm inner radius was 0.94s.Calcium will not be vaporized immediately after fed into the molten steel,and it is only when the vapor pressure of calcium is greater than the combined pressure of molten steel and atmospheric pressure that calcium begin gasifiying.The gasification behavior of calcium in liquid steel was nucleation,The gasification behavior of calcium on argon bubble was heterogeneous nucleation,which is easier to occur to drive the loss of calcium,the optimization of the diffusion behavior of calcium should prevent calcium from argon bubbles.Melting time of cored wire is proportional to the size of steel sheet and the radius of inner core,when designing the size of cored wire,absorptive amount of calcium per time in steel is an important index to analyze,different size of cored wire can often get the same Ca treatment effect,the irregular cross setion of cored wire may be useful to prevent the radial deviation and line break in wire-feeding process.Ca cored wire shows a better effect than SiCa cored wire in Ca treatment process.?3?The flow field characteristics and the diffusion behavior of calcium in the molten steel were simulated,and the optimization scheme of wire-feeding parameters was proposed.The results were as follows:Steel does a cylic motion in ladle as argon bubbles rise,the flow characteristics is a big circle tangent to the route of argon bubbles,the bigger argon blowing amount is,the shorter the mixing time of molten steel is,the movement locus of inclusions in the molten steel is similar to the steel flow characteristics,big size inclusion is easy to remove,because of the high viscosity between calcium and liquid steel,calcium mainly spread in the feeding region and then rises.The feeding speed of SiCa cored wire should be controlled at 3.15⁴.72m/s.Feeding tipsily is useful to prevent radial deviation and slag entrapment,when adding amount of Si Ca cored wire controlled at 400m⁵00m,or Ca cored wire at 300-600m,Ca yeild and[Ca]in steel is high.