Optimization Of Flow Field In170mm Slab Continuous Casting Mold

Mold is the final metallurgical vessel where molten steel is cleaned in the process of continuous casting. The fluid flow field in mold affects inclusion removal, slag entrapment, solidified shell formation and solidification structure greatly. To optimize the flow field in mold is important for improving the quality of slab and operation performance. An appropriate flow field in the mold can stabilize the surface of molten steel, prevent from the slag entrapment, and therefore plays an important role in reducing the inclusion, surface crack and the breakout ratio.From the170mm thickness slab mold in continuous casting, a physical model was established to study the downward angle, immersion depth, gas blowing and bottom outlet of SEN. Flow and temperature fields in the mold was analysed by using numerical simulation. The optimal process parameters and SEN were determined.For the mold with170mmx1700mm section size,7#SEN is reasonable at1.5m/min casting speed and0.16m3/h gas blowing, and the immersion depth of SEN is120mm～140mm. By using original SEN with0.16m3/h gas blowing and57mm (120mm in prototype) immersion depth, liquid level fluctuation in the mold is violent, the average waveheight and peak-valley difference in meniscus come up to0.4cm and0.45cm, respectively, the peak-valley difference is greater than0.6cm in1/4of mold width to the narrow face. The liquid level fluctuation is effectively restrained in the mold by using7#SEN, the average waveheight and peak-valley difference in meniscus was reduced to0.2cm and0.24cm, respectively. The level fluctuation at1/4of mold width is also improved and the waveheight is less than0.20cm. The liquid level in the mold is smooth and steady.The numerical simulation shows that the temperature in the upper circulation region of the mold is raised by1K～2K with7#SEN. According to the simulation results of the mold, Ar blowing in SEN changes the flow field in the mold, which thus varies the temperature field. The temperature in the upper circulation region of the mold is1814K～1815K by using7#SEN without gas blowing, while that is1818K with SEN gas blowing. Meanwhile, the temperature in the core of lower circulation region of the mold is lower by19K with7#SEN than that with the former SEN. Such temperature reduction in the mold will help to increase growth rate of solidified shell. This is favorable to increase the casting rate.