STUDY ON BEHAVIOR OF LARGE INCLUSIONS OF HIGH PERFORMANCE BUILDING STRUCTURAL STEEL Q420GJZ35
Experimental research was conducted on the types,quantities and sizes of large inclusions in high performance building structural steel Q420GJZ35 produced by HBIS Group Tangshan Mediume Heavy Plate Co.,Ltd.,and Ba,La,and Ce trace elements were added to the ladle slag,tundish covering agent,and tundish binder to track the source of the inclusions.The research results show that the overall content of large inclusions in the steady-state billet is 16.8 mg/10 kg.The highest content in non-stationary casting billet is 36.2 mg/10 kg.According to the tracer detection results,large inclusions are mainly deoxygenated inclusions formed by the collision of drainage sand and deoxygenated products.Some of the inclusions are adhered to steel ladle slag,mold powder,and casting powder,among which mold powder is an important source of inclusions.Through optimizing and improving the submersed nozzle,the nozzle was changed from a single port to a double port,the length of the side hole was changed from 105 mm to 100 mm,and the outlet of the nozzle was a square hole with a circular angle.The numerical simulation results show that the flow field distribution of the improved nozzle calculation mold is reasonable,with small surface fluctuations,which meets the design requirements and is conducive to the alloying of surface steel liquid and the floating of impurities.
high performance building structural steellarge inclusionstracer methodslab continuous castingmoldflow field
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