Evolution And Control Of Non-metallic Inclusions In IF Steel

In order to solve the quality problem of IF steel products produced by a steel group in northern China,I use tracer test and system sampling in the field to analyze the evolution and origin of non-metallic inclusions in the IF steel production process with our laboratory equipment.I also analyze the evolution of the cleanliness during casting and the evolution of the surface inclusions in the slab.At last,I Analyze the large Inclusions of IF Steel.The average content of micro inclusions in tundish stopper region is 6.1/mm2,which is significantly higher than that of 48 ppm and 4.1/mm2 in the impact zone.But the nitrogen content in the tundish is basically unchanged,We can know the tundish has a greater pollution to the molten steel.Measured by Factsage thermodynamics Software,the molten steel generates a large amount of Al2O3 inclusions and a small amount of Ti N inclusions after deoxidation alloying of RH refining.Steady-state slab w(T.O)content is 15 ppm and the nitrogen content is 21 ppm,the number of microscopic inclusions 4.3 / mm2.there are some inclusions,such as Al2O3 inclusions,Al2O3-Ti Ox inclusions,Ti N inclusions,Al2O3-Ti N inclusions,and the content of Al2O3 inclusion is highest.The content of w(TO),w[N] and micro inclusions shows a decreasing trend,and the cleanliness level of billet has a exaltation.When the meters from the spindle head is 28,w(TO)and micro inclusions are 16.3ppm and 5.3/mm2.Which is basically the same with the normal furnace slag cleanliness There is obvious aggregation phenomenon in the surface of the slab surface from 3 to 4 mm in the inner arc surface.Large inclusions larger than 300?m of the large inclusions accounted for 30% of the total,and its composition of complex,in which almost all contain La,Ce,K,Na and other tracer slag elements.These mainly are deoxygenation of the product,ladle slag,tundish Slag,mold powder and refractory material involved in molten steel.The maximum particle size of the inclusions in the slab is predicted to be 197 ?m,and the actual measurement of large sample electrolysis is 220?m,which the error is 10%.