| The manufacture of cleanliness steel has been the developing mainstream of the steel material in 21th century. For most corporations, putting forward the reasonable measures is a feasible way to meet the trend through the producing and technologic researches of typical steel.20MnSi reinforced steel is one of the construction materials in common use, which has the fuctions of damping and sustaining. The cleanliness of 20MnSi produced by the route of converter—ladle furnace—three strands billet caster in Shuicheng steel was studied and the factors affecting the cleanliness were found and discussed.①By sampling in each process, combining large sample electrolysis, oxygen and nitrogen analysis, metallographical observation, SEM and EDS etc, the behavior of inclusions in liquid steel and billet was studied during smelting-casting, and the cleanliness level was educed, which provided proofs to optimize technology and improve the cleanliness of 20MnSi.②Total oxygen contents are 157.73×10-6 and the total amount of the inclusions is 2550mg/10kg of the liquid steel before Ar stirring, 30.77×10-6 and 850mg/10kg decrease respectively after Ar stirring, 103.49×10-6 of liquid steel in tundish with 579.79mg/10kg for prophase, 1.33×10-6 and 53.39mg/10kg decrease respectively for anaphase, 74.79×10-6 T[O] and 251.88mg/10kg of inclusions in billet. The results showed that it had a large distance between 20MnSi in Shuicheng and other developed companies, however, there are improving space for 20MnSi cleanliness.③Through the analysis upwards, the factors mostly affecting the cleanliness of 20MnSi liquid steel and billet were deoxidization system, Ar stiring system, the structure of tundish, and the slags down from ladle during unstable casting period, the low ablity of tundish slags for absorbing inclusions and the entanglement of mould fluxes accounting for the low cleanliness of 20MnSi, the fluctuation of operation and technology during the production could not be ignored.④The factors influenting 20MnSi liquid steel and billet were analysed. The deoxidization system, Ar stiring system and the structure of tundish were discussed for changing the pattern of inclusions and boosting the removement of inclusions apart, and there ware some suggestions for avoiding the slags form ladle, the second oxidization of the liquid steel and the entanglement of mould fluxes, all of these bulit basement of clean steel production for shuicheng steel corporation. |
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