| W20B steel used the core of electric motor as electric silicon steel, should have stable electromagnetic properties in use and fine mechanical properties in machining. Meanwhile, the non-metallic inclusions in W20B steel do harm to these properties. Therefore, the controlling of the content, shape and distribution of inclusions are essential to improve the quality of W20B steel.Based on consulting the extensive literature and summarizing the studies on the non-metallic inclusions at home and abroad, the investigation of inclusions in W20B steel has been carried out in BAr-CC system of the 2nd steel plant of WISCO. The samples which are from different stages in production field have been analyzed by means of chemical analysis, metallographic analysis and Scanning Electron Microscope. The composition of molten steel and slag, the content, composition, shape and distribution of inclusions are studied. And then the forming and sources of inclusions are analyzed.The main conclusions are drawn as follows: After BAr process, T[O] reaches to 25ppm, [C] reaches to 21ppm, [N] reaches to 21ppm and the average content of inclusions per square millimeter is 7.095. These illustrate that the BAr process is effective. In tundish pouring, the effect of removing inclusions is not good, so further performance of the metallurgy in tundish is required. The steel cleanliness is very regularly, the peak of the inclusions is appeared in the 1/4 thickness of the inside direction,but it is average on the width direction. The sources of inclusions at different stages are mainly: reoxidization, slag-falling and refractory wear.According to the researches, in order to improve quality of W20B steel under current conditions, the followings are some measure and suggestions: perfecting protective casting, decreasing slag-falling, fully utilizing the function of tundish, optimizing the operation of ladle refining, controlling the shape of inclusions.
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