Analysis of Cleanliness of P12 High-pressure Boiler Steel

The cleanliness of P12 steel produced with EAF-LF-VD-MC process was studied systematically by sampling in various process stages in the production and with multiple analyzing techniques investigating the shape,size,quantity and component of inclusions.The results indicate that,in the refining process,T[O] and microinclusions in steel reduce 51.2 percents and 50.8 percents respectively.After VD treatment,average nitrogen increase rate of molten steel is 54.2 percents right to forging ingot and secondary oxidation of molten steel is rather noticeable.The average amount of oxygen,microinclusions and large inclusions are 20×10^-6,6.19 per square millimeter and 0.35mg/kg respectively,reaching rather high levels.