In-situ Observation of Non-metallic Inclusion Precipitation in Non-ori ented Silicon Steel with Different Manganese Concentrations

Based on the high temperature optical microscope,in-situ observation on precipitation of nonmetallic inclusion in non-oriented silicon steel with different manganese concentration had been carried out.The observation showed that the numbers of non-metallic inclusions was 1 000 × 10⁴/mm³ and 1 600 × 10⁴/mm³ when the manganese concentration was 0.77% and 0.32%, respectively. The precipitation temperature range of non-metallic inclusions was from 1 115 ℃ to 1 098 ℃ and from 1 068 ℃ to 1 032 ℃ for 0.77% manganese concentration,and was from 1 086 ℃ to 1 068 ℃ for 0.32% manganese concentration.For the 0.77% manganese concentration the spherical and elliposidal MnS will precipitate first,with small quantity and large size,can retard the precipitation of AlN and Cu_xS effectively; on the other hand,MnS will precipitate first and can be adopted as the core of AlN,and form the composition of MnS and AlN during the reheating and cooling processes,which is more and larger for 0.32% manganese concentration.