Effect of Crucible Material on Inclusions in 55SiCr Spring Steel

doi:10.12068/j.issn.1005-3026.2020.02.009

Abstract

Abstract: The effects of MgO and MgO-CaO refractories on inclusions in 55SiCr spring steel were studied in a MoSi₂ furnace. The results indicate that both MgO and MgO-CaO crucibles can adjust the composition of the steel within the aiming range. Moreover， compared with MgO crucible， MgO-CaO crucible is more effective in purifying the molten steel， in which the contents of P， S，［Al］_s and T.O in 55SiCr spring steel smelted by MgO-CaO crucible are reduced to 56×10^-6， 10×10^-6， ≤5×10^-6 and 4×10^-6， respectively. The average diameter of inclusions in steel decreases from 1.376μm to 1.222μm， and the ratio of the inclusions with the size <2μm increased from 79% to 89%. This is mainly because the MgO-CaO crucible has not only the functions of dephosphorization， desulfurization and deoxidization， but also CaO reacts with Al₂O₃ inclusions in steel to form hybrid inclusions with lower melting point， which is easier to float and remove， so that the molten steel is further purified.

Key words: spring steel, 55SiCr, inclusions, MgO crucible, MgO-CaO crucible

CLC Number:

TF769.2

LI Yang， CHEN Chang-yong， QIN Guo-qing， JIANG Zhou-hua. Effect of Crucible Material on Inclusions in 55SiCr Spring Steel[J]. Journal of Northeastern University Natural Science, 2020, 41(2): 200-207.

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