Change of Spinel in High Ca Treament at 38CrMoAl Steel

Abstract

In this study, 38CrMoAl steel was treated with calcium under the pressure of 2 MPa, and four groups of high aluminum steels with the highest calcium content of 0.01% were obtained. Spinel inclusions with high MgO content, CaO and MgO inclusions with original spinel morphology were found by testing and analyzing the morphology towards composition of inclusions in the high Ca content steel. Combined with thermodynamic calculation, a Ca–Al spinel reaction model was proposed, the solid/liquid phase denaturation mechanism of calcium treated spinel was explored, and the influence of total oxygen content on phase equilibrium in denaturation process was analyzed. At last, it was obtained that the spinel denaturation products is MgO+Spinel, CaO–Al₂O₃–MgO and CaO–Al₂O₃ when the mass fraction of calcium was low; And the spinel denaturation products with high calcium content are MgO+Spinel, MgO and CaO.