Theoretical Analysis and Experimental Verification of Formation of As-Bearing Rare Earth Inclusions in Steel

It is a feasible method to improve the quality of steel products by adding rare earth to change the state of arsenic in steel to avoid its harm. In this study, the As-bearing rare earth inclusions in steel were extracted by non-aqueous electrolysis method, and their types were fully understood. Wagner activity model and non-equilibrium solidification model were used to calculate the formation process of rare earth inclusions in liquid and solidification process. The formation mechanism of single-phase and complex As-bearing rare earth inclusions was verified by laboratory experiments. The results showed that La2O3 and La2O2S were formed in the liquid phase, then the As-bearing rare earth inclusions La–S–As and La–As began to form during the solidification process of steel liquid. The composite inclusions of La–O–S–As with distinct stratification were further precipitated.