Thermodynamic analysis of X80 pipeline steel after calcium treatment

Based on thermodynamic calculation, analysis the inclusions and thermodynamics of X80 before and after calcium treatment on the sample of a steel production.Results show that the effect of Al2O3 inclusions degeneration is good and S would exist in a dissolved state so that avoids the CaS inclusion precipitation when the ω(Als) is 0.04%,ω(O) is adjusted to 0.7×10 -4 %~18×10 -4 %,ω(Ca) is adjusted to 6×10 -4 %~24×10 -4 %,in the meanwhile control of ω(S) below 0.009% at 1873K; Al2O3 inclusions in steel is effectively modified into calcium aluminate,the number and the size of inclusions were reduced,most of them below 5μm,and the shape more regular.