Effects of Ce on Microstructure and Mechanical Properties of LDX2101 Duplex Stainless Steel

Abstract

In the present study, the effects of rare earth metal (REM) Ce on the number, size distribution and type of inclusions, as well as the grain size, tensile and impact properties of LDX2101 duplex stainless steel, were investigated using thermodynamic analysis, optical microscope, image software, scanning electron microscope, tensile and impact testing machines. The results indicate that when the Ce content in steel is 0%, the main inclusions are irregular and large size Al2O3 and Al2O3-MnS. When the Ce content in steel is 0.005% or 0.02%, the inclusions are mainly spherical and small size inclusions CeAlO3, Ce2O2S and Ce2O3. With the increase in Ce content, the proportion of small size inclusions gradually increases; the number of inclusions per unit area decreases from 122 to 58 and the average grain size reduces from 16 ± 0.7 μm to 12 ± 0.3 μm. Moreover, the mechanical properties of steels are improved, and the tensile strength, yield strength and elongation are elevated by 4.69%, 2.83% and 4.9%, respectively. The impact fracture mode of steel without Ce is cleavage fracture, however, the fracture mode is transformed into a mixed fracture of cleavage and dimple after adding 0.005% and 0.02% Ce.