Effect of Cr content of Fe-10Mn-xCr (x = 0.5, 1, 2, 3 and 4 masspct) on slag/steel reaction and as-cast microstructure

Abstract

With the development of medium/high manganese steel which has excellent mechanical properties, research on its corrosion resistance is attracting more attention. In this study, the effect of anti-corrosion element Cr on the reaction between Fe-10Mn-xCr alloy and CaO-SiO2-Al2O3-MgO refining slag, as well as the as-cast microstructure of steel were investigated by adding different Cr content (0.5, 1, 2, 3, 4 mass pct). The results showed that Mn content in steel was significantly reduced, and Cr content changed little after slag/steel reaction. The Cr2O3 content in slag increased a little with the increase of initial Cr content, while MnO content presented the opposite trend. The inclusion types in steel remained the same with different Cr content, including MnO and MnO-SiO2 type, of which MnO-SiO2 inclusions was the main type. Most inclusions were spherical-shaped with size less than 3 μm. Thermodynamic analysis indicated that the reaction between Mn in steel and SiO2 in slag was the mechanism of steel and slag composition change and inclusion types. The above results indicate that adding Cr has little effect on the reaction between Fe-10Mn and CaO-SiO2-Al2O3-MgO top slag. After slag/steel reaction, the as-cast microstructure of steel specimens were lath martensite with BCC structure. With Cr content increasing, the microhardness increased gradually.