Cementite Characterization with Chromium and Vanadium Contents Using Indentation Technique

Cast irons with some kinds of cementite with different chromium and vanadium contents were characterized. Fracture toughness was determined by using an indentation technique, along with microhardness and elastic modulus. The results show that at the load of 1 N, microhardness of the cementite with 5. 1% Cr is 10. 53 GPa, the microhardness for cementite with 9. 2% Cr increased to 11. 25 GPa and for cementite with 4. 5% V the microhardness is 9. 18 GPa. The cementite with 9. 2% Cr presented the highest elastic modulus of 230. 4 GPa and the cementite with 4% V presented the lowest value of 201. 32 GPa. Cementite with 5. 1% Cr presented higher fracture toughness than cementite with 9. 2% Cr; however, cementite with 4. 5% V presented the highest fracture toughness of 2. 74 MPa · m½ and the lowest brittleness index of 3. 35 μm−½.