Hardness, toughness and cracking systems of primary (Cr,Fe)23C6 and (Cr,Fe)7C3 carbides in high-carbon Cr-based alloys by indentation

The current investigation evaluates the hardness, indentation toughness (KC) and cracking systems of primary carbides in high-carbon Cr-based alloys using the indentation technique and compares the results calculated from different model equations. The primary carbides in high-carbon Cr-based alloys are (Cr,Fe)23C6 and (Cr,Fe)7C3 carbides. The results reveal that KC evaluation of primary carbides by the Vickers indentation method strongly depends on the selection of KC equations, crack systems and crack length. The cracking systems of primary carbides shown by the polishing procedure are Palmqvist cracks. Niiharaʹs equation with the Palmqvist crack is most appropriate to evaluate the KC of primary carbides, after experimentally assessing its applicability. The KC values of primary (Cr,Fe)23C6 and (Cr,Fe)7C3 carbides are 3.8 ± 0.2 and 2.4 ± 0.1 MPa m1/2.