Increasing the Accuracy of Measuring the Hardness of Surface-Hardened Steel Products

Abstract The results of hardness tests of a sample of a gear wheel made of 14KhN3MA steel, which has passed a full cycle of chemical-thermal treatment (carburization, hardening, low tempering), are presented. The hardness was measured using Vickers method at an indenter load of 1.961 N and 4.903 N at different distances from the sample surface. It is established that the results of hardness tests at load of 1.961 N have a greater scatter of hardness values than with load of 4.903 N. It is shown that increasing of the scatter of measurement results with lower load is due to structural inhomogeneity (banding) of the sample. An approximating dependence was obtained between hardness HV0.2 and hardness measured during tests with load of 4.903 N, which promotes increasing of hardness measurement accuracy of surface-strengthened steel products.