Abstract:
Different variants of the hardness of the wheel/rail friction pair were
investigated to determine the optimal hardness range of the wheel/rail that
ensures the minimum wear under selected test conditions. A pair of tests was
performed on an MI-2 machine with a cylindrical wheel steel roller and a rail
steel liner. The hardness of the wheel steel specimens ranged from 275 to 900
HVw. The selected of the rail steel samples of 345-455 HVr covers the possible
hardness variations (350-405 HVr) of R65 type long rails produced on the
standard ST RK 2432-2013 “Railway Rails Differentially Hardened and Nonheat-strengthened.” Technical Requirements. The optimal ratio of wheel/rail
hardness, which ensures minimum wear due to weight loss of the tested
samples, is the interval HVw/HVr–1.41-1.59. This ratio of wheel/rail hardness
is practically confirmed when linear wear is determined by micrometric
measurement of the impression size with HVw/HVr–1.39-1.56. The results of
the laboratory tests and the suggestions for the optimal ratio of wheel/rail
hardness to improve wear resistance should be verified under field conditions.
Oscillography of the destruction process of plasma-hardened and nonstrengthened specimens was performed to evaluate the resistance to crack
initiation and propagation.
