Study of the thermo-mechanical damage in steels for shoe-braked railway wheels using innovative small-scale tests

The behavior of three railway wheel steels (HYPERLOS®, ER-TEN, and SUPERLOS®) coupled with two brake block materials (cast iron and organic composite) and R260 rail steel was studied by means of an innovative small-scale test bench, hereafter called 4-contact machine. This test bench is capable of alternating brake block type and rail type contacts on the surface of a wheel steel specimen and makes it possible to reproduce the combined thermal and mechanical damage that occurs on a real railway wheel during braking. Through comparative tests under the same conditions, the damage due to rolling contact fatigue and wear was evaluated for each material coupling. The results are consistent with actual damage observed during operation and highlight the differences in application of the materials. Cast iron brake blocks have been shown to have a greater wear than composite brake blocks. They also cause a layer of carryover material to build on the wheels. Due to the varying material qualities and application areas for which they were developed, the three wheel steels tested showed similar behavior with different intensities.