Effects of Dynamic Loading under Extreme Conditions on Wear Resistance of T105Mn120 Castings for Railway Safety Systems

Hadfield steels are materials with high wear resistance used in the construction of parts that work in abrasive friction, high pressures and mechanical shock conditions. Four experimental samples, obtained from commercial T105Mn120 steel, were subjected to isothermal dynamic mechanical analysis in strain sweep mode (DMA-SS), by means of a dual cantilever specimen holder, at two temperatures, − 40 and + 50°C, with two SS frequencies: 0.5 and 16.66 Hz. These temperatures and frequencies correspond to the extreme conditions encountered during railway exploitation, being caused by environmental temperature or wagon wheel speed, respectively. The samples were work hardened through dynamic loadings and present different surface profilometries. Wear tests were carried out, and mean friction coefficient was determined based on friction torque measurements. Prior and after wear test, surface morphology was analyzed using scanning electron microscopy coupled with energy dispersive spectroscopy and micro-hardness determinations. The results indicate that the tested samples underwent work hardening through a wear mechanism that can explain the remarkable surface resistance of these executive elements of railway safety systems cast from Hadfield steel.