Dry sliding wear behaviour of pearlitic wheel steels used for Indian railways

Abstract

The present work is focused on the dry sliding wear behaviour of two industrially manufactured pearlitic wheel steels used for high-speed railway applications, having varying content of C, Mn and V. A constant wear load of 10 N with different sliding velocity of 3 m/s and 5 m/s has been used for both the investigated samples. A detailed electron microscopic analysis has been carried out to correlate the microstructural counterparts with the wear behaviour of the specimens. C1_3 m/s showed the worst wear resistance property due to the higher strain accumulation in the primary worn surface, leading to the detachment of carbide particles and the generation of microcracks. On the other hand, the C2_5 m/s specimen results into ∼55 % improvement in specific wear rate compared to C1_3 m/s due to the generation of dynamically recrystallized (DRx) sub-micron sized ferrite grains (0.350 ± 0.01 μm) surrounded by high angle grain boundaries in the white etching layer (WEL), resisting the wear loss of C2_5 m/s specimen. The occurrence of dynamic recrystallization in C2_5 m/s specimen can be related with the increase in temperature compared to C1_3 m/s and favours DRx. A softer white etching layer (WEL) and enhanced elastic recovery were observed in C2_5 m/s, as revealed by nano-indentation analysis. Compared to C1, the C2 specimen contained higher volume fraction of VC precipitates which refine the prior austenite grains, pearlite ILS, colony, and parallelly increasing the precipitation strengthening, thereby improving the wear resistance.