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The effect of duplex shot peening treatments with Al 2 O 3 particles and MoS 2 solid lubricants on wear reduction of wheel specimens was investigated in extensive dry rolling/ sliding contact tests. The duplex shot peening treatments provided excellent wear reduction under severe loading and sliding conditions because the uniform and minute surface roughness given by the primary shot peening treatment with Al 2 O 3 particles could keep the duplex treated MoS 2 layers with low friction coefficients on the wheel specimen surfaces. Furthermore, the crystal orientation of the duplex treated MoS 2 layer was well aligned and contributed to excellent wear reduction.

A newly developed full scale wheel-rail contact testing machine is used to obtain detailed data on flange climb behavior with covering various loads and displacements at the wheel flange and rail contact under both rolling-sliding and pure sliding conditions. The effects of different surface roughness of the wheel flange on coefficient of friction at the contact point in wheel flange climb mechanism were investigated. A correlation between different state of the interface (i.e. surface of dry, wet, rust, oily and different lubricated condition by solid lubricant) and wheel flange surface roughness with rail were drawn. The coefficient of friction was significantly influenced in pure sliding conditions than that of rolling-sliding conditions by the degree of the asperities on the wheel flange surface. Moreover, solid lubricant showed better performance to reduce coefficient of friction. However, the rust on the rail surfaces was one of the important factors to destabilize the friction behavior.