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The comparative assessments and an overview of mechanical, chemical, and physical properties of rail axles are presented. This review focused on the effects of compositions and microstructure on fatigue, fretting and corrosion fatigue of rail axles. The two main steel grades: low carbon steels for commuter trains and high strength low alloy steels for high-speed trains have ferrite-pearlite microstructures with 20–40 µm ferrite grain sizes. Minimum allowable yield and ultimate tensile strengths are 330 MPa and 600 MPa, and the minimum longitudinal and transverse toughnesses are 35 J and 22 J. Most axle failures are associated with surface and sub-surface defects with micro-cracks nucleating from ballast (small-sized pebbles in rail tracks), minute oscillatory movement leading to fretting, microstructural inclusions, and corrosion pits. The implications for structural integrity are highlighted and areas for future research directions are highlighted. [ABSTRACT FROM AUTHOR]

Corrosion behaviour of Ti25-0.5xV40Cr35-0.5xRhx (x= 0, 0.5, 1 at %) alloy electrode in 6M KOH was investigated. The V-rich alloy was produced under argon atmosphere in an open hearth crucible furnace. The microstructure of the arc-melted alloy was examined by scanning electron microscopy, and the phases were identified by X-ray diffraction. The as-cast alloys contained a primary (V) body centered cubic phase and an intergranular aTi phase. Rhodium (Rh) decreased the Ecorr from -767 mV to -793 mV for 0.05 Rh and -825 mV for 0.10 Rh. The corrosion current also decreased from 1 µA/cm² in Rh-free alloy to 0.77 µA/cm² with addition of 0.05 at % Rh and 0.37 µA/cm² with addition of 0.10 at.% Rh. Addition of 0.05 at. % Rh decreased the corrosion rate from 0.0110 to 0.0009 mm/y and to 0.001 mm/y with addition of 0.10 at.% Rh. Hardness of the alloy electrode decreased with addition of rhodium. [ABSTRACT FROM AUTHOR]