Wear between wheel and rail: A pin-on-disc study of environmental conditions and iron oxides

Railways operate in an open environment where temperature, humidity, and the oxidation conditions are subjected to change. An experimental investigation used a pin-on-disc machine to examine the influence of environmental conditions and iron oxides on the wear performance of the wheel–rail contact. The wear mechanisms were analyzed using scanning electron microscopy and found to be highly dependent on the environmental conditions. On clean contacts, adhesive wear is predominant under low-moisture conditions, becoming more serious with decreasing temperature. With high moisture and at room temperature (i.e., 20 °C and 10 °C) oxide flakes would self-produce and protect the pins from severe wear, as oxidative wear is the main wear mechanism. Samples experienced a transformation of the wear mechanism from adhesive to oxidative with increasing humidity on clean contacts. Complex three-body wear in abrasion form has been determined to dominate oxidized contacts. Under dry conditions, pins underwent severe wear appearing as delamination at 20 °C and crushed wear debris at 3 °C. Raising the moisture level helps the pins to avoid severe wear. • Effect of environment and iron oxides on wear between wheel and rail was studied. • Clean tests at all temperatures and low relative humidity underwent adhesive wear. • With increasing humidity, wear mechanism changed from adhesive to oxidative. • Self-produced oxides showed a protection effect. • Oxidized tests acted abrasive wear and become severe with decreasing temperature.