Influencing rolling contact fatigue through top of rail friction modifier application – A full scale wheel–rail test rig study

Continuing from research reported at CM2006, we report further investigation of the interaction of rail with friction modifiers (FM) related to wear and RCF generation. This work examines the relative effects of FM on standard (R260) and premium (R350HT) rail using a test rig. Under dry conditions, the premium rail shows clearly reduced wear and RCF generation compared to the standard rail. Application of FM reduces wear and RCF propensity for both standard and premium rail, with the best result achieved by a combination of R350HT and FM. Results on plastic flow were similar and consistent with the wear and RCF pattern. Longer term testing with FM application was terminated after four times the normal test cycle length without any RCF formation. Application of FM to pre-existing RCF cracks did not lead to acceleration of crack growth (e.g. by hydropressurization) under the experimental conditions used. Field results were reviewed for both premium rail and FM effects on RCF, and are found to be generally consistent with test rig results.