Corrosion induced fatigue failure of railway wheels

• The failed wheel was examined carefully, and the mechanism of failure was analyzed.
• The effects of corrosion on fatigue limit of the wheel steel were investigated by fatigue testing.
• The safety of the wheels with different corrosion state was evaluated using Finite element method and Sines’ criterion.
• The critical depth of corrosion pit permitted on the wheel plate was recommended.

Two AAR class B rolled wheels for locomotives failed after about two years of service. The fracture surfaces of the failed railway wheels were examined. The examination showed that there were corrosion pits on the back plate surface of the failed wheels. All of the fracture originated from corrosion pits at the wheel plate surface and fatigue propagated to a length and then expanded rapidly by cleavage. Fatigue specimens cut from the wheel plate were corroded with different time duration in an artificial corrosion environment to simulate the corrosion states of the wheels. The fatigue properties of the un-corroded specimens and the specimens corroded with different times were tested in air. Finite element method (FEM) and Sines' criterion were used to evaluate the safety of the wheels. The results showed that the wheel plates without corrosion pits exhibited an excellent resistance to failure. The corrosion pits could promote the initiation of fatigue cracks and drastically lower the fatigue limits of corroded specimens. The real root cause of the failure of the subject wheels was due to the corrosion pits at the wheel plate surfaces. A critical depth of the corrosion pit on the wheel plate 300 μm was recommended. Protection of the wheel plate was important to ensure the safety of wheels and the rust prevention oil was recommended to be applied on the wheel plate regularly.