Technology Digests / High Performance Wheels Test Update

TD24-007

August 9, 2024
Authors
  • Kerry Jones
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Key Findings

  • The HPW2 revenue service test data showed:
    - Statistically higher wear rates for flange height (Type 10) and for tread hollow (Types 3 and 13).
    - No statistical wear differences among the HPW2 wheels for flange thickness or rim thickness.
  • Due to the early formation of subsurface fatigue cracks, wheels with pearlitic-bainitic microstructures did not perform well in these tests.
  • Tensile-to-yield strength ratio is an important material property that affects both wheel performance and wheel life.
  • The HPW test steel microcleanliness differences have not been apparent in the performance results to date.
  • Although no single property determines performance or life, optimizing key properties, such as tensile-to-yield ratio, fracture toughness, and microcleanliness, can improve both wheel performance and wheel life.

High Performance Wheels Test Update

MxV Rail has been conducting two long-term high performance wheel (HPW) tests under the Association of American Railroads’ (AAR) Strategic Research Initiatives program on Wheel Performance and Integrity. The results of the first HPW test (HPW1) have been reported in previous Technology Digests,1–3 including reporting on laboratory testing and on-track testing.3,4 In 2016, to evaluate current state-of-the-art wheel steels, researchers began the second test, HPW2, consisting of laboratory testing, on-track testing under controlled conditions at MxV Rail’s Facility for Accelerated Service Testing (FAST®), and revenue service testing. The test wheelsets accumulated a mean of 96,500 miles by the end of FAST 2022 operations. At that time, seven wheels had been removed for subsurface fatigue cracks; one wheel had developed a shattered rim, and one wheel had reached its flange wear limit. On-track testing resumed at FAST in 2023, and both the wheel condition and wear will be monitored. Revenue service…