Changes in the Microstructure and Mechanical Properties of Railway Wheel Steels as a Result of the Thermal Load Caused by Shoe Braking

An investigation was carried out to study the effects caused by shoe braking on the microstructure and mechanical properties of ER7, CLASS B, CLASS C, and SANDLOS® wheels as a result of the thermal load. Particular attention was given to cases of exposure to medium and high temperatures, namely from 700 °C to 970 °C, followed by air cooling. Hardness measurements, tensile tests, toughness tests, fatigue crack growth tests, and microstructural observations were carried out on samples extracted from new wheels, with and without heat treatments simulating the microstructural modifications caused by shoe braking. The experiments showed that the hardness, yield strength and ultimate tensile strength of the steels all decrease with the heat-treatment temperature up to 750 °C due to globular pearlite formation. However, after the heat treatment at 970 °C, these properties show a trend inversion, as the globular pearlite no longer appears, while, in some cases, traces of bainite and martensite are observed. On the other hand, the fracture toughness, crack propagation threshold, and rate are not significantly altered by the heat treatments, showing the steels to have a good stability under the thermal loads caused by shoe braking.

[1]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[2]  S. Avner.  Introduction to Physical Metallurgy , 1964 .

[3]  J. Knott,et al.  Fundamentals of Fracture Mechanics , 2008 .

[4]  I. Bernstein,et al.  The role of microstructure on the strength and toughness of fully pearlitic steels , 1976 .

[5]  A. Marder,et al.  The effect of morphology on the strength of pearlite , 1976 .

[6]  Y. J. Park,et al.  The process of crack initiation and effective grain size for cleavage fracture in pearlitic eutectoid steel , 1979 .

[7]  A. Bower.  The influence of crack face friction and trapped fluid on surface initiated rolling contact fatigue cracks , 1988 .

[8]  K. Johnson.  The Strength of Surfaces in Rolling Contact , 1989 .

[9]  G. Moyar,et al.  An analysis of the thermal contributions to railway wheel shelling , 1991 .

[10]  Y. C. Li.  Analysis of fatigue phenomena in railway rails and wheels , 1994 .

[11]  O. Orringer,et al.  THERMAL CRACKING IN RAILROAD VEHICLE WHEELS SUBJECTED TO HIGH PERFORMANCE STOP BRAKING , 1995 .

[12]  B. Karlsson,et al.  Microstructural evaluation and interpretation of the mechanically and thermally affected zone under railway wheel flats , 1999 .

[13]  B. Karlsson,et al.  Analytical 1D model for analysis of the thermally affected zone formed during railway wheel skid , 1999 .

[14]  Tore V Vernersson,et al.  Noise-related roughness of tread braked railway wheels - experimental measurements and numerical simulations , 2000 .

[15]  Z. X. Liu,et al.  Failure modes and materials performance of railway wheels , 2000 .

[16]  A. H. Yegneswaran,et al.  Effect of interlamellar spacing on the mechanical properties of 0.65% C steel , 2001 .

[17]  K. Hono,et al.  Effect of partitioning of Mn and Si on the growth kinetics of cementite in tempered Fe–0.6 mass% C martensite , 2007 .

[18]  B. Karlsson,et al.  Monotonic and cyclic deformation of a high silicon pearlitic wheel steel , 2011 .

[19]  Y. Kimura,et al.  Surface cracks initiation on carbon steel railway wheels under concurrent load of continuous rolling contact and cyclic frictional heat , 2010 .

[20]  B. Karlsson,et al.  Thermal degradation of pearlitic steels: influence on mechanical properties including fatigue behaviour , 2011 .

[21]  R. Stock,et al.  Effect of Large Shear Deformations on the Fracture Behavior of a Fully Pearlitic Steel , 2011 .

[22]  W. Marsden.  I and J , 2012 .

[23]  A. Malakizadi,et al.  Mechanical properties and fatigue behaviour of railway wheel steels as influenced by mechanical and thermal loadings , 2016 .

[24]  Luis Reis,et al.  Experimental characterization of the mechanical properties of railway wheels manufactured using class B material , 2016 .

[25]  L. Lu,et al.  Optimization of strength and toughness of railway wheel steel by alloy design , 2016 .

[26]  Luis Reis,et al.  Experimental characterization of the mechanical properties of railway wheels manufactured using class C material , 2016 .

[27]  L. Lu,et al.  Influence of solid solution strengthening on spalling behavior of railway wheel steel , 2017 .

[28]  T. Kato,et al.  Effect of fracture toughness on vertical split rim failure in railway wheels , 2017 .

[29]  A. Mazzù,et al.  Experimental and Numerical Investigation of the Thermal Effects on Railway Wheels for Shoe-Braked High-Speed Train Applications , 2018, Metallurgical and Materials Transactions A.

[30]  C. Petrogalli,et al.  Effect of desert sand on wear and rolling contact fatigue behaviour of various railway wheel steels , 2018 .

[31]  Aaas News,et al.  Book Reviews , 1893, Buffalo Medical and Surgical Journal.