Development of High Performance Steels for Rail Applications

Abstract

Higher requirements of efficiency on railroad systems have set off (among other measures) higher axle load on rails. The increase in axle loads can contribute to a series of defects on perhaps the most unappreciated component of a railroad system. Higher axle loads can lead to excessive wear, fatigue and ultimately fracture of the steel rails. Therefore to answer the challenge demanded by the increase in axle loads the development of high performance steels for rail applications is of primary importance. A research program to study the microstructural aspects of near-eutectoid steels with improved mechanical properties and wear resistance was recently completed. The new high performance rail steels were developed through a combination of advanced alloy design-thermomechanical processing-and-controlled cooling. The mechanical properties exhibited by the new steels have exceeded the AREMA requirements for this type of rail steel application. The wear resistance of the newly developed steels was evaluated and the results obtained compared to commercial rails were superior under the testing conditions used in this study. The alloy design philosophy, thermomechanical processing and properties of the new steels will be presented and discussed in this paper.

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“…Прийнято вважати, що зносостійкість рейкової сталі безпосередньо залежить від твердості і МВП. У той же час, в роботі [9] встановлено, що присутність доевтектоїдного цементиту і розмір зерна аустеніту також грають важливу роль в появі контактної втоми кочення і зносу.…”

Research and Development of U68CuCr Rail Steel

“…The sample of cross-section hardness gets from cross-section of railhead,as fig. 5 As shown in a great number of investigations [1][2][3][4][5][6][7][8][9][10][11] , the performance of pearlite mainly depends on microstructure morphology,and it obeys the Hall-Petch formula between yield strength(σ 0.2 ), tensile strength(σ b ) and hardness and Pearlite spacing (S) [10][11][12][13] .The formula is : σs=σ i +kS -n (2) in which, σ i is friction of single crystal dislocation movement and nothing to do with the spacing;K is the value of stress concentration when the film dislocation source start between adjacent pearlite,and is related to material nature but nothing to do with spacing; n is a constant independent of material properties,maybe 1 or 1/2;S is pearlite spacing.…”