RAIL ANALYSIS. VOLUME 5: FATIGUE AND FRACTURE BEHAVIOR OF CARBON-STEEL RAILS
The Ad Hoc Committee on Rail Research, which is composed of representatives from the American Railway Engineering Association (AREA), the Association of American Railroads (AAR), and the American Iron and Steel Institute (AISI) Committee on Railroad Materials, formulated a program to investigate the effects of metallurgical properties, mechanical properties, and applied-stress conditions on the service fracture behavior of carbon-steel rails. This report on work conducted under contract with the AAR and the AISI, describes the fatigue and fracture behavior of five rails having extremes in room-temperature tensile properties and Charpy V-notch toughness, and gives an analysis of the effect of this behavior on the in-service useful life of carbon-steel rails. These five rails were selected from a population of about 90 rails that were removed from service because they contained service-developed defects. A companion report describes the results of chemical analysis, of hardness and tension tests, and of wear, deformation, metallographic, and fractographic analysis. The results of the fractographic investigation (also conducted under AAR-AISI contract), which are presented in the companion report, showed that in-service fatigue cracks initiated from inclusions having a width of about 1.0 mil (0.025 mm). The results of the present investigation showed that fatigue-crack initiation from such small discontinuities occurs when the magnitude of the stress fluctuations applied to the rail head with the passage of each wheel is about equal to the tensile strength of the steel. The thin inclusion stringers from which fatigue cracks initiated in the long-service-life rails of this study cannot be detected with current nondestructive inspection procedures, and production of rails without such inclusion would be economically prohibitive. The results also showed that the fatigue-crack-propagation behavior of the various carbon-steel rails was essentially identical, and was independent of chemical composition or mechanical properties. Moreover, the dynamic fracture toughness of these rails at the minimum operating temperature of about minus 30 F (minus 35 C) was about 25 ksi/sq in. (27.5 MPa/sq m) and a significant increase in the fracture toughness of the rails would result in a negligible increase in their useful fatigue life.
- Work performed as part of AISI-AREA-AAR Rail Research Program.
United States Steel Corporation125 Jamison Lane
Monroeville, PA USA 15146
- Barsom, J M
- Imhof Jr, E J
- Publication Date: 1978-3
- Features: Figures; References; Tables;
- Pagination: 50 p.
- TRT Terms: Cracking; Defects; Fracture properties; Low temperature; Rail (Railroads); Rail steel; Service life; Stresses
- Uncontrolled Terms: Crack propagation; Fatigue analysis
- Old TRIS Terms: Rail steel metallurgy; Rail stress
- Subject Areas: Design; Railroads;
- Accession Number: 00183708
- Record Type: Publication
- Source Agency: United States Steel Corporation
- Report/Paper Numbers: R-301 Res Rpt.
- Files: TRIS
- Created Date: Dec 3 1978 12:00AM