RAILROAD COUPLER SAFETY RESEARCH AND TEST PROJECT. STUDY OF THE FATIGUE LIFE CHARACTERISTICS OF CAST STEELS USED IN THE RAILROAD INDUSTRY

This investigation evaluated the fatigue properties of three commercial grades of cast steel utilized by the railroad industry. The tests were conducted using a 3/4" thick, 10-inch long flat plate specimen tested in reversed bending about a zero mean load. The specimens were provided by different manufacturers with their actual cast surfaces. Significant differences in fatigue behavior were rationalized considering four parameters: hardness, surface conditions, decarburization and inclusions at the surface. From this analysis, it was concluded that pits or irregularities in the cast surface rather than surface roughness determine the final fatigue behavior. The detrimental effect of these pits increase with their size. The decarburization reduces the fatigue strength of the lower strength Grades B and C steels more than the higher strength Grade E. From the various types of inclusions produced at the surface by mold-metal or gas-metal reactions, those that penetrated from the cast surface with a crack-like oxide along the grain boundaries were the most deleterious to the endurance ratio at all tensile strengths. Casting surface defects as pinholes, laps, slag or sand inclusions caused large reductions of the endurance life. All surface problems caused a greater reduction in the fatigue strength of the higher tensile strength steels.

Media Info

  • Features: Appendices; Figures; Tables;
  • Pagination: 122 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00193747
  • Record Type: Publication
  • Source Agency: Association of American Railroads
  • Report/Paper Numbers: AAR Rpt. 299 No. 9 Tech Rpt.
  • Files: TRIS
  • Created Date: May 26 1979 12:00AM