THE EFFECTS OF MICROSTRUCTURAL VARIATIONS ON THE STRENGTH AND TOUGHNESS OF RAIL STEELS

An experimental program was carried out on fully-pearlitic rail steel to determine the effects of microstructural variations on tensile and impact properties. A heat treating schedule was developed to isolate the effects of prior austenitic grain size, pearlite interlamellar spacing, and to a minor extent, pearlite colony size. Grain size was varied by a factor of ten, and pearlite spacing by a factor of two. Room temperature yield strength increased monotonically with decreasing interlameller spacing, with the latter controlled by the transformation temerature and prior austenitic grain size. Charpy impact tests were performed to obtain an evaluation of toughness, and showed that toughness increased with decreasing grain size, and was largely independent of an influence of pearlite spacing. Dynamic fracture toughness values, (KID), obtained from instrumented impact testing of precracked Charpy bars, were compared with the standard Charpy results, and yielded Similar findings. Thus, it was found that strength and toughness are controlled by different microstructural parameters, and can be varied independent of each other to optimize service performance.

Media Info

  • Features: Figures; References;
  • Pagination: 33 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00098080
  • Record Type: Publication
  • Source Agency: Association of American Railroads
  • Report/Paper Numbers: R-168
  • Files: TRIS
  • Created Date: Aug 13 1976 12:00AM