FRACTURE TOUGHNESS OF STRUCTURAL GRADE BRIDGE STEELS (PART I)

The brittle fracture resistance or toughness of a bridge steel tends to vary inversely with its grain size at service temperature. The service temperature grain size in turn tends to be proportional to the steel's austenitic grain size at the final rolling or normalizing temperature used to process it. The McQuaid-Ehn test, however, measures the austenitic grain size of a steel specimen at 1700F, a temperature which may or may not be representative of the final processing temperature of the plate from which the specimen derived. Since the austenitic grain size varies with the final processing temperature, it follows, that the McQuaid-Ehn grain size doesn't necessarily correlate with fracture toughness. Hence, specifying a fine grain practice, verified by McQuaid-Ehn grain size tests, does not insure that hot rolled steel will be fine grained or suitably resistant to brittle fracture at service temperatures. It only insures that the steel may have these properties if it is control rolled below 1900F or normalized. These correlations and the basis for these conclusions are discussed in this report.

Media Info

  • Pagination: 20 p.

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Filing Info

  • Accession Number: 00151734
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: CADOTTL-6708-1-76-34, FHWA/RD-77-S0581
  • Files: NTIS, TRIS, USDOT, STATEDOT
  • Created Date: Apr 27 2003 12:00AM