PRECIPITATE SIZE AND DISTRIBUTION EFFECTS ON FATIGUE CRACK INITIATION AND PROPAGATION IN A HIGH STRENGTH STEEL

It has been observed that high yield strength metals do not necessarily exhibit an equally high fatigue strength. Thus the dependence of fatigue failure on the precipitate size and distribution is investigated. Also, it is proposed that the permanent axial strain resulting from cyclic torsion is indicative of the metal response to cyclic loading. Microscopic observation of the failed specimens showed that failure at plus or minus 0.005 in/in twist strain occurred by the propagation of a single shear macrocrack linking with shear microcracks. The initiation of the shear microcracks was found to depend upon the precipitate size and distribution. With fine particles localized deformation bands became microcracks, but with coarser particles crack initiation began at the particle-matrix interface. (Author Modified Abstract)

• Corporate Authors:

  George Washington Transportation Research Institute. Center for Intelligent Systems Research

  ,    
• Authors:
  • Gilmore, C M
  • Wood, W A
• Publication Date: 1973-3

Media Info

• Pagination: 12 p.

Subject/Index Terms

• TRT Terms: Cracking; Fatigue (Mechanics); Fatigue cracking; Grain size (Geology); Loads; Microstructure; Repeated loads; Steel; Strain (Mechanics); Yield point
• Uncontrolled Terms: Crack propagation
• Old TRIS Terms: Crack formation; Dispersion hardening; Loading mechanics; Precipitate size; Steel 8co 1mo 2cr 10ni
• Subject Areas: Marine Transportation; Materials;

Filing Info

• Accession Number: 00047610
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: TR-13 Tech Rpt
• Contract Numbers: N00014-67A-0214-0011
• Files: TRIS
• Created Date: Oct 18 1973 12:00AM