THE EFFECTS OF SURFACE LAYER ON PLASTIC DEFORMATION AND CRACK PROPAGATION

A change in proportional limit after cycling was observed for aluminum 2014-T6. Cycling below the endurance limit increases the proportional limit. However, when the surface layer was eliminated by relaxation, the proportional limit was restored to its original value. These data show that the work hardening is confined mainly in the surface layer. The etch pit distribution of dislocations in Fe-3Si steel was investigated. The threshold stress for the appearance of slip steps in untreated and SSLE treated specimens of aluminum 2014-T6 was determined. The percent of grains deformed in specimens of aluminum 2014-T6 which are stressed to various values was observed. The effect of SSLE treatment on the threshold stress intensity for 4130 steel was established. A diametral gage to measure the surface layer stress of notched specimens was manufactured.

• Corporate Authors:

  Army Materials and Mechanics Research Center

  Watertown, MA  United States  02172
• Authors:
  • Kumar, I R
• Publication Date: 1972-1

Media Info

• Features: References;
• Pagination: 14 p.

Subject/Index Terms

• TRT Terms: Cracking; Failure; Plastic deformation; Repeated loads
• Uncontrolled Terms: Crack propagation
• Old TRIS Terms: Cyclic fatigue
• Subject Areas: Marine Transportation; Materials;

Filing Info

• Accession Number: 00032218
• Record Type: Publication
• Source Agency: Ship Structure Committee
• Report/Paper Numbers: AMMRC CR-71-2/3
• Contract Numbers: DAAG 46-70-C-0102
• Files: TRIS
• Created Date: Apr 21 1972 12:00AM