EVALUATION OF WELD-JOINT FLAWS AS INITIATING POINTS OF BRITTLE FRACTURE

This report describes a study made of the conditions needed for initiation of a brittle fracture from flaws 4 in. or less in length. Experiments performed demonstrated that residual and reaction stresses (local stresses) join with applied stresses to make up the total stress that is involved in the initiation of many brittle fractures. If local stresses are high in the vicinity of a flaw, then the applied stress may be low when brittle fracture initiates from that flaw provided that the steel is at or near the nil ductility temperature (NDT). Stress conditions that are expected to exist in ship structures were incorporated in the test specimen. Various techniques were employed to determine the magnitude of the stresses in the area of the flaw front. Some brittle fractures were initiated from flaws 4 in. or less in length at an applied stress of less than 6000 psi. Thus the results provided some insight concerning the state of stress that probably existed in structures that have failed in service at low applied stress. Service failures and the results obtained on this project show that flaws, (especially cracks), of almost any size are potential initiation points of brittle fracture. On the other hand, these results have shown that a total stress of yield-point value or higher, in conjunction with some stress-raising condition, is necessary to initiate brittle fracture under service conditions from flaws of various sizes and types (such as a crack or lack of fusion in a weld joint). In other words, it takes a combination of conditions to initiate a brittle fracture.

  • Corporate Authors:

    Battelle Memorial Institute

    505 King Avenue
    Columbus, OH  United States  43201

    Ship Structure Committee

    National Academy of Science, 2101 Constitution Avenue, NW
    Washington, DC  United States  20418
  • Authors:
    • Sopher, R P
    • Lowe Jr, A L
    • Rieppel, P J
  • Publication Date: 1958-8-29

Media Info

  • Pagination: 51 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00331717
  • Record Type: Publication
  • Source Agency: Ship Structure Committee
  • Report/Paper Numbers: SSC-107 Final Rpt.
  • Contract Numbers: NObs-61748
  • Files: TRIS
  • Created Date: May 21 1981 12:00AM