WELD FLAW EVALUATION
This is a detailed final report on a series of investigations made to determine a basis for the evaluation of the ability of weld flaws to initiate brittle fracture. The report is in four parts dealing successively with (1) brittle fracture mechanics based on the Griffith theory and on Irwin's strain-energy release rate adaptations, (2) static tests on flawed butt welds, (3) static and dynamic tests on small butt weld flaws with and without residual stress, and (4) static tests on weld flaws in a controlled field of high residual stress. All welding flaws in selected materials were simulated flaws, varied to represent lack of penetration, porosity, lack of fusion, or sharp internal weld cracks. The major objective was to examine the effect of given flaws in various environments, in order to determine the environment essential to initiate brittle fracture under low static stress conditions. Low temperature was generally an essential part of the environment, but low static stress initiation could not be procured below the nominal yield point unless the static stress was augmented by either a dynamic stress or a high previously-incurred residual stress. The residual stress environment proved to be most significant. Brittle fractures were initiated from short internal cracks with as small as 2000 psi of applied static stress at temperatures in the order of 0 deg F. If total brittle fracture did not result, arrested fractures occurred from small buried flaws, with the arrested crack forming a potential source of fracture initiation. Finally, this report emphasizes the important bearing that residual stress has on the brittle fracture problem and the need for extended investigations in brittle fracture mechanics based on strain-energy release rates to furnish a complete engineering basis for flaw evaluation.
Swarthmore CollegeDepartment of Civil Engineering
Swarthmore, PA United States
Ship Structure CommitteeNational Academy of Science, 2101 Constitution Avenue, NW
Washington, DC United States 20418
- Carpenter, S T
- Linsenmeyer, R F
- Publication Date: 1958-7-29
- Features: References;
- Pagination: 117 p.
- TRT Terms: Butt welds; Defects; Flaw detection; Fracture mechanics; Welds
- Identifier Terms: Ship Structure Committee
- Uncontrolled Terms: Weld defects
- Subject Areas: Marine Transportation; Materials;
- Accession Number: 00331715
- Record Type: Publication
- Source Agency: Ship Structure Committee
- Report/Paper Numbers: SSC-105 Final Rpt.
- Contract Numbers: NObs-72060
- Files: TRIS
- Created Date: May 21 1981 12:00AM