A comparison of Weibull and. beta. sub Ic analysis of transition range fracture toughness data

Technical Report · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5933995

McCabe, D E ^[1]

---

1. Oak Ridge National Lab., TN (United States)

Characteristics of extremal statistics that are used to predict size effects on cleavage fracture toughness in the transition range were explored. A 533 grade B steel base and weld metals were tested using compact specimens ranging in size from {1/2}TC(T) to 8TC(T) and with sufficient replication in some cases to provide good fits to Weibull distributions. The classical specimen size effect on data scatter and median K{sup Jc} toughness at a given test temperature was observed in the low- to mid-transition range. These effects were well predicted with external statistics. However, the same model is not applicable on the lower shelf, and it also becomes extremely weak and unreliable in the mid- to high-transition range. The Irwin {beta}{sub c}{minus}{beta}{sub Ic} relationship was also explored as a model and was found to predict similar size effects. The predictive characteristics of the latter seemed better suited to deal with the diminution of size effects in the near- to low-shelf toughness range. In the rising toughness part of the transition, the predictive characteristics were about the same as the statistical model up to where {beta}{sub c} ({beta}{sub Jc} in this study) of the baseline (small specimen) data were {pi} or less. This work could be used in the establishment of a framework for transition temperature test criteria. Upper- and lower-bound {beta}{sub Jc} criteria could be used to define optimum conditions for the application of either of the aforementioned models. For surveillance programs, sensible rules should be specified as to specimen size requirements and numbers of specimens to be tested in order to apply these analytical models. Another need would be the definition of a procedure for the Weibull distribution fitting. The present report suggests items to be considered for requirements in application of these predictive techniques.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of Engineering; Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: NRC; Nuclear Regulatory Commission, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5933995
• Report Number(s): NUREG/CR-5788; ORNL/TM--11959; ON: TI92007824
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ALLOYS
ARC WELDING
CARBON STEELS
CLEAVAGE
COMPARATIVE EVALUATIONS
CRACK PROPAGATION
CRYSTAL STRUCTURE
DISTRIBUTION FUNCTIONS
EVALUATION
FABRICATION
FAILURES
FERRITIC STEELS
FRACTURE MECHANICS
FRACTURE PROPERTIES
FRACTURES
FUNCTIONS
IRON ALLOYS
IRON BASE ALLOYS
JOINING
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
PHYSICAL PROPERTIES
SIZE
STATISTICAL MODELS
STEEL-ASTM-A533-B
STEELS
SUBMERGED ARC WELDING
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
WELDING