Engineering approaches to the application of fracture toughness data in the nuclear industry

Conference · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5651557

Merkle, J G

The procedures for measuring the plane strain fracture toughness, K{sub Ic}, of metals were originally developed for relatively high yield strength materials, the toughnesses of which were not affected by strain rate. The application of these procedures to lower yield strength and higher toughness structural and pressure vessel steels have since revealed a perplexing combination of problems involving the effects of geometry, stable crack growth and strain rate on the measured values of toughness. Only the geometric problems were encountered in the development of the procedures for measuring K{sub Ic}. For fracture in the linear elastic range of the load-displacement curve, these problems were overcome by specifying specimen dimensions sufficiently large with respect to the plastic zone size at fracture. However, in the case of structural and pressure vessel steels, it is not always possible to test specimens large enough for fracture to occur prior to general yielding. Therefore, in these cases, the effects of large-scale yielding prior to fracture cannot be avoided, but since they presently have no analytical explanation they are being treated empirically. The problems of geometry and strain rate effects on toughness discussed herein are complex and difficult to solve. However, taking advantage of the improvements that have recently been made in the hardware and software available for performing three-dimensional elastic-plastic and viscoplastic stress analysis, it should be possible to significantly improve the analysis of small-specimen, elastic-plastic fracture toughness data.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: NRC
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5651557
• Report Number(s): CONF-8707219-1; ON: DE90001596
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220200 -- Nuclear Reactor Technology-- Components & Accessories
36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CONTAINERS
CRACK PROPAGATION
CRYSTAL STRUCTURE
FAILURES
FRACTURE MECHANICS
FRACTURES
HARDNESS
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
PRESSURE VESSELS
STEELS
STRAIN RATE
YIELD STRENGTH