Fracture Toughness Measurements in the Transition Regime Using Small Size Samples

2009 ◽  
pp. 214-214-24 ◽  
Author(s):  
R Chaouadi
Keyword(s):  
Fracture Toughness ◽  
Transition Regime

scholarly journals Prediction of Characteristic Length and Fracture Toughness in Ductile-Brittle Transition

2008 ◽  
Author(s):  
Z. X. Wang ◽  
H. M. Li ◽  
Y. J. Chao ◽  
P. S. Lam
Keyword(s):  
Finite Element Method ◽  
Fracture Toughness ◽  
Finite Element ◽  
Characteristic Length ◽  
Crack Tip ◽  
Critical Distance ◽  
Transition Regime ◽  
Temperature Dependent ◽  
Brittle Transition ◽  
Element Method

Finite element method was used to analyze the three-point bend experimental data of A533B-1 pressure vessel steel obtained by Sherry, Lidbury, and Beardsmore [1] from −160 to −45 °C within the ductile-brittle transition regime. As many researchers have shown, the failure stress (σf) of the material could be approximated as a constant. The characteristic length, or the critical distance (rc) from the crack tip, at which σf is reached, is shown to be temperature dependent based on the crack tip stress field calculated by the finite element method. With the J-A2 two-parameter constraint theory in fracture mechanics, the fracture toughness (JC or KJC) can be expressed as a function of the constraint level (A2) and the critical distance rc. This relationship is used to predict the fracture toughness of A533B-1 in the ductile-brittle transition regime with a constant σf and a set of temperature-dependent rc. It can be shown that the prediction agrees well with the test data for wide range of constraint levels from shallow cracks (a/W = 0.075) to deep cracks (a/W = 0.5), where a is the crack length and W is the specimen width.

Transition Regime Fracture Toughness-temperature Properties of two Advanced Ferriticmartensitic Steels

2000 ◽  
Vol 653 ◽  
Author(s):  
Philippe Spätig ◽  
Eric Donahue ◽  
George R. Odette ◽  
Glenn E. Lucas ◽  
Max Victoria
Keyword(s):  
Fracture Toughness ◽  
Transition Regime

A Proposal for the Maximum KIc for Use in ASME Code Flaw and Fracture Toughness Evaluations

2011 ◽  
Author(s):  
Mark T. Kirk ◽  
Gary L. Stevens ◽  
Marjorie Erickson ◽  
Shengjun Sean Yin
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Empirical Models ◽  
Ferritic Steels ◽  
Transition Regime ◽  
Upper Limit ◽  
Pressurized Thermal Shock ◽  
Asme Code ◽  
The One ◽  
Reactor Pressure

Nonmandatory Appendices A [1] and G [2] of Section XI of the ASME Code use the KIc curve (indexed to the material reference transition temperature, RTNDT) in reactor pressure vessel (RPV) flaw evaluations, and for the purpose of establishing RPV pressure-temperature (P-T) limits. Neither of these appendices places an upper-limit on the KIc value that may be used in these assessments. Over the years, it has often been suggested by some of the members of the ASME Section XI Code committees that are responsible for maintaining Appendices A and G that there is a practical upper limit of 200 ksi√in (220 MPa√m) [4]. This upper limit is not well recognized by all users of the ASME Code, is not explicitly documented within the Code itself, and the one source known to the authors where it is defended [4] relies on data that is either in error, or is less than 220 MPa√m. However, as part of the NRC/industry pressurized thermal shock (PTS) reevaluation effort, empirical models were developed that propose common temperature dependencies for all ferritic steels operating on the upper shelf. These models relate the fracture toughness properties in the transition regime to those on the upper shelf and, combined with data for a wide variety of RPV steels and welds on which they are based, suggest that the practical upper limit of 220 MPa√m exceeds the upper shelf fracture toughness of most RPV steels by a considerable amount, especially for irradiated steels. In this paper, available models and data are used to propose upper bound limits of applicability on the KIc curve for use in ASME Code, Section XI, Nonmandatory Appendices A and G evaluations that are consistent with available data for RPV steels.

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