Reconstitution of Fracture Toughness Specimen for Surveillance Test

2009 ◽  
pp. 470-470-14 ◽  
Author(s):  
M Tomimatsu ◽  
S Kawaguchi ◽  
M Iida
Keyword(s):  
Fracture Toughness ◽  
Fracture Toughness Specimen

Small fracture toughness specimen for post-irradiation experiments

2007 ◽  
Vol 367-370 ◽  
pp. 599-602 ◽  
Author(s):  
H.-C. Schneider ◽  
J. Aktaa ◽  
R. Rolli
Keyword(s):  
Fracture Toughness ◽  
Post Irradiation ◽  
Fracture Toughness Specimen

Standardization of CTOD Toughness Correction for Constraint Loss in Steel Components

2008 ◽  
Author(s):  
Fumiyoshi Minami ◽  
Mitsuru Ohata
Keyword(s):  
Fracture Toughness ◽  
Fracture Criterion ◽  
Shape Parameter ◽  
Pipeline Steel ◽  
Fracture Initiation ◽  
Failure Assessment ◽  
Fracture Assessment ◽  
Steel Welds ◽  
Weibull Stress ◽  
Fracture Toughness Specimen

A standardized procedure for correction of CTOD fracture toughness for constraint loss in steel components is presented. The equivalent CTOD ratio β = δ/δWP is developed on the basis of the Weibull stress fracture criterion, where δ and δWP are CTODs of the standard fracture toughness specimen and the wide plate component, respectively, at the same level of the Weibull stress. With the CTOD ratio β, the critical CTOD δWP, cr of the wide plate that is equivalent to δcr at brittle fracture initiation is given as δWP, cr = δcr/β. Nomographs of β are provided as a function of the crack type and size in the component, the yield-to-tensile ratio of the material and the Weibull shape parameter m. The fracture assessment with β is shown within the context of a failure assessment diagram (FAD), which includes the pipeline steel welds with a notch in the weld metal.

Constraint Based Assessments of Large-Scale Cracked Straight Pipes and Elbows

2015 ◽  
Author(s):  
Marius Gintalas ◽  
Robert A. Ainsworth
Keyword(s):  
Fracture Toughness ◽  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Large Scale ◽  
Initiation Point ◽  
T Stress ◽  
Advanced Analysis ◽  
Material Fracture ◽  
Fracture Toughness Specimen

The paper presents T-stress solutions developed to characterize constraint levels in large-scale cracked pipes and elbows. Stress intensity factor, KI, solutions for pipes and elbows are normalised by material fracture toughness to define the Kr parameter in fitness-for-service procedures, such as R6. Adding knowledge on levels of T-stress allows more advanced analysis through a normalised constraint parameter βT. The paper presents analyses for 6 pipes and 8 elbows. Values of the normalised constraint parameter βT are calculated for each pipe and elbow at the experimentally measured crack initiation point. Comparison of constraint levels in the pipes and elbows with those in various types of fracture toughness specimen are used to predict the initiation loads using the R6 method and to provide guidelines for transferability.

Use of Small Specimens for Evaluation of Irradiated Materials

2013 ◽  
Author(s):  
Mikhail A. Sokolov ◽  
Randy K. Nanstad
Keyword(s):  
Fracture Toughness ◽  
Small Volume ◽  
Radioactive Material ◽  
Surveillance Programs ◽  
Series Of Experiments ◽  
Point Bend ◽  
Impact Data ◽  
Surveillance Specimens ◽  
Reactor Pressure ◽  
Fracture Toughness Specimen

Small specimens are playing the key role in evaluating properties of irradiated materials. The use of small specimens provides several advantages. Typically, only small volume of material can be irradiated in a reactor at desirable conditions in terms of temperature, neutron flux, and neutron dose. Small volume of irradiated material may also allow for easier handling of specimens. Smaller specimens reduce the amount of radioactive material, minimizing personnel exposures and waste disposal. However, use of small specimens imposes variety of challenges as well. These challenges are associated with proper accounting for size effects and transferability of small specimen data to the real structures of interest. The PCVN specimen as well as any fracture toughness specimen that can be made out of the broken halves of standard Charpy specimens may have exceptional utility for evaluation of RPVs. The Charpy V-notch specimen is the most commonly used specimen geometry in surveillance programs. Precracking and testing of Charpy surveillance specimens would allow one to determine and monitor directly actual fracture toughness instead of requiring indirect predictions using correlations established with impact data. However, there is a growing number of indications that there might be a bias in the reference fracture toughness transition temperature, To values derived from PCVN and compact specimens. The present paper summarizes data from the series of experiments that use subsize specimens for evaluation of the transition fracture toughness of reactor pressure vessel (RPV) steels. Two types of compact specimens and three types of three-point bend specimens from five RPV materials were used in these subsize experiments. The current results showed that To determined from PCVN specimens with width (W) to thickness (B) ratio W/B = 1, on average, are lower than To determined from compact specimens with W/B = 2. At the same time, three-point bend specimens with W/B = 2 exhibited To values that were very similar to To values derived from compact specimens. Constraint corrections developed by Dodds et al. are applied to assess the bias.

scholarly journals Yield Load Solutions for SE(B) Fracture Toughness Specimen with I-Shaped Heterogeneous Weld

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 214
Author(s):  
Pejo Konjatić ◽  
Marko Katinić ◽  
Dražan Kozak ◽  
Nenad Gubeljak
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Fracture Behavior ◽  
Lower Yield ◽  
Yield Load ◽  
Weld Metals ◽  
Lower Yield Strength ◽  
Fracture Toughness Specimen ◽  
Good Agreement

The objective of this work was to investigate the fracture behavior of a heterogeneous I-shaped welded joint in the context of yield load solutions. The weld was divided into two equal parts, using the metal with the higher yield strength and the metal with the lower yield strength compared to base metal. For both configurations of the I-shaped weld, one with a crack in strength in the over-matched part of the weld and one for a crack in the under-matched part of the weld, a systematic study of fracture toughness SE(B) specimen was carried out in which the crack length, the width of the weld and the strength mismatch factor for both weld metals were varied, and the yield loads were determined. As a result of the study, two mathematical models for determination of yield loads are proposed. Both models were experimentally tested with one strength mismatch configuration, and the results showed good agreement and sufficiently conservative results compared to the experimental results.

Evaluation of Thermal Shock Fracture Toughness for ATJ Graphite Using Laser Irradiation Method

2004 ◽  
Vol 261-263 ◽  
pp. 93-98 ◽  
Author(s):  
Jae Hoon Kim ◽  
Young Shin Lee ◽  
Duck Hoi Kim ◽  
N.S. Park ◽  
Soon Il Moon
Keyword(s):  
Fracture Toughness ◽  
Temperature Distribution ◽  
Thermal Shock ◽  
Laser Irradiation ◽  
Laser Power ◽  
Laser Source ◽  
Surface Phenomenon ◽  
Heat Resistant ◽  
The Common ◽  
Fracture Toughness Specimen

Graphite has been developed as heat resistant material. To apply a reliable structural design using graphite, it is very important to investigate thermal shock characteristics. The common experimental methods of thermal shock fracture toughness are quenching and arc discharging heating methods. This paper describes experimental technique to evaluate the thermal shock fracture toughness using laser irradiation and proposes that a critical value of laser power can be a measurement to evaluate heat resistant materials. The laser source is CO2 laser having maximum power of 4.0kW. The range of laser beam is from 1.0 to 2.7 kW and the beam duration is fixed at 1sec. K and C type thermocouples were used to measure the temperature distribution of a thermal shock fracture toughness specimen. In this study, the temperature distribution of specimen surfaces and critical laser power was investigated. After test, the surface phenomenon of specimen is examined using radiography and SEM. It is concluded that the critical laser power causing fracture can be the major factor of thermal shock fracture toughness of ATJ graphite.

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