Application of SDS Method to Predict Fracture Toughness Temperature Dependency of A533B Steel

2017 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Kenichi Ishihara ◽  
Hiroki Nakano
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Tensile Tests ◽  
Fracture Load ◽  
Reference Temperature ◽  
Small Scale ◽  
Temperature Dependency ◽  
Yielding Condition ◽  
Scale Yielding ◽  
Higher Temperature

Recently, the authors have proposed a new method for scaling the crack tip stress distribution under small scale yielding condition and named it as T-scaling method [1, 2]. This method identifies the different stress loads for materials with different tensile properties but identical in terms of K or J. Then by accepting the knowledge “fracture stress for slip induced cleavage fracture is temperature independent [3],” a framework to predict the fracture load Pc and fracture toughness Jc at an arbitrary temperature from the already known Pcr and Jcr at a reference temperature Tr was proposed and validated for 0.55% carbon steel JIS S55C [1, 2]. This framework was named as SDS method. This paper presents that the SDS method was valid to predict 1TCT Jc temperature dependency of A533B steel [4] in the range of −9 ≤ T-T0 ≤ 27 °C, where T0 is the master curve reference temperature. The SDS method seems to have a possibility to solve the problem the master curve is facing in the relatively higher temperature region, by requiring only tensile tests.

Prediction of the Temperature Dependence on Fracture Toughness by New Stress Distribution Scaling Method

2017 ◽  
Author(s):  
Kenichi Ishihara ◽  
Takeshi Hamada ◽  
Toshiyuki Meshii
Keyword(s):  
Fracture Toughness ◽  
Stress Distribution ◽  
Temperature Dependence ◽  
Temperature Region ◽  
Tensile Tests ◽  
Fracture Load ◽  
Small Scale ◽  
Scaling Method ◽  
Element Analysis ◽  
Scale Yielding

In this paper, a new method for scaling the crack tip stress distribution under small scale yielding condition was proposed and named as T-scaling method. This method enables to identify the different stress distributions for materials with different tensile properties but identical load in terms of stress intensity factor (K) or J-integral (J). Then, a method to predict the fracture load at an arbitrary temperature from the already known fracture load at a reference temperature was proposed by assuming that the temperature dependence of a material is represented as the stress-strain relationship temperature dependence. This method was combined with the T-scaling method and the knowledge “fracture stress for slip induced cleavage fracture is temperature independent.” Once the fracture load is predicted, fracture toughness Jc at the temperature under consideration can be evaluated by running elastic-plastic finite element analysis. Finally, the above-mentioned framework to predict the Jc temperature dependency of a material in the ductile-to-brittle temperature region was validated for 0.55 % carbon steel JIS S55C. The proposed framework seems to have a possibility to solve the problem the master curve is facing in the relatively higher temperature region, by requiring only tensile tests.

Fracture Toughness in Ultra Fine-Grained Magnesium Alloy

2006 ◽  
Vol 503-504 ◽  
pp. 155-160 ◽  
Author(s):  
Hidetoshi Somekawa ◽  
Toshiji Mukai
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Small Scale ◽  
Plane Strain Fracture Toughness ◽  
Small Scale Yielding ◽  
Fine Grained ◽  
Yielding Condition ◽  
Strain Fracture ◽  
Scale Yielding

The fracture toughness was investigated using in an extruded AZ31 magnesium alloy with an initial grain size of 1.0 μm. Since the small scale yielding condition was not satisfied with the present thin thickness, the value of plane-strain fracture toughness, KIC = 27.9 MPam1/2, was measured from Stretched Zone analysis. The values of KIC in AZ31 magnesium alloys were dependent on the grain size. The grain refinement was found to be one of the improvement methods for fracture toughness in magnesium alloy.

Evaluationof fracture toughness ofalpha-Nb5Si3 by micro-sized cantilever beam testing

2015 ◽  
Vol 1760 ◽  
Author(s):  
Shiori Suzuki ◽  
Nobuaki Sekido ◽  
Takahito Ohmura ◽  
Seiji Miura
Keyword(s):  
Fracture Toughness ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Small Scale ◽  
Testing Method ◽  
Yielding Condition ◽  
Linear Load ◽  
Scale Yielding ◽  
Fracture Tests

ABSTRACTA micro-sized fracture testing method has been applied to investigate fracture toughness of alpha-Nb5Si3. Chevron-notched single crystal specimens with a size of 3 x 3 x 15 μm3 were prepared in a grain of polycrystalline alpha-Nb5Si3 by focused ion beam, FIB, technique. Fracture tests were conducted using a nanoindenter at room temperature and linear load-displacement curves and smooth fracture surfaces were obtained. This fracture behavior was presumed to be brittle fracture similar to bulk alpha-Nb5Si3. The average of fracture toughness KQ is 3.45 ± 0.29 MPa√m under a small-scale yielding condition.

On the Crack Quasi-Static Growth

2019 ◽  
Vol 827 ◽  
pp. 312-317
Author(s):  
Vitalijs Pavelko
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Plastic Material ◽  
Small Scale ◽  
Invariant Equation ◽  
Practical Applications ◽  
Wide Range ◽  
Scale Yielding ◽  
Elastic Plastic Material ◽  
Principal Assumption

The theoretical model of quasi-static crack growth in the elastic-plastic material under load variation in a wide range. Small-scale yielding is principal assumption and main restriction of proposed theory. The model of crack growth provides for continues and interrelated both the crack propagation and plastic deformation development. The nonlinear first-order differential equation describes the quasi-static process of crack growth. In dimensionless form this equation invariant in respect to geometrical configuration and material. The critical size of the plastic zone is proposed as the characteristics of material resistance which is directly connected with the fracture toughness, but more convenient in practical applications of invariant equation. The demonstration of solution is performed for the double cantilever beam that widely used as the standard (DCB) sample for measurement of the mode-I interlaminar fracture toughness. he short analysis of some properties of solution of the invariant equation and its application is done.

A Combined Model Approach for Estimating T0

2019 ◽  
Author(s):  
Marjorie Erickson
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Reference Temperature ◽  
Initiation Toughness ◽  
Correlation Model ◽  
Combined Model ◽  
Best Estimate ◽  
Curve Model ◽  
Asme Code ◽  
Model Approach

Abstract The current best-estimate model describing the fracture toughness of ferritic steels is the Master Curve methodology standardized in ASTM E1921. Shortly following standardization by ASTM, efforts were undertaken to incorporate this best-estimate model into the framework of the ASME Code to reduce the conservatisms resulting from use of a reference temperature based on the nil-ductility temperature (RTNDT) to index the plane strain fracture initiation toughness (KIc). The reference temperature RTT0, which is based on the ASTM E1921-defined T0 value, was introduced in ASME Code Cases N-629 (replaced by Code Case N-851) and N-631 to replace RTNDT for indexing the ASME KIc curve. Efforts are continuing within the ASME Code to implement direct use of the Master Curve model; using the T0 reference temperature to index an elastic-plastic, KJc fracture toughness curve. Transitioning to a direct T0-based fracture toughness assessment methodology requires the availability of T0 estimates for all materials to be assessed. The historical Charpy and NDT-based regulatory approach to characterizing toughness for reactor pressure vessel (RPV) steels results in a lack of T0 values for a large population of the US nuclear fleet. The expense of the fracture toughness testing required to estimate a valid T0 value makes it unlikely that T0 will ever be widely available. Since direct implementation of best-estimate, fracture toughness models in codes and regulatory actions requires an estimate of T0 for all materials of interest it is necessary to develop an alternative means of estimating T0. A project has been undertaken to develop a combined model approach to estimating T0 from data that may include limited elastic-plastic fracture toughness KJc, Charpy, tensile, ductile initiation toughness, arrest toughness, and/or nil-ductility temperature data. Using correlations between these properties and T0 a methodology for combining estimates of T0 from several sources of data was developed. T0 estimates obtained independently from the Master Curve model, the Simple T28J correlation model, and a more complex Charpy correlation model were combined using the Mixture Probability Density Function (PDF) method to provide a single estimate for T0. Using this method, the individual T0 estimates were combined using weighting factors that accounted for sample size and individual model accuracy to optimize the accuracy and precision of the combined T0 estimate. Combining weighted estimates of T0 from several sources of data was found to provide a more refined estimate of T0 than could be obtained from any of the models alone.

OS1427 Evaluation method of crack growth in reactor piping subjected to seismic loading beyond small scale yielding condition

2013 ◽  
Vol 2013 (0) ◽  
pp. _OS1427-1_-_OS1427-3_
Author(s):  
Yoshihito YAMAGUCHI ◽  
Makoto UDAGAWA ◽  
Yinsheng LI ◽  
Jinya KATSUYAMA ◽  
Kunio ONIZAWA
Keyword(s):  
Crack Growth ◽  
Evaluation Method ◽  
Seismic Loading ◽  
Small Scale ◽  
Small Scale Yielding ◽  
Yielding Condition ◽  
Scale Yielding

Fracture Toughness Transferability Study Between the Master Curve Method and a Pressure Vessel Nozzle Using Local Approach

2003 ◽  
Author(s):  
Anssi Laukkanen ◽  
Pekka Nevasmaa ◽  
Heikki Keina¨nen ◽  
Kim Wallin
Keyword(s):  
Fracture Toughness ◽  
Pressure Vessel ◽  
Master Curve ◽  
Structural Integrity ◽  
Reference Temperature ◽  
Cleavage Crack ◽  
Local Approach ◽  
Master Curve Method ◽  
Curve Method ◽  
Constitutive Parameters

Local approach methods are to greater extent used in structural integrity evaluation, in particular with respect to initiation of an unstable cleavage crack. However, local approach methods have had a tendency to be considered as methodologies with ‘qualitative’ potential, rather than quantitative usage in realistic analyses where lengthy and in some cases ambiguous calibration of local approach parameters is not feasible. As such, studies need to be conducted to illustrate the usability of local approach methods in structural integrity analyses and improve upon the transferability of their intrinsic, material like, constitutive parameters. Improvements of this kind can be attained by constructing improved models utilizing state of the art numerical simulation methods and presenting consistent calibration methodologies for the constitutive parameters. The current study investigates the performance of a modified Beremin model by comparing integrity evaluation results of the local approach model to those attained by using the constraint corrected Master Curve methodology. Current investigation applies the Master Curve method in conjunction with the T-stress correction of the reference temperature and a modified Beremin model to an assessment of a three-dimensional pressure vessel nozzle in a spherical vessel end. The material information for the study is extracted from the ‘Euro-Curve’ ductile to brittle transition region fracture toughness round robin test program. The experimental results are used to determine the Master Curve reference temperature and calibrate local approach parameters. The values are then used to determine the cumulative failure probability of cleavage crack initiation in the model structure. The results illustrate that the Master Curve results with the constraint correction are to some extent more conservative than the results attained using local approach. The used methodologies support each other and indicate that with the applied local approach and Master Curve procedures reliable estimates of structural integrity can be attained for complex material behavior and structural geometries.

Prediction of Initiation Toughness Under Small Scale Yielding (SSY) and J0.2BL vs. Q Fracture Locus Using Local Approach Methodologies in 304SS

2012 ◽  
Author(s):  
A. Wasylyk ◽  
A. H. Sherry ◽  
J. K. Sharples
Keyword(s):  
Fracture Toughness ◽  
Small Scale ◽  
Initiation Toughness ◽  
Single Edge ◽  
Small Scale Yielding ◽  
Local Approach ◽  
Three Point Bending ◽  
Fracture Locus ◽  
Scale Yielding ◽  
Cracked Specimens

Structural integrity assessments of structures containing defects require valid fracture toughness properties as defined in national and international test standards. However, for some materials and component geometries, the development of valid toughness values — particularly for ductile fracture — is difficult since sufficiently large specimens cannot be machined. As a consequence, the validity of fracture toughness properties is limited by the development of plasticity ahead of the crack tip and the deviation of crack tip conditions at failure from small scale yielding. This paper described the use of local approach models, calibrated against invalid test data, to define initiation toughness in 304 stainless steel pipe material. Three fracture toughness geometries were tested, shallow cracked single edge cracked specimens tested under three point bending, deep cracked single edge cracked specimens tested under three point bending, and deep cracked single edge cracked specimen tested under tension. Initiation toughness and J-Resistance curves were defined for each specimen using the multi-specimen technique. All initiation toughness values measured were above the specimen validity limits. The fracture conditions at initiation were analysed using three local approach models: the Generalised Rice & Tracey, High Constraint Rice & Tracey and the Work of Fracture. The adequacy of local approaches to define the fracture conditions under large strains in 304 stainless steels was demonstrated. A modified boundary layer analysis combined with the local approach models was used to predict the “valid” initiation toughness under small scale yielding condition in this material by defining a J-Q fracture locus. The analytically derived fracture locus was compared to the J-Q values obtained experimentally and shown to be consistent.

Validation of the Master Curve Approach With Various Welding Conditions: Groove Shapes, Heat Inputs and Welding Processes

2020 ◽  
Author(s):  
Jin Ho Lee ◽  
Ji Hoon Kim ◽  
Myung Hyun Kim
Keyword(s):  
Fracture Toughness ◽  
Master Curve ◽  
Impact Test ◽  
Structural Integrity ◽  
Charpy Impact ◽  
Test Sample ◽  
Charpy Impact Test ◽  
Theoretical Background ◽  
Reference Temperature ◽  
Welding Processes

Abstract Engineering critical assessment (ECA) is a procedure for evaluating the soundness of structures with flaws and has been widely applied for assessing the structural integrity. ECA procedure requires reliable fracture toughness data to assess the effect of defects. Ideal data are typically obtained from samples taken during construction of an engineering structure or from the structure afterward, but there are cases in which removal of the test samples is impossible due to the continued operation of the structure. To this end, Appendix J of the BS 7910 provides a procedure for estimating fracture toughness values from appropriate Charpy impact test data. However, the correlation between Charpy impact energy and fracture toughness is known to be overly conservative with not sufficient theoretical background in fracture mechanics perspective. In this regard, the revised BS 7910:2019 provides an improved method for calculating the reference temperature by applying the yield strength and the Charpy upper shelf energy based on empirical data. The target of this study is to validate the master curve approach in the modified BS 7910 for two common offshore grade steels with explicit considerations for various groove shapes, heat inputs and welding processes. For the purpose, the master curves are compared in terms of the reference temperature calculated from Charpy impact test according to BS 7910:2013 and the newly revised 2019 version of BS 7910. The modified master curve resulted in less conservative fracture toughness values anticipated from the decreased reference temperature. The estimated fracture toughness values exhibited a good correlation with experimentally obtained toughness values. The influence of various groove shapes, heat inputs and welding processes in estimating fracture toughness based on the master curve approach is discussed. In addition, the effect of impact test sample locations within weld metals toward estimated fracture toughness values is evaluated.

Sign in / Sign up

Export Citation Format

Share Document