A Method to Quantify Thermal Aging Effect on Fracture Toughness of Cast Stainless Steels Using Small Punch Test

2014 ◽  
Author(s):  
Jun-Young Jeon ◽  
Dong-Il Ryu ◽  
Yun-Jae Kim ◽  
Mi-Yeon Lee ◽  
Jin-Weon Kim
Keyword(s):  
Fracture Toughness ◽  
Test Data ◽  
Stainless Steels ◽  
Fracture Strain ◽  
Fracture Toughness Test ◽  
Small Punch ◽  
Fracture Simulation ◽  
Toughness Test ◽  
Axial Fracture ◽  
Strain Model

In this study, a method to predict fracture toughness of aged cast austenitic stainless steels (CASSs) using small punch (SP) test and finite element (FE) analysis is proposed. Grade CF8M is considered and thermally aged up to 5,000 hours at 400°C. SP tests and fracture toughness test using compact tension (C(T)) specimen are conducted with virgin (unaged) and aged CF8M. FE analyses performed in this study use ductile fracture simulation technique with ‘the multi-axial fracture strain model’. The multi-axial fracture strain model for each aged CF8M are determined from SP test data and FE analyses. Fracture toughness of aged CF8M are predicted by conducting fracture toughness test simulations using FE damage analyses. Predicted fracture toughness results are compared with C(T) data to validate the method suggested in this study. The predicted initiation toughness values are predicted well and fracture toughness values are slightly conservative compared to test data.

J-R Curve Prediction of Pre-Strained Stainless Steel 316 Material Using FE Damage Analysis Method

2018 ◽  
Author(s):  
Jun-Min Seo ◽  
Ji-Soo Kim ◽  
Yun-Jae Kim
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Damage Model ◽  
Damage Analysis ◽  
Fracture Toughness Test ◽  
Toughness Test ◽  
Cold Worked ◽  
Axial Fracture ◽  
Stainless Steel 316 ◽  
Strain Model

In this study, a method to predict J-R curve of SUS316 material using FE damage analysis is proposed. As experimental data, tensile and fracture toughness test results of cold worked SUS316 are used. The damage model used in this study is multi-axial fracture strain model and the model is determined by simulating the tensile and fracture toughness test according to the procedure in R6 code [1]. A pre-strain constant is newly introduced to consider pre-strain damage caused by the pre-strain, and the damage for various degrees of pre-strain are calculated. As a result, the predicted J-R curves using FE damage model show good agreement with the experimental data.

Evaluation of Fracture Toughness Test Data for Multilayer Dissimilar Joint Welds Using a Weibull Stress Model

2012 ◽  
pp. 357-376
Author(s):  
Yasuhito Takashima ◽  
Mitsuru Ohata ◽  
Masaru Seto ◽  
Yoshitomi Okazaki ◽  
Fumiyoshi Minami
Keyword(s):  
Fracture Toughness ◽  
Test Data ◽  
Dissimilar Joint ◽  
Fracture Toughness Test ◽  
Stress Model ◽  
Toughness Test ◽  
Weibull Stress

Ductile Tearing Simulation of Circumferential Cracked Pipe Under Cyclic Loading Using Damage Criteria Determined by Monotonic Pipe Test Data

2018 ◽  
Author(s):  
Jin-Ha Hwang ◽  
Gyo-Geun Youn ◽  
Naoki Miura ◽  
Yun-Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Ductile Fracture ◽  
Test Data ◽  
Strain Energy ◽  
Fracture Strain ◽  
Damage Model ◽  
Fracture Toughness Test ◽  
Ductile Tearing ◽  
Damage Criteria

To evaluate the structural integrity of nuclear power plant piping, it is important to predict ductile tearing of circumferential cracked pipe from the view point of Leak-Before-Break concept under seismic conditions. CRIEPI (Central Research Institute of Electric Power Industry) conducted fracture test on Japanese carbon steel (STS410) circumferential through-wall cracked pipes under monotonic or cyclic bending load in room temperature. Cyclic loading test conducted variable experimental conditions considering effect of stress ratio and amplitude. In the previous study, monotonic fracture pipe test was simulated by modified stress-strain ductile damage model determined by C(T) specimen fracture toughness test. And, ductile fracture of pipe under cyclic loading simulated using damage criteria based on fracture strain energy from C(T) specimen test data. In this study, monotonic pipe test result is applied to determination of damage model based on fracture strain energy, using finite element analysis, without C(T) specimen fracture toughness test. Ductile fracture of pipe under variable cyclic loading conditions simulates using determined fracture energy damage model from monotonic pipe test.

Evaluation of Fracture Toughness Test Data for Multilayer Dissimilar Joint Welds Using a Weibull Stress Model

2012 ◽  
Vol 9 (3) ◽  
pp. 103979
Author(s):  
Yasuhito Takashima ◽  
Mitsuru Ohata ◽  
Masaru Seto ◽  
Yoshitomi Okazaki ◽  
Fumiyoshi Minami
Keyword(s):  
Fracture Toughness ◽  
Test Data ◽  
Dissimilar Joint ◽  
Fracture Toughness Test ◽  
Stress Model ◽  
Toughness Test ◽  
Weibull Stress

Constraint Effects in Ductile Fracture on J-Resistance Curve for Full-Scale Cracked Pipes and Fracture Toughness Testing Specimens

2014 ◽  
Author(s):  
Jae-Jun Han ◽  
Yun-Jae Kim ◽  
R. A. Ainsworth
Keyword(s):  
Fracture Toughness ◽  
Ductile Fracture ◽  
Full Scale ◽  
Battelle Memorial Institute ◽  
Fracture Parameter ◽  
Fracture Toughness Test ◽  
Integrity Assessment ◽  
Fracture Simulation ◽  
Circumferential Crack ◽  
Toughness Test

Fracture toughness is an important quantity in structural integrity assessment of pressurised vessels and piping. This paper reports J resistance (J-R) curves for toughness test specimens and full-scale pipes with a circumferential crack in a carbon steel. Full-scale pipes with a circumferential crack subjected to four-point bending are investigated with single edge-notched-tension specimens, SE(T), under fixed grip and pin-loaded conditions and compact tension, C(T), fracture toughness test specimens. Finite element (FE) damage analyses based on a stress-modified fracture strain model are used to simulate ductile fracture. An element-size-dependent critical damage model is introduced and applied to the large-scale components. Fracture parameter J values are calculated using both experimental data and FE analysis. In the first part of this paper, experimental results performed by Battelle Memorial Institute are compared with results from FE simulations to gain confidence in the ductile fracture simulation. Subsequently, different types of fracture toughness tests and thickness variations are considered to address the effect of in-plane and out-of plane constraint, respectively. Also, pipe geometries and crack depth are varied systematically. In conclusion, the transferability of J-R curves from toughness test specimens to full-scale cracked pipes is discussed.

Issue of Application for the Pre-Cracked Charpy Specimens to Estimate WWER-1000 RPV Metal Embrittlement

2016 ◽  
Author(s):  
Volodymyr M. Revka ◽  
Liudmyla I. Chyrko
Keyword(s):  
Fracture Toughness ◽  
Test Data ◽  
Charpy Impact ◽  
Pressure Vessels ◽  
Reference Temperature ◽  
Fracture Toughness Test ◽  
Toughness Test ◽  
Standard Specimens ◽  
High Level ◽  
Reactor Pressure

In this study the analysis of fracture toughness test data has been performed in terms of estimation of the proper T0 value for several WWER-1000 RPV materials in unirradiated condition. The surveillance test data for the standard and reconstituted specimens were included in the analysis. It was found that a reference temperature T0 for reconstituted specimens is 31°C higher on average in comparison to the standard specimens. The possible reason is a high level of the stress intensity factor Kmax during the cycle at the stage of completion of crack tip sharpening for standard specimens. Furthermore, the Charpy impact and fracture toughness test data for standard and reconstituted specimens have been compared considering the known relationship between the reference temperature T0 and the transition temperature T28J which corresponds to the Charpy energy level of 28 J. Another objective of this study was to compare the RPV metal embrittlement rate for the two reactor pressure vessels using surveillance test data from standard and reconstituted fracture toughness specimens. The analysis has shown that test data for the reconstituted specimens is consistent with the test data for the standard specimens with regard to the embrittlement rate.

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