Evaluation of the Japanese Fatigue Test Data in Gr.91 for Elevated Temperature Design

2021 ◽  
Author(s):  
Masanori Ando ◽  
Kodai Toyota ◽  
Ryuta Hashidate ◽  
Takashi Onizawa
Keyword(s):  
Elevated Temperature ◽  
Fatigue Curve ◽  
Fatigue Tests ◽  
Temperature Dependent ◽  
Lower Confidence Bound ◽  
Creep Fatigue ◽  
Elevated Temperature Design ◽  
Grade 91 ◽  
Curve Equation ◽  
Best Fit

Abstract The ASME Boiler and Pressure Vessel Code (ASME BPVC) Section III, Division 5, Subsection HB, Subpart B provided only one design fatigue curve for Grade 91 steel (Gr.91) at 540 °C (or 1000 °F) in 2019 and earlier versions. To overcome this disadvantage, The ASME Section III Working Group on Creep-Fatigue and Negligible Creep (WG-CFNC) had taken an action to incorporate the temperature-dependent design fatigue curves for Gr. 91 developed by Japan Society of Mechanical Engineers (JSME) into ASME BPVC Section III Division 5. As a result, the temperature dependent design fatigue curves are provided in the 2021 edition of the ASME BPVC. To clear the features of the best-fit fatigue curve equation developed by the JSME, 305 data stored in the database were analyzed. Details of the database and relationship between the best-fit fatigue curve equation and the data including the statistic values and the values of 95% and 99% lower confidence bound calculated by failure probability assessment were clarified through analysis. In addition to the best-fit fatigue curve equation, an equation for dynamic stress-strain response showing the behavior of Gr.91 steel under cyclic loading of is also provided based on the same database. Moreover, some additional available data of fatigue and creep-fatigue tests obtained in Japan are also provided for considering the creep-fatigue damage evaluation under elevated temperature condition.

Proposal for the Implementation of Elevated Temperature Design Fatigue Curve for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V Steels

2004 ◽  
Author(s):  
Tatsumi Takehana ◽  
Takeru Sano ◽  
Susumu Terada ◽  
Hideo Kobayashi
Keyword(s):  
Elevated Temperature ◽  
Fatigue Strength ◽  
High Strength ◽  
Fatigue Curve ◽  
Temperature Limit ◽  
Fatigue Tests ◽  
Low Alloy Steels ◽  
Alloy Steels ◽  
Elevated Temperature Design

2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels have been used extensively as materials for elevated temperature and high-pressure hydro-processing reactors. These steels have both of high strength at elevated temperature and high resistance against elevated temperature hydrogen attack due to the addition of vanadium. The operating temperature of these reactors is between 800 and 900deg.F. The fatigue evaluations of these reactors per ASME Sec. VIII Div.2 and Div.3 can’t be performed in spite of demand for fatigue analysis because the temperature limit of design fatigue curve in ASME Sec. VIII Div.2 and Div.3 for carbon and low alloy steels is 700deg.F. Results of load and strain controlled fatigue tests conducted over the temperature range from room temperature to 932deg.F (500deg.C) are reported for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels. These data were compared with data for 2-1/4Cr-1Mo steels available from the literatures. The fatigue strength for a 2-1/4Cr-1Mo-V steel in high cycle region is higher than that for 2-1/4Cr-1Mo steels and in low cycle region is lower. The fatigue strength for a 3Cr-1Mo-V steel is almost same as that for 2-1/4Cr-1Mo-V steels. Therefore an elevated temperature design fatigue curve for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels is newly proposed. It is found from the case study that the different fatigue life can be predicted by using different mean stress correction procedure.

scholarly journals Evaluation of Mean Stress Correction on Fatigue Curves of Grade 91 and Alloy 617 in ASME Section III Division 5

2020 ◽  
Author(s):  
Y. Wang ◽  
M. D. McMurtrey ◽  
R. I. Jetter ◽  
T.-L. Sham
Keyword(s):  
Construction Material ◽  
Fatigue Curve ◽  
Stress Effect ◽  
Mean Stress ◽  
Alloy 617 ◽  
Fatigue Design ◽  
Creep Fatigue ◽  
The Mean ◽  
Elevated Temperature Design ◽  
Grade 91

Abstract The current ASME Boiler and Pressure Vessel (B&PV) Code Section III, Division 5, Subsection HB, Subpart B has only one design fatigue curve for grade 91 steel (Gr. 91) at 540 °C (or 1000 °F). The ASME Section III Working Group on Creep-Fatigue and Negligible Creep (WG-CFNC) has taken an action to incorporate the temperature-dependent design fatigue curves for Gr. 91 developed by Japan Society of Mechanical Engineers (JSME) into ASME Section III Division 5. During the process, issues regarding the effect of mean stress on fatigue analysis, and how to consider the mean stress effect for elevated-temperature design, were brought up. To evaluate whether the design fatigue curves of Gr. 91 needed adjustment to account for mean stress, critical tests were designed and performed at 371 °C (700 °F) and 540 °C (1000 °F). This study is similar to the work performed on Alloy 617 when its fatigue design curves were established for temperature range of 538–704°C (1000–1300°F) as part of the Code Case package for Alloy 617 to be used as Class A construction material in Division 5. The effects of mean stress on Alloy 617 were evaluated at 550°C (1022°F). The results showed that the mean stresses introduced by the non-zero mean strain could not be maintained under strain-controlled fatigue and resulted in negligible effect on the fatigue life. Mean stress correction was not recommended for Alloy 617 fatigue design curves in Division 5. This study shows the same conclusion for Gr. 91.

On a Design Acceptability of 90° Elbow According to Pipe Length at Elevated Temperature Condition

2016 ◽  
Author(s):  
Seong-Yun Jeong ◽  
Min-Gu Won ◽  
Jae-Boong Choi ◽  
Nam-Su Huh ◽  
Young-Jin Oh
Keyword(s):  
Elevated Temperature ◽  
Structural Integrity ◽  
Seismic Damage ◽  
Design Codes ◽  
Finite Element Analyses ◽  
Promising Candidate ◽  
Pipe Length ◽  
Integrity Assessment ◽  
Creep Fatigue ◽  
Elevated Temperature Design

Sodium-cooled Fast Reactor, SFR is promising candidate of Generation-IV reactor. SFR is operated at high temperature and low pressure. For reducing high thermal stress, thin-walled components and structures are employed for SFR. However, thins-walled components are vulnerable to seismic damage[1]. In this paper, the structural integrity assessment are performed to investigate the effect of piping length on creep-fatigue and seismic damage at elevated temperature. L-shaped elbow is considered for piping design and finite element analyses are conducted to calculate creep-fatigue and seismic damage. The evaluation of creep fatigue damage is carried out according to the elevated temperature design codes of ASME B&PV Sec. III Subsec. NH-3200[2]. Seismic damage are evaluated based ASME B&PV Sec. III Subsec. NB-3600[3] and ASME B&PV Sec. III Div.5 HBB-3200[4]. From the results of creep-fatigue and seismic damage, limit length of piping is determined.

Development of New Design Fatigue Curves in Japan: Discussion of Best-Fit Curves Based on Large-Scale Fatigue Tests of Carbon and Low-Alloy Steel Plates

2018 ◽  
Author(s):  
Masahiro Takanashi ◽  
Hiroshi Ueda ◽  
Toshiyuki Saito ◽  
Takuya Ogawa ◽  
Kentaro Hayashi
Keyword(s):  
Large Scale ◽  
Phase 1 ◽  
Fatigue Curve ◽  
Fatigue Tests ◽  
Steel Plates ◽  
Phase 2 ◽  
Test Results ◽  
Low Alloy Steel ◽  
Best Fit ◽  
Deep Crack

In Japan, the Design Fatigue Curve (DFC) Phase 1 and Phase 2 subcommittees were organized under the Atomic Energy Research Committee in the Japan Welding Engineering Society and have proposed new design fatigue curves for carbon, low-alloy, and austenitic stainless steels. To confirm the validity of the proposed design fatigue curves, a Japanese utility collaborative project was launched. In this project, fatigue tests were conducted on large-scale and small-sized specimens, and the test data were provided to the DFC Phase 2 subcommittee. This paper discusses the best-fit curves proposed by the DFC Phase 1 subcommittee, focusing on the results of large-scale fatigue tests for carbon steel and low-alloy steel plates. The fatigue test results for large-scale specimens were compared with the best-fit curve proposed by the DFC Phase 1 subcommittee. This comparison revealed that the fatigue lives given by the proposed curves correspond to those of approximately 1.5–4.0-mm-deep crack initiation in large-scale specimens. In this program, fatigue tests with a mean strain were also carried out on large-scale specimens. These tests found that the fatigue lives were almost equivalent to those of approximately 4.4–7.0-mm-deep crack initiation in large-scale specimens. In determining a design fatigue curve, strain-controlled tests are usually performed on small-sized specimens, and the fatigue life is then defined by the 25% load drop. It is reported that the cracks reach nearly 3–4-mm depth under those 25% drop cycles. The test results confirm that the fatigue lives of large-scale specimens agree with those given by the best-fit curve for carbon and low-alloy steels, and no remarkable size effects exist for the crack depths compared in this study.

Study on Life Prediction Method for Creep-Fatigue Interaction at Elevated Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 190-194
Author(s):  
Nian Jin Chen ◽  
Zeng Liang Gao ◽  
Wei Zhang ◽  
Yue Bao Le
Keyword(s):  
Elevated Temperature ◽  
Prediction Model ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Hold Time ◽  
Prediction Method ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Creep Fatigue ◽  
316L Austenitic Stainless Steel

The law of low-cycle fatigue with hold time at elevated temperature is investigated in this paper. A new life prediction model for the situation of fatigue and creep interaction is developed, based on the damage due to fatigue and creep. In order to verify the prediction model, strain-controlled low-cycle fatigue tests at temperature 693K, 823K and 873K and fatigue tests with various hold time at temperature 823K and 873K for 316L austenitic stainless steel were carried out. Good agreement is found between the predictions and experimental results.

Verification of the Prediction Methods of Strain Range in Notched Specimens Made of Mod.9Cr-1Mo

2010 ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Shingo Date ◽  
Sota Watanabe ◽  
Yasuhiro Enuma ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Tests ◽  
Estimation Methods ◽  
Prediction Methods ◽  
Test Machine ◽  
Notched Specimens ◽  
Creep Fatigue

Several innovative prediction methods of strain range have been developed in order to apply to the Generation IV plants. In a component design at elevated temperature, ‘strain range’ is used to calculate the fatigue and creep-fatigue damage. Therefore, prediction of ‘strain range’ is one of the most important issues to evaluate the components’ integrity during these lifetimes. To verify the strain prediction method of discontinues structures at evaluated temperature, low cycle fatigue tests were carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo, because it is a candidate material for a primary and secondary heat transports system components of JSFR (Japanese Sodium Fast Reactor). Deformation control fatigue tests and thermal fatigue tests were performed by ordinary uni-axial push-pull test machine and equipment generating the thermal gradient in the notched plate by induction heating. Stress concentration level was changed by varying the notch radius in the both kind of tests. Crack initiation and propagation process during the fatigue test were observed by the digital micro-scope and replica method. Elastic and inelastic FEAs were also carried out to estimate the ‘strain range’ for the prediction of fatigue life. Then the ranges of several strain predictions and estimations were compared with the test results. These predictions were based on the sophisticated technique to estimate the ‘strain range’ from elastic FEA. Stress reduction locus (SRL) method, simple elastic follow-up method, Neuber’s rule method and the methods supplied by elevated temperature design standards were applied. Through these results, the applicability and conservativeness of these strain prediction and estimation methods, which is the basis of the creep-fatigue life prediction, is discussed.

Accuracy and Margin in Creep-Fatigue Evaluation for Modified 9Cr-1Mo Steel

2007 ◽  
Author(s):  
Yukio Takahashi
Keyword(s):  
Stress Relaxation ◽  
Nuclear Power ◽  
Creep Damage ◽  
Assessment Method ◽  
Fatigue Tests ◽  
Simple Method ◽  
Component Design ◽  
Creep Fatigue ◽  
Grade 91 ◽  
Fatigue Evaluation

Modified 9Cr-1Mo steel (ASME SA-213, Grade 91) is regarded as a promising candidate for structural materials in some of the nuclear power generation plants considered in Generation-IV project. If it is used at high temperature conditions, consideration of creep-fatigue interaction in addition to simple creep rupture is needed in component design. The author has been conducting many creep-fatigue tests for the steel at temperatures between 550°C and 650°C in order to search for a suitable creep-fatigue assessment method. It was found that creep damage at failure estimated by applying the time fraction approach to measured stress relaxation data strongly depended on the test temperature and became quite small at 550°C. However, application of calculated stress relaxation brought about the increase of creep damage over the linear damage summation line. Furthermore, addition of design factors significantly increased the values of creep and fatigue damages, making margin against failure quite large. A new definition of creep damage as a ductility consumer in strain based approach gave a simple method to estimate creep damage more properly and stably with a much smaller sensitivity on the stress relaxation behavior.

Creep-Fatigue Life Determination of Grade 91 Steel Using a Strain-Range Separation Method

2009 ◽  
Author(s):  
Wolfgang Hoffelner
Keyword(s):  
Stress Rupture ◽  
Strain Range ◽  
Inelastic Strain ◽  
Fatigue Curve ◽  
Cyclic Softening ◽  
Least Square ◽  
Creep Failure ◽  
Creep Fatigue ◽  
Grade 91 ◽  
Grade 91 Steel

The method of strain range partitioning developed by Manson offers a possibility for treatment of creep-fatigue interactions. It partitions the strain-range of a complex hysteresis loop into four elementary strain range types. Although the method has its merits it is difficult to apply because of lacking experimental data and difficult loop reconstructions. The paper describes an approach which separates the inelastic strain range only into a fatigue portion and a creep portion following both a power law Coffin-Manson relationship. Coefficients and exponents were determined by a simple least square fitting procedure from a set of literature data. The plastic part agreed very well with the experimentally determined fatigue curve. The creep part could, however, only be understood using fatigue-modified stress rupture data accounting for cyclic softening. With this approach it was possible to determine number of cycles to creep failure as a function of the pure creep strain range. This procedure was applied to a set of literature data of grade 91 steel which covered a temperature range of 500°C, 550°C, 600°C with stress controlled and strain controlled hold-times. Life-times were predicted in a range corresponding with the scatter of pure fatigue or creep curves, which means that a very good agreement was obtained. The paper will give a thorough description of the procedure and demonstrate its applicability to design codes.

Creep-Fatigue Tests and Life Prediction Models for Structural Integrity Assessment of 9Cr-1Mo (Grade 91) Steels

2013 ◽  
Author(s):  
Mauro Filippini ◽  
Riccardo Catelli ◽  
Mihaela E. Cristea
Keyword(s):  
Life Prediction ◽  
Structural Integrity ◽  
Prediction Models ◽  
Martensitic Steel ◽  
Fatigue Tests ◽  
Integrity Assessment ◽  
Creep Fatigue ◽  
Grade 91 ◽  
Temperature Strain ◽  
Calculation Procedures

High temperature strain controlled fatigue and creep-fatigue tests have been carried out on Grade 91 martensitic steel, according to the procedure of the newly developed ASTM E2714 standard. In this paper, the results of these tests are discussed and evaluated according to different damage calculation procedures (e.g. time fraction rule, ductility exhaustion method) for the purpose of validating life prediction models that could be used for the assessment of structural integrity of components in Grade 91 steels operating at high temperatures.

Verification of the Estimation Methods of Strain Range in Notched Specimens Made of Mod.9Cr-1Mo Steel

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Shingo Date ◽  
Sota Watanabe ◽  
Yasuhiro Enuma ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Elevated Temperature ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Tests ◽  
Estimation Methods ◽  
Test Machine ◽  
Component Reliability ◽  
Notched Specimens ◽  
Creep Fatigue

Several methods of estimating strain range at a structural discontinuity have been developed in order to assess component reliability. In a component design at elevated temperature, estimation of strain range is required to evaluate the fatigue and creep-fatigue damage. Therefore, estimation of strain range is one of the most important issues when evaluating the integrity of a component during its lifetimes. To verify the methods of estimating strain range for discontinuous structures, low cycle fatigue tests were carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo steel, because it is a candidate material for a primary and secondary heat transport system components of Japan Sodium-cooled Fast Reactor (JSFR). Displacement control fatigue tests and thermal fatigue tests were performed by ordinary uniaxial push–pull test machine and equipment generating the thermal gradient in the notched plate by induction heating. Several notch radii were employed to vary the stress concentration level in both kinds of tests. Crack initiation and propagation process during the tests were observed by a digital microscope and the replica method to define the failure cycles. Elastic and inelastic finite element analyses were also performed to estimate strain range for predicting fatigue life. Then, these predictions were compared with the test results. Several methods such as stress redistribution locus (SRL) method, simple elastic follow-up (SEF) method, Neuber's law, and the procedures employed by elevated temperature design codes were applied. Through these comparisons, the applicability and conservativeness of these strain range estimation methods, which is the basis of the fatigue and creep-fatigue life prediction, are discussed.

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