scholarly journals Alloy 617 Creep–Fatigue Damage Evaluation Using Specimens With Strain Redistribution

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Yanli Wang ◽  
T.-L. Sham ◽  
Robert I. Jetter
Keyword(s):  
Hold Time ◽  
Damage Evaluation ◽  
Test Results ◽  
Structural Components ◽  
Cyclic Life ◽  
Alloy 617 ◽  
Creep Fatigue ◽  
Asme Code ◽  
Time Test

The simplified model test (SMT) method is an alternate approach to determine the cyclic life at elevated temperature. It is based on the use of creep–fatigue hold time test data from test specimens with elastic follow-up conservatively designed to bound the response of general structural components. In this paper, the previously documented development of the SMT approach and applicable restrictions are reviewed; the design of the Alloy 617 SMT specimen, measurement issues and constraints are presented; initial test results and their application to a prototypic design curve are presented; and further testing and analysis for ASME code incorporation are discussed.

Creep-Fatigue Properties of the Candidate Materials of 700°C-USC Boiler

2007 ◽  
Author(s):  
Keiji Kubushiro ◽  
Hiroki Yoshizawa ◽  
Takuya Itou ◽  
Hirokatsu Nakagawa
Keyword(s):  
Hold Time ◽  
Strain Range ◽  
Small Strain ◽  
Fatigue Tests ◽  
Holding Time ◽  
Experimental Results ◽  
Fatigue Properties ◽  
Alloy 617 ◽  
Creep Fatigue ◽  
Cycles To Failure

Creep-fatigue properties of candidate materials of 700°C-USC boiler are investigated. The candidate materials are Alloy 230, Alloy 263, Alloy 617 and HR6W. Creep-fatigue tests were conducted at 700°C and the effect of both strain range and hold time were studied. Experimental results showed that at 1.0% strain range, cycles to failure with 60 min strain holding is about 10% of that without strain holding, but at 0.7% strain range, cycles to failure with 60 min strain holding decreases down to about 1% of without strain holding. It appears that cycles to failure is decreased by increasing strain holding time at all tested strain ranges, and the effect of holding time is emphasized at small strain range. These phenomena depend on the kind of alloys.

scholarly journals Determination of the Creep-Fatigue Interaction Diagram for Alloy 617

2016 ◽  
Author(s):  
J. K. Wright ◽  
L. J. Carroll ◽  
T.-L. Sham ◽  
N. J. Lybeck ◽  
R. N. Wright
Keyword(s):  
Fatigue Testing ◽  
Hold Time ◽  
Strain Range ◽  
Fatigue Tests ◽  
Alloy 617 ◽  
Interaction Diagram ◽  
Creep Fatigue ◽  
Intermediate Heat Exchanger ◽  
Cycles To Failure

Alloy 617 is the leading candidate material for an intermediate heat exchanger for the very high temperature reactor (VHTR). As part of evaluating the behavior of this material in the expected service conditions, creep–fatigue testing was performed. The cycles to failure decreased compared to fatigue values when a hold time was added at peak tensile strain. At 850°C, increasing the tensile hold duration continued to degrade the creep–fatigue resistance, at least to the investigated strain–controlled hold time of up to 60 minutes at the 0.3% strain range and 240 minutes at the 1.0% strain range. At 950°C, the creep–fatigue cycles to failure are not further reduced with increasing hold duration, indicating saturation occurs at relatively short hold times. The creep and fatigue damage fractions have been calculated and plotted on a creep–fatigue interaction D–diagram. Test data from creep–fatigue tests at 800 and 1000°C on an additional heat of Alloy 617 are also plotted on the D–diagram.

Low Cycle Fatigue and Creep-Fatigue Behavior of Alloy 617 at High Temperature

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Celine Cabet ◽  
Laura Carroll ◽  
Richard Wright
Keyword(s):  
High Temperature ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Dominant Role ◽  
Hold Time ◽  
Outlet Temperature ◽  
Cycle Fatigue ◽  
Alloy 617 ◽  
Creep Fatigue

Alloy 617 is the leading candidate material for an intermediate heat exchanger (IHX) application of the very high temperature nuclear reactor (VHTR), expected to have an outlet temperature as high as 950 °C. Acceptance of Alloy 617 in Section III of the ASME Code for nuclear construction requires a detailed understanding of the creep-fatigue behavior. Initial creep-fatigue work on Alloy 617 suggests a more dominant role of environment with increasing temperature and/or hold times evidenced through changes in creep-fatigue crack growth mechanisms and failure life. Continuous cycle fatigue and creep-fatigue testing of Alloy 617 was conducted at 950 °C and 0.3% and 0.6% total strain in air to simulate damage modes expected in a VHTR application. Continuous cycle fatigue specimens exhibited transgranular cracking. Intergranular cracking was observed in the creep-fatigue specimens and the addition of a hold time at peak tensile strain degraded the cycle life. This suggests that creep-fatigue interaction occurs and that the environment may be partially responsible for accelerating failure.

Comparison of Creep-Fatigue Evaluation Methods With Notched Specimens Made of Mod.9Cr-1Mo Steel

2011 ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Takanori Karato ◽  
Sota Watanabe ◽  
Osamu Inoue ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fast Reactor ◽  
Evaluation Methods ◽  
Fatigue Tests ◽  
Test Results ◽  
Notched Specimens ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Fatigue Life Evaluation

In a component design at elevated temperature, creep-fatigue is one of the most important failure modes, and assessment of creep-fatigue life in structural discontinuity is important issue to evaluate structural integrity of the components. Therefore a lot of creep-fatigue life evaluation methods were proposed until now. To compare and assess these evaluation methods, a series of creep-fatigue tests was carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo steel, which it is a candidate material for a primary and secondary heat transport system components of JSFR (Japan Sodium-cooled Fast Reactor). Mechanical creep-fatigue tests and thermal creep-fatigue tests were performed by using conventional uni-axial push-pull fatigue test machine and thermal gradient generating system with an induction heating coil. Stress concentration levels were adjusted by varying the diameters of notch roots in the both tests. In the test, creep-fatigue lives, crack initiation and propagation processes were observed by digital micro-scope and replica method. Besides those, a series of elastic Finite Element Analysis (FEA) were carried out to predict the number of cycles to failure by several creep-fatigue life evaluation methods. Then these predictions were compared with test results. Several types of evaluation methods which are stress redistribution locus (SRL) method, simple elastic follow-up method and the methods described in JSME FR (Fast Reactor) code were applied. The applicability and conservativeness of these methods were discussed. It was appeared that SRL method gave rational prediction of creep-fatigue life with conservativeness when the factor of κ = 1.6 was applied for all the conditions tested in this study. Comparison of SRL method and simple elastic follow-up method indicated that SRL method applied factor of κ = 1.6 gave the smallest creep-fatigue life in practicable stress level. JSME FR code gave an evaluation 70∼100 times conservative lives comparing with the test results.

Creep-Fatigue Assessment Methods Using Elastic Analysis Results and Adjustments

1991 ◽  
Vol 113 (1) ◽  
pp. 34-40 ◽  
Author(s):  
L. K. Severud
Keyword(s):  
Elevated Temperature ◽  
Stress Analysis ◽  
Elastic Analysis ◽  
Practical Application ◽  
New Methods ◽  
Inelastic Analysis ◽  
Creep Fatigue ◽  
Adjustment Factors ◽  
Asme Code

The design of mechanical components that operate in elevated temperature environment where creep effects are significant usually requires creep-fatigue assessments. The ASME Code Case N-47 contains rules for these assessments based on both inelastic and elastic stress analysis. Although an inelastic stress analysis generally more accurately predicts effects from creep and plasticity, an elastic analysis is often preferred since it is much simpler and less costly. New creep-fatigue rules for use with elastic analysis results have recently been proposed to enhance the rules’ accuracy and usefulness. This paper describes such new methods and rules for creep-fatigue assessments. Ingredients of the new methods include elastic follow-up, ratcheting, multiaxiality, plasticity, creep, and relaxation considerations and associated adjustment factors. The basis for the adjustments and a comparison of results to those obtained using inelastic analysis are provided. The new methods will provide a wider range of practical application of elastic creep-fatigue rules than permitted by previous code methods in design of components for elevated temperature service.

scholarly journals Report on FY15 Alloy 617 SMT Creep-Fatigue Test Results

2015 ◽  
Author(s):  
Yanli Wang ◽  
Robert I. Jetter ◽  
Seth T. Baird ◽  
Chao Pu ◽  
Sam Sham
Keyword(s):  
Fatigue Test ◽  
Test Results ◽  
Alloy 617 ◽  
Creep Fatigue

Creep and Creep-Fatigue Deformation and Life Assessment of Ni-Based Alloy 740H and Alloy 617

2018 ◽  
Author(s):  
Shengde Zhang ◽  
Yukio Takahashi
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Hold Time ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Life Assessment ◽  
Prediction Methods ◽  
Creep Tests ◽  
Alloy 617 ◽  
Creep Fatigue

This paper presents creep and creep-fatigue deformations and lives of both Ni-based alloys, Alloy 740H and Alloy 617. Creep tests were performed using solid bar specimens at 650°C-800°C, and effect of cyclic loading on creep deformation and rupture was discussed. Strain controlled creep-fatigue tests were also performed under triangular and trapezoidal waveforms at 700°C. Alloy 740H showed stronger creep-fatigue resistance compared to Alloy 617. Creep-fatigue lives in trapezoidal waveform were smaller than those in the pure fatigue test and the creep-fatigue lives decreased as the hold time increased. Applicability of four representative creep-fatigue life prediction methods was discussed.

scholarly journals Evaluation of Creep-Fatigue Damage Based on Simplified Model Test Approach

2013 ◽  
Author(s):  
Yanli Wang ◽  
Tianlei Li ◽  
T.-L. (Sam) Sham ◽  
Robert I. Jetter
Keyword(s):  
Fatigue Damage ◽  
High Temperatures ◽  
Test Data ◽  
Model Test ◽  
Hold Time ◽  
Simplified Model ◽  
Creep Fatigue ◽  
Asme Code ◽  
Cyclic Damage ◽  
Very High

Current methods used in the ASME Code, Subsection NH for the evaluation of creep-fatigue damage are based on the separation of elevated temperature cyclic damage into two parts, creep damage and fatigue damage. This presents difficulties in both evaluation of test data and determination of cyclic damage in design. To avoid these difficulties, an alternative approach was identified, called the Simplified Model Test or SMT approach based on the use of creep-fatigue hold time test data from test specimens with elastic follow-up conservatively designed to bound the response of general structural components of interest. A key feature of the methodology is the use of the results of elastic analysis directly in design evaluation similar to current methods in the ASME Code, Subsection NB. Although originally developed for current material included in Subsection NH, recent interest in the application of Alloy 617 for components operating at very high temperatures has caused renewed interest in the SMT approach because it provides an alternative to the proposed restriction on the use of current Subsection NH simplified methods at very high temperatures. A comprehensive review and assessment of five representative simplified methods for creep-fatigue damage evaluation is presented in Asayama [1]. In this review the SMT methodology was identified as the best long term approach but the need for test data precluded its near term implementation. Asayama and Jetter [2] is a summary of the more comprehensive report by Asayama [1] with a summary of the SMT approach presented by Jetter [3]. In this paper, the previously documented development of the SMT approach and applicable restrictions are discussed and reviewed; the design of the SMT specimen, measurement issues and constraints are presented; the test apparatus and measurement system is described; initial test results and their application to a prototypic design curve are presented; and further testing and analysis for ASME Code incorporation are discussed.

Comparison and Assessment of the Creep-Fatigue Evaluation Methods With Notched Specimen Made of Mod.9Cr-1Mo Steel

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Takanori Karato ◽  
Sota Watanabe ◽  
Osamu Inoue ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Fast Reactor ◽  
Evaluation Methods ◽  
Test Machine ◽  
Test Results ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Fatigue Life Evaluation

In components design at elevated temperature, creep-fatigue is one of the most important failure modes, and assessment of creep-fatigue life in structural discontinuities is an important issue in evaluating the integrity of components. Therefore, a lot of creep-fatigue life evaluation methods were proposed until now. To compare and assess the evaluation methods, a series of creep-fatigue test was carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo steel, which is a candidate material for primary and secondary heat transport system components of the Japan sodium-cooled fast reactor (JSFR). Mechanical creep-fatigue tests and thermal creep-fatigue test were performed by using a conventional uni-axial push–pull fatigue test machine and a thermal gradient generating system with an induction heating. The stress concentration levels were adjusted by varying the notch radius in the each test. The creep-fatigue lives, crack initiation, and propagation processes were monitored by a digital microscope and the replica method. A series of finite element analysis (FEA) was carried out to predict the number of cycles to failure by the several creep-fatigue life evaluation methods. Then, these predictions were compared with the test results. Several types of evaluation methods such are stress redistribution locus (SRL) method, simple elastic follow-up method and the methods described in the design and constriction code for fast reactor (FR) published by the Japan Society of Mechanical Engineers (JSME FRs code) were applied. Through the comparisons, it was appeared that SRL method gave rational conservative prediction of the creep-fatigue life when the factor of κ = 1.6 was applied for all conditions tested in this study. A comparison of SRL method and simple elastic follow-up method indicated that SRL method applied factor of κ = 1.6 gave the smallest creep-fatigue life in practicable stress range level. The JSME FRs code gave an evaluation 70–100 times conservative lives comparing with the test results.

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