Proposal of Fatigue Life Equations for Carbon and Low-Alloy Steels and Austenitic Stainless Steels as a Function of Tensile Strength

2013 ◽  
Author(s):  
Hiroshi Kanasaki ◽  
Makoto Higuchi ◽  
Seiji Asada ◽  
Munehiro Yasuda ◽  
Takehiko Sera
Keyword(s):  
Tensile Strength ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Room Temperature ◽  
Austenitic Stainless Steels ◽  
Low Alloy Steels ◽  
Strength Based ◽  
Fatigue Data ◽  
Current Design ◽  
Alloy Steels

Fatigue life equations for carbon & low-alloy steels and also austenitic stainless steels are proposed as a function of their tensile strength based on large number of fatigue data tested in air at RT to high temperature. The proposed equations give a very good estimation of fatigue life for the steels of varying tensile strength. These results indicate that the current design fatigue curves may be overly conservative at the tensile strength level of 550 MPa for carbon & low-alloy steels. As for austenitic stainless steels, the proposed fatigue life equation is applicable at room temperature to 430 °C and gives more accurate prediction compared to the previously proposed equation which is not function of temperature and tensile strength.

Development of New Design Fatigue Curves in Japan: Proposal of a New Fatigue Evaluation Method

2018 ◽  
Author(s):  
Seiji Asada ◽  
Akihiko Hirano ◽  
Toshiyuki Saito ◽  
Yasukazu Takada ◽  
Hideo Kobayashi
Keyword(s):  
Stainless Steels ◽  
Evaluation Method ◽  
Austenitic Stainless Steels ◽  
Fatigue Tests ◽  
Carbon Steels ◽  
Low Alloy Steels ◽  
Stress Effect ◽  
Fatigue Data ◽  
Alloy Steels ◽  
Fatigue Evaluation

In order to develop new design fatigue curves for carbon steels & low-alloy steels and austenitic stainless steels and a new design fatigue evaluation method that are rational and have clear design basis, Design Fatigue Curve (DFC) Phase 1 subcommittee and Phase 2 subcommittee were established in the Atomic Energy Research Committee in the Japan Welding Engineering Society (JWES). The study on design fatigue curves was actively performed in the subcommittees. In the subcommittees, domestic and foreign fatigue data of small test specimens in air were collected and a comprehensive fatigue database (≈6000 data) was constructed and the accurate best-fit curves of carbon steels & low-alloy steels and austenitic stainless steels were developed. Design factors were investigated. Also, a Japanese utility collaborative project performed large scale fatigue tests using austenitic stainless steel piping and low-alloy steel flat plates as well as fatigue tests using small specimens to obtain not only basic data but also fatigue data of mean stress effect, surface finish effect and size effect. Those test results were provided to the subcommittee and utilized the above studies. Based on the above studies, a new fatigue evaluation method has been developed.

Evaluation of Fatigue Damage in LWR Water With and Without Threshold and Moderation Factor

2003 ◽  
Author(s):  
Makoto Higuchi ◽  
Kazuya Tsutsumi ◽  
Katsumi Sakaguchi
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Power Plants ◽  
Light Water Reactor ◽  
Low Alloy Steels ◽  
Light Water ◽  
Water Reactor ◽  
Fatigue Data ◽  
Fatigue Life Reduction

During the past twenty years, the fatigue initiation life of LWR structural materials, carbon, low alloy and stainless steels has been shown to decrease remarkably in the simulated LWR (light water reactor) coolant environments. Several models for evaluating the effects of environment on fatigue life reduction have been developed based on published environmental fatigue data. Initially, based on Japanese fatigue data, Higuchi and Iida proposed a model for evaluating such effects quantitatively for carbon and low alloy steels in 1991. Thereafter, Chopra et al. proposed other models for carbon, low alloy and stainless steels by adding American fatigue data in 1993. Mehta developed a new model which features the threshold concept and moderation factor in Chopra’s model in 1995. All these models have undergone various revisions. In Japan, the MITI (Ministry of International Trade and Industry) guideline on environmental fatigue life reduction for carbon, low alloy and stainless steels was issued in September 2000, for evaluating of aged light water reactor power plants. The MITI guideline provide equations for calculations applicable only to stainless steel in PWR water and consequently Higuchi et al. proposed in 2002 a revised model for stainless steel which incorporates new equations for evaluation of environmental fatigue reduction in BWR water. The paper compares the latest versions of these models and discusses the conservativeness of the models by comparison of the models with available test data.

Review and Consideration of Unsettled Problems on Evaluation of Fatigue Damage in LWR Water

2006 ◽  
Vol 129 (1) ◽  
pp. 186-194
Author(s):  
Makoto Higuchi ◽  
Katsumi Sakaguchi
Keyword(s):  
Fatigue Life ◽  
Mechanical Test ◽  
Low Alloy Steels ◽  
Test Results ◽  
Considerable Effort ◽  
Test Conditions ◽  
Fatigue Data ◽  
Alloy Steels ◽  
Fatigue Life Reduction ◽  
Year 2000

Reduction in the fatigue life of structural materials of nuclear components in Light Water Reactor (LWR) water was initially detected and examined by the authors in the 1980s, who subsequently directed considerable effort to the development of a method for evaluating this reduction quantitatively. Since the first proposal of equations to calculate environmental fatigue life reduction for carbon and low-alloy steels was published in 1985 by Higuchi and Sakamoto (J. Iron Steel Inst. Jpn. 71, pp. 101–107), many revisions were made based on a lot of additional fatigue data in various environmental and mechanical test conditions. The latest models for evaluation using Fen of the environmental fatigue life correction factor were proposed for carbon and low alloy steels in the year 2000 and for austenitic stainless steel, in 2002. Fen depends on some essential variables such as material, strain rate, temperature, dissolved oxygen and sulfur concentration in steel. The equation for determining Fen is given by each parameter for each material. These models, having been developed three to five years ago, should be properly revised based on new test results. This paper reviews and discusses five major topics pertinent to such revision.

Use of NUREG/CR-6909 Environmentally-Assisted Fatigue Rules for a Nuclear Plant License Renewal Application

2011 ◽  
Author(s):  
William F. Weitze ◽  
Matthew C. Walter ◽  
Keith R. Evon
Keyword(s):  
Stainless Steels ◽  
Water Environment ◽  
Austenitic Stainless Steels ◽  
Nuclear Regulatory Commission ◽  
The United States ◽  
Nuclear Plant ◽  
Lessons Learned ◽  
Low Alloy Steels ◽  
Alloy Steels ◽  
Regulatory Commission

As part of the process of renewing the operating license for an additional 20 years after the original 40-year design life, nuclear plant owners in the United States (US) are required to show that they are managing the effects of aging of systems, structures, and components. US Nuclear Regulatory Commission (NRC) report NUREG-1801, the “Generic Aging Lessons Learned (GALL) Report,” identifies acceptable aging management programs, including programs for fatigue and cyclic operation. This includes fatigue usage analyses that account for reduced fatigue life for components in a reactor water environment. Earlier revisions of the GALL report required plants to perform environmentally-assisted fatigue (EAF) analyses using the rules in reports NUREG/CR-6583 (for carbon and low alloy steels) and NUREG/CR-5704 (for austenitic stainless steels), which were developed in 1998 and 1999, respectively. However, GALL Revision 2, issued in December 2010, requires that the rules in NUREG/CR-6909, issued in 2007, be used for nickel alloy materials, and allows it to be used for carbon, low-alloy and stainless steels as an alternative to those in the previous reports. This paper presents an application of the NUREG/CR-6909 rules, and makes several observations about the differences between using the newer and older rules. The analyses presented were performed for a sample set of boiling water reactor (BWR) locations.

Low-Cycle Fatigue Behavior of TP347H Austenitic Stainless Steels at Room Temperature

2013 ◽  
Vol 815 ◽  
pp. 875-879 ◽  
Author(s):  
Hong Wei Zhou ◽  
Yi Zhu He ◽  
Yu Wan Cen ◽  
Jian Qing Jiang
Keyword(s):  
Fatigue Life ◽  
Stainless Steels ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Austenitic Stainless Steels ◽  
Fracture Morphology ◽  
Cycle Fatigue ◽  
Response Curves

Low-cycle fatigue (LCF) tests were performed with different strain amplitudes from 0.4% to 1.2% at room temperature (RT) to investigate fatigue life and fracture morphology of TP347H austenitic stainless steels. The results show that there is initial cyclic hardening for a few cycles, followed by continuous softening until fatigue failure at all strain amplitudes in stress response curves. The fatigue life of the steels follows the strain-life Coffin-Manson law. Fracture morphology shows that fatigue cracks initiate from the specimen free surface instead of the interior of the specimen, and ductile fracture appears during LCF loading. More sites of crack initiation and quicker propagation rate of fatigue crack at high strain amplitudes than those at low strain amplitudes are responsible for reduced fatigue life with the increasing of strain amplitude.

A Proposal of Fatigue Life Correction Factor Fen for Austenitic Stainless Steels in LWR Water Environments

2002 ◽  
Author(s):  
Makoto Higuchi ◽  
Kunihiro Iida ◽  
Akihiko Hirano ◽  
Kazuya Tsutsumi ◽  
Katsumi Sakaguchi
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Reduction Factor ◽  
New Models ◽  
Fatigue Data ◽  
Few Data ◽  
Fatigue Life Reduction ◽  
Remarkable Reduction

The fatigue life of austenitic stainless steel has recently been shown to undergo remarkable reduction with decrease in strain rate and increase in temperature in water. Either of these parameters as a factor of this reduction has been examined quantitatively and methods for predicting the fatigue life reduction factor Fen in any given set of conditions have been proposed. All these methods are based primarily on fatigue data in simulated PWR water owing to the few data available in simulated BWR water. Recent Japanese fatigue data in simulated BWR water clearly indicated the effects of the environment on fatigue degradation to be milder than under actual PWR conditions. A new method for determining Fen in BWR water was developed in the present study and a revised Fen in PWR water is also proposed based on new data. These new models differ from those previously used primarily with regard to the manner in which strain amplitude is considered to affect Fen in the environment.

Plan and Status of Development of Design Fatigue Curves: Phase 1

2013 ◽  
Author(s):  
Seiji Asada ◽  
Akihiko Hirano ◽  
Masao Itatani ◽  
Munehiro Yasuda ◽  
Takehiko Sera ◽  
...  
Keyword(s):  
Stainless Steels ◽  
Phase 1 ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Carbon Steels ◽  
Low Alloy Steels ◽  
Energy Research ◽  
Research Committee ◽  
Engineering Society ◽  
Alloy Steels

In order to develop and propose new design fatigue curves for austenitic stainless steels, carbon steels and low alloy steels that are rational and have clear design basis, Design Fatigue Curve (DFC) subcommittee has been established in the Atomic Energy Research Committee in the Japan Welding Engineering Society and the study on design fatigue curves are going on. This paper introduces the plan and status of the activities of the DFC subcommittee.

Discussion of Fatigue Data for Austenitic Stainless Steels

2014 ◽  
Author(s):  
Paul Wilhelm ◽  
Paul Steinmann ◽  
Jürgen Rudolph
Keyword(s):  
Fatigue Life ◽  
Stainless Steels ◽  
National Laboratory ◽  
Hold Time ◽  
Argonne National Laboratory ◽  
Austenitic Stainless Steels ◽  
Reduction Factor ◽  
Fatigue Model ◽  
Fatigue Data ◽  
Number Of Cycles

The first results of a detailed fatigue model for austenitic stainless steels in general and for the grades 1.4541 and 1.4550 are presented to describe the effect of the light water reactor (LWR) coolant environments on the fatigue life. The statistical evaluations are based on strain (and load) controlled test series from different institutions. The compiled fatigue data include not only results from America (Keller (1971), Conway (1975), Hale (1977), and Argonne National Laboratory (ANL)(1999–2005)), but also from Europe (Solin (2006), Le Duff (2008–2010), De Baglion (2011, 2012), Huin (2013),…) and Japan (Kanasaki (1997)). The fatigue life is defined as the number of cycles necessary for tensile stress to drop 25 percent from its peak value. Fatigue lives defined by other failure criteria are normalized to the load reduction of 25 percent, before the statistical analysis is performed. The fatigue data are expressed in terms of the Langer equation and the parameter “material variability and data scatter” is quantified. Additionally, fatigue data in air of roughened specimens are compiled and discussed. A reduction factor of 2.5 on number of cycles is derived to cover the maximum allowed surface roughness. Based on the derived best-fit curves, design-curves in air and, in a second step, environmentally assisted fatigue (EAF) curves for LWR environments, which consider temperature, strain rate, dissolved oxygen content, and hold-time effects, will be incorporated in the detailed fatigue model in the future.

The Effect of LWR Coolant Environments on the Fatigue Life of Reactor Materials

2006 ◽  
Author(s):  
Omesh K. Chopra ◽  
William J. Shack
Keyword(s):  
Stainless Steels ◽  
Type Strain ◽  
Water Flow Rate ◽  
Austenitic Stainless Steels ◽  
Environmental Parameters ◽  
Light Water Reactor ◽  
Low Alloy Steels ◽  
Alloy Steels ◽  
Reactor Materials ◽  
American Society

The existing fatigue strain–vs.–life (ε–N) data illustrate potentially significant effects of light water reactor (LWR) coolant environments on the fatigue resistance of pressure vessel and piping steels. This paper reviews the existing fatigue ε–N data for carbon and low–alloy steels and austenitic stainless steels in LWR coolant environments. The effects of key material, loading, and environmental parameters, such as steel type, strain amplitude, strain rate, temperature, dissolved oxygen level in water, flow rate, surface finish, and heat-to-heat variation, on the fatigue lives of these steels are summarized. An updated version of the ANL statistical models is presented for estimating the fatigue ε–N curves for these steels as a function of the material, loading, and environmental parameters. The Fen (environmental fatigue correction factor) approach for incorporating the effects of LWR coolant environments into the fatigue evaluations of the American Society of Mechanical Engineers Code is presented.

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