Re-Evaluation of Fatigue Crack Growth Curve for Austenitic Stainless Steels in BWR Environment

2012 ◽  
Author(s):  
Masao Itatani ◽  
Takuya Ogawa ◽  
Chihiro Narazaki ◽  
Toshiyuki Saito
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Reference Curve ◽  
Growth Data ◽  
Crack Growth Curve ◽  
Confidential Limit

The Rules on Fitness-for-Service for Nuclear Power Plants of the Japan Society of Mechanical Engineers (JSME Code) has the reference fatigue crack growth curve for austenitic stainless steels in BWR environment. This reference curve was determined as the upper bound of crack growth data excluding the outlier data. However, the other reference curves for fatigue crack growth rate such as austenitic stainless steels and ferritic steels in air environment and ferritic steels in water environment in the ASME Boiler and Pressure Vessel Code, Section XI and the JSME Code, austenitic stainless steels in PWR environment in the JSME Code and Ni-base alloys in PWR environment in the JSME Code Case are determined based on the 95% upper confidential limit by statistic data treatment. In the present study, the fatigue crack growth data of austenitic stainless steels in BWR environment were re-evaluated statistically. It was found that the current reference curve almost coincides with 95% upper confidential limit of fatigue crack growth data in the Paris region. Consequently, the current reference fatigue crack growth curve for austenitic stainless steels in BWR environment in the JSME Code can be regarded to stand on the same technical bases with other reference fatigue crack growth curves. Furthermore, the authors proposed to extend applicable upper bound of load rising time tr from 1000 s to 32000 s.

Fatigue Crack Growth Curve for Austenitic Stainless Steels in PWR Environment

2004 ◽  
Author(s):  
Yuichiro Nomura ◽  
Kazuya Tsutsumi ◽  
Hiroshi Kanasaki ◽  
Naoki Chigusa ◽  
Kazuhiro Jotaki ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Stress Intensity Factor Range ◽  
Reference Curve ◽  
Pressurized Water ◽  
Crack Growth Curve

Although reference fatigue crack growth curves for austenitic stainless steels in air environments and boiling water reactor (BWR) environments were prescribed in JSME S NA1-2002, similar curves for pressurized water reactors (PWR) were not prescribed. In order to propose the reference curve in PWR environment, fatigue tests of austenitic stainless steels in simulated PWR primary water environment were carried out. According to the procedure to determine the reference fatigue crack growth curve of BWR, which of PWR is proposed. The reference fatigue crack growth curve in PWR environment have been determines as a function of stress intensity factor range, Temperature, load rising time and stress ratio.

scholarly journals Fatigue Crack Growth Curve for Austenitic Stainless Steels in PWR Environment

2003 ◽  
Vol 2003 (0) ◽  
pp. 917-918
Author(s):  
Yuichiro Nomura ◽  
Kazuya Tsutsumi ◽  
Hiroshi Kanasaki ◽  
Morihito Nakano ◽  
Kazuhiro Jotaki ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Crack Growth Curve

Fatigue Crack Growth Curve for Austenitic Stainless Steels in PWR Environment

2006 ◽  
Author(s):  
Yuichiro Nomura ◽  
Katsumi Sakaguchi ◽  
Hiroshi Kanasaki ◽  
Shigeki Suzuki
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Growth Curve ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Crack Growth Curve

Reference fatigue crack growth rate curves for austenitic stainless steels in pressurized water reactors (PWR) environments were prescribed in JSME S NA1-2004(1) in Japan. The reference fatigue crack growth curve in PWR environment had been determined as a function of stress intensity factor range, temperature, load rising time and stress ratio. In order to confirm the applicability of the reference fatigue crack growth rate curve under high stress ratio, low rising time and low stress intensity range, fatigue crack propagation tests of austenitic stainless steels 316, 316 weld metal, 304 and 304 weld metal were carried out. It is concluded that the reference fatigue crack growth curve in PWR environment is applicable to predict fatigue crack growth rate of this study test conditions.

Fatigue Crack Growth Curve for Austenitic Stainless Steels in BWR Environment

2000 ◽  
Vol 123 (2) ◽  
pp. 166-172 ◽  
Author(s):  
M. Itatani ◽  
M. Asano ◽  
M. Kikuchi ◽  
S. Suzuki ◽  
K. Iida,
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Stainless Steels ◽  
Stress Ratio ◽  
Austenitic Stainless Steels ◽  
Reference Curve

Fatigue crack growth data obtained in the simulated BWR water environment were analyzed to establish a formula for reference fatigue crack growth rate (FCGR) of austenitic stainless steels in BWR water. The effects of material, mechanical and environmental factors were taken into the reference curve, which was expressed as: da/dN=8.17×10−12s˙Tr0.5s˙ΔK3.0/1−R2.121≦ΔK≦50 MPam where da/dN is fatigue crack growth rate in m/cycle, Tr is load rising time in seconds, ΔK is range (double amplitude) of K–value in MPam, and R is stress ratio. Tr=1 s if Tr<1 s, and Tr=1000 s if Tr cannot be defined. ΔK=Kmax−Kmin if R≧0.ΔK=Kmax if R<0.R=Kmin/Kmax. The proposed formula provides conservative FCGR at low stress ratio. Although only a few data show higher FCGR than that by proposed formula at high R, these data are located in a wide scatter range of FCGR and are regarded to be invalid. The proposed formula is going to be introduced in the Japanese Plant Operation and Maintenance Standard.

A Fatigue Crack Growth Model for Type 304 Austenitic Stainless Steels in an Elevated Temperature Air Environment

2021 ◽  
Author(s):  
Kathleen C. Barron
Keyword(s):  
Fatigue Crack ◽  
Elevated Temperature ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Reference Curve ◽  
Paris Law ◽  
R Ratio ◽  
Type 304

Abstract The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section XI utilizes reference fatigue crack growth rate (FCGR) curves for flaw evaluations. The current ASME reference curve for austenitic stainless steels in air environments is a Paris-Law relation with a single ΔK exponent that covers the entire ΔK range. Since generation of the model that became the ASME reference curve, extensive additional FCGR testing of Type 304, Type 304L, and Type 304/304L dual-certified stainless steel and the corresponding weld metal has been performed in an elevated temperature air environment. This testing revealed fatigue crack growth (FCG) behaviors that were not adequately captured by the ASME reference curve. In particular, the ASME reference curve failed to capture a flattening of the FCGR curve in the intermediate ΔK range before the FCGRs sharply dropped off as the threshold behavior is approached. Additionally, the FCGR data showed a slight frequency-dependence. Based on this new data, a new FCGR model was generated for Type 304 austenitic stainless steels in air environments between 250°C and 338°C. A tri-linear Paris-Law style correlation was chosen for the updated FCGR model to accommodate both the flattening of the FCGR curve at intermediate ΔK levels and the sharp downturn in the near-threshold ΔK regime. Each of the three branches of the FCGR curve exhibit a different R-ratio dependence, with the near-threshold regime being the most sensitive to changes in the R-ratio.

scholarly journals High Resistance of Fatigue Crack Growth for Austenitic Stainless Steels Containing Nitrogen.

1999 ◽  
Vol 65 (634) ◽  
pp. 1343-1348 ◽  
Author(s):  
Hisashi HIRUKAWA ◽  
Saburo MATSUOKA ◽  
Etsuo TAKEUCHI ◽  
Takahito OMURA ◽  
Koji YAMAGUCHI ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
High Resistance ◽  
Stainless Steels ◽  
Austenitic Stainless Steels

A Flaw Tolerance Concept for Plant Maintenance Using Virtual Fatigue Crack Growth Curve

2013 ◽  
Author(s):  
Masayuki Kamaya ◽  
Takao Nakamura
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Curve ◽  
Growth Behavior ◽  
Plant Design ◽  
Flaw Tolerance ◽  
Plant Maintenance ◽  
Crack Growth Curve

Incorporation of the flaw tolerance concept in plant design and maintenance is discussed in order to consider the reduction in fatigue life due to the high-temperature water environment of class 1 components of NPPs. The flaw tolerance concept has been included in Section XI of the ASME BPVC. The structural factor (safety factor) for the flaw evaluation is considered in the stress, whereas it was considered in the design fatigue curve in Section III of the ASME BPVC. In order to apply the flaw tolerance concept to plant design and maintenance, it is necessary to assume the crack initiation and growth behavior. In this study, first, crack initiation and growth behavior during fatigue tests was reviewed and a relationship between the crack growth and fatigue life was quantified. Then, the safety factor was considered in the crack growth curve. It was shown that the crack size could be correlated to the usage factor and the flaw tolerance concept was reasonably considered in the plant maintenance by using the proposed virtual fatigue crack growth curve.

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