Technical Basis for a Revised Fatigue Crack Growth Rate Reference Curve for Ferritic Steels in Air

1992 ◽  
Vol 114 (1) ◽  
pp. 80-86 ◽  
Author(s):  
E. D. Eason ◽  
J. D. Gilman ◽  
D. P. Jones ◽  
S. P. Andrew
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Ferritic Steels ◽  
Reference Curve ◽  
R Ratio ◽  
Technical Basis

Appendix A of the ASME Boiler and Pressure Vessel Code, Section XI, contains a reference curve for fatigue crack growth rates in air in ferritic steels that was established in 1973 with a limited amount of data. In the past 15 years, many additional data have been collected that do not agree with the trend exhibited by this original reference curve. In light of these new data, an analysis has been undertaken to re-evaluate the fatigue crack growth rate curve in the Code. As a result, an improved reference curve that considers the dependence of crack growth rate on R-ratio and ΔK has been developed. This paper presents the technical basis for the improved curve, some details on the analysis used to determine it, and comparison of the current Section XI Code with the available ferritic steel database and the new reference curve. The format proposed for adoption of the new reference curve is presented, with comments on the practical effect of the proposed change.

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.

scholarly journals Fatigue Crack Growth Rate of the Long Term Operated Puddle Iron from the Eiffel Bridge

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
Grzegorz Lesiuk ◽  
José A. F. O. Correia ◽  
Michał Smolnicki ◽  
Abílio M. P. De Jesus ◽  
Monika Duda ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Fatigue Crack Growth Rate ◽  
Crack Opening ◽  
Low Carbon ◽  
R Ratio

The paper summarises an experimental study on the fatigue crack propagation and cracks paths in ancient steel—19th-century puddle iron from the Eiffel bridge. The tests were performed with the load R-ratio equal to 0.05 and 0.5. All tests were performed under different notch inclinations (mode I + II). The fatigue crack growth rate in the tested material is significantly higher than its “modern” equivalent—low carbon mild steel. The crack closure phenomenon occurs in specimens during the process of crack growth. Understanding this aspect is crucial for the examination of a stress R-ratio influence on kinetic fatigue fracture diagram (KFFD) description. Both the experimental and numerical approach, using the HP VEE environment, has been applied to the crack closure as well as the crack opening forces’ estimation. These analyses are based on the deformation of the hysteresis loop. The algorithm that was implemented in the numerical environment is promising when it comes to describing the kinetics of fatigue crack growth (taking into consideration the crack closure effect) in old metallic materials.

Technical Basis of Fatigue Crack Growth Rate Curve for Ni-Base Alloy in BWR Water Environment

2014 ◽  
Author(s):  
Takuya Ogawa ◽  
Masao Itatani ◽  
Toshiyuki Saito ◽  
Hiroshi Nagase ◽  
Satoru Aoike ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Base Alloy ◽  
Water Environment ◽  
Reference Curve ◽  
Rising Time

When the flaws are detected in Japanese nuclear power components by in-service inspection, structural integrity assessment are performed in the technical judgment on continuous service. If cyclic loading is assumed, fatigue crack growth analysis should be conducted based on the Rules on Fitness-for-Service for Nuclear Power Plants of the Japan Society of Mechanical Engineers Code (JSME FFS Code). However, fatigue crack growth analysis for BWR components consisting of Ni-base alloy is currently impossible, since the reference curve of fatigue crack growth rate for Ni-base alloy in BWR water environment is not yet prescribed in the JSME FFS Code. In this study, fatigue crack growth behavior of Ni-base alloy used for Japanese BWR plants in BWR water environment was investigated. Based on the experimental data, the fatigue crack growth rate curve was evaluated. Four test parameters of material, corrosion potential, stress ratio and load rising time were considered. As a result of fatigue crack growth tests, the effects of all test parameters on the fatigue crack growth behavior were found. A Mean curve of fatigue crack growth rate in Paris law format, which was a function of stress ratio and rising time, was formulated based on crack growth data in normal water chemistry (corrosion potential was over 150 mVSHE) for weld metal and heat affected zone (HAZ), respectively. A reference curve of fatigue crack growth rate was also formulated by the statistical treatment considering the scatter of crack growth rate. Further, in order to determine the threshold stress intensity factor range ΔKth of reference curve of fatigue crack growth, ΔK decreasing tests were conducted under the test condition of 1 second of rising time. As a result, the threshold value of ΔK was evaluated based on the ASTM E 647, and the ΔKth of the reference curve was conservatively determined considering the margin.

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