Stress-induced martensitic transformation in metastable austenitic stainless steels: Effect on fatigue crack growth rate

1996 ◽  
Vol 5 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Z. Khan ◽  
M. Ahmed
2000 ◽  
Vol 123 (2) ◽  
pp. 166-172 ◽  
Author(s):  
M. Itatani ◽  
M. Asano ◽  
M. Kikuchi ◽  
S. Suzuki ◽  
K. Iida,

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.


Author(s):  
Yuichiro Nomura ◽  
Katsumi Sakaguchi ◽  
Hiroshi Kanasaki ◽  
Shigeki Suzuki

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.


Author(s):  
Yuichiro Nomura ◽  
Katsumi Sakaguchi ◽  
Hiroshi Kanasaki

Japanese reference fatigue crack growth rate (FCGR) curves for ferrite and austenitic stainless steels in light water reactor environments are prescribed in JSME S NA1-2004. However, similar reference FCGR curve for nickel-based alloys for pressurized water reactors (PWR) are not prescribed. In order to propose reference FCGR curve for nickel-based alloys, under high stress ratio and low rising time, the effect of the welding method, the effect of specimen orientation and low stress intensity range fatigue crack propagation tests of nickel-based alloys 600, 132 and 82 weld metals were conducted as part of the Environmental Fatigue Test (EFT) projects of Japan Nuclear Energy Safety Organization (JNES). The results show that the effect of heat, welding methods, specimen orientations and environmental water conditions on the FCGR was not significant for Alloys 600, 132 and 82. The FCGR increased with increase of stress ratio, and cyclic loading frequency. According to the procedure for determining the reference FCGR curve of austenitic stainless steels in PWR environment of nickel-based alloys is proposed based on the reference data and the results of this study. The reference FCGR curve for nickel-based alloys in PWR environment are determined as a function of stress intensity factor range, temperature, load rising time and stress ratio.


2007 ◽  
Vol 120 ◽  
pp. 103-110
Author(s):  
Jien Jong Chen ◽  
Yan Shin Shih

James performed a series of experimental study on austenitic stainless steels and suggested an equation for assessing the influences of temperature, stress ratio and loading frequency on the fatigue crack growth rate. Authors have studied the effect of either loading frequency alone or of temperature alone on the fatigue crack growth rate by employing the mechanical behaviors of material. In this study, the mechanical behaviors of material are employed for evaluating the combined effect of loading frequency and temperature. Using the derived dimensionless functions of yielding stresses and Young’s modulus, the equation represented the combined effect of loading frequency and temperature on fatigue crack growth rate of 304SS was proposed.


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