scholarly journals Crack Growth Rate and Fracture Toughness Tests on Irradiated Cast Stainless Steels

2013 ◽  
Author(s):  
Y. Chen ◽  
B. Alexandreanu ◽  
K. Natesan

1981 ◽  
Vol 13 (4) ◽  
pp. 477-481 ◽  
Author(s):  
V. T. Troshchenko ◽  
A. V. Prokopenko ◽  
V. N. Torgov


Author(s):  
Michael A. Tognarelli ◽  
Ramgopal Thodla ◽  
Steven Shademan

Corrosion fatigue and fracture toughness in sour environments of APIX65 5L have typically been studied in relatively severe environments like NACE A and NACE B solutions. There are very limited data in sweet and mildly sour environments that are of interest in various applications. This paper presents fatigue crack growth frequency scans in a range of sweet and mildly sour environments as well as on different microstructures: Parent Pipe, Heat Affected Zone (HAZ) and Weld Center Line (WCL). The fatigue crack growth rate (FCGR) increased with decreasing frequency and reached a plateau value at low frequencies. FCGR in the sweet environments that were investigated did exhibit a frequency dependence (increasing with decreasing frequency) and had plateau FCGR in the range of 10–20× the in-air values. In the mildly sour environments that were investigated, FCGR was found to be about 25 to 30× higher than the in-air values. By comparison, in NACE A environments the FCGR is typically about 50× higher than the in-air values. The FCGRs of parent pipe and HAZ were found to be similar over a range of environments, whereas the WCL FCGR data were consistently lower by about a factor of 2×. The lower FCGR of the WCL is likely due to the lower concentration of diffusible hydrogen in the weld. FCGRs as a function of ΔK (stress integrity factor range) were measured on parent pipe at the plateau frequency. The measured Paris law curves were consistent with the frequency scan data. Rising displacement fracture toughness tests were performed in a range of sweet and sour environments to determine the R-curve behavior. Tests were performed in-situ at a slow K-rate of 0.05Nmm−3/2/s over a range of environmental conditions on parent pipe. The initiation toughness and the slope of the R-curve decreased sharply in the sour environments. The initiation toughness and slopes were largely independent of the notch location as well as environmental conditions. Typical values of initiation toughness were in the range of 90–110N/mm.



Author(s):  
Jeremy S. Daily ◽  
Nathan W. Klingbeil

A technique to predict the variability of the Paris regime fatigue crack growth rates in ductile materials based on bulk property (yield strength, hardening modulus, and fracture toughness) variation is presented. The prediction, based on the plastic dissipation in the reversed plastic zone ahead of the crack tip, is carried out for Ti-6Al-4V. The empirical distributions of the bulk properties of Ti-6Al-4V are characterized and directly used in the probabilistic assessment of the fatigue crack growth rate. Since computing the plastic dissipation is a computationally intensive procedure, a novel sampling scheme based on confidence interval minimization was used to generate the empirical distribution of fatigue crack growth rate. This technique also predicts correlation between fatigue crack growth rate and fracture toughness, which may be useful in probabilistic design of turbines.



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.



1986 ◽  
Vol 22 (3) ◽  
pp. 258-262 ◽  
Author(s):  
A. A. Popov ◽  
E. I. Mamaeva ◽  
G. A. Drobakhin ◽  
T. K. Kashirina


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