Correlating Stress Ratio Effects on the Fatigue Crack Growth Rate of a Nickel Base Superalloy IN718

2020 ◽  
pp. 375-381
Author(s):  
Sharanagouda G. Malipatil ◽  
Anuradha N. Majila ◽  
D. Chandru Fernando ◽  
C. M. Manjunatha
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Stress Ratio ◽  
Nickel Base Superalloy ◽  
Nickel Base ◽  
Base Superalloy

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.

The Influence of Stress Ratio and Temperature on the Fatigue Crack Growth Rate Behavior of ARALL®

1993 ◽  
Vol 15 (1) ◽  
pp. 46 ◽  
Author(s):  
WS Johnson ◽  
JE Masters ◽  
TK O'Brien ◽  
GC Salivar ◽  
CA Gardini
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Stress Ratio ◽  
Rate Behavior

1015 Study on Fatigue Crack Growth Rate Curve for Nickel-Base Alloy in Air

2010 ◽  
Vol 2010 (0) ◽  
pp. 1220-1222
Author(s):  
Takuya OGAWA ◽  
Chihiro NARAZAKI ◽  
Akihiko HIRANO ◽  
Hideki YONEDA
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Base Alloy ◽  
Rate Curve ◽  
Nickel Base Alloy ◽  
Nickel Base

Effects of a Single Overload Event on the Fatigue Crack Growth Rate of a Low Alloyed Rotor Steel

2008 ◽  
Author(s):  
J. C. Le Roux ◽  
F. Hasnaoui
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Stress Ratio ◽  
Numerical Results ◽  
Experimental Results ◽  
Single Overload

The aim of this work is to study the effect of the overload on the fatigue crack growth rate properties of a low alloyed steel used for rotor disk. On one hand, experimental fatigue tests during which a single overload event is applied are performed on CT specimens. Different loading conditions are imposed in order to study the effects of these parameters on the retardation of the fatigue crack due to the overload. On the other hand, two dimensions elastic plastic Finite Element calculations of crack propagation using nodes release method were used to estimate the effects of a single overload event on the fatigue crack growth rate. Different loading conditions, as for the experimental tests, are used in order to study numerically the effects of these parameters on the retardation of the fatigue crack due to the overload. The experimental and numerical results show the decrease of the crack growth rate due to the overload. This decrease depends on different parameters as overload ratio, stress ratio used for the constant amplitude cyclic loading and ΔK at which the overload is applied. From experimental test results, it can be observed that the decrease is as significant as the overload ratio is high, and as the ΔK at which overload is applied and stress ratio are low. Numerical results show similarities with experimental results, for instance the decrease of the fatigue crack growth is linked to the increase of the overload ratio or to the decrease to the ΔK at which overload is applied. Differences are also observed i.e. the increase of the stress ratio seems to increase the effect of the overload in the numerical calculations in contrary of the experimental results. By comparing to the numerical results, the quality of the results obtained from simplified models has been assessed in regard of the overload effect. A modified Kim and al. model seems to be representative of the different effects of the overload on the fatigue crack growth rate. The future work to be done consists to improve the comparison between experimental and numerical studies.

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