Investigation of the crack growth behavior of Inconel 718 by high temperature Moiré interferometry

2004 ◽  
Vol 39 (6) ◽  
pp. 1967-1973 ◽  
Author(s):  
Xingbo Liu ◽  
B. Kang ◽  
W. Carpenter ◽  
E. Barbero
Author(s):  
Tatsuru Misawa ◽  
Takanori Kitada ◽  
Takao Nakamura

Abstract It has been clarified that the fatigue life is decreased in the fatigue test of high-temperature and high-pressure water that simulates PWR reactor coolant environment compared to that in the atmosphere. Temperature, strain rates, dissolved oxygen concentration, etc. affect the decrease of fatigue life. The influence of crack growth behavior on the fatigue life of Type 316 austenitic stainless steel [1] in simulated PWR reactor coolant environment of different temperatures was investigated in this study. Fatigue tests were conducted under different temperatures (200°C and 325°C) in a simulated PWR reactor coolant environment with interrupting, and cracks generated on the specimen surface were observed with two-step replica method. From the results of observation, the influence of crack growth behavior in different temperatures on the fatigue life was clarified. As a result, it was confirmed that the decrease of the fatigue life due to high temperature is mainly caused by the acceleration of crack propagation rate in the depth direction by the increase of crack coalescence frequency due to the increase of crack initiation number and crack propagation rate in the length direction.


1979 ◽  
Vol 101 (3) ◽  
pp. 191-198 ◽  
Author(s):  
D. A. Hale ◽  
C. W. Jewett ◽  
J. N. Kass

The fatigue crack growth behavior of four structural alloys was studied and the effects of high temperature (288°C), high purity oxygenated water, cycle frequency, and mean stress were evaluated. The results for carbon and low alloy steel show that while crack growth rates are affected by the water environment, modified ASME code procedures result in conservative predictions of growth. Often, higher crack growth rates are found for shallow cracks than for deep cracks. For stainless steels and Inconel the measured growth rates in water were similar to data obtained in air over the range of cycle frequencies studied.


Author(s):  
Yoichi Takeda ◽  
Hirofumi Sato ◽  
Shuhei Yamamoto ◽  
Takamichi Tokunaga ◽  
Akio Ohji

Advanced ultra supercritical (A-USC) steam power generation, in which high-pressure steam is raised to beyond 700°C, is being studied internationally. The creep strength of Ni-based super alloys evaluated at these high temperatures in an air environment makes these materials promising candidates for the material to be used for the structural components of these generators. Since they are exposed to high temperature steam, it is important that the effect of the environment on the degradation of these materials is investigated. In this investigation, the crack growth rate under cyclic loading in a 750°C steam environment using a compact tension specimen was evaluated. Crack length monitoring using the direct current potential drop technique was applied to the growing crack in a high temperature environment in order to evaluate the time-dependent behavior of the crack growth. The dependence of the loading rate and amplitude in terms of the stress intensity factor was obtained. The crack growth rate increased with decreasing loading rate and increasing amplitude. Multiple loading patterns were applied to a single specimen during crack length monitoring. When the loading pattern was changed to a different pattern, in most of the cases, the crack growth rate started to change and then became stable aftera transition period. The influence of intermetallics and different phases on the crack growth behavior is discussed based on the oxidation rate of these phases.


2009 ◽  
Vol 58 (2) ◽  
pp. 122-127
Author(s):  
Fumiko KAWASHIMA ◽  
Takumi TOKIYOSHI ◽  
Toshihide IGARI ◽  
Akihiro KANAYA ◽  
Junichi KUSUMOTO ◽  
...  

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