Low cycle fatigue crack propagation and fractography of a SUS 304 stainless steel at elevated temperatureKoterazwa, R. and Nosho, T. J. Soc. Mater. Sci. Jpn. Sept. 1988 37, (420), 1090–1096 (in Japanese)

1989 ◽  
Vol 11 (4) ◽  
pp. 284-284
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
304 Stainless Steel ◽  
Cycle Fatigue

scholarly journals Description of short fatigue crack propagation under low cycle fatigue regime

2016 ◽  
Vol 2 ◽  
pp. 3010-3017 ◽  
Author(s):  
Pavel Hutař ◽  
Jan Poduška ◽  
Alice Chlupová ◽  
Miroslav Šmíd ◽  
Tomáš Kruml ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Short Fatigue Crack

LOW CYCLE FATIGUE BEHAVIOR OF Zn-22Al ALLOY IN SUPERPLASTIC REGION AND NON-SUPERPLASTIC REGION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5477-5482 ◽  
Author(s):  
ATSUMICHI KUSHIBE ◽  
TSUTOMU TANAKA ◽  
YORINOBU TAKIGAWA ◽  
KENJI HIGASHI
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Crack Tip ◽  
The Other ◽  
Al Alloy ◽  
Cycle Fatigue ◽  
Secondary Cracks

The crack propagation properties for ultrafine-grained Zn -22 wt % Al alloy during low cycle fatigue (LCF) in the superplastic region and the non-superplastic region were investigated and compared with the corresponding results for several other materials. With the Zn - 22 wt % Al alloy, it was possible to conduct LCF tests even at high strain amplitudes of more than ±5%, and the alloy appeared to exhibit a longer LCF lifetime than the other materials examined. The fatigue life is higher in the superplastic region than in the non-superplastic region. The rate of fatigue crack propagation in the superplastic region is lower than that in the other materials in the high J-integral range. In addition, the formation of cavities and crack branching were observed around a crack tip in the supereplastic region. We therefore conclude that the formation of cavities and secondary cracks as a result of the relaxation of stress concentration around the crack tip results in a reduction in the rate of fatigue crack propagation and results in a longer fatigue lifetime.

Fatigue Crack Propagation Tests on 304 Stainless Steel in High Temperature Water: Accelerated Cracking Rates and Transition to Lower Rates

2004 ◽  
Author(s):  
G. L. Wire ◽  
W. M. Evans ◽  
W. J. Mills
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
High Temperature ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Hold Time ◽  
304 Stainless Steel ◽  
High Temperature Water ◽  
Stress Ratios ◽  
Temperature Water

Previous fatigue crack propagation (FCP) tests on a single heat of 304 stainless steel (304 SS) specimens showed a strong acceleration of rates in high temperature water with 40–60 cc H2/kg H2O at 288°C, with rates up to 20X the air rates. The accelerated rates were observed under fully reversed conditions (R = −1) (Wire and Mills, 2001) and high stress ratios (R = 0.7 and 0.83) (Evans and Wire, 2001). In this study, a second heat of 304 SS has been tested at 243°C and 288°C and lower positive stress ratios (R = 0.3, 0.5). The second heat showed the large acceleration of rates at 288°C observed previously. Rates were up to two times lower at 243°C, but were still 7–8X the air rates. A time-based correlation successfully correlates the accelerated rates observed, and is nearly identical to fits of literature data in hydrogen water chemistry (HWC), which has hydrogen added at a lower level of about 1 cc/kg H2O. The accelerated rates on the second heat were not stable under two different test conditions. In contrast to the first heat, the second heat showed a reduction in environmental enhancement at long rise times, accompanied by a change in fracture mode. Addition of a constant load hold time of 1200 s between cycles also caused a marked reduction in crack propagation rates in both heats, with reduction to nearly air rates in the second heat. The differing rise time effects between the two heats could be rationalized by time-dependent deformation. More hold time testing is required to define the material and loading conditions which lead to reduced rates.

The Fatigue and Fracture Analysis of Steam Turbine Rotor Shafts Containing Defects

2019 ◽  
Vol 795 ◽  
pp. 254-261
Author(s):  
Shang Wang ◽  
Wei Qiang Wang ◽  
Ming Da Song ◽  
Hao Zhang
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Steam Turbine ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Turbine Rotor ◽  
Initial Surface ◽  
Cycle Fatigue ◽  
Steam Turbine Rotor ◽  
Fatigue Crack Propagation Life

In this study, the assessment and calculation methods for the crack propagation life of steam turbine rotor shafts containing defects are presented. The analytic methods for estimating the average stress and the alternating stress amplitude of the steam turbine rotor shafts are introduced. The defects on/in the rotor shafts were regularized by the method of fracture mechanics, and the high cycle fatigue crack propagation life and low cycle fatigue crack propagation life of the rotor shafts are estimated from Paris formula. Taking the 60MW turbine rotor shafts containing an initial surface defect and an initial internal defect as the examples respectively, the crack propagation life of them were calculated. The results indicated that the assessment method for the crack propagation life can preliminarily be both used to estimate the safety-operating life and to analyze the fracture reason of a steam turbine rotor shaft containing defects. This paper can provide reference for periodic maintenance and safety evaluation of turbine rotor shafts.

Fatigue Crack Modeling and Simulation Based on Continuum Damage Mechanics

2006 ◽  
Vol 129 (1) ◽  
pp. 96-102 ◽  
Author(s):  
Masakazu Takagaki ◽  
Toshiya Nakamura
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Present Theory ◽  
Continuum Damage ◽  
Cycle Fatigue

Numerical simulation of fatigue crack propagation based on fracture mechanics and the conventional finite element method requires a huge amount of computational resources when the cracked structure shows a complicated condition such as the multiple site damage or thermal fatigue. The objective of the present study is to develop a simulation technique for fatigue crack propagation that can be applied to complex situations by employing the continuum damage mechanics (CDM). An anisotropic damage tensor is defined to model a macroscopic fatigue crack. The validity of the present theory is examined by comparing the elastic stress distributions around the crack tip with those obtained by a conventional method. Combined with a nonlinear elasto-plastic constitutive equation, numerical simulations are conducted for low cycle fatigue crack propagation in a plate with one or two cracks. The results show good agreement with the experiments. Finally, propagations of multiply distributed cracks under low cycle fatigue loading are simulated to demonstrate the potential application of the present method.

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