Elastic–plastic FEM analysis on low cycle fatigue behavior for alumina dispersion-strengthened copper/stainless steel joint

2004 ◽  
Vol 329-333 ◽  
pp. 1567-1570 ◽  
Author(s):  
H. Nishi
Keyword(s):  
Stainless Steel ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fem Analysis ◽  
Cycle Fatigue ◽  
Elastic Plastic ◽  
Steel Joint

Effects of Surface Finish and Loading Conditions on the Low Cycle Fatigue Behavior of Austenitic Stainless Steel in PWR Environment for Various Strain Amplitude Levels

2009 ◽  
Author(s):  
Jean Alain Le Duff ◽  
Andre´ Lefranc¸ois ◽  
Jean Philippe Vernot
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Strain Amplitude ◽  
Surface Finish ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Complex Loading ◽  
Loading Conditions ◽  
Test Results ◽  
Cycle Fatigue

In February/March 2007, The NRC issued Regulatory Guide “RG1.207” and Argonne National Laboratory issued NUREG/CR-6909 that is now applicable in the US for evaluations of PWR environmental effects in fatigue analyses of new reactor components. In order to assess the conservativeness of the application of this NUREG report, Low Cycle Fatigue (LCF) tests were performed by AREVA NP on austenitic stainless steel specimens in a PWR environment. The selected material exhibits in air environment a fatigue behavior consistent with the ANL reference “air” mean curve, as published in NUREG/CR-6909. LCF tests in a PWR environment were performed at various strain amplitude levels (± 0.6% or ± 0.3%) for two loading conditions corresponding to a simple or to a complex strain rate history. The simple loading condition is a fully reverse triangle signal (for comparison purposes with tests performed by other laboratories with the same loading conditions) and the complex signal simulates the strain variation for an actual typical PWR thermal transient. In addition, two various surface finish conditions were tested: polished and ground. This paper presents the comparisons of penalty factors, as observed experimentally, with penalty factors evaluated using ANL formulations (considering the strain integral method for complex loading), and on the other, the comparison of the actual fatigue life of the specimen with the fatigue life predicted through the NUREG report application. For the two strain amplitudes of ± 0.6% and ± 0.3%, LCF tests results obtained on austenitic stainless steel specimens in PWR environment with triangle waveforms at constant low strain rates give “Fen” penalty factors close to those estimated using the ANL formulation (NUREG/6909). However, for the lower strain amplitude level and a triangle loading signal, the ANL formulation is pessimistic compared to the AREVA NP test results obtained for polished specimens. Finally, it was observed that constant amplitude LCF test results obtained on ground specimens under complex loading simulating an actual sequence of a cold and hot thermal shock exhibits lower combined environmental and surface finish effects when compared to the penalty factors estimated on the basis of the ANL formulations. It appears that the application of the NUREG/CR-6909 in conjunction with the Fen model proposed by ANL for austenitic stainless steel provides excessive margins, whereas the current ASME approach seems sufficient to cover significant environmental effects for representative loadings and surface finish conditions of reactor components.

The Effect of Nitrogen Alloying on the Low Cycle Fatigue and Creep-Fatigue Interaction Behavior of 316LN Stainless Steel

2013 ◽  
Vol 794 ◽  
pp. 441-448 ◽  
Author(s):  
G.V. Prasad Reddy ◽  
R. Sandhya ◽  
M.D. Mathew ◽  
S. Sankaran
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Hold Time ◽  
Cyclic Plasticity ◽  
Dynamic Strain ◽  
Cycle Fatigue ◽  
Intergranular Cracking ◽  
Creep Fatigue

Low cycle fatigue (LCF) and Creep-fatigue interaction (CFI) behavior of 316LN austenitic stainless steel alloyed with 0.07, 0.11, 0.14, .22 wt.% nitrogen is briefly discussed in this paper. The strain-life fatigue behavior of these steels is found to be dictated by not only cyclic plasticity but also by dynamic strain aging (DSA) and secondary cyclic hardening (SCH). The influence of the above phenomenon on cyclic stress response and fatigue life is evaluated in the present study. The above mentioned steels exhibited both single-and dual-slope strain-life fatigue behavior depending on the test temperatures. Concomitant dislocation substructural evolution has revealed transition in substructures from planar to cell structures justifying the change in slope. The beneficial effect of nitrogen on LCF life is observed to be maximum for 316LN with nitrogen in the range 0.11 - 0.14 wt.%, for the tests conducted over a range of temperatures (773-873 K) and at ±0.4 and 0.6 % strain amplitudes at a strain rate of 3*10-3 s-1. A decrease in the applied strain rate from 3*10-3 s-1 to 3*10-5 s-1 or increase in the test temperature from 773 to 873 K led to a peak in the LCF life at a nitrogen content of 0.07 wt.%. Similar results are obtained in CFI tests conducted with tensile hold periods of 13 and 30 minutes. Fractography studies of low strain rate and hold time tested specimens revealed extensive intergranular cracking.

Effects of Surface Finish and Loading Conditions on the Low Cycle Fatigue Behavior of Austenitic Stainless Steel in PWR Environment: Comparison of LCF Test Results With NUREG/CR-6909 Life Estimations

2008 ◽  
Author(s):  
Jean Alain Le Duff ◽  
Andre´ Lefranc¸ois ◽  
Jean Philippe Vernot
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Austenitic Stainless Steel ◽  
Environmental Effects ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Complex Signal ◽  
Loading Conditions ◽  
Test Results ◽  
Cycle Fatigue

During mid 2006, ANL issued a NUREG/CR-6909 [2] report that is now applicable in The US for evaluations of PWR environmental effects in the fatigue analysis of new reactor components. In order to assess the conservativeness of the application of this NUREG report, low cycle fatigue (LCF) tests were performed by AREVA NP on austenitic stainless steel specimens in a PWR environment. The selected material exhibits in an air environment a fatigue behavior consistent with the ANL reference “air” mean curve. Tests were performed for two various loading conditions: for fully reverse triangular signal (for comparison purpose with tests performed by other laboratories with same loading conditions) and complex signal, simulating strain variation for actual typical PWR thermal transients. Two surface finish conditions were tested: polished and ground. The paper presents on one side the comparison of environmental penalty factors (Fen = Nair,RT/Nwater) as observed experimentally with the ANL formulation (considering the strain integral method for complex loading), and, on the other hand, the actual fatigue life of the specimen with the fatigue life predicted through the NUREG/CR-6909 application. Low Cycle Fatigue test results obtained on austenitic stainless steel specimens in PWR environment with triangle waveforms at constant low strain rates gives Fen penalty factors close to those estimated using the ANL formulation (NUREG report 6909). On the contrary, it was observed that constant amplitude LCF test results obtained under complex signal reproducing an actual sequence of a cold and hot thermal shock exhibits significantly lower environmental effects when compared to the Fen penalty factor estimated on the basis of the ANL formulations. It appears that the application of the NUREG/CR-6909 [2] in conjunction with the Fen model proposed by ANL for austenitic stainless steel provides excessive margins whereas the current ASME approach seems sufficient to cover significant environmental effect for components.

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