A Study on the Notch Effect on the Low Cycle Fatigue of Metals in Creep-Fatigue Interacting Conditions at Elevated Temperature

1983 ◽  
Vol 105 (2) ◽  
pp. 75-80 ◽  
Author(s):  
M. Sakane ◽  
M. Ohnami
Keyword(s):  
Elastic Stress ◽  
Low Cycle Fatigue ◽  
Hold Time ◽  
Cycle Fatigue ◽  
Time Effects ◽  
Notched Specimen ◽  
Notched Specimens ◽  
Creep Fatigue ◽  
Neuber's Rule ◽  
Modified Equation

Frequency and hold-time effects on fatigue lives of cylindrical notched specimens of SUS 316 stainless steel were studied at 600° C in air. From the tests, the following conclusions were obtained: Neuber’s rule, as used in the ASME N-47 Code, predicts very conservatively the life of notched specimens in tests without a hold-time. But it gives a nonconservative estimate for the reduction in the life of the material by the introduction of a hold-time. An empirical formula of a “frequency-elastic stress concentration factor modified equation” was obtained by analysing the experimental data. It predicts accurately the life of the notched specimen tested at different frequencies.

Frequency and Hold-Time Effects on Low Cycle Fatigue Life of Notched Specimens at Elevated Temperature

1989 ◽  
Vol 111 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Masao Sakane ◽  
Masateru Ohnami ◽  
Teruyoshi Awaya ◽  
Nakao Shirafuji
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Hold Time ◽  
Strain Range ◽  
Fem Analysis ◽  
Time Dependent ◽  
Cycle Fatigue ◽  
Time Effects ◽  
Notched Specimens ◽  
Cycle Dependent

This paper describes the frequency and hold-time effects on high temperature low cycle fatigue for round notched specimens. Unnotched and notched specimens having different elastic stress concentration factors were fatigued under triangular and trapezoidal stress waves at frequencies ranging from 5 Hz to 0.0001 Hz at 873 K. The three specific fracture characteristics were observed: cycle dependent, time dependent, and cycle-time dependent. The respective notch sensitivity occurred in the respective fracture regime. The fatigue life of notched specimens was predicted from the elastic-plastic-creep cyclic FEM analysis using the linear damage rule and the strain range partitioning rule. Both the life prediction methods predicted the creep-fatigue life within almost a factor of two scatter band.

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.

Hold time effects on low cycle fatigue behavior of HAYNES 230® superalloy at high temperatures

2005 ◽  
Vol 409 (1-2) ◽  
pp. 282-291 ◽  
Author(s):  
Y.L. Lu ◽  
L.J. Chen ◽  
G.Y. Wang ◽  
M.L. Benson ◽  
P.K. Liaw ◽  
...  
Keyword(s):  
High Temperatures ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Hold Time ◽  
Cycle Fatigue ◽  
Time Effects ◽  
Haynes 230

Study on Life Prediction Method for Creep-Fatigue Interaction at Elevated Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 190-194
Author(s):  
Nian Jin Chen ◽  
Zeng Liang Gao ◽  
Wei Zhang ◽  
Yue Bao Le
Keyword(s):  
Elevated Temperature ◽  
Prediction Model ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Hold Time ◽  
Prediction Method ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Creep Fatigue ◽  
316L Austenitic Stainless Steel

The law of low-cycle fatigue with hold time at elevated temperature is investigated in this paper. A new life prediction model for the situation of fatigue and creep interaction is developed, based on the damage due to fatigue and creep. In order to verify the prediction model, strain-controlled low-cycle fatigue tests at temperature 693K, 823K and 873K and fatigue tests with various hold time at temperature 823K and 873K for 316L austenitic stainless steel were carried out. Good agreement is found between the predictions and experimental results.

Low Cycle Fatigue and Creep-Fatigue Behavior of Alloy 617 at High Temperature

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Celine Cabet ◽  
Laura Carroll ◽  
Richard Wright
Keyword(s):  
High Temperature ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Dominant Role ◽  
Hold Time ◽  
Outlet Temperature ◽  
Cycle Fatigue ◽  
Alloy 617 ◽  
Creep Fatigue

Alloy 617 is the leading candidate material for an intermediate heat exchanger (IHX) application of the very high temperature nuclear reactor (VHTR), expected to have an outlet temperature as high as 950 °C. Acceptance of Alloy 617 in Section III of the ASME Code for nuclear construction requires a detailed understanding of the creep-fatigue behavior. Initial creep-fatigue work on Alloy 617 suggests a more dominant role of environment with increasing temperature and/or hold times evidenced through changes in creep-fatigue crack growth mechanisms and failure life. Continuous cycle fatigue and creep-fatigue testing of Alloy 617 was conducted at 950 °C and 0.3% and 0.6% total strain in air to simulate damage modes expected in a VHTR application. Continuous cycle fatigue specimens exhibited transgranular cracking. Intergranular cracking was observed in the creep-fatigue specimens and the addition of a hold time at peak tensile strain degraded the cycle life. This suggests that creep-fatigue interaction occurs and that the environment may be partially responsible for accelerating failure.

Fatigue Behavior of K447A Superalloy under Low Cycle Fatigue and Creep-Fatigue Interaction Conditions

2015 ◽  
Vol 750 ◽  
pp. 121-126 ◽  
Author(s):  
Hui Chen Yu ◽  
Cheng Li Dong ◽  
Ying Li
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Hold Time ◽  
Strain Ratio ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Creep Fatigue ◽  
Cyclic Damage ◽  
Mean Stresses

Strain-controlled low cycle fatigue (LCF) and creep-fatigue interaction (CFI) tests of K447A are conducted at 760oC in order to investigate the effects of different dwell times and strain ratios on the fatigue behavior and life. For the cases of stain ratio Rε=-1 with balanced hold time, the tensile and compressive mean stresses will generate. For the case of stain ratio Rε=-1 with compressive holding 60s, the tensile mean stress will produce. For the case of stain ratio Rε=-1 with tensile holding 60s, the compressive mean stress will produce. For the cases of stain ratio Rε=0.1 and Rε=-1with no hold time, the tensile mean stress will produce. The cyclic damage accumulation (CDA) method and modified CDA method were employed to predict the fatigue life for K447A, respectively. The fatigue life predicted by CDA method is within the scatter band of 18.2X. The fatigue life predicted by the modified CDA method agrees very well with the experimental life and the predicted life is well within the scatter band of 3.1X, which means that the modified CDA method is able to consider the influences of dwell time and strain ratio on the fatigue life of K447A.

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