Fatigue Behavior of Stainless Steel 304L Including Strain Hardening, Prestraining, and Mean Stress Effects

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Julie Colin ◽  
Ali Fatemi ◽  
Said Taheri
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Stress Relaxation ◽  
Fatigue Behavior ◽  
Control Mode ◽  
Mean Stress ◽  
Continuous Increase ◽  
Stainless Steel 304L ◽  
Mean Stress Relaxation ◽  
Mean Strain

This paper discusses cyclic deformation and fatigue behaviors of stainless steel 304L and aluminum 7075-T6. Effects of loading sequence, mean strain or stress, and prestraining were investigated. The behavior of aluminum is shown not to be affected by preloading, whereas the behavior of stainless steel is greatly influenced by prior loading. Mean stress relaxation in strain control and ratcheting in load control and their influence on fatigue life are discussed. Some unusual mean strain test results are presented for SS304L, where in spite of mean stress relaxation fatigue lives were significantly longer than fully-reversed tests. Prestraining indicated no effect on either deformation or fatigue behavior of aluminum, while it induced considerable hardening in SS304L and led to different results on fatigue life, depending on the test control mode. Possible mechanisms for secondary hardening observed in some tests, characterized by a continuous increase in the stress response and leading to runout fatigue life, are also discussed. The Smith–Watson–Topper parameter was shown to correlate most of the experimental data for both materials under different loading conditions.

scholarly journals Ratcheting-Fatigue Behavior of Harmonic-Structure-Designed SUS316L Stainless Steel

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 477
Author(s):  
Yang Song ◽  
Zhe Zhang ◽  
Hantuo Ma ◽  
Masashi Nakatani ◽  
Mie Ota Kawabata ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stainless Steels ◽  
Fatigue Behavior ◽  
Structure Design ◽  
Control Mode ◽  
Fatigue Properties ◽  
Mean Stress ◽  
Strain Accumulation ◽  
Harmonic Structure ◽  
Ratcheting Strain

Stainless steels with harmonic-structure design have a great balance of high strength and high ductility. Therefore, it is imperative to investigate their fatigue properties for engineering applications. In the present work, the harmonic-structured SUS316L stainless steels were fabricated by mechanical milling (MM) and subsequent hot isostatic pressing (HIP) process. A series of ratcheting-fatigue tests were performed on the harmonic-structured SUS316L steels under stress-control mode at room temperature. Effects of grain structure and stress-loading conditions on ratcheting behavior and fatigue life were investigated. Results showed that grain size and applied mean stress had a significant influence on ratcheting-strain accumulation and fatigue life. Owing to the ultrafine grained structure, tensile strength of the harmonic-structured SUS316L steels could be enhanced, which restrained the ratcheting-strain accumulation, resulting in a prolonged fatigue life. A higher mean stress caused a faster ratcheting-strain accumulation, which led to the deterioration of fatigue life. Moreover, a modified model based on Smith–Watson–Topper (SWT) criterion predicted the ratcheting-fatigue life of the harmonic-structured SUS316L steels well. Most of the fatigue-life points were located in the 5 times error band.

scholarly journals Fatigue behavior of 316L austenitic stainless steel in air and LWR environment with and without mean stress

2018 ◽  
Vol 165 ◽  
pp. 03012 ◽  
Author(s):  
Wen Chen ◽  
Philippe Spätig ◽  
Hans-Peter Seifert
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Austenitic Stainless Steel ◽  
Fatigue Limit ◽  
Fatigue Behavior ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Test Results ◽  
316L Austenitic Stainless Steel

The fatigue life design curves in nuclear codes are generally derived from uniaxial straincontrolled fatigue test results. Evidently, the test conditions are very different from the actual components loading context, which involves much more complex thermo-mechanical loading including mean stress, static load holding time and variation in water chemistry, etc. In this work, the mean stress and environmental effects on fatigue life of 316L austenitic stainless steel in air and light water reactor (LWR) environment were studied using hollow fatigue specimens and testing under load-controlled condition. Both positive (+50 MPa) and negative (-20 MPa) mean stresses showed beneficial effect on fatigue life in LWR environment and in air. This is tentatively attributed to mean stress enhanced cyclic hardening, which leads to smaller strain response at the same loading force. -20 MPa mean stress was found to increase fatigue limit, whereas the effect of +50 MPa mean stress on fatigue limit is still unclear. The preliminary results illustrate that the environmental reduction of fatigue life is amplified in load-controlled fatigue tests with tensile mean stress.

Influence of Mean Strain on Fatigue Life of Stainless Steel (Effect of Constant and Ratcheting Mean Strain)

2014 ◽  
Author(s):  
Masayuki Kamaya
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Effective Strain ◽  
Mouth Opening ◽  
Strain Range ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Crack Mouth ◽  
The Mean ◽  
Mean Strain

The influence of mean strain on fatigue life was investigated for Type 316 stainless steel at room temperature in ambient environment. Two types of mean strain were simulated in the fatigue tests: constant and increasing (ratcheting) mean strains. In order to apply the constant mean strain, prestraining was induced prior to fatigue tests. Although the stress amplitudes became larger due to the prestraining, fatigue lives were almost the same as those obtained using non-prestrained specimens for the same strain range. Change in the maximum peak stress and stress amplitude due to the prestraining had little influence on the fatigue life. It was shown that the mean strain showed little influence on the fatigue life under the same strain range. The ratcheting mean strain was observed during the fatigue tests under mean stress. The fatigue life was reduced by applying the mean stress for the same strain range. The degree of the reduction was increased with the magnitude of the ratcheting mean strain. It was deduced that the increasing mean strain enhanced the crack mouth opening and increased the effective strain range. It was concluded that the ratcheting mean strain reduced the fatigue life for the same strain range, and the reduction in fatigue life could be predicted conservatively by assuming the crack mouth was never closed during the fatigue tests.

Creep-Fatigue Behavior and Life Prediction of 316L Stainless Steel Under Different Loading Levels

2009 ◽  
Author(s):  
Huifeng Jiang ◽  
Xuedong Chen ◽  
Zhichao Fan ◽  
Jie Dong ◽  
Heng Jiang
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Cyclic Deformation ◽  
Life Prediction ◽  
316L Stainless Steel ◽  
Control Mode ◽  
Creep Fatigue ◽  
Material Creep ◽  
Minimum Stress ◽  
Mean Strain

Stress controlled creep-fatigue interaction tests were carried out for 316L stainless steel under different loading levels at 550°C. Cyclic properties such as material life and mean strain were investigated for 316L stainless steel. When the maximum stress is keeping fixed, with increasing minimum stress, the material creep-fatigue life increases first and then decreases. When the stress amplitude is equal to 167.5MPa (minimum stress is equal to 50MPa), material creep-fatigue life reaches its maximum value. Moreover, under stress control mode, dynamic strain aging was found to manifest itself macroscopically as displacement or mean strain abrupt jumps during cyclic deformation. When the minimum stress is less than 0MPa, abrupt displacement jumps occur at the early stage of cyclic deformation and there are many jumps during the whole process. While the minimum stress is larger than 0MPa, displacement only jumps once at the end of deformation. Additionally, by employing a life prediction method on the basis of the Hull-Rimmer creep cavity growth theory, the creep-fatigue life was assessed for 316L stainless steel at 550°C under different loading levels. The predicted lives were compared with the tested ones and a good agreement was found between them.

Cyclic Deformation and Fatigue Behaviors of Stainless Steel 304L Including Mean Stress and Pre-Straining Effects

2008 ◽  
Author(s):  
Jean-Christophe Le Roux ◽  
Said Taheri ◽  
Jean-Philippe Sermage ◽  
Julie Colin ◽  
Ali Fatemi
Keyword(s):  
Experimental Data ◽  
Stainless Steel ◽  
Cyclic Deformation ◽  
Fatigue Behavior ◽  
Secondary Hardening ◽  
Mean Stress ◽  
Stainless Steel 304L ◽  
Stress Effects ◽  
Test Conditions ◽  
Significant Change

This paper discusses cyclic deformation and fatigue behavior of three grades of stainless steel 304L. Effects of pre-straining and mean stress were investigated and it was observed that these parameters influence both deformation and fatigue behaviors. At HCF, significant secondary hardening was observed for two of the materials, leading to a significant change in fatigue behavior at long lives. For two of the materials, pre-strained tests were also conducted. Hardening was observed as a consequence of pre-straining and affected further deformation and fatigue behaviors significantly. Mean stress effects on fatigue lives were as expected, as compressive mean stress lengthened life and tensile mean stress shortened life. The Smith-Watson-Topper (SWT) parameter was used to correlate the experimental data from all test conditions for the three materials and was found to correlate the experimental data reasonably well.

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