Environmental Fatigue Testing of Type 316 Stainless Steel in 310 °C Water

2005 ◽  
Author(s):  
Hyunchul Cho ◽  
Byoung Koo Kim ◽  
In Sup Kim ◽  
Seung Jong Oh ◽  
Dae Yul Jung ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Pure Water ◽  
Cyclic Stress ◽  
Strain Rates ◽  
Low Oxygen ◽  
Test Environment ◽  
316 Stainless Steel

Low cycle fatigue tests were conducted to investigate fatigue behaviors of Type 316 stainless steel in 310 °C low oxygen water. In the tests, strain rates were 4 × 10−4, 8 × 10−5 s−1 and applied strain amplitudes were 0.4, 0.6, 0.8, and 1.0%. The test environment was pure water at a temperature of 310 °C, pressure of 15 MPa, and dissolved oxygen concentration of < 1 ppb. Type 316 stainless steel underwent a primary hardening, followed by a moderate softening for both strain rates in 310 °C low oxygen water. The primary hardening was much less pronounced and secondary hardening was observed at lower strain amplitude. On the other hand, the cyclic stress response in room temperature air exhibited gradual softening and did not show any hardening. The fatigue life of the studied steel in 310 °C low oxygen water was shorter than that of the statistical model in air. The reduction of fatigue life was enhanced with decreasing strain rate from 4 × 10−4 to 8 × 10−5 s−1.

Cyclic Hardening Behaviors and Reduction in Fatigue Life of Type 316LN Austenitic Stainless Steel in 310°C Low Oxygen-Containing Water

2006 ◽  
Author(s):  
Hyunchul Cho ◽  
Byoung Koo Kim ◽  
Changheui Jang ◽  
In Sup Kim ◽  
Seung Mo Hong
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Fatigue Resistance ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Secondary Hardening ◽  
Cyclic Behavior ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Low Oxygen

Low cycle fatigue tests were conducted to investigate the cyclic behavior and the fatigue life of type 316LN stainless steel (SS) at various strain rates in 310°C low oxygen-containing water. The strain rates were 0.008, 0.04, and 0.4%/s, and the applied strain amplitude was varied from 0.4 to 1.0%. The dissolved oxygen concentration of the test water was maintained below 1 ppb. The test material in 310°C low oxygen-containing water experienced a primary hardening, followed by a softening. From our data, we confirm the occurrence of the dynamic strain aging (DSA), and finally it can be considered that the primary hardening was brought about by the DSA. The secondary hardening was observed distinctly for 0.4%/s and 0.4%. The improvement of fatigue resistance and the secondary hardening occurred under the same loading condition. Therefore, the improvement of fatigue resistance may be related to the occurrence of the secondary hardening. When the secondary hardening occurs, intense slip bands are replaced by the corduroy structure. The corduroy structure can induce retardation of crack initiation, and ultimately the fatigue resistance is improved. Comparative study between the fatigue life generated in the current study and some prediction models was performed to evaluate the reliability of our data.

Low Cycle Fatigue Life of Type 316 Stainless Steel Notched Specimen Under Proportional and Non-Proportional Multiaxial Loadings

2010 ◽  
Author(s):  
Takamoto Itoh
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Strain Path ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Notched Specimen ◽  
Life Estimation ◽  
316 Stainless Steel ◽  
Strain Parameter ◽  
Strain Paths

This study discusses multiaxial low cycle fatigue life of notched specimen under proportional and non-proportional loadings at room temperature. Strain controlled multiaxial low cycle fatigue tests were carried out using smooth and circumferentially notched round-bar specimens of type 316 stainless steel. Four kinds of notched specimens were employed of which elastic stress concentration factors, Kt, are 1.5, 2.5, 4.2 and 6.0. The strain paths include proportional and non-proportional loadings. The former employed a push-pull straining or a reversed torsion straining. The latter was achieved by strain path where axial and shear strains has 90 degree phase difference but their amplitudes is the same based on von Mises’ criterion. The notch dependency of multiaxial low cycle fatigue life and the life estimation are discussed. The lives depend on both Kt and strain path. The strain parameter for the life estimation is also discussed with the non-proportional strain parameter proposed by the author with introducing Kt. The proposed parameter gives a satisfactory correlation with multiaxial low cycle fatigue life of notched specimen of type 316 stainless steel under proportional and non-proportional loadings.

Low Cycle Fatigue of Nuclear Pipe Components

1974 ◽  
Vol 96 (3) ◽  
pp. 171-176 ◽  
Author(s):  
J. D. Heald ◽  
E. Kiss
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Room Temperature ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
304 Stainless Steel ◽  
Code Design ◽  
Hydraulic Pressure ◽  
Cycle Fatigue ◽  
Cyclic Bending

This paper presents the results of low-cycle fatigue testing and analysis of 26 piping components and butt-welded sections. The test specimens were fabricated from Type-304 stainless steel and carbon steel, materials which are typically used in the primary piping of light water nuclear reactors. Components included 6-in. elbows, tees, and girth butt-welded straight sections. Fatigue testing consisted of subjecting the specimens to deflection-controlled cyclic bending with the objective of simulating system thermal expansion type loading. Tests were conducted at room temperature and 550 deg F, with specimens at room temperature subjected to 1050 psi constant internal hydraulic pressure in addition to cyclic bending. In two tests at room temperature, however, stainless steel elbows were subjected to combined simultaneous cyclic internal pressure and cyclic bending. Predictions of the fatigue life of each of the specimens tested have been made according to the procedures specified in NB-3650 of Section III[1] in order to assess the code design margin. For the purpose of the assessment, predicted fatigue life is compared to actual fatigue life which is defined as the number of fatigue cycles producing complete through-wall crack growth (leakage). Results of this assessment show that the present code fatigue rules are adequately conservative.

Direct Strain-Controlled Variable Strain Rate Low Cycle Fatigue Testing in Simulated PWR Water

2016 ◽  
Author(s):  
Tommi Seppänen ◽  
Jouni Alhainen ◽  
Esko Arilahti ◽  
Jussi Solin
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Strain Rate ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Reference Value ◽  
Hot Water ◽  
Feedback Signal ◽  
Cycle Fatigue ◽  
Experimental Values

A tailored-for-purpose environmental fatigue testing facility was previously developed to perform direct strain-controlled tests on stainless steel in simulated PWR water. Strain in specimen mid-section is generated by the use of pneumatic bellows, and eddy current measurement is used as a feedback signal. The procedure conforms with the ASTM E 606 practice for low cycle fatigue, giving results which are directly compatible with the major NPP design codes. Past studies were compiled in the NUREG/CR-6909 report and environmental reduction factors Fen were proposed to account for fatigue life reduction in hot water as compared to a reference value in air. This database exclusively contained non-stabilized stainless steels, mainly tested under stroke control. The applicability of the stainless steel Fen factor for stabilized alloys was already challenged in past papers (PVP2013-97500, PVP2014-28465). The results presented in this paper follow the same overall trend of lower experimental values (4.12–11.46) compared to those expected according to the NUREG report (9.49–10.37). In this paper results of a dual strain rate test programme on niobium stabilized AISI 347 type stainless steel are presented and discussed in the context of the NUREG/CR-6909 Fen methodology. Special attention is paid to the effect of strain signal on fatigue life, which according to current prediction methods does not affect the value of Fen.

A Study of the Low Cycle Fatigue Characteristics of Annealed AISI 347 Stainless Steel And Overaged 6951-T6 Aluminum Push-Pull Specimens

1977 ◽  
Vol 99 (3) ◽  
pp. 391-398
Author(s):  
J. A. Friedericy ◽  
R. F. Graves
Keyword(s):  
Stainless Steel ◽  
Stress Field ◽  
Room Temperature ◽  
Elastic Limit ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Cyclic Stress ◽  
Test Machine ◽  
Cycle Fatigue ◽  
Temperature Levels

In a cyclic application the Neuber theory becomes the Wetzel-Morrow approach. The Neuber theory for stresses and strains in a notch is extended to apply to specimens for which the nominal stresses and strains in the material in the field adjacent to the notch may exceed the elastic limit. Also, when the cyclic nominal stresses and strains exceed the elastic or proportional limit of the materials, this extension can be applied if a mechanism external to the nominal stress field is applied to cause the stress field to change in a predetermined manner for each successive cycle. In the case of a notched push-pull specimen, the external mechanism would be a tensile test machine and the field adjacent to the notch would be that of the nominally induced stresses and strains by means of the machine. The state of stress and strain in the notch is the result of the shape and size of the notch as well as the nominal stresses and strains adjacent to the notch. A supporting test program is discussed which dealt with the low cycle fatigue testing of two metals, AISI 347 stainless steel and 6951-T6 aluminum. A push-pull specimen was used which was designed to handle fully reversed cyclic loads from 100 cycles on up. Both fatigue and cyclic stress-strain tests were performed. The strain ranges predicted by the extended theory were inserted in the Universal Slopes equation and the cyclic lives of the specimens at various applied stress levels were determined, including those exceeding the elastic limit of the material. Good correlation was obtained between theory and experiment at the temperature levels tested. The steel specimens were tested at room temperature and 1000°F (537°C) and the aluminum specimens at room temperature and 300°F (149°C).

Strain Waveform Effects for Low Cycle Fatigue in Simulated PWR Water

2017 ◽  
Author(s):  
Tommi Seppänen ◽  
Jouni Alhainen ◽  
Esko Arilahti ◽  
Jussi Solin
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Reference Value ◽  
Steel Specimen ◽  
Feedback Signal ◽  
Test Results ◽  
Testing Facility ◽  
Reference Curves

In order to perform design code (ASME III, RCC-M, JSME) compatible direct strain-controlled tests in simulated PWR water, a unique environmental fatigue testing facility was previously developed. Pneumatic bellows are used to generate strain in the stainless steel specimen mid-section, while eddy current based measurement is used as a feedback signal. The NUREG/CR-6909 report gathered a large database of test results and proposed environmental reduction factors (Fen) to account for a reduction in fatigue life in simulated LWR environment when comparing to a reference value in air. The database was composed of non-stabilized stainless steels tested using methods which are not directly comparable to those used in air to define the reference curves. Applicability of the stainless steel Fen factors has already been challenged in previous PVP papers (PVP2013-97500, PVP2014-28465, PVP2016-63294). Results in this paper continue to show this trend of lower experimental Fen factors compared to predictions made by the NUREG report. Dual strain rate tests were performed, specifically focusing on the effect of strain waveform shape on fatigue life. Similarly to last year’s results (PVP2016-63294) a distinct effect of strain waveform, presently inadequately accounted for in Fen predictions, was observed.

Fatigue Life of the Strain Hardened Austenitic Stainless Steel in Simulated PWR Primary Water

2012 ◽  
Author(s):  
Kazuya Tsutsumi ◽  
Nicolas Huin ◽  
Thierry Couvant ◽  
Gilbert Henaff ◽  
Jose Mendez ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Strain Hardening ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Axial Strain ◽  
Correlation Factor ◽  
304L Stainless Steel ◽  
Pressurized Water ◽  
Primary Water

Over the last 20 years or so, many studies have revealed the deleterious effect of the environment on fatigue life of austenitic stainless steels in pressurized water reactor (PWR) primary water. The fatigue life correlation factor, so-called Fen, has been standardized to consider the effect on fatigue life evaluation. The formulations are function of strain rate and temperature due to their noticeable negative effect compared with other factors [1,2]. However, mechanism causing fatigue life reduction remains to be cleared. As one of possible approaches to examine underlying mechanism of environmental effect, the authors focused on the effect of plastic strain, because it could lead microstructural evolution on the material. In addition, in the case of stress corrosion cracking (SCC), it is well known that the strain-hardening prior to exposure to the primary water can lead to remarkable increase of the susceptibility to cracking [3,4]. However, its effect on fatigue life has not explicitly been investigated yet. The main effort in this study addressed the effect of the prior strain-hardening on low cycle fatigue life of 304L stainless steel (SS) exposed to the PWR primary water. A plate of 304LSS was strain hardened by cold rolling or tension prior to fatigue testing. The tests were performed under axial strain-controlled at 300 °C in primary water including B/Li and dissolved hydrogen, and in air. The effect on environmental fatigue life was investigated through a comparison of the Fen in experiments and in regulations, and also the effect on the fatigue limit defined at 106 cycles was discussed.

scholarly journals Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4070
Author(s):  
Andrea Karen Persons ◽  
John E. Ball ◽  
Charles Freeman ◽  
David M. Macias ◽  
Chartrisa LaShan Simpson ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Models ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Wearable Sensors ◽  
Fatigue Tests ◽  
Proof Of Concept ◽  
Cycle Fatigue ◽  
Wearable Sensing ◽  
Failure Data

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

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