Low-Cycled Fatigue Life of S30408 Stainless Steel at Liquid-Nitrogen Temperature

2018 ◽  
Author(s):  
Yingzhe Wu ◽  
Huaijian Xu ◽  
Qunjie Lu ◽  
Jinyang Zheng ◽  
Ping Xu
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Liquid Nitrogen ◽  
Strain Amplitude ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Liquid Nitrogen Temperature ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Fatigue Tests

This paper is concerned with the low-cycled fatigue life of S30408 austenitic stainless steel at 77 K. Strain-controlled low-cycled fatigue tests were performed in a liquid-nitrogen bath covering a strain-amplitude range of 0.4%–1.0%. The role of the reduced temperature is examined during the low-cycled fatigue tests by comparing the fatigue performance to the one at ambient temperature that was obtained in our previous work. It is found that the cryogenic low-cycled fatigue life is significantly improved by a factor of 5–10 in the low strain-amplitude range of 0.4%–0.5%, resulting from the pronounced hardening effect due to the low temperature. However, the cryogenic improvement gradually reduces with the increasing strain-amplitude. At 77 K, the cyclic stress amplitude increases rapidly at the beginning of the fatigue test, and no cyclic softening is found due to the cryogenically constrained movement of the dislocations. The fatigue hysteresis loops and fatigue stress-strain curves shows that the cyclic plastic strain at cryogenic temperature accounts for a limited proportion in the total cyclic strain, and the damage may occurs explosively at the beginning of the cyclic load at 77 K.

Cyclic Stress in 316L Austenitic Stainless Steel at Low Temperatures

2007 ◽  
Vol 567-568 ◽  
pp. 401-404 ◽  
Author(s):  
Jaroslav Polák ◽  
Martin Petrenec ◽  
Jiří Man
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Plastic Strain ◽  
Strain Amplitude ◽  
Stress Component ◽  
Hysteresis Loops ◽  
Cyclic Stress ◽  
Plastic Strain Amplitude ◽  
Test Method ◽  
Step Test

Austenitic stainless steel was cycled at a series of temperatures in the interval from 296 K to 113 K. Constant plastic strain amplitude loading at different levels of plastic strain amplitude and testing similar to multiple step test method were applied at different temperatures. The stress amplitude was continually recorded and selected hysteresis loops were stored and later analyzed using statistical theory of the hysteresis loop. Effective stress component and probability density function as a function of temperature were evaluated. The results were discussed in terms of the temperature dependence of the cyclic yield stress and its sources.

Predicting Fatigue Initiation Life of Sn/3.8Ag/0.7Cu Solder using Endochronic Cyclic Damage-Coupled Viscoplastic Theory

2008 ◽  
Vol 24 (4) ◽  
pp. 369-377 ◽  
Author(s):  
C. F. Lee ◽  
Z. H. Lee
Keyword(s):  
Strain Amplitude ◽  
Hysteresis Loops ◽  
Inelastic Strain ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Cyclic Behavior ◽  
Dendritic Microstructure ◽  
Fatigue Initiation ◽  
Cyclic Damage ◽  
Good Agreement

AbstractThis paper studied cyclic behavior Sn/3.8Ag/0.7Cu solder with dendritic microstructure. A cyclic damage factor D under constant strain amplitude fatigue tests, was defined by using the reducing rate of maximum cyclic tensile stress σa. The critical cyclic damage DC and it's fatigue initiation life NI were determined very consistently by using separately the experimental σavs. N curves and the percolation theory. The endochronic cyclic damage-coupled viscoplastic theory proposed by the 1st author was used to simulate cyclic stress-strain hysteresis loops with damage under strain amplitude (εa) 0.8% at 298K. The results were in very good agreement with data. Combining the evolution equation of intrinsic damage and the computed cyclic stress-inelastic strain relation, a modified Coffin-Manson relationship was derived. By setting DC = 0.3, it predicted very effectively the NI data under σa from 0.2% to 1.0%.

scholarly journals Flat-Cladding Fiber Bragg Grating Sensors for Large Strain Amplitude Fatigue Tests

2021 ◽  
Author(s):  
Aihen Feng ◽  
Daolun Chen ◽  
Cheng Li ◽  
Xijia Gu
Keyword(s):  
Fiber Bragg Grating ◽  
Strain Amplitude ◽  
Large Strain ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Fatigue Tests ◽  
Bragg Grating ◽  
Large Strain Amplitude ◽  
Bragg Grating Sensor ◽  
Cyclic Strain Amplitude

We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor.

Low Cycle Fatigue Behavior of Spray Formed Superalloy Rings

2011 ◽  
Vol 399-401 ◽  
pp. 1937-1941 ◽  
Author(s):  
Wen Yong Xu ◽  
Guo Qing Zhang ◽  
Zhou Li
Keyword(s):  
Strain Amplitude ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Total Strain ◽  
Total Strain Amplitude ◽  
Cycle Fatigue

Low cycle fatigue behavior of spray formed superalloy GH738 at 650°C has been investigated under fully reversed total strain-controlled mode. When strain amplitude (Δεt/2) is between 0.32% and 0.4%, cyclic stress response is stable under fully reversed constant total strain amplitude. The stabilized hysteresis loops narrowing sharply to a straight line indicates that the alloy exhibits typical elastic strain. The crack initiates single site from the surface. When strain amplitude is between 0.6% and 1.0%, cyclic hardening is observed until fracture. The tendency for hardening is found to increase with strain amplitude. The hyperesis loops expand gradually, which indicates that plastic deformation happens during cyclic deformation process. The crack initiates multi-sites from the surface. The cyclic strain-stress relationship of spray formed GH738 at 650°C can be illustrated by Δσ/2 =2017(Δεp/2)0.1489.The total strain-life function can expressed by Δεt/2=0.0071(2Nf)-0.0781+0.0647(2Nf) )-0.4914.

Effect of Pre-Deformation on the Cyclic Behavior and Fatigue of 304L SS

2016 ◽  
Vol 703 ◽  
pp. 125-131 ◽  
Author(s):  
Lakhdar Taleb ◽  
Crescent Kpodekon
Keyword(s):  
Fatigue Life ◽  
Cyclic Strain ◽  
Cyclic Hardening ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Cyclic Behavior ◽  
304L Stainless Steel ◽  
Strain Control ◽  
Hardening Process ◽  
Second Category

This study deals with the effect of the loading history on the cyclic behavior and the fatigue life of a 304L stainless steel at room temperature. The experiments have been performed using two specimens’ categories. The first one (virgin) has been submitted to only classical fatigue tests while in the second category, prior to the fatigue test; the specimen was subjected to a pre-hardening process under either monotonic or cyclic strain control. Cyclic softening followed by cyclic hardening are observed for the virgin specimens while only cyclic softening is exhibited by the pre-hardened specimens. The obtained results show that fatigue life is strongly influenced by the pre-hardening: the latter seems beneficial under stress control but detrimental under strain control, even in the presence of a compressive mean stress. The results are discussed regarding the cyclic evolution of the elastic modulus as well as the isotropic and kinematic parts of the strain hardening in different configurations: with or without pre-hardening, stress or strain control.

scholarly journals Flat-Cladding Fiber Bragg Grating Sensors for Large Strain Amplitude Fatigue Tests

2021 ◽  
Author(s):  
Aihen Feng ◽  
Daolun Chen ◽  
Cheng Li ◽  
Xijia Gu
Keyword(s):  
Fiber Bragg Grating ◽  
Strain Amplitude ◽  
Large Strain ◽  
Hysteresis Loops ◽  
Cyclic Strain ◽  
Fatigue Tests ◽  
Bragg Grating ◽  
Large Strain Amplitude ◽  
Bragg Grating Sensor ◽  
Cyclic Strain Amplitude

We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor.

Long Life Fatigue Performance of Stainless Steel

2011 ◽  
Author(s):  
Jussi Solin ◽  
Sven Reese ◽  
Wolfgang Mayinger
Keyword(s):  
Stainless Steel ◽  
Endurance Limit ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Life Extension ◽  
Thermal Transients ◽  
Operation Temperature ◽  
Wide Range ◽  
Material Sample

Fatigue of Niobium stabilized austenitic stainless steel (X6CrNiNb1810 mod) was studied using specimens extracted from a solution annealed and quenched primary piping material sample. This paper reports and discusses results of non-standard experiments to complement previously published test data. The NPP primary piping components spend long times in operation temperature between fatigue cycles originating from thermal transients. This was roughly simulated by fatigue tests periodically interrupted for intermediate annealing in elevated temperature. Fatigue endurance was notably increased when low strain amplitudes were used. The life extension is explained by the cyclic stress strain response. Hardening followed by slow cyclic softening was consistently observed after annealing. It is generally assumed that cumulative accumulation of fatigue damage occurs at a wide range of loading amplitudes. We performed two level and spectrum straining tests combining amplitudes above and below the (Nf > 107) endurance limit. The endurance limit seems to be effective also in variable amplitude loading. In terms of modified Miner rule, even “negative damage” was obtained in two level tests below and above the constant amplitude endurance limit. This behavior is linked to prominent secondary hardening of the steel.

Rate Dependent Constitutive Equations of Cyclic Softening

1985 ◽  
Vol 40 (7) ◽  
pp. 653-665
Author(s):  
J. S. Mshana ◽  
A. S. Krausz
Keyword(s):  
Stress Relaxation ◽  
Low Temperature ◽  
Constitutive Equations ◽  
Strain Softening ◽  
Structural Characteristics ◽  
High Stress ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Cyclic Softening ◽  
Stress Softening

Constitutive equations of cyclic strain and stress softening for materials with low internal stress levels are derived from the rate theory. The study shows that over the high stress and low temperature range where the description of plastic flow in cyclic softening can be approximated with activation over a single energy barrier, cyclic strain softening is well related to stress relaxation process while cyclic stress softening is related to creep process. The material structural characteristics for cyclic strain softening, cyclic stress softening and stress relaxation are identical. Subsequently, it is shown that cyclic stress and strain softening within the high stress and low temperature range can be evaluated from the constitutive equations using the material structural characteristics measured from a simple stress relaxation test.

An Investigation of Cyclic Transient Behavior and Implications on Fatigue Life Estimates

1997 ◽  
Vol 119 (2) ◽  
pp. 161-170 ◽  
Author(s):  
Yanyao Jiang ◽  
Peter Kurath
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Cyclic Hardening ◽  
Transient Behavior ◽  
Fatigue Tests ◽  
304 Stainless Steel ◽  
Deformation History ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Track Deformation

Current research focuses on proportional cyclic hardening and non-Massing behaviors. The interaction of these two hardenings can result in the traditionally observed overall softening, hardening or mixed behavior exhibited for fully reversed strain controlled fatigue tests. Proportional experiments were conducted with five materials, 304 stainless steel, normalized 1070 and 1045 steels, and 7075-T6 and 6061-T6 aluminum alloys. All the materials display similar trends, but the 304 stainless steel shows the most pronounced transient behavior and will be discussed in detail. Existing algorithms for this behavior are evaluated in light of the recent experiments, and refinements to the Armstrong-Frederick class of incremental plasticity models are proposed. Modifications implemented are more extensive than the traditional variation of yield stress, and a traditional strain based memory surface is utilized to track deformation history. Implications of the deformation characteristics with regard to fatigue life estimation, especially variable amplitude loading, will be examined. The high-low step loading is utilized to illustrate the effect of transient deformation on fatigue life estimation procedures, and their relationship to the observed and modeled deformation.

Application of the Cyclic Strain Approach to the Fatigue Failure of Ship Structural Details

1987 ◽  
Vol 31 (03) ◽  
pp. 177-185
Author(s):  
Wolfgang Fricke ◽  
Hans Paetzold
Keyword(s):  
Fatigue Life ◽  
Plastic Region ◽  
Steel Structure ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Damage Parameter ◽  
Elastic Plastic ◽  
Strain Behavior ◽  
Structural Details ◽  
The Relationship

The cyclic strain approach is useful for determining the fatigue life of notches strained in the elastic-plastic region. Examples are the flame-cut edges of cutouts in the ship steel structure. After the description of the cyclic stress-strain behavior of the usual mild steel, the individual elements of the approach are described: the probability distribution of load amplitudes, the relationship between load and local elastic-plastic strain, the relationship between the damage parameter and fatigue life, and finally the damage accumulation law. The approach is illustrated by two examples of longitudinal/transverse web intersections. In the first, the predicted life is confirmed by experimental results. The second example shows the approach for complicated load combinations. It is hoped that this paper will contribute to sound and crack-free ship structural details, particularly if unusual loads are applied to well-tried details or if simplified designs are introduced.

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