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Journal ArticleDOI

Low and High Cycle Fatigue Interaction in 316L Stainless Steel

01 Mar 2001-Journal of Testing and Evaluation (American Society for Testing and Materials)-Vol. 29, Iss: 2, pp 138-145
TL;DR: In this paper, the interaction between initial low cycle fatigue and high cycle fatigue in 316L stainless steel is reported, and it is concluded that initial LCF causes substantial irreversible damage, subsequently reducing fatigue life in the HCF regime.
Abstract: The interaction between initial low cycle fatigue (LCF) and high cycle fatigue (HCF) in 316L stainless steel is reported. Specimens were introduced to varying degrees of LCF and subsequently subjected to HCF until failure. LCF involves bulk plasticity where stress levels are usually above the yield strength of the material. On the other hand, HCF is predominantly elastic, and stress levels are below the yield strength of the material. Fatigue was carried out under strain control where two strain amplitudes in the LCF range with a common HCF strain amplitude were investigated. Results show that fatigue life decreased when specimens were introduced to increasing numbers of initial LCF. A linear life trend is observed for high numbers of LCF introduction, which deviates from linearity when lower numbers of LCF were introduced. It is therefore concluded that initial LCF causes substantial irreversible damage, subsequently reducing fatigue life in the HCF regime.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors performed cyclic axial and bending tests on structural carbon steel, cold-formed carbon steel and stainless steel, with a total of 62 experiments, with strain amplitudes up to ±15%.

231 citations


Cites result from "Low and High Cycle Fatigue Interact..."

  • ...12 The importance of the level of cold-work on strain-life response can be observed by comparing the data from the current study to existing LCF data from other studies [1-5, 25-29], as shown in Figs 19 and 20, though it is worth noting that materials in cold-formed structural members will typically undergo higher levels of cold-work than the cold-worked steel sheets tested in the literature....

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Journal ArticleDOI
TL;DR: In this article, the effect of bulk damage on fatigue crack initiation was investigated by electron backscatter diffraction (EBSD) and scanning electron microscopy, and it was concluded that although bulk damage surely exists, the fatigue life can be restored to that of the untested specimen by removing the surface cracks.
Abstract: To investigate the effect of bulk damage on fatigue crack initiation, crack initiations due to low-cycle fatigue of Type 316 stainless steel were observed by electron backscatter diffraction (EBSD) and scanning electron microscopy. The EBSD observations showed that local misorientation developed inhomogeneously due to the cyclic strain, and many cracks were initiated from the slip steps and grain boundaries where the local misorientation was relatively large. The crack initiations could be categorized into two types: enhancement of the driving force by geometrical discontinuity (slip steps and notches), and reduction of material resistance against crack initiation caused by accumulated bulk damage at grain boundaries. In particular, more than half of the cracks were initiated from grain boundaries. However, in spite of the significant bulk damage, the fatigue life was extended by removing the surface cracks under strain of 1 and 2% amplitude. The stress state at the microstructural level was changed by the surface removal, and the damaged portion did not suffer further damage. It was concluded that although bulk damage surely exists, the fatigue life can be restored to that of the untested specimen by removing the surface cracks.

39 citations

Journal ArticleDOI
TL;DR: In this article, the loading sequence effect in fatigue damage assessment for a component design was discussed, and the reason for the change in effective strain amplitude was investigated experimentally in order to consider the loading-sequence effect.

33 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the damage factors of high-cycle fatigue for Type 316 stainless steel, and a procedure for predicting the fatigue life of two-step tests was discussed.
Abstract: To predict fatigue life under variable loading accurately, it is important to understand the damage factors determining fatigue life. In this study, the damage factors of high-cycle fatigue were investigated for Type 316 stainless steel and a procedure for predicting the fatigue life of two-step tests was discussed. Fully-reversed axial fatigue tests were performed in ambient air at room temperature. In order to evaluate applicability of the linear damage accumulation rule, two-step tests were performed. The crack initiation and propagation were investigated by replica observations. It was found that the linear damage accumulation rule did not always evaluate the fatigue life conservatively due to stress dependence of crack size against normalized fatigue life. Furthermore, the fatigue limit decreased in the two-step test. In order to evaluate the role of cracking on the fatigue life, the surface layer of specimens was removed after the first step of the two-step tests. The fatigue lives of the surface-removed specimens were almost equivalent to that of undamaged specimens, although the fatigue limit was less than that of the undamaged specimens. It was revealed that the fatigue limit of surface-removed specimens decreased due to cyclic softening caused by the cyclic loading in the first step. The fatigue lives correlated with the strain amplitude rather than the stress amplitude and fatigue limit was almost the same for the surface-removed, undamaged, and undamaged specimens subjected to constant strain tests. It was concluded that the fatigue life of Type 316 stainless steel should be predicted based on the strain amplitude even for the high-cycle regime. Accuracy of the fatigue life prediction could be improved by considering the stress dependency of the crack size in addition to the cyclic softening and hardening material behavior.

19 citations

Journal ArticleDOI
TL;DR: In this article, the cumulative fatigue damage under sequential low cycle fatigue and high cycle fatigue (HCF) cycling was investigated at 923k (650k) by conducting HCF tests on specimens subjected to prior LCF cycling at various strain amplitudes.
Abstract: Cumulative fatigue damage under sequential low cycle fatigue (LCF) and high cycle fatigue (HCF) cycling was investigated at 923 K (650 °C) by conducting HCF tests on specimens subjected to prior LCF cycling at various strain amplitudes. Remnant HCF lives were found to decrease drastically with increase in prior fatigue exposure as a result of strong LCF–HCF interactions. The rate of decrease in remnant lives varied as a function of the applied strain amplitude. A threshold damage in terms of prior LCF life-fraction was found, below which no significant LCF–HCF interaction takes place. Similarly, a critical damage during the LCF pre-cycling marking the highest degree of LCF–HCF interaction was identified which was found to depend on the applied strain amplitude. In view of the non-linear damage accumulation behavior, Miner’s linear damage rule proved to be highly non-conservative. Manson’s damage curve approach, suitably modified, was found to be a better alternative for predicting the remnant HCF life. The single constant (β) employed in the model, which reflects the damage accumulation of the material under two/multi-level loading conditions is derived from the regression analysis of the experimental results and validated further.

12 citations

References
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Book
01 May 2009
TL;DR: In this article, a course focused on the experimental study of mechanical behavior of engineering materials is presented, where the theoretical background and techniques used for testing are extensively discussed in class, alongside the lab sessions.
Abstract: Through lectures and laboratory work, this course focuses on the experimental study of mechanical behavior of engineering materials. The theoretical background and techniques used for testing are extensively discussed in class, alongside the lab sessions. The lab work involves several lab projects as well as various testing demonstrations. The majority of the projects involve specimen design, analysis, instrumentation, theoretical prediction, and discussion. The class is divided into groups, with each group responsible for all aspects of a particular project. The course is concluded by a student led Annual Workshop on Construction Materials covering presentations of various group final projects.

739 citations

Journal ArticleDOI
C.E Feltner1, C Laird1
TL;DR: Hardening and softening produced by cyclic strain in annealed and cold-worked polycrystalline f.c. metals and alloys has been studied in the range of cyclic strains giving lives of less than 104 cycles to failure.

411 citations

Journal ArticleDOI
C.E Feltner1, C Laird1
TL;DR: In this article, the effects of slip character, prior history, temperature and amplitude on the cyclic strain hardening and softening curves of copper and Cu-7.5% Al have been investigated by transmission electron microscopy.

329 citations

Journal ArticleDOI
TL;DR: In this article, the authors re-examined the Double Linear Damage Rule (DLDR) approach with the intent of improving its accuracy and simplicity of application to engineering problems.

153 citations