The Small Fatigue Crack Growth Behavior of an AM60 Magnesium Alloy

Chen, Zhe; Shyam, Amit; Huang, J.; Decker, R. F.; LeBeau, S. E.; Boehlert, C. J.

doi:10.1007/s11661-012-1449-1

Cited by 9 publications

(5 citation statements)

References 24 publications

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“…The results in the state of pure fatigue were almost similar to the study by Chen et al [ 12 ]. According to the data shown in Fig 5 , the fretting fatigue condition had a shorter fatigue lifetime than the pure fatigue condition.…”

Section: Resultssupporting

confidence: 88%

“…The effects of the thermomechanical process and subsequent heat-treating on the material behavior of a magnesium alloy (AM60) for the small fatigue crack growth have been examined by Chen et al [ 12 ]. They looked at how crack growth rates varied over a variety of stress intensity variables in materials with various microstructures and values of the yield stress, applied under different processing circumstances.…”

Section: Introductionmentioning

confidence: 99%

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Amazing epsilon-shaped trend for fretting fatigue characteristics in AM60 magnesium alloy under stress-controlled cyclic conditions at bending loads with zero mean stress

Rezanezhad

Azadi

2023

PLoS ONE

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In the present article, fatigue properties (pure and fretting) of magnesium alloys (AM60) under cyclic bending loading were compared. For this objective, a rotary fatigue testing device was utilized with a fretting module on standard cylindrical samples under bending loads with zero means stress. The fretting fatigue condition decreased fatigue lifetime compared with pure fatigue but in an amazing Epsilon-shaped trend. Comparatively speaking to the state of pure fatigue, the fatigue lifetime of the fretting fatigue condition reduced by 91.0% and 44.8%, respectively, between the lowest level of stress (80 MPa) and the greatest level of stress (120 MPa). To study the fracture behavior and the fractography analysis, field-emission scanning electron microscopy (FESEM) was utilized. In general, since both quasi-cleavage and cleavage were seen; therefore, the fracture behavior for all samples was brittle. In both test conditions (fretting fatigue and pure fatigue), at higher stress levels, the average crack length was higher than at low-stress levels. In addition, the number of cracks (in high- and low-stress levels) was observed to be less in fretting fatigue conditions than in pure fatigue conditions, but the average crack length in fretting fatigue conditions in high-stress levels and low-stress levels was 212.82% and 259.47% higher than the average crack length under the pure fatigue condition, respectively.

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Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Amazing epsilon-shaped trend for fretting fatigue characteristics in AM60 magnesium alloy under stress-controlled cyclic conditions at bending loads with zero mean stress

Rezanezhad

Azadi

2023

PLoS ONE

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“…This in turn suggests that the effect of the residual stresses on the growth of small, naturally occurring cracks in an AM part may also be small. This hypothesis is consistent with the findings that were reported in [84] for the growth of small cracks in annealed cast AM60 magnesium alloy specimens, where it was stated that the "Maximum stress did not appear to affect the crack propagation rate of small cracks in the stress and crack size ranges considered," and in [50], where it was shown that the growth of small cracks in a cast rail steel was essentially independent of the R ratio. Interestingly, the authors of [50] also revealed that the da/dN versus ΔK curves associated with for the growth of small cracks in LENS Ti-6Al-4V essentially coincided with that seen in this particular cast steel.…”

Section: Residual Stresses: Am Replacement Parts and Cold Spraysupporting

confidence: 91%

Review of Requirements for the Durability and Damage Tolerance Certification of Additively Manufactured Aircraft Structural Parts and AM Repairs

et al. 2020

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The USAF requirements for the durability and damage tolerance certification for additively manufactured (AM) aircraft structural parts, which are detailed in Structures Bulletin EZ-19-01, raise a number of new and, as yet, unanswered questions. The present paper attempts to address three questions: How to perform a fracture mechanics-based analysis of crack growth in an AM part so as to account for the residual stresses, how to perform a fracture mechanics-based durability analysis of a cold spray repair so as to account for both the induced residual stresses and the presence of multiple co-located cracks, and how to perform a fracture mechanics-based durability analysis of an AM part so as to account for the presence of multiple collocated surface braking cracks. In this context, the present paper reveals the potential of the Hartman–Schijve variant of the NASGRO crack growth equation to accurately predict the growth of each of the individual (collocated) cracks that arose in a cold spray-repaired specimen and in a specimen from a crack that nucleated and grew from a rough surface.

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“…A dislocation based fracture mechanics model for small fatigue crack growth that takes into account effects such as temperature, microstructure, maximum stress, heat treatment and R ‐value has been proposed. This model is predicated on the Bilby, Cottrell and Swinden theory of continuously distributed dislocations at the surface of cracks and whose validity for small surface cracks has been shown by Edwards and Zhang.…”

Section: Discussionmentioning

confidence: 99%

“…The knee in the fatigue crack growth curves for the as-received material at σ max of 300 and 400 MPa is not because of near-threshold behaviour but the crack growth increasing as it emerges from the notch-tip plastic field retardation at the higher stresses. 23 A dislocation based fracture mechanics model for small fatigue crack growth that takes into account effects such as temperature, microstructure, maximum stress, heat treatment and R-value has been proposed [9][10][11][12]24 . This model is predicated on the Bilby, Cottrell and Swinden 25 theory of continuously distributed dislocations at the surface of cracks and whose validity for small surface cracks has been shown by Edwards and Zhang 26,27 .…”

Section: Small Crack Propagation Behaviour Of Examined Tool Steelsmentioning

confidence: 99%

Effect of submillimeter size holes on the fatigue limit of a high strength tool steel

Shyam

Blau

Jordan

et al. 2013

Fatigue Fract Eng Mat Struct

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The very high cycle fatigue and small fatigue crack growth behaviour of a generic tool steel material for diesel fuel injector application are described. The small crack growth tests for the tool steel material with and without the hardening heat treatment revealed the mechanisms of crack propagation and threshold behaviour. Based on the small fatigue crack propagation threshold value, an elastic plastic fracture mechanics methodology for the prediction of the endurance limit of specimens with submillimeter holes is proposed. The advantages of the new methodology are discussed in relation to existing methodologies for endurance limit prediction of specimens with small holes.

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The Small Fatigue Crack Growth Behavior of an AM60 Magnesium Alloy

Cited by 9 publications

References 24 publications

Amazing epsilon-shaped trend for fretting fatigue characteristics in AM60 magnesium alloy under stress-controlled cyclic conditions at bending loads with zero mean stress

Amazing epsilon-shaped trend for fretting fatigue characteristics in AM60 magnesium alloy under stress-controlled cyclic conditions at bending loads with zero mean stress

Review of Requirements for the Durability and Damage Tolerance Certification of Additively Manufactured Aircraft Structural Parts and AM Repairs

Effect of submillimeter size holes on the fatigue limit of a high strength tool steel

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