Extremely-low-cycle fatigue behaviors of Cu and Cu–Al alloys: Damage mechanisms and life prediction

Liu, R.; Zhang, Z.J.; Zhang, P.; Zhang, Z.F.

doi:10.1016/j.actamat.2014.10.002

Cited by 116 publications

(40 citation statements)

References 41 publications

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“…For damage reduction, it can be roughly classified into damage decrease and damage dispersion: the former puts emphasis on the absolute quantity of damage, and the latter focuses on the distribution of damage. Fatigue damage can be diminished by eliminating the initial damage (changing the density of original defects) or improving the deformation reversibility (changing the deformation mechanisms via alloying20). Damage dispersion is realized mainly by improving the homogeneity of fatigue damage accumulation, which could also be achieved in different forms including the diminish of micro-cracks (avoiding over-severe deformation processes), and the decrease of extra-large grains (increasing the homogeneity in crystalline sizes as well as their cyclic stability).…”

Section: Discussionmentioning

confidence: 99%

“…According to previous works, two methods can effectively im’prove the fatigue properties: alloying42021 and grain refining1819. For the first method, the alloying elements can contribute more than the solution strengthening effect.…”

mentioning

confidence: 99%

“…For the first method, the alloying elements can contribute more than the solution strengthening effect. By adding the components which help decrease the stacking fault energy (SFE) of alloys (as Al for Cu-Al alloys), dislocation cross-slip can be suppressed, leading to the improvement of both the microstructure stability and the deformation reversibility41820, thus better fatigue damage resistances can be obtained. For the second method, severe plastic deformation (SPD) was conducted in order to refine the grains down to the nano-scale2223.…”

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confidence: 99%

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Exceptional high fatigue strength in Cu-15at.%Al alloy with moderate grain size

Liu

Tian

Zhang

et al. 2016

Sci Rep

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It is commonly proposed that the fatigue strength can be enhanced by increasing the tensile strength, but this conclusion needs to be reconsidered according to our study. Here a recrystallized α-Cu-15at.%Al alloy with moderate grain size of 0.62 μm was fabricated by cold rolling and annealing, and this alloy achieved exceptional high fatigue strength of 280 MPa at 107 cycles. This value is much higher than the fatigue strength of 200 MPa for the nano-crystalline counterpart (0.04 μm in grain size) despite its higher tensile strength. The remarkable improvement of fatigue strength should be mainly attributed to the microstructure optimization, which helps achieve the reduction of initial damage and the dispersion of accumulated damage. A new strategy of “damage reduction” was then proposed for fatigue strength improvement, to supplement the former strengthening principle. The methods and strategies summarized in this work offer a general pathway for further improvement of fatigue strength, in order to ensure the long-term safety of structural materials.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Exceptional high fatigue strength in Cu-15at.%Al alloy with moderate grain size

Liu

Tian

Zhang

et al. 2016

Sci Rep

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“…It is well accepted that the fatigue damage is mainly caused by the irreversibility of slipping dislocations, [27] and that improved deformation reversibility can effectively reduce the fatigue damage during cyclic loading. [28] Therefore, decreasing the density of slipping dislocations will reduce the amount of irreversible slipping dislocations, which inhibits the fatigue damage and facilitates the parameter b.…”

mentioning

confidence: 99%

“…Moreover, the impaction on the GBs by slipping dislocations may be released by TBs in this case (Figures 3(e) and (f) and 4(d)), leading to slight strain localization at the TBs, furthermore improving the deformation homogeneity and delaying the nucleation of the micro-scale fatigue cracks. [16,28] Therefore, the asreceived TWIP steels should be easily fatigue damaged due to the absence of TBs; and the fatigued as-received TWIP steels have intense GB damage and low deformation uniformity. While the deformation twins introduced by the pre-straining may benefit the deformation uniformity and delay the nucleation of fatigue cracking, both of which restrain the fatigue damage.…”

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confidence: 99%

Improving the High-Cycle Fatigue Lives of Fe-30Mn-0.9C Twinning-Induced Plasticity Steel Through Pre-straining

Wang

Zhang

Shao

et al. 2015

Metall Mater Trans A

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The tensile properties, high-cycle fatigue properties, and microstructure evolutions during fatigue process of asreceived and pre-strained Fe-30Mn-0.9C twinning-induced plasticity (TWIP) steel were investigated. It is found that the fatigue lives of the TWIP steel can be effectively improved through pre-straining, since the deformation twins induced by pre-straining could effectively lead to the improved yield strength and the homogenized deformation. This study may provide possible ways for improving the high-cycle fatigue properties of TWIP steels.In recent years, the advanced high-strength steels have been widely used in automobile industry to satisfy the weight reducing, energy saving, and security principles of new generation cars. [1] Twinning-induced plasticity (TWIP) steels have an excellent combination of high strength and good ductility, so that they are very attractive for automotive industry; therefore, much attention has been paid on the development of TWIP steels. So far, researchers mainly focus on the alloy designing, basic mechanical properties, and the corresponding microstructure evolution during deformation of TWIP steels. [2][3][4][5][6][7][8][9][10] Generally, most automobile parts are under cyclic loading condition during their service, thus, the fatigue resistance is one of the key factors for the practical utilization of TWIP steels. There are many reports about the low-cycle fatigue properties of TWIP steels, [11][12][13][14][15][16] and the pre-strain method was developed to improve their low-cycle fatigue properties. [11,16] As for the high-cycle fatigue, there have been some investigations about the bending fatigue properties of TWIP steels. [17][18][19][20] Hamada et al. [17][18][19] and Karjalainen et al. [20] showed that TWIP steels have quite high bending fatigue strength. However, there are no research findings on the high-cycle fatigue properties of the TWIP steels under axial loading, and the effects of pre-strain on the high-cycle fatigue properties are still not clear so far.In order to improve the fundamental understanding on the axial high-cycle fatigue behaviors of TWIP steels and supplement experimental data, the axial high-cycle fatigue tests of as-received and pre-strained Fe-30Mn-0.9C TWIP steel were performed and the corresponding microstructure evolutions were observed in the current study. The main goal of the current study is to explore further improvement of the high-cycle fatigue properties of TWIP steel via pre-straining.In this study, Fe-30Mn-0.9C (wt pct) TWIP steel was used. The cast ingot was austenized at 1473 K (1200°C) for 4 h, then immediately hot forged into plate with final dimension of 40 9 100 mm 2 at 1223 K to 1473 K (950°C to 1200°C), and finally cooled in air. The plate was annealed at 1323 K (1050°C) for 1 hour and water-quenched, and then dog-bone shaped tensile and fatigue specimens were cut into sectional dimensions of 15 9 3 9 3 and 10 9 5 9 4 mm 3 from the annealed plate, respectively; and the length direction of tensile and fatigue specimen...

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Low‐Cycle Fatigue Behavior and Life Prediction of Copper Busbar

et al. 2016

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Copper has many applications especially in rotor parts subjected to fatigue loading. From them, a typical copper busbar is chosen to mainly investigate the low-cycle fatigue (LCF) behaviors, fracture morphologies, dislocation patterns and crack initiation mechanism. It is found that with total strain amplitude increasing, cyclic softening appears in all the samples; the fatigue crack initiation sites transform mainly from slip bands to grain boundaries; the dislocation spacing of the post-fatigue samples decreases; by comparison, the Basquin-Manson-Coffin and the simplified hysteresis energy relations are relatively simple and accurate methods to predict fatigue life. Finally, the LCF properties of the coppers with different grain sizes prepared by different technologies are compared and optimized.

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Extremely-low-cycle fatigue behaviors of Cu and Cu–Al alloys: Damage mechanisms and life prediction

Cited by 116 publications

References 41 publications

Exceptional high fatigue strength in Cu-15at.%Al alloy with moderate grain size

Exceptional high fatigue strength in Cu-15at.%Al alloy with moderate grain size

Improving the High-Cycle Fatigue Lives of Fe-30Mn-0.9C Twinning-Induced Plasticity Steel Through Pre-straining

Low‐Cycle Fatigue Behavior and Life Prediction of Copper Busbar

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