Effect of shot peening on the fatigue life of a Zr-based bulk metallic glass

Raghavan, R.; Ayer, Raghavan; Jin, Hyunwoo; Marzinsky, C. N.; Ramamurty, Upadrasta

doi:10.1016/j.scriptamat.2008.03.009

Cited by 44 publications

(35 citation statements)

References 12 publications

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“…8,9 Shot peening was performed on polished surfaces of the as-cast BMG according to the AMS-S-13165 standard, using cast steel balls with 280 mm mean diameter, resulting in a deformed layer thickness of 40 mm and a residual compressive stress field of $150 mm. 10 The surfaces of the bulk specimens were polished to a mirror finish before instrumented indentation was performed on a MTS NanoXP indenter (Eden Prairie, MN) at constant loading rates up to a maximum load of 500 mN using cube corner and Berkovich diamond tips. In addition, in situ indentation experiments inside a Zeiss DSM962 scanning electron microscope (SEM; Oberkochen, Germany) were performed using a microindenter driven by a stack piezo with a built-in displacement measurement (a detailed description of the instrument can be found in Ref.…”

Section: Methodsmentioning

confidence: 99%

“…The biaxial compressive residual stress that exists in the peened layer of the SP sample, estimated to be $1.9 GPa by Zhang et al, 16 elevates the flow stress, and in turn enhances the measured hardness. 17 Raghavan et al, 10 who measured the hardness on the transverse section of the peened layer using a nanoindenter with a Berkovich tip, found the hardness values of the peened layer to be actually lower than the bulk hardness. This is because the biaxial residual stress is relaxed due to sectioning and the "actual" hardness is lower because of the deformation-induced softening.…”

Section: Hardnessmentioning

confidence: 99%

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Free-volume dependent pressure sensitivity of Zr-based bulk metallic glass

et al. 2009

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Instrumented indentation experiments on a Zr-based bulk metallic glass (BMG) in as-cast, shot-peened and structurally relaxed conditions were conducted to examine the dependence of plastic deformation on its structural state. Results show significant differences in hardness, H, with structural relaxation increasing it and shot peening markedly reducing it, and slightly changed morphology of shear bands around the indents. This is in contrast to uniaxial compressive yield strength, s y , which remains invariant with the change in the structural state of the alloys investigated. The plastic constraint factor, C = H/s y , of the relaxed BMG increases compared with that of the as-cast glass, indicating enhanced pressure sensitivity upon annealing. In contrast, C of the shot-peened layer was found to be similar to that observed in crystalline metals, indicating that severe plastic deformation could eliminate pressure sensitivity. Microscopic origins for this result, in terms of shear transformation zones and free volume, are discussed.

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Section: Methodsmentioning

confidence: 99%

Section: Hardnessmentioning

confidence: 99%

Free-volume dependent pressure sensitivity of Zr-based bulk metallic glass

et al. 2009

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“…However, subsequent studies showed that shot peening produced a soft layer (tens of micrometres), which may sacrifice the fatigue property of BMG. 6,7 Similar to but having more advantages over shot peening, laser shock peening (LSP) has been widely used to improve wear resistance and fatigue performance in metallic materials. [8][9][10] In the LSP process, a shock wave is generated and propagates into the target through the interaction of a pulsed high intensity laser beam and absorption layer on the metallic target surface.…”

Section: Introductionmentioning

confidence: 99%

Deformation feature and properties of Zr based bulk metallic glass treated by laser shock peening

Yan

Wei

2014

Materials Research Innovations

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Laser shock peening is promising surface treatment technique to improve the mechanical properties of metals material through introducing a deep compressive residual stresses region. In this work, LSP was employed to treat Zr based bulk metallic glasses (BMGs). In contrast to the work softening in BMGs, laser shock peened BMG shows significant hardening in the plastic deformed region. Furthermore, the plastic deformation region exhibits unique deformation features, which is dependent on the thickness of the samples. The deformation morphology under the impacted region was also studied. The mechanism for the hardening and formation of unique deformation features is discussed.

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“…3 However, unlike crystalline alloys, (steels are a classic example) where there is a synergistic interaction between residual stresses and work hardening of the surface layers, strain softening in BMGs counteracts the potential benefit of compressive residual stresses. 4,5 Therefore, no net enhancement in fatigue life could be obtained through this method.…”

Section: Introductionmentioning

confidence: 99%

“…4,5 Therefore, no net enhancement in fatigue life could be obtained through this method. 3 The second and more obvious option to improve fatigue life is to introduce a "microstructure" to the BMG. This can be done in a number of different ways.…”

Section: Introductionmentioning

confidence: 99%

Near-threshold fatigue crack growth in bulk metallic glass composites

et al. 2009

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A major drawback in using bulk metallic glasses (BMGs) as structural materials is their extremely poor fatigue performance. One way to alleviate this problem is through the composite route, in which second phases are introduced into the glass to arrest crack growth. In this paper, the fatigue crack growth behavior of in situ reinforced BMGs with crystalline dendrites, which are tailored to impart significant ductility and toughness to the BMG, was investigated. Three composites, all with equal volume fraction of dendrite phases, were examined to assess the influence of chemical composition on the near-threshold fatigue crack growth characteristics. While the ductility is enhanced at the cost of yield strength vis-à-vis that of the fully amorphous BMG, the threshold stress intensity factor range for fatigue crack initiation in composites was found to be enhanced by more than 100%. Crack blunting and trapping by the dendritic phases and constraining of the shear bands within the interdendritic regions are the micromechanisms responsible for this enhanced fatigue crack growth resistance.

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Effect of shot peening on the fatigue life of a Zr-based bulk metallic glass

Cited by 44 publications

References 12 publications

Free-volume dependent pressure sensitivity of Zr-based bulk metallic glass

Free-volume dependent pressure sensitivity of Zr-based bulk metallic glass

Deformation feature and properties of Zr based bulk metallic glass treated by laser shock peening

Near-threshold fatigue crack growth in bulk metallic glass composites

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