Effects of shot‐peening intensity on fretting fatigue crack‐initiation behaviour of Ti–6Al–4V

Sabelkin, V.; Martinez, S. A.; Mall, S.; Sathish, Shamachary; Blodgett, Mark P.

doi:10.1111/j.1460-2695.2005.00871.x

Cited by 38 publications

(36 citation statements)

References 28 publications

(73 reference statements)

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“…This can be due to plasticity in surface layers [85,98,99,109,111,118,119] or due to elevated service temperature [85,106,120]. For example, about 30% of the residual stresses generated by shot peening relaxed during a test at 260°C, resulting in a reduction in fretting fatigue life [85].…”

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confidence: 99%

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The Fretting Fatigue Behavior of Ti-6Al-4V

Neu

2008

KEM

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Abstract. This paper reviews the understanding of fretting fatigue with an emphasis on the behavior of Ti-6Al-4V. Advances in life prediction and assessment approaches are highlighted. The role of microstructure on fretting fatigue and its use to detect fretting fatigue damage can now be considered in assessment strategies. Various palliatives are used to enhance the fretting fatigue resistance. These include treatments to introduce compressive residual stress and surface coatings that reduce friction and/or protect the underlying structural material. IntroductionThis paper reviews the tremendous progress over the past decade to understand and predict the fretting fatigue behavior of Ti-6Al-4V, a common alloy used in applications requiring high specific strength. Fretting fatigue is of particular concern for dovetail attachments between the blades and disks in compressors of aerospace gas turbines, spline couplings of shafts, and mechanical joints in orthopedic implants. In the past decade there has been considerable focus on the fretting fatigue behavior of the duplex microstructure consisting of 60 vol. % equiaxed primary α (hcp structure) and 40 vol. % secondary lamellar α+β domains about 10 to 15 µm in size composed of alternating lathes of α and bcc-structured β. This was the baseline microstructure used for several projects carried out under the Air Force High Cycle Fatigue (HCF) program from 1995 to 2005 [1,2]. Unless noted otherwise, the majority of the data reported in this review was generated on this or similar microstructure. The microstructure has an initial random texture with yield strength 930 MPa, ultimate tensile strength 978 MPa, and cyclic yield strength of 797 MPa [1].The fretting fatigue process can be divided into two parts. The first is the formation of fretting cracks and the second is the growth of fretting fatigue cracks. The drivers for each of these processes are different. Both processes must occur to realize a catastrophic fretting fatigue failure. If fretting cracks do not form, fretting fatigue will not occur. But even if fretting cracks form, a catastrophic fretting fatigue failure will not occur if these cracks do not grow outside of the fretting fatigue process volume (FFPV) associated with the formation of the crack. Hence, the fretting fatigue limit is associated with the threshold limit for propagating the fretting cracks. In most fretting fatigue experiments and in applications, the drivers for fretting crack formation and crack growth outside of the FFPV cannot be easily separated, so there is an apparent coupling between the two. However, experiments involving the independent control of the drivers for fretting crack formation and crack growth (e.g., [3,4]) suggest that these two processes can be separated for the purposes of material response and prediction analyses. This is extremely helpful in understanding how different palliatives mitigate the fretting drivers. Some palliatives are aimed at fretting crack formation while others at reducing the fretting fatigue crack...

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confidence: 99%

“…The most common processes include shot peening [105][106][107][108][109][110][111][112], laser shock peening (LSP) [110,111,113], and low plasticity burnishing (LPB), also known as deep rolling [34,108,111,113,114]. Both LSP and LPB generate considerably deeper compressive residual stresses while inducing less cold work compared to shot peening.…”

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confidence: 99%

The Fretting Fatigue Behavior of Ti-6Al-4V

Neu

2008

KEM

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“…In the case of SP, the induced residual stress extended deeper into the specimen (Fig. 11) such that the effects of residual stress was retained up to a depth of about 180 lm from the contact surface which would prevent subsurface crack initiation, and it was the case in the actual tests [23]. Further, the maximum values of MSSR parameter are almost equal in both CSP and SP specimens.…”

Section: Resultsmentioning

confidence: 74%

“…For all three conditions of residual stresses (100% RS, 50% RS, and 0% RS), the maximum values of MSSR parameter were located at the contact surface. This suggests that crack would initiate at the contact surface in the shot peened specimen, which was the case in the actual tests [23]. It should be noted here that the complete residual stress relaxation state (0% RS) represents the untreated virgin specimen and it is same for CSP and SP specimens.…”

Section: Resultsmentioning

confidence: 94%

Analysis of Fretting Fatigue of Cavitation Shotless Peened Ti–6Al–4V

Lee

Mall

2010

Tribol Lett

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Fretting fatigue behavior of cavitation shotless peened titanium alloy, Ti-6Al-4V coupons was investigated using finite element method and a critical planebased multi-axial fatigue parameter. Cavitation shotless peening (CSP)-induced compressive residual stress, which was larger at the contact surface than its counterpart from the shot peening (SP). However, compressive residual stress decreased more sharply with distance from the contact surface in CSP than in SP. Analysis using a critical plane-based multi-axial fatigue parameter demonstrated that the crack initiation would occur inside the cavitation shotless peened specimen which matched with the experimental observations. On the other hand, crack initiation would occur on the contact surface in the shot peened specimen which again was in agreement with experiments. The analysis also showed that the crack propagation part of the total fretting fatigue life was longer in the shot peened specimen than in the cavitation shotless peened specimen while the crack initiation part was almost equal from both peening methods. Therefore, CSP could not improve the fretting fatigue life/strength as much as the SP did but it improved relative to the un-peened specimen.

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“…10. Many research studies [18,19] have reported that the surface damage will be more significant with increasing relative slip amplitude. It is also known that the combination of low tangential stress and high compressive stress at the contact edge will enhance FF strength and vice versa will reduce FF strength.…”

Section: Effect Of Rigidity Of Contact Pad On Ff Strengthmentioning

confidence: 98%

Effect of contact pad rigidity and fretting fatigue design curve

Mutoh

Jayaprakash

Asai

et al. 2010

Trans Indian Inst Met

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In fretting fatigue the nucleation and early propagation of fatigue crack depends on the state of stress near the contact edge. Contact pad rigidity is one of the factors that influence the stress state near the contact edge, there by influencing fretting fatigue strength. In the present study the effect of contact pad rigidity on fretting fatigue strength of turbine steels (Ni-Cr-Mo-V steel specimen with 12 Cr steel contact pads) were investigated. To study the effect of contact pad rigidity, contact pads with different pad foot height were used. FEA was performed to evaluate the stress distribution near the contact edge. The results showed that with increase in contact pad rigidity the fretting fatigue strength decreased. The results obtained were explained based on the stress distribution near the contact edge evaluated by using FEA. By combining the experimental results and FEA, fretting fatigue design curves were proposed. relationship between rigidity of contact pad and fretting fatigue strength is also clarified and then fretting fatigue design based on rigidity of contact pad can be developed. These design curves helps in real industrial applications to avoid FF failures.In the present study the effect of contact pad rigidity on fretting fatigue strength was investigated by using the contact pads with different foot height and contact length. Finite element analysis (FEA) was also performed to evaluate the stress distribution and the relative slip amplitude at the contact edge. From the results, it is confirmed that the contact pad rigidity influences the stress state at the contact edge (tangential stress and compressive stress) and then plays a dominant role in determining FF strength. Finally, by combining the experimental and FEA results fretting fatigue design curves were proposed, based on the dependence of FF life on both the tangential stress and compressive stress at the contact edge. Experimental procedure 2.1 MaterialThe material used in the present study was Ni-Cr-Mo-V steel, which was commonly used for steam turbine rotors. The contact pads were made of 12 Cr steel, which was commonly used for steam turbine blades. To study the effect of contact pad rigidity, contact pad with four different foot heights were used. The dimensions of the specimen and the contact pads are shown in Figs. 1 and 2, respectively. The chemical composition and mechanical properties of the specimen and the pad materials are shown in Table 1 and 2, respectively.

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Effects of shot‐peening intensity on fretting fatigue crack‐initiation behaviour of Ti–6Al–4V

Cited by 38 publications

References 28 publications

The Fretting Fatigue Behavior of Ti-6Al-4V

The Fretting Fatigue Behavior of Ti-6Al-4V

Analysis of Fretting Fatigue of Cavitation Shotless Peened Ti–6Al–4V

Effect of contact pad rigidity and fretting fatigue design curve

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