Fretting Fatigue at Elevated Temperatures in Two Steam Turbine Steels

Mutoh, Yoshiharu; Satoh, Toyoichi; Tsunoda, Eiji

doi:10.1111/j.1460-2695.1989.tb00549.x

Cited by 15 publications

(2 citation statements)

References 24 publications

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“…The stress state at contact edge depends on many factors, such as contact pressure, relative slip, cyclic stress and rigidity of contact pad. Many research studies have been reported on fretting fatigue of turbine materials [8][9][10][11], but no detailed information about the influence of contact pad rigidity on fretting fatigue strength.…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

Effect of contact pad rigidity and fretting fatigue design curve

Mutoh

Jayaprakash

Asai

et al. 2010

Trans Indian Inst Met

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“…They believed that the similar behavior of COF at room temperature and at 260 C resulted from the fact that the glaze oxide layers did not form on the Ti-6Al-4V surface at 260 C. More results on fretting behavior at elevated temperatures can be found in other studies. [15][16][17][18] Sarhan et al 19 showed that hard anodized coating on Al 7075-T6 can significantly improve fretting fatigue life of specimens at low stress, while at high stress, the extent of fretting fatigue life decreases. The reason for the decrease is believed to be the brittleness of the coating material.…”

Section: Introductionmentioning

confidence: 99%

Fretting and plain fatigue behavior of Al 7075-T651 at elevated temperatures

Majzoobi

Soori

2013

Proceedings of the Institution of Mechanical Engineers, Part J:

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Fretting fatigue behavior of Al 7075-T651 is investigated at temperatures of 20 ℃, 150 ℃, 250 ℃ and 350 ℃ and at different stress levels. The results show that: (a) fatigue life increases from 15% to 160% for low stresses and reduces from −20% to −40% for higher stresses and (b) fretting fatigue life increases from 155% to 290% for low stress levels and reduces from −12% to −65% for high stress levels. All life changes have been measured with respect to the lives at ambient temperature. It is believed that under low stresses, the effect of glaze oxide layer created through surface oxygen absorption prevails and gives rise to improvement of plain and fretting fatigue of material at elevated temperatures. Precipitation and solid solution hardening and good lubrication of the oxide layer are the main reasons for this improvement. For the higher stresses, 180, 200 and 280 MPa, the oxide layer breaks down and the degradation due to reduction in ultimate strength dominates the fatigue behavior of material and diminishes the fatigue lives. Fractography of specimens reveals brittle fracture mode in the fracture surface regardless of the test temperature. Optical microscopy of specimens shows more germination of precipitates at lower temperatures and shorter aging durations and more growth of precipitates for higher temperatures and longer aging durations.

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Fretting Fatigue of Stainless Steel 316l at Elevated Temperatures

Hamdy

Raddad

1992

Mechanical Behaviour of Materials VI

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Fretting Fatigue at Elevated Temperatures in Two Steam Turbine Steels

Cited by 15 publications

References 24 publications

Effect of contact pad rigidity and fretting fatigue design curve

Effect of contact pad rigidity and fretting fatigue design curve

Fretting and plain fatigue behavior of Al 7075-T651 at elevated temperatures

Fretting Fatigue of Stainless Steel 316l at Elevated Temperatures

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