Crack appearance of a laser shock-treated single crystal nickel-base superalloy after isothermal fatigue failure

Lu, Guoxin; Liu, J.D.; Qiao, Hongchao; Jin, Tao; Sun, Xiaofeng

doi:10.1016/j.surfcoat.2017.04.044

Cited by 13 publications

(4 citation statements)

References 17 publications

(17 reference statements)

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“…The WLSP treated specimens show far fewer river marks within the crack propagation zone in comparison to the untreated material which could indicate a difference in fracture mode. In contrast, Lu et al [66] found no change in fracture mechanism under isothermal fatigue conditions following LP though as they reported that cracks formed from micropores rather than at the surface (Figure 8c,d). However, they do suppose that once a crack reaches the LP-affected zone, the compressive residual stresses inhibit its movement and thus prolong fatigue life.…”

Section: Mechanical Property Evolutionmentioning

confidence: 79%

A Review of Laser Peening Methods for Single Crystal Ni-Based Superalloys

Holtham

Davami

2022

Metals

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Single crystal Ni-based superalloys are often used to create gas turbine engine blades for their high strength under intense thermo-mechanical loading. Though they are remarkably capable under these conditions, a particular class of premature failure mechanisms known as surface-initiated damage mechanisms can lead to the early fracture of an otherwise healthy blade. This review paper discusses the current progress of post-processing techniques that can greatly mitigate the potency of surface-initiated damage mechanisms. In particular, laser peening (LP) is of significant interest due to the relatively low amount of cold work it induces, greater depth of compressive residual stresses than other cold working methods, ability to accommodate complex part geometries, and the minuscule effect it has on surface roughness. The residual stresses imparted by LP can greatly hinder crack growth and consequently allow for enhanced fatigue life. Given that turbine blades (constructed with single crystal Ni-based superalloys) are prone to fail by these mechanisms, LP could be a worthy choice for increasing their service lives. For this reason, initiative has been taken to better understand the mechanical and microstructural modifications imparted by LP on single crystal Ni-based superalloys and a summary of these investigations are presented in this review. Results from several works show that this class of alloy responds well to LP treatment with improvements such as ~30–50% increase in microhardness, 72% increase in low cycle fatigue life, and elevated resistance to hot corrosion. The primary objective of this review is to provide insight into current state-of-the-art LP techniques and summarize the findings of numerous works which have utilized LP for increasing the service lives of single crystal Ni-based superalloy components.

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Section: Mechanical Property Evolutionmentioning

confidence: 79%

A Review of Laser Peening Methods for Single Crystal Ni-Based Superalloys

Holtham

Davami

2022

Metals

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“…LSP is a non-contact processing method that has excellent surface strengthening effects on Ni-based superalloy materials [41,42]. Compared with traditional surface mechanical processing technology, LSP has better processing adaptability to complex structures.…”

Section: Lsp Requirements For Turbine Tenon Joint Materialsmentioning

confidence: 99%

Improving the fretting performance of aero-engine tenon joint materials using surface strengthening

Liu

Lin

et al. 2019

Materials Science and Technology

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This paper summarises the regulation mechanism of the traditional and emerging surface strengthening treatments – mechanical shot peening (SP) and laser shock processing (LSP) treatment, respectively – on the fretting fatigue behaviour of the tenon joint materials of aero-engine cold-end parts, as surface strengthening treatment contributes to the improvement of service performance. From the point of view of the actual service environment of turbine components, this paper also expounds on the key problems faced by surface strengthening treatments in improving the mechanical properties of joint materials for aero-engine hot-end components. The application of LSP in the fretting fatigue life extension of turbine joint materials has strong feasibility and development prospects.

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“…However, when exposed to higher temperatures (> 400 C) these treated superalloys undergo to stress relaxation potentially compromising fatigue resistance. A limited number of studies have investigated the effects of LP on SC Ni-based superalloys in fatigue and hot corrosive environments [5][6][7][8]. The interaction of hot corrosion and fatigue is caused by elevated temperatures, mechanical loading, combustion gases and airborne contaminants [9,10].…”

Section: Introductionmentioning

confidence: 99%

Effects of high energy laser peening followed by pre-hot corrosion on stress relaxation, microhardness and fatigue life and strength of single crystal nickel CMSX-4® superalloy

Morar

Holtham

Hackel

et al. 2023

Preprint

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This study investigated the stress relaxation and fatigue life and strength of laser peened single crystal nickel superalloy specimens compared to un-peened and shot peened specimens following hot corrosion exposure and then fatigue testing. The specimens were treated by conventional laser peening and a new cyclic laser peening plus thermal microstructure engineering process. The latter treatment supports the benefit of a unique process involving application of layers of laser peening using high energy with large footprint spots combined with interspersed cyclic annealing. Stress measurements by slitting showed the plastic penetration depth of laser peening exceeded shot peening by a factor of 24. Un-peened and peened specimens were exposed to sulphate corrosives at 700°C for 300 hours and then fatigue tested. Tests of five non-laser peened specimens all failed in low cycle fatigue regime whereas three identically tested laser peened specimens all achieved multi-million-cycle runout without failure, indicating fully consistent large benefit for life by laser peening. Additional tests also showed fatigue strength improvement of 2:1 by laser peening. Residual stress measurements post hot-corrosion exposure and fatigue testing showed notable 5 mm depth retention of residual eigenstress in a laser peened specimen.

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Crack appearance of a laser shock-treated single crystal nickel-base superalloy after isothermal fatigue failure

Cited by 13 publications

References 17 publications

A Review of Laser Peening Methods for Single Crystal Ni-Based Superalloys

A Review of Laser Peening Methods for Single Crystal Ni-Based Superalloys

Improving the fretting performance of aero-engine tenon joint materials using surface strengthening

Effects of high energy laser peening followed by pre-hot corrosion on stress relaxation, microhardness and fatigue life and strength of single crystal nickel CMSX-4® superalloy

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