Evaluating surface deformation and near surface strain hardening resulting from shot peening a tempered martensitic steel and application to low cycle fatigue

Soady, K.A.; Mellor, B.G.; West, Geoff; Harrison, G. F.; Morris, A.; Reed, P.A.S.

doi:10.1016/j.ijfatigue.2013.03.019

Cited by 57 publications

(52 citation statements)

References 28 publications

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“…The main monotonic tensile properties of the materials are shown in Table 1. The other mechanical properties, microstructure and composition of this material have been detailed in [21]. In this study, a U-notched specimen (stress concentration factor, = 1.58) representing the fir tree root geometry of a turbine blade has been used.…”

Section: Materials and Specimenmentioning

confidence: 99%

“…Many researchers have systematically studied the residual stress relaxation behaviour in shot-peened specimens during fatigue loading both experimentally and numerically [2,6,7,11,15,16,[21][22][23]. It was found that the residual stress distribution generally reached a stabilised state after a logarithmic relaxation process during fatigue loading.…”

Section: Introductionmentioning

confidence: 99%

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Numerical modelling of the fatigue crack shape evolution in a shot-peened steam turbine material

You

Achintha

et al. 2017

International Journal of Fatigue

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In this study, the short crack initiation and growth behaviour in a notched sample under low-cycle fatigue (LCF) was investigated in a low-pressure steam turbine material. Different crack initiation mechanisms and crack shape evolution processes were experimentally observed in samples subjected to different surface treatments: polished, T0 (industrially applied shot peening process) and T1 (a less intense shot peening process). To better understand the effects of shot peening on fatigue, a 3D finite element (FE) model was developed to investigate the interaction between crack growth and the effects induced by shot peening. Firstly, residual stress redistribution caused by both mechanical loading and the presence of a crack was numerically investigated. This model was also used to successfully predict the differences in crack shape evolution between varying surface conditions, and quantified the retardation of short crack growth behaviour resulting from shot peening. Finally, the 3D model introduced in this study was compared with a previously developed 2D model with plane strain assumptions to demonstrate the limitation of the 2D model in simulating the crack growth behaviour, and to emphasise the importance of taking the 3D crack shape into account when evaluating the short crack growth behaviour.

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Section: Materials and Specimenmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical modelling of the fatigue crack shape evolution in a shot-peened steam turbine material

You

Achintha

et al. 2017

International Journal of Fatigue

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“…However, for the T0 shot peened case, it is clear that the microhardness has increased significantly and this layer extends to around 350 μm beneath the surface. It should be noted that the extent of the strain hardened layer and the compressive residual stress distributions have also been determined for these two conditions via X-ray diffraction in previous studies [31,34] and the extent of both the strain hardened layer and the sub-surface zone of the residual compressive stress are greater in the T0 condition, and the maximum depth of the compressive residual stress zone also extends to ~350 μm beneath the surface. It seems likely therefore that microhardness evaluations are affected by both the strain hardened layer and the compressive residual stress zone.…”

Section: Discussionmentioning

confidence: 92%

“…A full description of the fatigue sample and experiment details have been provided in previous publications [31,[34][35][36] and the relevant details are reported here only briefly. The material in this study is a steam turbine blade material, FV448, a ferritic heat resistant steel with a tempered martensitic microstructure.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

“…The present study is part of a larger project detailed in [31,[34][35][36], focussed on understanding the effects of shot peening on fatigue crack initiation and propagation behaviour in steam turbine blade materials in the LCF regime. Both mechanical serial sectioning and X-ray tomography (using a lab source) were used to study in detail the 3D fatigue crack morphology under these shot peened conditions, and this paper focuses on these investigations.…”

Section: Introductionmentioning

confidence: 99%

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3-D analysis of fatigue crack behaviour in a shot peened steam turbine blade material

Katsamenis

Mellor

et al. 2015

Materials Science and Engineering: A

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Serial mechanical sectioning and high resolution X-ray tomography have been used to study the three-dimensional morphology of small fatigue cracks growing in a 12 Cr tempered martensitic steam turbine blade material. A range of surface conditions has been studied, namely polished and shot peened (with varying levels of intensity). In the polished (unpeened) condition, inclusions (alumina and manganese sulphide) played an important role in initiating and controlling early fatigue crack behaviour. When fatigue cracks initiated from an alumina stringer, the crack morphology was normally dominated by single stringers, which were always in the centre of the fatigue crack, indicating its primary role in initiation. Manganese sulphide inclusion groups however seemed to dominate and affect the crack path along both the surface and depth crack growth directions. The more intensely shot peened condition did not however evidence inclusion or stringer affected fatigue crack initiation or growth behaviour; sub-surface crack coalescence being clearly observed by both serial sectioning and CT (computed tomography) imaging techniques at a depth of about 150 ~ 180 μm. These sub-surface crack coalescences can be linked to both the extent of the compressive residual stress as well as the depth of the plastic deformation arising from the intense shot peening process. Shot peening appears to provide a different defect population that initiates fatigue cracks and competes with the underlying metallurgical defect populations. The most beneficial shot peening process would in this case appear to "deactivate" 2 the original metallurgical defect population and substitute a known defect distribution from the shot peening process from which fatigue cracks grow rather slowly in the strain hardened surface layer which also contains compressive residual stresses. A benefit to fatigue life in bending, even under Low Cycle Fatigue (LCF) conditions, has been observed in these tests if a sufficiently severe shot peening condition is applied in a constrained notch configuration.

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Fatigue strength prediction methodology of shot-peened materials

Mohamed

Guechichi

Benkabouche

2019

Int J Adv Manuf Technol

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Evaluating surface deformation and near surface strain hardening resulting from shot peening a tempered martensitic steel and application to low cycle fatigue

Cited by 57 publications

References 28 publications

Numerical modelling of the fatigue crack shape evolution in a shot-peened steam turbine material

Numerical modelling of the fatigue crack shape evolution in a shot-peened steam turbine material

3-D analysis of fatigue crack behaviour in a shot peened steam turbine blade material

Fatigue strength prediction methodology of shot-peened materials

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