Time- and cycle-dependent crack propagation in Haynes 282

Saarimäki, Jonas; Moverare, Johan; Colliander, Magnus Hörnqvist

doi:10.1016/j.msea.2016.01.111

Cited by 14 publications

(4 citation statements)

References 32 publications

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“…This effect of crack propagation through an oxide is generally explained as SAGBO. SAGBO is the most likely reason behind the observed dwell‐time effect seen in Figure a, which have also been observed and reported . The cast material did not exhibit any significant dwell‐time effect.…”

Section: Discussionsupporting

confidence: 81%

Grain Size Depending Dwell‐Fatigue Crack Growth in Inconel 718

2018

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Inconel 718 is a commonly used superalloy for turbine discs in the gas turbine industry. Turbine discs are normally subjected to dwell-fatigue as a result of long constant load cycles. Dwell-times have been shown to give rise to increased crack propagation rates in superalloys at elevated temperatures. Dwell-time crack propagation behavior in Inconel 718 has been tested at 550 C using Kb test samples with 2160 s dwell-times at maximum load and "pure fatigue" tests. The dwell-time effect has been studied for differently processed Inconel 718, that is, fine grained bar, grain enlarged bar, and cast material. This has been done in order to investigate the effect of grain size on crack propagation. Microstructure characterization is conducted using scanning electron microscopy techniques such as electron channeling contrast imaging and electron backscatter diffraction. Time dependent crack propagation rates are strongly affected by grain size. Propagation rates increase with decreasing grain size, whereas crack tip blunting increased with increasing grain size.

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Section: Discussionsupporting

confidence: 81%

Grain Size Depending Dwell‐Fatigue Crack Growth in Inconel 718

2018

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“…Data was evaluated using evaluation code for compact tension samples [24] and more details regarding the test setup are covered in reference [25]. A crack is not allowed to deviate by more that 10°from its point of initiation at the machined notch for a test to be considered valid the according to ASTM E647-08.…”

Section: Methodsmentioning

confidence: 99%

Anisotropy effects during dwell-fatigue caused by δ-phase orientation in forged Inconel 718

Saarimäki

Colliander

Moverare

2017

Materials Science and Engineering: A

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A B S T R A C TInconel 718 is a commonly used superalloy for turbine discs in the gas turbine industry. Turbine discs are often subjected to dwell-fatigue as a result of long constant load cycles. The effect of anisotropy on dwell-fatigue cracking in forged turbine discs have not yet been thoroughly investigated. Crack propagation behaviour was characterised using compact tension (CT) samples cut in different orientations from a real turbine disc forging. Samples were also cut in two different thicknesses in order to investigate the influence of plane strain and plane stress condition on the crack propagation rates. The samples were subjected to dwell-fatigue tests at 550°C with 90 s or 2160 s dwell-times at maximum load. Microstructure characterisation was done using scanning electron microscopy (SEM) techniques such as electron channelling contrast imaging (ECCI), electron backscatter diffraction (EBSD), and light optical microscopy (LOM). The forged alloy exhibits strong anisotropic behaviour caused by the non-random δ-phase orientation. When δ-phases were oriented perpendicular compared to parallel to the loading direction, the crack growth rates were approximately ten times faster. Crack growth occurred preferably in the interface between the γ-matrix and the δ-phase.

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“…It is widely reported that the addition of a dwell period at maximum load at high temperature can significantly increase the crack growth rate per fatigue cycle in Ni-base superalloys [40][41][42][43][44][45][46][47][48][49][50][51][52]. Among these literature, Gustafsson et al [51,[53][54][55] has reported systematic results on the crack propagation behaviours with different dwell periods at different temperatures of a forged IN718.…”

Section: Accelerated Crack Propagationmentioning

confidence: 99%

On the Microstructures and Anisotropic Mechanical Behaviours of Additively Manufactured IN718

Deng

2019

Linköping Studies in Science and Technology. Dissertations

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Additive manufacturing (AM), also known as 3D printing, offers great design flexibility for manufacturing components with complex geometries, and has attracted significant interest in the aero and energy industries in the past decades. Among the commercial AM processes, selective laser melting (SLM) and electron beam melting (EBM) are the two most widely used ones for metallic materials. Inconel 718 (IN718) is a nickel-base superalloy and has impressive combination of good mechanical properties, weldability and low cost. Due to its excellent weldability, IN718 has been intensively applied in the AM filed, to gain more understanding of the AM processes and fully realize AM's potentials. The study objects in the present thesis include both EBM and SLM IN718. The solidification conditions in EBM and SLM are very different and are different to that of conventional cast, leading to unique microstructures mechanical properties. Therefore, this thesis aims to gain better understanding of the microstructures and anisotropic mechanical behaviours of both EBM and SLM IN718, by detailed characterizations and by comparisons with the forged counterpart. The as-built microstructure of EBM IN718 is spatially dependent: the periphery (contour) region has a mixture of equiaxed and columnar grains, while the bulk (hatch) region has columnar grains elongated along the building direction; the last solidified region close to the top sample surface shows segregation and Laves phases, otherwise the rest of the whole sample is well homogenized. Differently, the as-built microstructure of SLM IN718 is spatially homogeneous: the grains is rather equiaxed and with subgrain cell structures. These microstructures also respond differently to the standard heat treatment routines for the conventional counterparts. Anisotropic mechanical properties are evident in the room temperature tensile tests and high temperature dwell-fatigue tests. The anisotropic tensile properties of EBM IN718 at room temperature are more likely due to the directional alignment of porosities along the building direction rather than the strong crys-In these papers I have been the main contributor, performing all the experimental work, characterization, analysis and manuscript writing, under the supervision of Johan Moverare and Ru Lin Peng.

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Time- and cycle-dependent crack propagation in Haynes 282

Cited by 14 publications

References 32 publications

Grain Size Depending Dwell‐Fatigue Crack Growth in Inconel 718

Grain Size Depending Dwell‐Fatigue Crack Growth in Inconel 718

Anisotropy effects during dwell-fatigue caused by δ-phase orientation in forged Inconel 718

On the Microstructures and Anisotropic Mechanical Behaviours of Additively Manufactured IN718

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