Thermo-mechanical fatigue of single crystal nickel-based superalloy DD8

Liu, F.; Wang, Z.G.; Ai, S. H.; Wang, Y.C.; Sun, Xiaofeng; Jin, Tao; Guan, H.R.

doi:10.1016/s1359-6462(03)00051-4

Cited by 31 publications

(8 citation statements)

References 13 publications

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“…The fracture mirror at the individual pores displays a square shape, which results from preferred in plane crack propagation in h110i directions and has been described for creep and fatigue fracture. [28,29] The fracture surfaces of all specimens revealed areas of mode I fracture initiated by porosity and fracture along crystallographic {111} planes. The ratio between mode I fracture and fracture along slip planes was about 0.5 in both heat-treated specimens and about 0.25 in the as-built SEBM specimen.…”

Section: Low Cycle Fatigue Strengthmentioning

confidence: 99%

Microstructure and Mechanical Properties of CMSX-4 Single Crystals Prepared by Additive Manufacturing

Körner

Ramsperger

Meid

et al. 2018

Metall Mater Trans A

128

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Currently, additive manufacturing (AM) experiences significant attention in nearly all industrial sectors. AM is already well established in fields such as medicine or spare part production. Nevertheless, processing of high-performance nickel-based superalloys and especially single crystalline alloys such as CMSX-4 Ò is challenging due to the difficulty of intense crack formation. Selective electron beam melting (SEBM) takes place at high process temperatures (~1000°C) and under vacuum conditions. Current work has demonstrated processing of CMSX-4 Ò without crack formation. In addition, by using appropriate AM scan strategies, even single crystals (SX SEBM CMSX-4 Ò ) develop directly from the powder bed. In this contribution, we investigate the mechanical properties of SX SEBM CMSX-4 Ò prepared by SEBM in the as-built condition and after heat treatment. The focus is on hardness, strength, low cycle fatigue, and creep properties. These properties are compared with conventional cast and heat-treated material.

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Section: Low Cycle Fatigue Strengthmentioning

confidence: 99%

Microstructure and Mechanical Properties of CMSX-4 Single Crystals Prepared by Additive Manufacturing

Körner

Ramsperger

Meid

et al. 2018

Metall Mater Trans A

128

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“…This was explained by that the maximum tensile stress is obtained in the cold end of the OP TMF cycle. Other research has found that the difference between IP and OP TMF life seems to be strain range dependent [4]. In that study IP TMF life was found to be shorter than OP at high strain ranges.…”

Section: Introductionmentioning

confidence: 62%

In- and out-of-phase thermomechanical fatigue of a Ni-based single-crystal superalloy

Segersäll

Moverare

Leidermark

et al. 2014

MATEC Web of Conferences

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Abstract. In this study, the difference between in-phase (IP) and out-of-phase (OP) thermomechanical fatigue (TMF) cycling from 100 to 750• C has been investigated for the Ni-based single-crystal superalloy MD2. In addition, two different crystal orientations were studied, the 001 and 011 orientations respectively. When comparing IP and OP TMF lives, a strain range dependency is found for the 001 direction. For high strain ranges, IP cycling leads to a higher number of cycles to failure compared to OP. However at lower strain ranges, OP cycling leads to a higher number of cycles to failure compared to IP. Microstructure investigation shows that for the 001 direction, deformation twinning within the γ /γ -microstructure is much more pronounced during OP conditions compared to IP. However for the 011 direction, the opposite is observed; twinning is more pronounced during IP TMF. From the microstructure investigation it is also visible that intersections between twins seems to trigger formation of TCP phases and recrystallization. These intersections also work as initiation points for TMF damage.

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“…Since compressive mean stresses hinder crack nucleation while tensile mean stresses promotes crack nucleation, IP cycling leads to better fatigue lives compared to OP TMF cycling. According to Liu et al [96], a comparison of IP and OP TMF reveals that there is a strain range dependency. At higher strain ranges, IP TMF life was shorter than OP TMF life.…”

Section: Thermomechanical Fatigue: a Literature Reviewmentioning

confidence: 99%

On Thermomechanical Fatigue of Single-Crystal Superalloys

Segersäll¹

2014

Linköping Studies in Science and Technology. Dissertations

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Thesis cover: Design by Maria J. SegersällPrinted by: LiU-Tryck, Linköping, Sweden, 2014 ISBN 978-91-7519-211-6 ISSN 0345-7524 Distributed by: Division of Engineering Materials, Department of Management and Engineering Linköping University SE-58183, Linköping, Sweden © 2014 Mikael SegersällThis document was prepared with L A T E X, October 17, 2014 AbstractThanks to their excellent mechanical and chemical properties at temperatures up to 1000°C, nickel-based superalloys are used in critical components in high-temperature applications such as gas turbines and aero engines. One of the most critical components in a gas turbine is the turbine blade, and to improve the creep and fatigue properties of this component, it is sometimes cast in single-crystal form rather than in the more conventional polycrystalline form. Gas turbines are most commonly used for power generation and the turbine efficiency is highly dependent on the performance of the superalloys.Today, many gas turbines are used as a complement for renewable energy sources, for example when the wind is not blowing or when the sun is not shining, which means that the turbine runs differently compared to earlier, when it ran for longer time periods with a lower number of start-ups and shutdowns. This new way of running the turbine, with an increased number of start-ups and shut-downs, results in new conditions for critical components, and one way to simulate these conditions is to perform thermomechanical fatigue (TMF) testing in the laboratory. During TMF, both mechanical strain and temperature are cycled at the same time, and one fatigue cycle corresponds to the conditions experienced by the turbine blade during one start-up and shut-down of the turbine engine.In the work leading to this PhD thesis, TMF testing of single-crystal superalloys was first performed in the laboratory and this was then followed microstructure investigations to study the occurring deformation and damage mechanisms. Specimens with different crystallographic directions have been tested in order to investigate the anisotropic behaviour shown by these materials. Results show a significant orientation dependence during TMF in which specimens with a low elastic stiffness perform better. However, it is also shown that specimens with a higher number of active slip systems perform better during TMF compared to specimens with less active slip sysiii tems. This is because a higher number of active slip systems results in a more widespread deformation and seems to be beneficial for the TMF life. Further, microscopy shows that the deformation during TMF is localised to several deformation bands and that different deformation and damage mechanisms prevail according to in which crystal orientation the material is loaded. Deformation twinning is shown to be a major deformation mechanism during TMF and the interception of twins seems to trigger recrystallization. This is certainly negative for the mechanical properties of single-crystal superalloys since no grain boundary strengthening elemen...

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Thermo-mechanical fatigue of single crystal nickel-based superalloy DD8

Cited by 31 publications

References 13 publications

Microstructure and Mechanical Properties of CMSX-4 Single Crystals Prepared by Additive Manufacturing

Microstructure and Mechanical Properties of CMSX-4 Single Crystals Prepared by Additive Manufacturing

In- and out-of-phase thermomechanical fatigue of a Ni-based single-crystal superalloy

On Thermomechanical Fatigue of Single-Crystal Superalloys

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