Development of Udimet 720 for High Strength Disk Applications

Sczerzenie, Frank; Maurer, G. E.

doi:10.7449/1984/superalloys_1984_573_580

Cited by 46 publications

(24 citation statements)

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“…Rather low tensile properties obtained for the DA alloy may arise from the slow cooling rate applied to the bar after SMX forging, leading to a coarse γ' precipitation. Both YS (at a 0.2% plastic strain) and UTS are in good agreement with results found in the literature for similar heat treatment schedules [1,2,10,11]. Only room temperature 0.2% proof stress results presented by Jackson and Reed on samples extracted from a forged billet which were given the thermal treatment sequence 4h 1105 C/OQ + various dwells at 700 C/AQ exhibit YS in the range 1425-1500 MPa [11], i.e.…”

Section: Grain Sizesupporting

confidence: 78%

“…Only room temperature 0.2% proof stress results presented by Jackson and Reed on samples extracted from a forged billet which were given the thermal treatment sequence 4h 1105 C/OQ + various dwells at 700 C/AQ exhibit YS in the range 1425-1500 MPa [11], i.e. an average of 150 MPa higher than our best YS results or Sczerzenie and Maurer ones [1]. Based on the results presented in Figure 7, it is observed that increasing the solution temperature from 1080 C to 1120 C do not produce any pronounced effect on tensile properties: for the same aging treatment producing the best 0.2% yield stresses (i.e.…”

Section: Grain Sizementioning

confidence: 39%

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Influence of Both γ' Distribution and Grain Size on the Tensile Properties of UDIMET 720Li At Room Temperature

Vaunois¹,

Devaux²,

Flageolet³

et al. 2010

7th International Symposium on Superalloy 718 and Derivatives (2010)

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The tensile properties of a forged UDIMET 720Li alloy have been investigated at room temperature. The aim of this study was to increase both yield and ultimate tensile stresses using adequate thermal treatments. Classical three steps heat treatments after hot forging were applied: a solution treatment followed by a quench and a two steps aging treatment. Several combinations were investigated: four hours solution treatments, either sub-solvus (1080 C -1120 C) or super-solvus (1160 C); two different cooling rates (10 C/min or 3600 C/min); four different two-steps aging treatments: 650 C/24h/Air Quench (AQ) + 760 C/16h/AQ, 760 C/16h/AQ + 650 C/24h/AQ, 700 C/24h/AQ + 815 C/16h/AQ, 815 C/16h/AQ + 700 C/24h/AQ. The tensile properties appeared to be maximized with the following combination of heat treatments: sub-solvus solutioning (1120 C or 1080 C), fast cooling rate (oil quench, 3600 C/min), and the 760 C/16h/AQ + 650 C/24h/AQ aging. Both EBSD measurements and systematic stereological analyses were performed to characterize for each condition, grain size and γ' distribution (primary γ', secondary γ', tertiary γ'), respectively. The increase of the 0.2% yield stress, is managed by a competition between keeping a small grain size (i.e. by using a low temperature sub-solvus solution treatment) and increasing the intragranular γ' content (i.e. by increasing the solutioning temperature). In order to evaluate the relative contributions to the deformation mechanisms of grain size and of γ' particles, especially intergranular one (primary γ'), Scanning Electron Microscope (SEM) insitu tensile tests have been performed at room temperature on both sub-and super-solvus samples. It is finally demonstrated that the main controlling parameter to reach a very high yield stress is grain size.

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Section: Grain Sizesupporting

confidence: 78%

Section: Grain Sizementioning

confidence: 39%

Influence of Both γ' Distribution and Grain Size on the Tensile Properties of UDIMET 720Li At Room Temperature

Vaunois¹,

Devaux²,

Flageolet³

et al. 2010

7th International Symposium on Superalloy 718 and Derivatives (2010)

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“…This paper points out complex processes of crystalline rotation combined with plasticity activity that lead to a high level of local stresses in micro-volumes (≈ a few µm 3 ) localized at grain boundaries. Such volumes develop themselves in one side of the boundary directly in relation with slip bands activated in the neighboring grain.…”

Section: Discussionmentioning

confidence: 99%

Mechanical Behavior and Damage Processes of Udimet 720Li: Influence of Localized Plasticity at Grain Boundaries

Villechaise¹,

Cormier²,

Billot³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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The creep-fatigue properties at 700°C of cast and wrought Udimet 720Li superalloy have been investigated. As expected, the introduction of a dwell time as low as 1s at maximum stress induces a creep-fatigue life debit compared to pure fatigue conditions. It is demonstrated that the mechanical behavior (plastic strain rate, ductility) is greatly affected by the grain size and precipitation distribution. Moreover, the creep-fatigue life seems to be hardly affected by the alloy microstructure, due to the development of localized damage. Whatever the environmental conditions (i.e. in air or under vacuum), failure has been identified to be intergranular.To get a better understanding of the contribution from grain boundaries to the first stage of plasticity and damage development, in-situ tensile tests were performed in a scanning electron microscope (SEM). In a first step to get a full understanding of the role of grain boundaries in controlling the mechanical properties and alloy durability, we first paid attention to the contribution of the local grain crystallography to the plasticity heterogeneity near grain boundaries. This was performed at room temperature where, compared to creepfatigue loading at 700°C, the role of viscoplasticity can be neglected. First evidences of slip activity were shown to depend only on the local Schmid factor and not on the grain size. In addition, these experiments were performed using samples with a homogeneous grain size and a homogeneous intragranular γ' particles distribution. By using the recently developed electron backscattered diffraction (EBSD) pattern cross-correlation technique, it has been shown that critical grain configurations exist, which lead to the activation of micro-volumes (~ 1-2 µm 3 at maximum) where intense plastic activity develop near grain boundaries. These volumes nucleate at grain boundaries separating two grains having a slip activity contrast: they develop in the grain less favorably oriented for slip, ahead of slip bands which had developed in the grain with easier slip. It is observed that the very first stages of development of intense plasticity micro-volumes are quite insensitive to a contrast in Schmid factors between neighboring grains. The local von Mises stress magnitude in these volumes can be as large as several GPa, sufficient enough to develop micro-cracking.

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“…Alloy 720Li is a typical highly alloyed superalloy, which was originally designed for cast and wrought (C&W) land based gas turbine blades [3]. Alloy 720Li was also adopted for other applications such as turbine disks.…”

Section: Introductionmentioning

confidence: 99%

An Advanced Cast/Wrought Technology for GH720Li Alloy Disk from Fine Grain Ingot

Zhao¹,

Zhang²,

Liu³

et al. 2010

7th International Symposium on Superalloy 718 and Derivatives (2010)

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The cast & wrought (C&W) route is one of the earliest production techniques and still commonly used in the overall production of turbine components due to its low cost and processing benefits. However, the C&W route can not be applied to some modern disk alloys that contain high volume fraction of γ′ phase and refractory alloying elements. Therefore, the latest Ni-base disk alloys such as RR1000, Rene 95 and ME3 are produced by powder metallurgy processing routes. However, the requirement of clean powder and subsequent thermo-mechanical processing steps economically limit its applications in some cases. Recent development in fine grain ingot casting technology is demonstrated in this investigation.The experimental results indicate that it is possible to convert highly alloyed GH720Li alloy directly from fine grain ingot to billet without powder process. The experimental fine grain ingot is sound and crack-free, typically with an uniform grain size ASTM 1~3. Hot ductility of the fine grain ingot has been systematically studied by hot compression testing, optical microscopy and scanning electron microscopy. Based on these results, a hot die forged pancake was produced with an ASTM 7 fine grain structure, which demonstrates the potential of GH720Li alloy disk to meet the component technical requirement.

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Development of Udimet 720 for High Strength Disk Applications

Cited by 46 publications

References 0 publications

Influence of Both γ' Distribution and Grain Size on the Tensile Properties of UDIMET 720Li At Room Temperature

Influence of Both γ' Distribution and Grain Size on the Tensile Properties of UDIMET 720Li At Room Temperature

Mechanical Behavior and Damage Processes of Udimet 720Li: Influence of Localized Plasticity at Grain Boundaries

An Advanced Cast/Wrought Technology for GH720Li Alloy Disk from Fine Grain Ingot

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Development of Udimet 720 for High Strength Disk Applications

Cited by 46 publications

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Influence of Both &gamma;' Distribution and Grain Size on the Tensile Properties of UDIMET 720Li At Room Temperature

Influence of Both &gamma;' Distribution and Grain Size on the Tensile Properties of UDIMET 720Li At Room Temperature

Mechanical Behavior and Damage Processes of Udimet 720Li: Influence of Localized Plasticity at Grain Boundaries

An Advanced Cast/Wrought Technology for GH720Li Alloy Disk from Fine Grain Ingot

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Influence of Both γ' Distribution and Grain Size on the Tensile Properties of UDIMET 720Li At Room Temperature

Influence of Both γ' Distribution and Grain Size on the Tensile Properties of UDIMET 720Li At Room Temperature