Microstructural Analysis after Reheat Treatments and Long- Term Heating in Cast Nickel Base Superalloy, GTD-111

Wangyao, Panyawat; Suvanchai, P.; Chuankrerkkul, Nutthita; Krongtong, V; Thueploy, Adisak; Homkrajai, W.

doi:10.1515/htmp.2010.29.4.277

Cited by 17 publications

(19 citation statements)

References 6 publications

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“…Typical HIP treatments performed on superalloys are running for short holding times of 3 or 5 h, at temperatures between 1100 and 1300 • C and pressure values up to 200 MPa [5,[7][8][9]. As explained before, the selection of the HIP temperature has a paramount importance on porosity reduction and on microstructure because at temperatures higher than the γ solvus the material will be HIPed only in presence of the soft gamma phase.…”

Section: Expected Consequences Of Applying Hip After Each Conventionamentioning

confidence: 99%

“…Therefore, it is an important issue not only to reduce the casting segregation by a subsequent heat treatment, which typically includes a solution annealing and an ageing treatment, but also to reduce the microporosity generated during casting, by means of a HIP treatment [5,[7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…The application of HIP on superalloys reduces the size and amount of porosity [5,[7][8][9][10] via a combination of plastic deformation, creep and diffusion bonding [7,8,11], a Corresponding author: lopez@wtech.rub.de at the same time that the alloy composition is homogenized to some extent due to the high used temperatures [4,5,7,9] and the γ /γ microstructure is modified mainly due to the used high temperatures and low cooling rates.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the cooling rate during heat treatment and hot isostatic pressing on the microstructure of a SX Ni-superalloy

Lopez‐Galilea

Huth

Theisen

2014

MATEC Web of Conferences

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Abstract. Single crystal Ni-based gas turbine blades show a combination of large casting pores and pores from the homogenization heat treatment. Both kinds of pores can only be reduced by HIP; however, HIP not only reduces porosity but also affects the size, number and morphology of γ particles. From the HIP parameters, pressure, temperature, holding time and cooling speed, the main effect on both, the porosity and the γ /γ microstructure is due to temperature and cooling rate. HIP temperatures above the γ solvus temperature allow the fastest and most effective reduction of the porosity, because only the soft γ phase is present. The recent and novel possibility of cooling the samples from the maximum HIP temperature with a fast cooling of about 200 K/min, results in a fine and homogeneous distribution of γ particles, which requires no additional solution annealing treatment to dissolve the developed γ particles during the extremely short cooling time. Therefore, the application of HIP at super γ solvus temperature followed by fast cooling on homogenized samples seems to have the most promising results: no porosity and fine γ /γ microstructure.

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Section: Expected Consequences Of Applying Hip After Each Conventionamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of the cooling rate during heat treatment and hot isostatic pressing on the microstructure of a SX Ni-superalloy

Lopez‐Galilea

Huth

Theisen

2014

MATEC Web of Conferences

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“…This condition could induce microstructural degradation of turbine blade, resulting in lower mechanical properties and service life time. Because mechanical properties of turbine blade are strongly related to the microstructures, many previous research works [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] have been carried out to investigate the relationship between microstructure and mechanical properties. The microstructural degradation mainly involves coarsening or rafting of γ ′ precipitated particles, resulting in lower volume or area fraction of γ ′ particle as well as lower effect of strengthening mechanism for the material.…”

Section: Introductionmentioning

confidence: 99%

Effect of Reheat Treatment on Microstructural Refurbishment and Hardness of the As-cast Inconel 738

Wongbunyakul¹,

Visuttipitukkul²,

Wangyao³

et al. 2014

High Temperature Materials and Processes

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This work investigates the effect of rejuvenation heat treatment conditions for refurbishment of the longterm serviced gas turbine blades, which were made of as-cast nickel base superalloy grade, Inconel 738. The reheat treatment conditions consist of solutionizing treatments at temperatures of 1,438, 1,458 and 1,478 K for 14.4 ks and aging treatments at temperatures of 1,133, 1,148 and 1,163 K for 43.2, 86.4, 129.6 and 172.8 ks. The results show that increase in aging times results in continuous increase of size and area fraction of gamma prime (γ′) particles. The higher solutionizing temperature leads to the lower area fraction and smaller size of gamma prime particles. Regarding the microstructure characteristics, the most proper reheat treatment condition should be solutionizing at temperature of 1,438 K for 14.4 ks and aging at temperature of 1,133 K for 172.8 ks, which provides the highest area fraction of gamma prime particles in proper size.

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“…Therefore, it is an important issue to reduce the microporosity generated during casting. In order to solve this task and to obtain superior mechanical behaviours, the application of HIP on the material reduces the size and amount of porosity [3] via a combination of plastic deformation, creep and diffusion bonding [4][5][6]. Simultaneously, the alloy composition is homogenized to some extent since the HIP partially dissolves γ´ [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Effect of HIP Parameters on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

Lopez‐Galilea

Huth

Bartsch

et al. 2011

AMR

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Abstract. For reducing the porosity of single crystal (SX) nickel-based superalloys, Hot Isostatic Pressing (HIP) is used. High pressures of about 100-170 MPa lead to local deformation, which close the pores. However, since HIP also requires high temperatures (1000-1200°C) it has a pronounced effect on the microstructure and the local distribution of elements. This contribution analyses the effect of different HIP treatments on both the microstructure and the segregation of the SX superalloy LEK94 in the as-precipitation-hardened state. In addition, the effects of rapid or slow cooling are analyzed. To distinguish the effect of pressure from those of temperature, the HIPed samples are compared with specimens annealed at atmospheric pressure. IntroductionSecond-generation of SX nickel-based superalloys exhibit a combination of excellent strength, good creep properties and fatigue resistance at high temperatures. These materials are currently used as blades in gas turbine and aircraft engines. They owe their properties to the large amount (~70 vol.% [1]) of finely dispersed precipitates of the ordered (L1 2 ) γ´ phase, which show a very high solvus temperature (~1200°C). One of the main drawbacks of Ni-based superalloys is the lack of strength and ductility due to the formation of microporosity during casting, which also results in the scatter of the mechanical properties of cast components [2]. Furthermore, the shrinkage cavities can act as crack initiation sites and promote crack propagation, leading to premature rupture of the components. Therefore, it is an important issue to reduce the microporosity generated during casting. In order to solve this task and to obtain superior mechanical behaviours, the application of HIP on the material reduces the size and amount of porosity [3] via a combination of plastic deformation, creep and diffusion bonding [4][5][6]. Simultaneously, the alloy composition is homogenized to some extent since the HIP partially dissolves γ´ [7][8][9]. There have been attempts to apply HIP both directly after casting and after precipitation hardening. In the present work, the HIP technology was applied to the SX Ni-based superalloy LEK94 to investigate the evolution of the microstructure -mainly the homogenization of the alloy composition and the morphology of the γ´ precipitates in the dendrite core -after HIP by using scanning electron microscopy. One aim of the study is to determine the relationship between the HIP parameters, mainly pressure and temperature, with the observed microstructure.

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Microstructural Analysis after Reheat Treatments and Long- Term Heating in Cast Nickel Base Superalloy, GTD-111

Cited by 17 publications

References 6 publications

Effect of the cooling rate during heat treatment and hot isostatic pressing on the microstructure of a SX Ni-superalloy

Effect of the cooling rate during heat treatment and hot isostatic pressing on the microstructure of a SX Ni-superalloy

Effect of Reheat Treatment on Microstructural Refurbishment and Hardness of the As-cast Inconel 738

Effect of HIP Parameters on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

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