Papers by Keyword: GTD-111

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Authors: Bong Keun Lee, Woo Young Song, Tae Kyo Han, Chang Ho Ye, Hyong Chol Whang, Chung Yun Kang
Abstract: In the case of transient liquid phase diffusion bonding with Ni base superalloy GTD-111, the bonding temperature was sustained at 1403K ~ 1453K. Thus, the microstructure of specimens heated at 1403K ~ 1453K was examined. In the raw material, γ-γ' eutectic phases, platelet η phases, MC carbide and PFZ were clearly observed in interdendritic regions or near the grain boundary and the size of primary γ' precipitates near the interdendritic regions were larger than the core. The primary γ' precipitated in the dendrite core dissolved early in the bonding process. γ' precipitated near the interdendritic regions were partially solubilized and their shape was changed. The dissolution rate increased with increasing temperature. Phases in the interdendritic regions or near the grain boundary changed continuously with time at the bonding temperature. At a bonding temperature of 1403K, the eutectic phases remained, but η phases were transformed from a platelet shape to a needle morphology and the PFZ region widened with time. The interdendritic region and near the grain boundary became partially liquid at 1423K and fully at 1453K by the reaction of η phases and PFZ. The interdendritic region and near grain the boundary became liquid and new phases which were mixed with η phases, PFZ and MC carbide crystallized during cooling at 1453K. Crystalline η phases were transformed from a rod shape to a platelet shape with increasing holding time.
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Authors: Sanjay Kumar Sondhi, Gaurav Singh, Francesco Mastromatteo
Abstract: Safe extrapolation of short-term creep data requires development of creep models where (a) the constitutive laws are physics based, and (b) majority of model parameters are calculated rather than empirically fitted. This paper details the structure of such a physics-based creep model and its application to DS GTD-111TM superalloy. The constitutive creep law is derived from the kinetics of dislocation-particle interactions in the presence of thermal activation. This constitutive creep law is further coupled with the evolution kinetics of controlling microstructural parameters and associated damages. The model is expected to provide vital inputs for component design as well as remaining life assessment. (GTD-111TM is a trademark of the General Electric Company).
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Authors: Kwai S. Chan, N.S. Cheruvu, G.R. Leverant
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Authors: Panyawat Wangyao, Tawanrat Eiriyakul, Sureerat Polsilapa, Pajaree Srigiofun, Ornin Srihakulang
Abstract: The objective of this research work is to investigate the effect of Aluminum addition in cast nickel base superalloy grade GTD-111 by vacuum arc melting process on microstructural modification and oxidation behavior at elevated temperatures of 900°C and 1000°C. The Al element, basically, could be added in cast nickel base superalloys in proper amount to form precipitated intermetallic phase with nickel atoms as gamma prime phase (γ’, Ni3Al) to increase mechanical properties at elevated temperatures. Furthermore, Al can assist nickel base superalloy to form protective oxide film, Al2O3 for better oxidation resistance at very high temperatures. In this research, all casted samples of GTD-111 with various Al additions for 1, 2 and 3 percent by weight were solutioning treated at 1125°C for 6 hours and following with precipitatation aging at 845°C for 24 hours. The oxidation tests were carried out at temperatures of 900°C and 1000°C up to 110 hours. From all obtained results, it was found that the sample that has the most microstructural stability after long-term heating as simulated working conditions is GTD-111 sample with 2%wt. Al addition. Furthermore, more Al addition had resulted in higher oxidation resistances for both testing temperatures.
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Authors: Woo Hyuk Choi, Sung Wook Kim, Chang Hee Lee, Jung Cheol Jang
Abstract: This study was carried out to investigate the effect of heating rate on dissolution and solidification behavior during transient liquid phase diffusion bonding of Ni-based superalloy GTD-111. The heating rate was varied by 0.1K/sec, 1K/sec, 10K/sec to the bonding temperatures 1373K and 1423K in vacuum. When the heating rate was slower and the bonding temperature was higher, the completion time of dissolution after reaching bonding temperature decreased. When the heating rate was very slow, the solidification proceeded before reaching bonding temperature and the time required for the completion of isothermal solidification was shorter. However, when the total time required for completion of solidification from the beginning of heating was considered, heating at 0.1K/sec was nearly the same as heating at 10K/sec.
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Authors: Panyawat Wangyao, Luksawee Phansri, Piyalak Hirisatja, Kritsayanee Saelor, Jozef Zrník, Zbysek Novy
Abstract: This research study has an aim to evaluate and investigate the effect of various rejuvenation heat treatments on microstructure of long-term serviced cast nickel base superalloy grade GTD-111 used as turbine blade material. The evaluated reheat treatment programs consist of solution treatment at 1195°C for 2, 3, 4 and 5 hours then following with primary aging at 1120C for 2 hours and secondary aging at 845°C for 25, 50, 75 and 100 hours, respectively. All reheat treated microstructures were examined and analyzed by SEM and image analyzer. From all obtained results, it was found that the most proper solution treatment duration was 5 hours to provide the most uniform microstructural characteristics, which consist of the uniform distribution of very dense gamma prime particles in the matrix as well as its highest hardness value. Furthermore, when increasing the duration at secondary aging at 845C over than 25 hours (which is according to standard heat treatment), such microstructure provided the most gamma prime phase stability comparing to those of other reheat treatment programs.
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Authors: Sureerat Polsilapa, Panyawat Wangyao, Pichayakit Boonpou, Aimamon Promboobpa, Suvanchai Pongsugitwat
Abstract: This research objective is to study the microstructural modification by Al additions in cast nickel base superalloy, GTD-111 by means of vacuum arc melting process. The Al additions to the alloy were 1, 2 and 3% by weight. After that, all casted specimens were performed with different reheat treatment conditions, which consist of solutioning temperatures of 1125°C, 1145°C, 1165°C, 1185°C and 1205°C, respectively, for 6 hours following with precipitation aging at 845°C for 24 hours. After all reheat treatments, the microstructures were investigated and analyzed by SEM. From all obtained results, it was founded that the specimens with Al additions for 1-2%wt. following with reheat treatment show the decrease in size of γ’ precipitated particles when increasing solutioning temperatures. 3%wt. of Al addition was too high content resulting in already improper microstructural characteristics. However all obtained data of area fractions of precipitate phase were almost the same. Effect of Al addition and solutioning temperature did not provide any significant effect in this case. The mechanical property behavior: hardness was investigated by using Vickers hardness tester. It was found that the hardness all was very similar and increased with higher solutioning temperatures.
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Authors: Bong Keun Lee, Tae Kyo Han, Woo Young Song, C.H. Ye, Chung Yun Kang
Abstract: The effect of a mixed powder on the wide gap transient liquid phase diffusion bonding of a directionally solidified Ni base superalloy, GTD-111 was investigated. The mixed powder consisted of a mixture of a powdered Ni base filler (GNi-3) and powdered base metal (GTD-111). The range of the base metal powder was 40 to 70wt%. Bonding was performed at a temperature of 1463K, using various holding time. In the case of a lower 50wt%, the base metal powders completely melted and base metal mating at the interface dissolved at an early time, and extent of dissolution of base metal decreased with increasing mixing ratio. Liquid was eliminated by isothermal solidification, which was controlled by the diffusion of B into the base metal. The solids in the bonded interlayer grew epitaxially from the mating base metal inward from the insert metal and the number of grain boundaries formed at the bonded interlayer corresponded with those of the base metal. The finishing time for isothermal solidification was about 74ks. In the case 60wt% and higher, the base metal powders partially melted and remained in the vicinity of bonded interlayer. The solid was formed from the remaining powder and base metal mating at the interface. Finally, the bonded interlayer underwent the poly-crystallization when isothermal solidification was complete. The contents of Al and Ti in the bonded interlayer with a holding of 74ks were equal to that of the base metal.
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