Microstructural evolution of directionally solidified DZ125 superalloy castings with different solidification methods

The properties of Ni-base superalloy castings are closely related to the uniformity of their as-cast microstructure, and different solidification methods have serious effect on microstructural uniformity. In this paper, the influences of high rate solidification (HRS) process (with or without superh...

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Main Authors: Ge Bingming, Liu Lin, Zhang Jun
Format: Article
Language:English
Published: Foundry Journal Agency 2013-01-01
Series:China Foundry
Subjects:
Online Access:http://www.foundryworld.com/uploadfile/2013020651999261.pdf
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author Ge Bingming
Liu Lin
Zhang Jun
author_facet Ge Bingming
Liu Lin
Zhang Jun
author_sort Ge Bingming
collection DOAJ
description The properties of Ni-base superalloy castings are closely related to the uniformity of their as-cast microstructure, and different solidification methods have serious effect on microstructural uniformity. In this paper, the influences of high rate solidification (HRS) process (with or without superheating) and liquid metal cooling (LMC) process on the microstructure of DZ125 superalloy were investigated. Blade-shape castings were solidified at rates of 40 μm·s-1 to 110 μm·s-1 using HRS process and a comparative experiment was carried out at a rate of 70 μm·s-1 by LMC process. The optical microscope (OM), scanning electron microscope (SEM) were used to observe the microstructure and the grain size was analyzed using electron back scattered diffraction (EBSD) technique. Results show that for the castings by either HRS or LMC process, the primary dendrite arm spacing and size of γ' precipitates decrease with increasing the withdrawal rate; the dendrites and γ' precipitates at the upper section of the blade are coarser than those in the middle, especially for the HRS castings without high superheating technique. When the withdrawal rate is 70 μm·s-1, the castings by HRS with high superheating technique have the smallest PDAS with fine γ' precipitates; while the size distribution of γ' precipitates is more homogenous in LMC castings, and the number of larger grains in LMC castings is smaller than that in the HRS castings. Moreover, high superheating technique yields smaller grains in the castings. Both the LMC method and HRS with high superheating technique can be used to prepare castings with reduced maximum grain size.
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spelling doaj.art-31c584d3d62f4735ba7b649f152815732022-12-21T17:48:39ZengFoundry Journal AgencyChina Foundry1672-64212013-01-011012428Microstructural evolution of directionally solidified DZ125 superalloy castings with different solidification methodsGe BingmingLiu LinZhang JunThe properties of Ni-base superalloy castings are closely related to the uniformity of their as-cast microstructure, and different solidification methods have serious effect on microstructural uniformity. In this paper, the influences of high rate solidification (HRS) process (with or without superheating) and liquid metal cooling (LMC) process on the microstructure of DZ125 superalloy were investigated. Blade-shape castings were solidified at rates of 40 μm·s-1 to 110 μm·s-1 using HRS process and a comparative experiment was carried out at a rate of 70 μm·s-1 by LMC process. The optical microscope (OM), scanning electron microscope (SEM) were used to observe the microstructure and the grain size was analyzed using electron back scattered diffraction (EBSD) technique. Results show that for the castings by either HRS or LMC process, the primary dendrite arm spacing and size of γ' precipitates decrease with increasing the withdrawal rate; the dendrites and γ' precipitates at the upper section of the blade are coarser than those in the middle, especially for the HRS castings without high superheating technique. When the withdrawal rate is 70 μm·s-1, the castings by HRS with high superheating technique have the smallest PDAS with fine γ' precipitates; while the size distribution of γ' precipitates is more homogenous in LMC castings, and the number of larger grains in LMC castings is smaller than that in the HRS castings. Moreover, high superheating technique yields smaller grains in the castings. Both the LMC method and HRS with high superheating technique can be used to prepare castings with reduced maximum grain size.http://www.foundryworld.com/uploadfile/2013020651999261.pdfdirectional solidificationmicrostructural evolutionhigh rate solidificationliquid metal coolingNi-base superalloy
spellingShingle Ge Bingming
Liu Lin
Zhang Jun
Microstructural evolution of directionally solidified DZ125 superalloy castings with different solidification methods
China Foundry
directional solidification
microstructural evolution
high rate solidification
liquid metal cooling
Ni-base superalloy
title Microstructural evolution of directionally solidified DZ125 superalloy castings with different solidification methods
title_full Microstructural evolution of directionally solidified DZ125 superalloy castings with different solidification methods
title_fullStr Microstructural evolution of directionally solidified DZ125 superalloy castings with different solidification methods
title_full_unstemmed Microstructural evolution of directionally solidified DZ125 superalloy castings with different solidification methods
title_short Microstructural evolution of directionally solidified DZ125 superalloy castings with different solidification methods
title_sort microstructural evolution of directionally solidified dz125 superalloy castings with different solidification methods
topic directional solidification
microstructural evolution
high rate solidification
liquid metal cooling
Ni-base superalloy
url http://www.foundryworld.com/uploadfile/2013020651999261.pdf
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AT liulin microstructuralevolutionofdirectionallysolidifieddz125superalloycastingswithdifferentsolidificationmethods
AT zhangjun microstructuralevolutionofdirectionallysolidifieddz125superalloycastingswithdifferentsolidificationmethods