Grain refinement effect of a pulsed magnetic field on as-cast superalloy K417

The grain refinement effect of a pulsed magnetic field on superalloy K417 was studied. The experimental results show that fine equiaxed grains are acquired with proper thermal control under the pulsed magnetic field. The refinement effect of the pulsed magnetic field is affected by the melt cooling rate and the melt superheating. The refinement effect of the pulsed magnetic field is attributed to the dissociation of nuclei from the mold wall by melt vibration and the subsequent dispersion of nuclei by melt convection. The Joule heat and the melt convection caused by the pulsed magnetic field may defer the formation of solidified shell, which prolongs the continuous refinement process. The decrease of melt cooling rate reduces the number of nuclei produced on the mold wall but prolongs the duration for the nuclei to depart from the mold wall and disperse in the melt, which enhances the refinement effect of the pulsed magnetic field. The increase of melt superheating lessens the survival probability of the nuclei in the melt, which weakens the refinement effect of the pulsed magnetic field.

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Grain Refinement and Nuclei Formation Mechanism of Ni-Based Superalloy K417 with Low Voltage Pulsed Magnetic Casting

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.428 ◽

2010 ◽

Vol 654-656 ◽

pp. 428-431

Author(s):

Yuan Sheng Yang ◽

Xiao Ping Ma ◽

Ying Ju Li

Keyword(s):

Magnetic Field ◽

Cooling Rate ◽

Grain Refinement ◽

Formation Mechanism ◽

Low Voltage ◽

Experimental Results ◽

Pulsed Magnetic Field ◽

Melt Flow ◽

Refinement Mechanism ◽

Refinement Effect

Low Voltage Pulsed Magnetic Casting (LVPMC) is developed for grain refinement castings in recent years. This paper investigates the grain refinement effect of LVPMC on superalloy K417 and deals with the effects of cooling rate and superheating on grain refinement, as well as grain refinement mechanism. The experimental results show that the grains in the alloy are equiaxed and refined to 60 m averagely. The melt flow and Joule heat during solidification are modeled and simulated to reveals the grain refinement mechanism. It is considered that the melt vibration and convection caused by the pulsed magnetic field, as well as cooling rate and superheating contribute to the refinement of solidified grains.

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The origin of nuclei and the refinement mechanism for solidified superalloy IN718 under pulsed magnetic field

Journal of Materials Research ◽

10.1557/jmr.2009.0445 ◽

2009 ◽

Vol 24 (12) ◽

pp. 3689-3692 ◽

Cited By ~ 4

Author(s):

Xiaoping Ma ◽

Yingju Li ◽

Yuansheng Yang

Keyword(s):

Magnetic Field ◽

Grain Refinement ◽

Mold Wall ◽

Mold Temperature ◽

Experimental Results ◽

Pulsed Magnetic Field ◽

Mold Surface ◽

Refinement Mechanism ◽

Equiaxed Grains ◽

Refinement Effect

The grain refinement effect of a pulsed magnetic field on superalloy IN718 was investigated. The experimental results show that fine equiaxed grains are acquired under the pulsed magnetic field. The refinement effect of the pulsed magnetic field is affected by the mold temperature. And the mixed grains are found in the solidified microstructures under the pulsed magnetic field. The origin of nuclei under the pulsed magnetic field is from the mold wall because of the rough mold surface, the undercooling, and the melt vibration, which all contribute to the refinement of solidified grains.

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Grain refinement effect of pulsed magnetic field on solidified microstructure of superalloy IN718

Journal of Materials Research ◽

10.1557/jmr.2009.0382 ◽

2009 ◽

Vol 24 (10) ◽

pp. 3174-3181 ◽

Cited By ~ 18

Author(s):

Xiaoping Ma ◽

Yingju Li ◽

Yuansheng Yang

Keyword(s):

Magnetic Field ◽

Delay Time ◽

Mold Wall ◽

Joule Heat ◽

Pulsed Magnetic Field ◽

Exciting Frequency ◽

Refinement Mechanism ◽

Grains Refinement ◽

Exciting Voltage ◽

Refinement Effect

The refinement mechanism of pulsed magnetic field (PMF) was discussed by experimental investigation, and the effects of exciting frequency, exciting voltage, and delay time of PMF on grains refinement of superalloy were studied. The experimental results show that, as exciting frequency or exciting voltage is increased, the grains are refined. However, the grains become coarse when frequency increases further. As delay time of PMF increases, the grain size increases. The refinement effect of PMF is attributed to the detachment of heterogeneous nuclei on the mold wall and subsequently separation of nuclei in the melt. The Joule heat can prolong the continuous nucleation process. However, the refinement effect will be impaired if the Joule heat is strong enough to remelt the detached nuclei.

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Grain refinement of pure aluminum by direct current pulsed magnetic field and inoculation

Transactions of Nonferrous Metals Society of China ◽

10.1016/s1003-6326(14)63191-5 ◽

2014 ◽

Vol 24 (5) ◽

pp. 1295-1300 ◽

Cited By ~ 7

Author(s):

Hang CHEN ◽

Jin-chuan JIE ◽

Ying FU ◽

Hong-jun MA ◽

Ting-ju LI

Keyword(s):

Magnetic Field ◽

Grain Refinement ◽

Direct Current ◽

Pure Aluminum ◽

Pulsed Magnetic Field

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Grain Refinement Performance of Al Cast Using Machining Chips

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.1444 ◽

2010 ◽

Vol 654-656 ◽

pp. 1444-1447 ◽

Cited By ~ 2

Author(s):

Yoshimi Watanabe ◽

Kenichi Tabushi ◽

Hisashi Sato ◽

Eri Miura-Fujiwara

Keyword(s):

Cooling Rate ◽

Grain Refinement ◽

Nucleation Site ◽

Grain Refiner ◽

Metallic Mold ◽

Refinement Effect

In this study, grain refinement performance of as-cast Al using machining chip of Al instead of the grain refiner is investigated. At first, the machining chips of pure Al are placed in metallic mold. Then, pure Al melt is inserted into the mold with the machining chips. From the microstructure of the as-cast Al using the machining chips, it is found that this machining chip in mold can induce grain refinement of as-cast Al. The increment of the Al chips enhances the grain refinement of the as-cast Al. Moreover, it is shown that preheating the mold can reduce the pore inside as-cast Al using the machining chips. This grain-refinement effect by the machining chips would come from the enhancement of cooling rate and the role of the nucleation site. Therefore, it is concluded that the machining chips of Al can enhance the grain refinement of as-cast Al.

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Effect of Low-Voltage Pulsed Magnetic Field on Solidified Structure of Superalloy K4169

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.423-426.725 ◽

2013 ◽

Vol 423-426 ◽

pp. 725-729

Author(s):

Xiao Hua Xie ◽

Quan Zhou ◽

Cheng Bo Xiao ◽

Xin Tang

Keyword(s):

Magnetic Field ◽

Grain Size ◽

Low Voltage ◽

Pulse Frequency ◽

Pulse Voltage ◽

Experimental Results ◽

Pulsed Magnetic Field ◽

Equiaxed Grains ◽

Dendritic Structures ◽

Refinement Effect

Effects of different pulse voltage and frequency on solidified structure of superalloy K4169 under low-voltage pulsed magnetic field (LVPMF) were investigated in this paper, and the related mechanism was also discussed. The experimental results show that grain of superalloy K4169 can be refined greatly by LVPMF treatment during the course of solidification. Growth of dendrite is restrained and primary grain is changed from large dendrites to smaller equiaxed grains. When the pulse voltage is at 0-280V, grain size of the alloy decreases as pulse voltage increases, and primary dendrites are fractured from well-developed dendrites into fine equiaxed grains and non-dendritic structures. When the pulse frequency is at 0-5Hz, the increase of pulse frequency enhances the refinement effect of LVPMF processing. With the increase of the pulse frequency, grain size of the alloy increases.

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