The Effect of Solidification Conditions upon the Primary Dendrite Arm Spacing

AbstractIn the present work, a coupled three-dimensional numerical model of fluid flow, heat transfer, and inclusion motion during the solidification of molten steel in slab continuous casting mold has been developed. Based on the model, this paper has studied the inclusion capture during the process. The influence of the primary dendrite arm spacing on inclusion capture has been considered. The inclusion distributions, total masses, and average diameters at different depth from the slab surface have been given out in the present paper. The simulation results revealed the inclusion concentration existed in the solidification process, and the inclusion capturing area varies with the depth from the slab surface.

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Relationship between Growth Rates and Dendritic Microstructure Parameters in Al-5wt. Zn Binary Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.765.215 ◽

2013 ◽

Vol 765 ◽

pp. 215-219 ◽

Cited By ~ 1

Author(s):

Emine Acer ◽

Harun Erol ◽

Mehmet Gündüz

Keyword(s):

Growth Rates ◽

Numerical Models ◽

Primary Dendrite ◽

Linear Regression Analysis ◽

Experimental Results ◽

Directionally Solidified ◽

Dendritic Microstructure ◽

Dendrite Arm Spacing ◽

Primary Dendrite Arm Spacing ◽

Microstructure Parameters

Al-5 wt.% Zn samples were prepared using high purity (99.99%) metals in graphite crucibles. The samples were directionally solidified upward with a constant temperature gradient (G= 5.5 Kmm-1) and different growth rates,V, (8.25-165 μm/s) in a Bridgman type directional solidification apparatus. The dendritic spacings (λ1: Primary dendrite arm spacing, and λ2: Secondary dendrite arm spacing) were measured from the longitudinal sections of the samples and λ1was also measured from the transverse sections. The measured spacings were expressed as functions of the growth rates by using a linear regression analysis. The effect ofVon λ1and λ2were investigated. The experimental results were compared with the results of the current theoretical and numerical models and similar previous experimental results.

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Microstructural Investigations of Nickel-Based Superalloys with Different Structure

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.592-593.557 ◽

2013 ◽

Vol 592-593 ◽

pp. 557-560

Author(s):

Maciej Pytel ◽

Andrzej Nowotnik ◽

Dariusz Szeliga ◽

Jan Sieniawski

Keyword(s):

Chemical Composition ◽

Single Crystal ◽

Primary Dendrite ◽

Nickel Superalloy ◽

Vacuum Furnace ◽

Polycrystalline Nickel ◽

X Ray ◽

Dendrite Arm Spacing ◽

Before And After ◽

Primary Dendrite Arm Spacing

This paper presents the results of analysis of superalloys microstructures with different structures: polycrystalline nickel-based superalloy René 80, Mar-M 200Hf directionally solidified with columnar grains and single crystal CMSX-4. Microstructure studies were performed using a scanning electron microscope Hitachi FE-SEM SU-70 and S-3400N equipped with a Thermo Scientific Noran System for analysis of chemical composition by X-ray dispersion. Metallographic microsections of the rods before and after heat treatment was performed, which were electrolytically etched using different reagents. The morphology of γ phase precipitates in the interdendritic areas and dendritic cores was analyzed. Single crystal rods of nickel superalloy CMSX-4 were cast by Bridgman technique in a vacuum furnace of ALD Vacuum Technologies. Rods were withdrawn with rate: 1mm/min and 5mm/min. EDS X-ray microanalysis showed significant differences in chemical composition between the cores dendrites and eutectic regions. Significant differences in the number of dendrites, the shape and length of the arms were observed. A lower speed rate causes that amount of eutectic is lower but value of primary dendrite arm spacing is higher, while a higher withdraw rate increases the amount of eutectic and decreases primary dendrite arm spacing.

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