Experimental Investigation and Modelling of the Angular Velocity as a Function of the Radius in Molten Ga75In25 Alloy and Mercury Stirred by Rotation Magnetic Field | Chapter 3 | Current Research Progress in Physical Science Vol. 9

The simulation of the solidification of alloys (like the steels or aluminium alloys) which calculates the melt flow induced by RMF, needs a correct angular velocity vs radius function of the melt. Because it is impossible to obtain information about the melt flow from industrial casting directly, this information can only be obtained from well-monitored experiments using low melting point metals or alloys (e.g., Hg, Ga, GaIn). In this work, the measuring methods suitable for determining this function and analysed for their advantages and disadvantages were first summarised. The angular velocity as a function of the radius was measured by two different methods.

The first one is the Pressure Compensation Method (PCM). In this case, closed TEFLON crucibles with 60 mm length and 12.5 mm radius and Ga75wt%In25wt% alloy were used. The angular velocity (ω) was calculated from the compensation pressure measured at r = 5, 7.5, 10, and 12.5 mm in the 0 – 90 mT range of magnetic induction.

In the case of the second one, a series of data from the literature was processed. The experiments were carried out with the Turbine Wheel Method (TWM), Hg flowing in a glass tube with a diameter of 60 mm, which can be considered practically infinitely long. The value of ω was determined as a function of the radius by an anemometer immersed in Hg. The maximum value of B was 25 mT. A Two-poles inductor with 50 Hz was used in both cases.

After processing the data, it was found that (i) the angular velocity varies significantly along the radius, growing from the wall to the centre of the crucible, contrary to the assumption often used in simulations that it is constant and (ii) at the wall of the crucible, the angular velocity is not zero, contrary to the generally accepted fact that it is definitely zero.

A physical model and two types of mathematical descriptions were developed based on the two ω (B, r) datasets. The two types of ω (B, r) functions could be suitable for the validation of the simulation of melt flow during the solidification of alloys produced by RMF.

 

Author (s) Details

Andras Roosz
Institute of Physical Metallurgy, Metalforming and Nanotechnology, University of Miskolc, 3515 Miskolc, Hungary and HUN-REN-ME Materials Science Research Group, 3515 Miskolc, Hungary.

 

Arnold Ronafoldi
Institute of Physical Metallurgy, Metalforming and Nanotechnology, University of Miskolc, 3515 Miskolc, Hungary and HUN-REN-ME Materials Science Research Group, 3515 Miskolc, Hungary.

 

Maria Sveda
Institute of Physical Metallurgy, Metalforming and Nanotechnology, University of Miskolc, 3515 Miskolc, Hungary and HUN-REN-ME Materials Science Research Group, 3515 Miskolc, Hungary.

 

Zsolt Veres
Institute of Physical Metallurgy, Metalforming and Nanotechnology, University of Miskolc, 3515 Miskolc, Hungary and HUN-REN-ME Materials Science Research Group, 3515 Miskolc, Hungary.

 

Please see the book here:- https://doi.org/10.9734/bpi/crpps/v9/4705

Numerical Investigation of Axial Magnetic Field Effects on Melt Flow and Macrosegregation in TC17 Alloy Vacuum Arc Remelting | Chapter 4 | | Proceedings of the 8th International Conference on Solidification and Gravity

The TC17 alloy ingot is produced through vacuum arc remelting (VAR). However, the self-induced electromagnetic force enhances forced convection, which can lead to potential macrosegregation, particularly as the ingot diameter increases. To address this issue, an engineering solution involves applying an axial magnetic field (AMF) to modify the flow in the molten pool. In this study, the solidification process of the VAR ingots was simulated using a built-in solidification model in ANSYS Fluent. The solver is based on the finite volume method. A 2D-axisymmetric simulation considering the swirl flow was performed, incorporating the multi-physics coupling of heat transfer, solute transfer, melt flow, and electromagnetic effects. The reasonable agreement between the simulation and experiment regarding the molten pool contour and segregation profile demonstrates the robustness and applicability of the model. On this base, a numerical parameter study was performed to study the effect of the AMF, with particular emphasis on the alternative AMF direction change and the resulting melt flow. The results show that the applied AMF generates an electromagnetic force in the tangential direction, creating a rotational swirl flow and a centrifugal force directed radially outward. Consequently, a secondary flow along the side walls towards the bottom centre within the molten pool is induced. This modified flow pattern in the molten pool helps reduce macrosegregation in VAR ingots, hence improving the service life and mechanical properties of aviation titanium alloys. Qualitative simulation-experiment agreement regarding the shape of the molten pool profile and segregation distribution is achieved. However, future model improvement, e.g. considering the solidification crystal morphology, multiphase flow, and potential formation of freckles, is necessary.

 

Author (s) Details

 

Chenbo Xu
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China and Department of Metallurgy, Montanuniversität Leoben, Franz-Josef Street 18, 8700 Leoben, Austria.

 

Jie Guo
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China.

 

Jincheng Wan
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China.

 

Junjie Li
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China.

 

Liqing Huang
Hunan Goldsky Titanium Industry Technology Co., Ltd., Changde 415001, China.

 

Kai Fan
Hunan Goldsky Titanium Industry Technology Co., Ltd., Changde 415001, China.

Haijie Zhang
Department of Metallurgy, Montanuniversität Leoben, Franz-Josef Street 18, 8700 Leoben, Austria.

 

Menghuai Wu
Department of Metallurgy, Montanuniversität Leoben, Franz-Josef Street 18, 8700 Leoben, Austria.

 

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-93-49473-95-9/CH4