Showing 4 results for Dendrite
Mirbagheri S.m.h., Chirazi A.,
Volume 2, Issue 3 (9-2005)
Abstract
A numerical model has been developed for the determination of liquid flow permeability through columnar dendrite during growth. The model is inclusive two stages, first numerical evolution of the dendrite shape during growth, and second numerical determination of the interdendritic liquid permeability. Simulation results shown which solute concentration by evolution of dendrite shape could result to reduction of the permeability during solidification time. Comparison between the experimental data from other authors and the present numerical model data, for the low and high solid fractions, has shown a good agreement rather than current numerical models. Therefore present permeability model, in this investigation, could be used for all of the micro solidification codes by coupling on the segregation and the Fick's equations in domain of the inter-dendritic liquid for mushy alloys.
S. Kianfar,, S. H. Seyedein, M. R.aboutalebi,
Volume 5, Issue 4 (12-2008)
Abstract
Abstract: The horizontal continuous casting process has received a significant attention for near net shape casting of
non ferrous metals and alloys. Numerical Simulation has been widely used for process design and optimization of
continuous casting process.
In the present study, a 3-dimensional heat flow model was developed to simulate the heat transfer and solidification in
a horizontal billet continuous casting system in which the air gap formation and its effect on heat extraction rate from
solidifying billet was also considered. In order to test the developed model, it was run to simulate the heat transfer
and solidification for an industrial billet caster. The predicted temperature distribution within the mold and billet was
compared with those measured on the industrial caster in which a good agreement was obtained.
Finally, parametric studies were carried out by validated model to evaluate the effects of different parameters on
solidification profile and temperature distribution within the model brass billet. The microstructure of cast billet was
analyzed to determine the secondary dendrite arm spacing (SDAS) under different cooling conditions. Based on
measured SDAS and predicted solidification rate a correlation between SDAS and cooling rate was proposed for
continuously cast brass billet.
M. Shahmiri,
Volume 13, Issue 4 (12-2016)
Abstract
Over the last few decades, there have been many mechanisms proposed to describe the formation of the non-dendritic microstructures during Semisolid Metal (SSM) processing; including dendrite fragmentation, spherical growth, cellular growth and recalescence. Dendrite fragmentation is the most popular mechanism of all these hypotheses. It is the purpose of the present article to examine the morphological evolution of the non-dendritic microstructures, based on models proposed by Flemings, Vogel, Cantor, and Doherty during SSM processing of the Al-Si (A356) alloy. Based on new microstructural evidences, including (1) - plastic deformation at the side arms by slip lines formation as a result of the thermal fatigue mechanism, (2) - crack formation at the root of the side arms and (3) – the interaction of a rapidly sheared hot viscous medium with these regions, i.e. erosion; it propose and hereby discuss a new mechanism called "fatigue –erosion", for dendrites fragmentation of the experimental alloy. Optical and Scanning Electron Microscopy (SEM) with EBSD and EDS, TEM, and AFM was used for the microstructural characterizations.
Seyed Reza Elmi Hosseini, Fatemeh Azarnia, Hassan Saghafiana, Javad Behzadifara,
Volume 21, Issue 0 (3-2024)
Abstract
In this study, the feasibility of laser welding on anodized aluminum alloy has been investigated. There are many demands in the industry for the welding of anodized aluminium sheets. Firstly, the anodizing process was performed by changing the anodizing time and keeping the other anodizing parameters constant. The anodizing process was performed at three different anodizing times of 30, 45, and 60 minutes. Then, the sample with the largest oxide layer thickness, which was obtained at the higher anodizing time, was chosen for the laser welding. The welding process was performed at a laser power of 1500 watts and a welding speed of 300 mm/s on an anodized 6061-T6 aluminum alloy with an oxide layer thickness of 17 microns. The current investigation depicted that the sound joint occurred between two anodized aluminium sheets. Although the anodized layer acts as an inhibitor for the joining of aluminum sheets due to its high melting point, the results showed a homogeneous distribution of the elements within the weld zone. In the meantime, the growth of dendrites across the weldment shows the concentration of elements in the interdendritic regions of the weldment.
