Characterization of Globular Microstructure in NMS Processed Aluminum A356 Alloy: The Role of Casting Size

2011 ◽  
Vol 264-265 ◽  
pp. 1868-1877 ◽  
Author(s):  
Farshad Akhlaghi ◽  
Amir H.S. Farhood
Keyword(s):  
A356 Alloy ◽  
Systematic Investigation ◽  
Globular Structure ◽  
Near Net Shape ◽  
Size And Morphology ◽  
Semi Solid ◽  
Aluminum A356 Alloy ◽  
Processing Steps

Semi-solid processing (SSP) technology, due to its ability to provide near-net-shape components with properties far exceeding those of other casting technologies is considered as an alternative for forgings and investment castings. Conventional semi-solid forming, involving the use of heated billets, melt stirring or using cooling slopes require many processing steps and supplementary equipments. This article describes Narrow Melt Stream (NMS), as an alternative process for semi-solid processing of aluminum alloys that eliminates capital cost expenditures, reduces the number of steps required, and hence reduces the costs of making components with a globular structure. However, the applicability of this technique in producing globular structures in the large molds has not been explored. In the present study the results of a systematic investigation on the effects of mold size on the size and morphology of the globular structures formed by NMS processing of Al 356 alloy is reported. For this purpose, five different series of molds were employed. Each series consisted of three molds with identical volumes but different casting moduluses. By using these molds, the effects of casting modulus at constant casting size as well as the effect of casting volume on the size and shape factor of the globular structures in aluminum A356 samples prepared by NMS technique is reported.

Characterization of Al3Fe Particle within Al-Al3Fe Functionally Graded Material Fabricated by Semi-Solid Forming

2005 ◽  
Vol 475-479 ◽  
pp. 1503-1506 ◽  
Author(s):  
Koichi Matsuda ◽  
Yoshimi Watanabe ◽  
Kazuhisa Yamagiwa ◽  
Yasuyoshi Fukui
Keyword(s):  
Volume Fraction ◽  
Functionally Graded ◽  
Shore Hardness ◽  
Graded Materials ◽  
Before And After ◽  
Graded Material ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Semi Solid

Near net shape forming of Al-Al3Fe functionally graded materials (FGMs) have been studied. FGM billets fabricated by a centrifugal method were extruded under the condition of a mixture of molten Al eutectic and solid Al3Fe particles. Both distribution and profile of Al3Fe particles were characterized by and the variation of volume fraction of Al3Fe particles was observed. Shore hardness of the Al matrix was also measured to evaluate the strength of the FGM before and after the semi-solid forming associated with the character of distributed Al3Fe particles. It was confirmed that Shore hardness increased with increasing the volume fraction of Al3Fe particles and after the semi-solid forming than before. This was due to the fact that Al3Fe particles after the semi-solid forming became fine by shear stress introduced by liquid Al flow.

Study of Microstructural Evolution and Phase’s Morphology after Partial Remelting in A356 Alloy

2008 ◽  
Vol 141-143 ◽  
pp. 367-372 ◽  
Author(s):  
A. Mahdavi ◽  
M. Bigdeli ◽  
M. Hajian Heidary ◽  
F. Khomamizadeh
Keyword(s):  
Dendritic Structure ◽  
A356 Alloy ◽  
Intermetallic Phases ◽  
Effective Parameters ◽  
Dendritic Microstructure ◽  
Globular Structure ◽  
Needle Morphology ◽  
Sima Process ◽  
Semi Solid ◽  
Globular Form

In this work, effective parameters of SIMA process to obtain non dendritic microstructure in A356 alloy were investigated. In addition, the effect of SIMA process on the evolution of morphology of silicon and intermetallic phases in this alloy was studied. Microstructure images obtained from optical microscopy and SEM observation showed that increase in plastic work up to 40% and then holding of samples in the semi solid state at temperature of 580oC, causes that primary dendritic structure changes to non dendritic, fine and globular structure, but optimum reheating time completely depended on initial thickness of samples. If all parameters of SIMA process are the same, the grain boundaries of thinner samples begin to wet and following globalization will be completed in shorter reheating time rather than thicker ones. Moreover, it was found that the intermetallic phases lost their angular or needle morphology and gradually changed to rounded morphology and even to globular form. Also the optimum reheating time thoroughly depends on primary casting microstructure as the finer casting microstructure begin to globalize faster than thicker one under more little stains.

Microstructural Investigation of Semisolid Aluminum A356 Alloy Prepared by the Combination of Electromagnetic Stirring and Gas Induction

2019 ◽  
Vol 285 ◽  
pp. 290-295
Author(s):  
Nora Nafari ◽  
Farnoush Yekani ◽  
Hossein Aashuri
Keyword(s):  
Aspect Ratio ◽  
Shape Factor ◽  
A356 Alloy ◽  
Average Diameter ◽  
Electromagnetic Stirring ◽  
Microstructural Investigation ◽  
Porous Graphite ◽  
Three Phase ◽  
Semi Solid ◽  
Aluminum A356 Alloy

A three phase electromagnetic stirrer was used to agitate aluminum A356 slurry and a dry and oxygen free argon gas was introduced in to the slurry by a porous graphite core at a same time. The prepared semi-solid slurry was then transferred into a metallic mold and was compacted by a drop weight. Results demonstrated a favorable increase in shape factor, decrease in aspect ratio and average diameter size at different intensities of stirring. The intensity of stirring was changed by altering the current passed through the magnetic coil and also bubbling intensity via the porous graphite diffuser. Different time intervals for electromagnetic stirring and gas induction were applied. Agitating the slurry for 90 Sec. separately by electromagnetic stirrer and GISS method, gave better results in terms of shape factor, decrease in average diameter of the globules and aspect ratio.

Research on Effect of La on Microstructure in Semi-Solid A356 Alloy

2010 ◽  
Vol 139-141 ◽  
pp. 693-697 ◽  
Author(s):  
Xiao Mei Liu ◽  
Zheng Liu ◽  
Yong Mei Hu
Keyword(s):  
Binary Alloy ◽  
Master Alloy ◽  
Eutectic Reaction ◽  
A356 Alloy ◽  
Size And Morphology ◽  
Semi Solid ◽  
Low Superheat

Semi-solid A356 alloy slurry grain-refined by Al-La master alloy is prepared by low superheat pouring. The effects of La on the morphology and size of primary grain in semi-solid A356 alloy are researched. The results indicate that the semi-solid A356 alloy slurry with particle-like and rosette-like primary grains can be prepared by low superheat pouring. The size and morphology of the primary grain in semi-solid A356 alloy are markedly improved by La. The refining mechanism of La on the morphology and size of the primary grain in semi-solid A356 alloy is delved. The eutectic reaction of Al-La binary alloy provides the effective nuclei for formation of the primary grains in semi-solid A356 alloy.

Role of the estrogen/estrogen-receptor-beta axis in the genomic response to pressure overload-induced hypertrophy

2011 ◽  
Vol 43 (8) ◽  
pp. 438-446 ◽  
Author(s):  
Georgios Kararigas ◽  
Daniela Fliegner ◽  
Jan-Åke Gustafsson ◽  
Vera Regitz-Zagrosek
Keyword(s):  
Heart Failure ◽  
Estrogen Receptor ◽  
Estrogen Receptor Beta ◽  
Pressure Overload ◽  
Microarray Dataset ◽  
Systematic Investigation ◽  
Genomic Response ◽  
Receptor Beta

Cardiac hypertrophy, the adaptive response of the heart to overload, is a major risk factor for heart failure and sudden death. Estrogen (E2) and estrogen receptor beta (ERbeta) offer protection against hypertrophy and in the transition to heart failure. However, the underlying pathways remain incompletely defined. We employed a publicly available microarray dataset of female wild-type (WT) and ERbeta knockout (BERKO) mice subjected to pressure overload-induced hypertrophy to perform a systematic investigation of the mechanisms involved in the protection conferred by the E2/ERbeta axis. We show that considerably more genes were modulated in response to pressure overload in BERKO mice than in WT mice. The majority of the identified candidates in BERKO mice were induced, while those in WT mice were repressed. Pathway analysis revealed a similar pattern. This study is the first to demonstrate that the lack of ERbeta led to a significant increase of inflammatory pathways. Mitochondrial bioenergetics- and oxidative stress-related pathways were also modulated. In conclusion, ERbeta acquires the role of gatekeeper of the genomic response of the heart to pressure overload-induced hypertrophy. This may offer the molecular explanation for its cardioprotective role. We consider the present study to be a useful resource and that it will contribute to downstream functional analysis and to the characterization of pathways with previously unknown role in hypertrophy.

Mechanical and Microstructure Characterization of A356 (Al/SiC) MMC

2014 ◽  
Vol 875-877 ◽  
pp. 135-144
Author(s):  
Nagwa E. Elzayady ◽  
R.M. Rashad ◽  
A. Elenany ◽  
A. Elhabak
Keyword(s):  
A356 Alloy ◽  
Stir Casting ◽  
Unreinforced Alloy ◽  
Compression Stress ◽  
Standard Samples ◽  
Casting Technique ◽  
Rotating Speed ◽  
Sic Ceramic ◽  
Semi Solid

The present investigation aims to study the microstructure and mechanical properties of (A365/ SiC particulate) MMC produced by stir casting technique. The A356 matrix was reinforced by the addition of 3% SiC ceramic particulate having particle size ranging from 20-90 μm. The SiC particles were added to the molten in the semi-solid state during stirring at rotating speed of 700 r.p.m for duration of 1 minute. The composite was then poured in a preheated metallic mould, after which standard samples were prepared for microstructure and mechanical testing characterization. The results of the study revealed that the consolidation of the SiC and its distribution in the A356 matrix as investigated from the microstructure has increased; the tensile stress from 170 to 195 MPa, compressive yield limit from 156.5 to 190 MPa and ultimate compression stress at 35% strain increased from 350 to 460 MPa. Also macro-hardness of composite material has increased from 72.5 HV for unreinforced alloy to 80 HV, while the elongation% and impact toughness was reduced by 25% and 55% respectively. On the other hand, a dramatic increase in the toughness value for un-notched impact samples of A356 alloy when it cast in SSM (20 J) rather than that when it cast in fully liquid state (6 J).

Numerical Modeling of Die Filling of Semi-Solid A356 Aluminum Alloy

2008 ◽  
Vol 141-143 ◽  
pp. 605-610 ◽  
Author(s):  
A. Foroughi ◽  
Hossein Aashuri ◽  
A. Narimannezhad ◽  
Ali Khosravani ◽  
M. Kiani
Keyword(s):  
A356 Alloy ◽  
Solidification Process ◽  
A356 Aluminum Alloy ◽  
Finite Element Software ◽  
Die Filling ◽  
Simulation Results ◽  
A356 Aluminum ◽  
Semi Solid ◽  
Constitutive Parameters ◽  
Aluminum A356 Alloy

Computer base and simulation technique have been applied for modeling the semi-solid die filling and part of the solidification process of aluminum A356 alloy. A fairly simple one-phase rheological model has been implemented into a fluid flow finite element software Procast, to solve the partial differential equations. This model is purely viscous nature and is implemented in the power law cut-off model of Procast. The constitutive parameters of this model were determined for a rheocast A356 alloy. Using these parameters and comparing the simulation results with experimental data showed good correlation with the model prediction. The designed die for rheocasting was applied for the production of a small propeller with thin section.

Cooling Curve Analysis of A356 Alloy by Conventional Casting and the Effect of Stirring

2022 ◽  
Vol 327 ◽  
pp. 300-305
Author(s):  
Gerardo Sanjuan-Sanjuan ◽  
Ángel Enrique Chavez-Castellanos
Keyword(s):  
Eutectic Reaction ◽  
A356 Alloy ◽  
Cooling Curve ◽  
Cooling Curves ◽  
Resistance Furnace ◽  
Globular Structure ◽  
Second Derivatives ◽  
Cooling Curve Analysis ◽  
Aluminum A356 Alloy ◽  
Electrical Resistance Furnace

The present investigation attempted to explore the effect of stirring during solidification of Aluminum A356 alloy, mainly focusing on the change from dendrite to globular structure. For this purpose samples of A356 alloy were melted in the electrical resistance furnace and cooling curves were recorded for each level agitation. The experimental curves were numerically processed by calculating first and second derivatives. From these were determined temperatures and times of start nucleation of alpha solid and eutectic reaction.

Microstructure Evolution of Conventional and Semi-Solid A356 Alloy with Addition of Strontium

2015 ◽  
Vol 1087 ◽  
pp. 488-492
Author(s):  
Yuan Sieng Seo ◽  
Laila Masrur Mohd Nasir ◽  
Hussain Zuhailawati ◽  
Anasyida Abu Seman
Keyword(s):  
Phase Analysis ◽  
Eutectic Alloy ◽  
Cast Alloy ◽  
Dendritic Structure ◽  
A356 Alloy ◽  
Melting Furnace ◽  
Eutectic Structure ◽  
Globular Structure ◽  
Semi Solid ◽  
Steel Mould

In this study, modification of aluminium silicon eutectic alloy by grain modifier, strontium was investigated on conventional and slope cast A356 alloy. A356 alloy with addition of 0 to 0.97 wt.% Sr was prepared by conventional and slope casting in melting furnace. The molten metal of A356 alloy was casted into steel mould. Microstructure was observed using SEM. Phase analysis was done using XRD. Microhardness was conducted using Vicker microhardness. Microstructure of conventional cast displayed dendritic structure whereas slope cast displayed globular structure. Addition of Sr refined eutectic structure in both conventional and slope cast alloy. Phase analysis revealed the presence of Al2Sr phase in conventional cast Al-6Si-0.97Sr. Microhardness of the conventional cast alloy decreased with increasing of Sr up to 0.97 wt.%.

Semi-solid microstructure evolution during reheating of aluminum A356 alloy deformed severely by ECAP

2008 ◽  
Vol 466 (1-2) ◽  
pp. 67-72 ◽  
Author(s):  
S. Ashouri ◽  
M. Nili-Ahmadabadi ◽  
M. Moradi ◽  
M. Iranpour
Keyword(s):  
Microstructure Evolution ◽  
A356 Alloy ◽  
Semi Solid ◽  
Aluminum A356 Alloy
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