Effect of Primary α-Al Morphology in Slurry on Segregation during 357 Semi-Solid Die Casting

2019 ◽  
Vol 285 ◽  
pp. 398-402 ◽  
Author(s):  
Hong Zhang ◽  
Da Quan Li ◽  
Wen Ying Qu ◽  
Fan Zhang ◽  
Min Luo ◽  
...  
Keyword(s):  
High Temperature ◽  
Liquid Metal ◽  
Solid Fraction ◽  
Die Casting ◽  
Dendritic Structure ◽  
Solid Particles ◽  
Pouring Temperature ◽  
Seed Processing ◽  
Semi Solid ◽  
Solid Temperature

Controlling the morphology of the microstructure of the slurry is important during semi-solid die casting. For this project, semi-solid slugs were produced using the SEED (Swirled Enthalpy Equilibrium Device) process, where a fully liquid metal is poured into a steel crucible and cooled into the semi-solid temperature range, and the crucible and slurry are then swirled and cooled to the appropriate temperature (and solid fraction) for semi-solid casting. The pouring temperature of the melt into the crucible during SEED processing has been shown to influence the morphology and size of the aluminum solid particles within the slurry, which can influence the distribution and segregation of the solid particles during die casting. In this study, a specially-designed die with a serpentine-shaped flow channel has been used to study the distribution of the solid particles during semi-solid die casting. The experimental results show that a dendritic structure is formed when the liquid is poured from a high temperature, while a globular semi-solid morphology is more easily formed when poured from a low superheat. The current results also show that a dendritic structure leads to severe segregation during die casting.

Short-Term Oxidation Behavior, Microstructure Evolution and Compression Behavior of Nickel-Based Superalloy GH4037 in Solid and Semi-Solid States

2022 ◽  
Vol 327 ◽  
pp. 11-25
Author(s):  
Guan Fei Xiao ◽  
Ju Fu Jiang ◽  
Ying Wang ◽  
Ying Zhe Liu ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Deformation Mechanism ◽  
Deformation Zone ◽  
Solid Particles ◽  
Isothermal Treatment ◽  
Short Term ◽  
Solid States ◽  
Nickel Based Superalloy ◽  
Semi Solid ◽  
Solid Temperature

Semi-solid processing combines the advantages of traditional forging and casting methods, so it has received much attention recently. However, the research on semi-solid behaviors of Nickel-based superalloys has been rarely reported. In order to investigate the behaviors of Nickel-based superalloy at solid and semi-solid states, oxidation experiments, isothermal treatment experiments and deformation experiments of GH4037 alloy were studied. Short-term oxidation experiments of GH4037 alloy were carried out at a solid temperature (1200 °C) and a semi-solid temperature (1360 °C). The results indicated that the oxides formed at 1200 °C were mainly composed of TiO2, Cr2O3 and a small amount of spinels NiCr2O4, while the oxides formed at 1360 °C consisted of the spinels of NiCr2O4, NiWO4 and NiMoO4 besides TiO2 and Cr2O3. Microstructure evolution of GH4037 alloy after semi-solid isothermal treatment at 1370 °C and 1380 °C was studied. The results indicated that semi-solid microstructures consisted of equiaxed solid grains and liquid phases. The average grains size and shape factor of solid grains were affected by melting mechanism and grain growth mechanism. Compression behaviors of GH4037 alloy after compressed at 1200 °C and 1360 °C were investigated. The results indicated that the flow stress of 1360 °C decreased significantly compared to that of 1200 °C. The deformation zones in the specimens were divided into three parts: the difficult deformation zone, the large deformation zone, and the free deformation zone. At 1200 °C, the deformation mechanism was plastic deformation mechanism. At 1360 °C, sliding between solid particles (SS), liquid flow (LF), flow of liquid incorporating solid particles (FLS), plastic deformation of solid particles (PDS) coexisted in the compression specimen.

Die Design for Main Bearing Cap of Engine Block Based Semi-Solid Die Casting Process and the Comparison Analysis with Squeeze Casting Process

2019 ◽  
Vol 285 ◽  
pp. 429-435 ◽  
Author(s):  
Song Chen ◽  
Da Quan Li ◽  
Fan Zhang ◽  
Min Luo ◽  
Xiao Kang Liang ◽  
...  
Keyword(s):  
Squeeze Casting ◽  
Die Casting ◽  
Dendritic Structure ◽  
Casting Process ◽  
Die Design ◽  
Main Bearing ◽  
Block Based ◽  
Semi Solid ◽  
Bearing Cap ◽  
Squeeze Casting Process

There are two new processes to development automobile structural components which have certain thickness. In the present paper, taking a main bearing cap product as an example, analyses die design by comparing the experimental and computational numerical simulation results. For the main bearing cap, product structure and mold design were designed to be suitable for characters of SSM die casting and squeeze process. Semi-solid slurry has significantly higher viscosity than liquid metal. This character of fluidity and solid fraction phase make the flow condition more laminar than liquid squeeze casting with the partial fill experiment. And compared with squeeze casting process, the globular shape grain size is smaller than dendritic structure. And mechanical property result shows that the elongation of SSM die casting can achieve more than twice than squeeze casting.

Numerical Simulation on the Filling Process of Rheological Die Casting and Forming Defects Analysis

2012 ◽  
Vol 192-193 ◽  
pp. 293-298 ◽  
Author(s):  
Fan Zhang ◽  
Nan Nan Song ◽  
Jun Zhang ◽  
Yong Lin Kang ◽  
Qiang Zhu
Keyword(s):  
Numerical Simulation ◽  
Die Casting ◽  
A356 Alloy ◽  
Casting Process ◽  
Solid Particles ◽  
Filling Process ◽  
Die Casting Process ◽  
Defects Analysis ◽  
Semi Solid ◽  
Forming Defects

According to semi-solid slurry rheological behavior, an apparent viscosity model of A356 alloy developed based on the Carreau model was established to simulate filling process of rheo-diecasting about automobile shock absorber parts and to compare with conventional liquid filling process. Numerical simulation results showed that the filling process of rheo-diecasting was smooth but difficult to splash, which reduced the tendency of the alloy oxidation and inclusion. Meanwhile, a certain percentage of the primary solid particles precipitated before filling and solidification shrinkage of semi-solid slurry were small. This benefited to reduce or eliminate shrinkage defects of the castings. Compared with conventional liquid die casting process, rheo-diecasting process had unique advantages in reducing the internal defects and improving mechanical properties of castings.

Effect of Solid Fraction on Microstructure and Casting Faults of AZ91D Alloys in New Type Semi-Solid Injection Process

2006 ◽  
Vol 116-117 ◽  
pp. 441-444 ◽  
Author(s):  
Kenji Miwa ◽  
Rudi S. Rachmat ◽  
Takuya Tamura
Keyword(s):  
Solid Fraction ◽  
Testing Machine ◽  
Solid Particles ◽  
Casting Defects ◽  
Permanent Mold ◽  
Forming Process ◽  
Injection Process ◽  
Controlling System ◽  
New Type ◽  
Semi Solid

We have developed new type semi-solid injection process, that is, runner-less injection process. In order to investigate the effects of solid fraction on microstructure and casting defects of AZ91D in new type semi solid injection process, semi-solid forming testing machine which has the same system as a runner-less injection machine has been made on an experimental basis. Its temperature controlling system has been established to obtain the homogeneous solid-liquid coexisted state in its injection cylinder. AZ91D billets are injected into a permanent mold by this machine in the semi-solid state. A shearing in the part of nozzle of injection cylinder is the most important to reveal thixotropic property of alloy slurry in semi solid forming process by injection machine. So it needs controlling of solid fraction to affect thixotropic property. In order to decrease casting defects and hold homogeneous structure, solid fraction more over 50% is needed. But when the solid fraction increases more than 50%, primary solid particles grow coarser, and then controlling method is required to suppress coarsening. In the case of less than 50% of solid fraction, liquid part preferentially fills inside the permanent mold and alloy slurry continue to fill the mold behind alloy liquid. Then large casting defects form at the boundary of both flows.

Formation of Globular Microstructure in A380 Aluminum Alloy by Cooling Slope Casting

2011 ◽  
Vol 264-265 ◽  
pp. 272-277 ◽  
Author(s):  
Nurşen Saklakoğlu ◽  
S. Gencalp ◽  
Şefika Kasman ◽  
İ.E. Saklakoğlu
Keyword(s):  
Aluminum Alloy ◽  
Slope Angle ◽  
Casting Process ◽  
Solid Particles ◽  
Inclined Plate ◽  
Pouring Temperature ◽  
Cooling Slope ◽  
Semi Solid ◽  
Cooling Slope Casting ◽  
The Many

Thixoforming and related semi-solid processing (SSP) methods require thixotropic materials. One of the many SSP techniques is the cooling slope (CS) casting process, which is simple and has minimal equipment requirements, and which is able to produce feedstock materials for semisolid processing. When the feedstock is reheated to the semisolid temperature range, non-dendritic, spheroidal solid particles in a liquid matrix suitable for thixoforming are obtained. In this study, equipment for the CS technique was first established, and then the effects of the pouring temperature and inclined slope angle on the microstructures of A380 aluminum alloy (ISOAlSi8Cu3Fe) were studied. Optimum parameters for thixoforming experiments were selected, and it was found that the microstructure produced by the inclined plate depended on its angle and the pouring temperature.

Making Non-Dendritic Structure via Modified Cooling Slope Technique

2014 ◽  
Vol 915-916 ◽  
pp. 602-607 ◽  
Author(s):  
Y.T. Chen ◽  
Chi Y.A. Tsao ◽  
C.H. Chiang
Keyword(s):  
Cooling Rate ◽  
Solid Fraction ◽  
Process Parameters ◽  
Water Flow Rate ◽  
Slope Angle ◽  
Dendritic Structure ◽  
Pouring Temperature ◽  
Cooling Slope ◽  
Inclined Slope ◽  
Dendritic Microstructures

The cooling slope technique has been developed in recent years, which controls the nucleation and growth of the primary grains during solidification to achieve fine and non-dendritic microstructures. In this study, A356 Al alloys were processed through a modified cooling slope technique to obtain fine, non-dendritic microstructures, in which the cooling rate of the cast crucible was controlled. Three process parameters, namely pouring temperature, inclined slope angle, and the cooling rate of the cast crucible, were varied during the processing. The cooling slope was water-cooled with a constant water flow rate. The solid fraction and the size distributions of the primary grains along the vertical and horizontal positions of the cast ingots were measured individually. The macro-segregation was examined in terms of the distribution of the solid fraction. The yields of the ingots were calculated for studying the efficiency of the cooling slope technique. The effects of the three process parameters on the microstructures, macro-segregation, and yields were studied by the Taguchi method.

Addition of Swarf to Produce a Semi-Solid Slurry during High Pressure Die-Casting of AS9U3 Aluminum Alloy

2019 ◽  
Vol 285 ◽  
pp. 271-276
Author(s):  
Hooman Hadian ◽  
M. Haddad-Sabzevar ◽  
Mohammad Mazinani
Keyword(s):  
High Pressure ◽  
Aluminum Alloy ◽  
Solid Fraction ◽  
Die Casting ◽  
Internal Cooling ◽  
High Solid ◽  
Cooling Agent ◽  
High Solid Fraction ◽  
Semi Solid ◽  
Pressure Die Casting

An internal cooling agent is used in rapid slurry forming (RSF) process to produce a high solid fraction slurry for a short period of time. In the process used in this research, the swarf which is known to be a low enthalpy material was added to the melt as the internal cooling agent. During the process, the swarf started to melt and a semi-solid slurry with a relatively high solid fraction was formed. This slurry was formed by exchanging the enthalpies between the low and high enthalpy materials. A commercial Al-Si-Cu alloy, i.e. AS9U3 Aluminum alloy, was used in this investigation. The microscopic examination showed that the Al-Si eutectic colonies start to melt during the melting process of swarf material resulting in the formation of globular Alpha-Al grains due to the multiplication of secondary dendrites arms. The fracture of dendrites arms and the subsequent spheroidization were suggested to be the origin of non-dendritic globular grains in the final microstructure. The amount of primary globular Alpha-phase was measured by the image analysis software. The results showed that during high pressure die-casting of AS9U3 Aluminum alloy using 4 mm thick samples, around 35 percent solid has been formed at the temperature of 580 oC.

Effects of Solid Fractions in a Slurry Die Casting Process on Defects of 7075 Aluminum Alloy

2015 ◽  
Vol 752-753 ◽  
pp. 7-10 ◽  
Author(s):  
Waraporn Jumpol ◽  
Jessada Wannasin ◽  
Somjai Janudom ◽  
Rungsinee Canyook ◽  
Thawatchai Plookphol ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Solid Fraction ◽  
Die Casting ◽  
Casting Process ◽  
7075 Aluminum Alloy ◽  
Die Casting Process ◽  
Semi Solid

The effects of Gas Induced Semi-Solid (GISS) in the slurry die casting process on defects of 7075 aluminum alloy were studied, different initial solid fractions with 10, 15, and 20 sec of rheocasting time were investigated. The results showed that the percentage of porosity in semi-solid die casting was smaller than in the liquid die casting. In terms of the initial solid fraction in 7075 aluminum alloy, it was found that the defects were found when the initial solid fraction was high. In addition.

Research on the Self-Thickening Effects in the Process of Fabricating Aluminum Foam Using Semi-Solid Melt by Mechanical Stirring

2011 ◽  
Vol 675-677 ◽  
pp. 633-637
Author(s):  
Nan Li ◽  
Shu Ming Xing ◽  
Pei Wei Bao ◽  
Zhi Min Liu
Keyword(s):  
Solid Fraction ◽  
Aluminum Foam ◽  
Metal Foam ◽  
High Viscosity ◽  
Solid Particles ◽  
The Self ◽  
Mechanical Stirring ◽  
Blowing Agents ◽  
Stirring Time ◽  
Semi Solid

This paper investigated the self-thickening effects on fabricating close cell aluminum foam directly using semi-solid melt by mechanical stirring without adding other particles. Using the high viscosity character of semi-solid melt as well as mechanical stirring technique, blowing agents (TiH2) could be homogeneously distributed without other thickening additions such as CaO or TiC which were commonly used to thicken aluminum melt in metal foam industry. It was observed that the semi-solid melt could reach a proper condition for the blowing agents to separate and foam after self-thickening process and the solid fraction played a key role in self-thicken effects compared to the stirring time and speed. The self-thickening effects could meet the purity requirement of melt as well as to fabricate aluminum foam with small pores and good structure using precursors. Aluminum foam was a multi-functional material with features of ultra-light, high-toughness, impact resistance, high specific strength, high specific stiffness, heat isolation and fire retardant [1]. The viscosity of melt was extremely important in the process of fabricating aluminum foam. Jin.I and Kenny.LD did some research on the effects of adding solid particles to thicken the melt and their study showed that the best thickening effect could be obtained when the particle size of 5-20 mm and the proportion of 10~20% of liquid aluminum [2]. Miyoshi.T also did some research on the stirring time in the thickening process and showed that adding Ca particles of 1.5~3%(wt) could effectively controlled the viscosity [2]. Research by J.Banhart showed shat 1-5 %(wt) Al2O3 and SiC adding particles could also thicken the semi-solid melt very effectively[3] [4]. Berry.CB and Hall.CG’s research showed that blowing air, oxygen or other gases could also reach thickening effect [2]. There were several methods to thicken the melt but the same ultimate goal was to obtain a suitable melt environment for distribution and foaming of blowing agents. This paper mainly investigated the effects of the self-thickening semi-solid melt on the distribution behavior of blowing agents. Taking the advantage of the high viscosity of semi-solid melt as well as mechanical stirring technique, without adding other thickening particles, blowing agents (TiH2) could be homogeneously distributed in the semi-solid melt. The parameters such as solid fraction, stirring time and speed were investigated in this paper.

Development of the Gas Induced Semi-Solid Metal Process for Aluminum Die Casting Applications

2008 ◽  
Vol 141-143 ◽  
pp. 97-102 ◽  
Author(s):  
J. Wannasin ◽  
S. Junudom ◽  
T. Rattanochaikul ◽  
M.C. Flemings
Keyword(s):  
Solid Fraction ◽  
Die Casting ◽  
Casting Machine ◽  
Gas Bubbles ◽  
Solid Metal ◽  
Heat Extraction ◽  
Shot Sleeve ◽  
Semi Solid

A simple and efficient rheocasting process that has recently been invented is being developed for aluminum die casting applications. The process called Gas Induced Semi-Solid (GISS) utilizes the combination of local rapid heat extraction and agitation achieved by the injection of fine gas bubbles through a graphite diffuser to create semi-solid slurry. In the GISS process, the die casting machine and the process cycle remain little changed from those of conventional die casting. The GISS unit creates a low solid fraction of semi-solid slurry in the ladle during the ladle transfer to the shot sleeve. The semi-solid slurry is then poured directly into the shot sleeve. This paper presents the detailed description of the process. The results of the semi-solid die casting experiments with ADC10 alloy using the GISS process are also reported and discussed.

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