Microstructures and Casting Defects of Magnesium Alloy Made By A New Type of Semisolid Injection Process

2011 ◽  
pp. 107-112 ◽  
Author(s):  
Yuichiro Murakami ◽  
Naoki Omura ◽  
Mingjun Li ◽  
Takuya Tamura ◽  
Shuji Tada ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Casting Defects ◽  
Injection Process ◽  
New Type

Development of New Type Semi-Solid Injection Process for Magnesium Alloy

2014 ◽  
Vol 217-218 ◽  
pp. 361-365
Author(s):  
Yuichiro Murakami ◽  
Kenji Miwa ◽  
Naoki Omura ◽  
Shuji Tada
Keyword(s):  
Magnesium Alloy ◽  
Volume Fraction ◽  
Solid Particles ◽  
Casting Defects ◽  
Microstructure Observation ◽  
Injection Process ◽  
Fraction Solid ◽  
The Matrix ◽  
New Type ◽  
Semi Solid

We have developed new type semi-solid injection process for magnesium alloy. This process does not require to use any cover gases and the special magnesium billet such as thixo-billet. In this study, plate specimens were produced by injecting the semi-solid billet with different fraction solid. The microstructure observation, detection of casting defects by an X-ray computed tomography scanner, and tensile test were carried out. With increasing fraction solid, the size and shape of α-Mg solid particles became smaller and more spherical. In the condition of low fraction solid or forming in liquid state, the casting defects were located in the center of the specimen at the thickness direction. Additionally, the volume fraction of the casting defect decreased with increasing fraction solid. Moreover, the casting defects can be reduced by preventing solidifying and clogging of the top of the nozzle. Then, the specimen which has few casting defects could be obtained by injecting the slurry of fraction solid 0.5. However, the tensile strength and yield strength were highest in fraction solid 0.4. It is contemplated that the composition of the solid solution component element in the matrix was increased in fraction solid of 50%, therefore the matrix became brittle.

Microstructures and Casting Defects of Magnesium Alloy Made by a New Type of Semisolid Injection Process

2011 ◽  
pp. 107-112 ◽  
Author(s):  
Yuichiro Murakami ◽  
Naoki Omura ◽  
Mingjun Li ◽  
Takuya Tamura ◽  
Shuji Tada ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Casting Defects ◽  
Injection Process ◽  
New Type

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.

Effect of Volume Fraction Solid and Injection Speed on Mechanical Properties in New Type Semi-Solid Injection Process

2008 ◽  
Vol 141-143 ◽  
pp. 761-766 ◽  
Author(s):  
Naoki Omura ◽  
Yuichiro Murakami ◽  
Ming Jun Li ◽  
Takuya Tamura ◽  
Kenji Miwa
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Volume Fraction ◽  
Testing Machine ◽  
Permanent Mold ◽  
Injection Speed ◽  
Injection Process ◽  
Fraction Solid ◽  
New Type ◽  
Semi Solid

We have developed new type semi-solid injection process, that is, runner-less injection process which can obtain high material yield of about 90% for magnesium alloy. In this process, alloy billets are heated to the semi-solid temperature in the injection cylinder and are injected into a permanent mold. In order to investigate the effects of volume fraction solid and injection speed on microstructure and mechanical properties of AZ91D magnesium alloy injected into the permanent mold, semi-solid forming testing machine which has the same system as a runner-less injection machine, has been made on an experimental basis. The magnesium billet precisely controlled at given temperature has been injected into a permanent mold with two kinds (slow and high) of speed and plate-like specimens with each fraction solid have been fabricated. Microstructure has been observed by optical microscopy and X-ray computerized tomography (CT) scanner. Mechanical properties have been measured by tensile test. The effects of volume fraction solid of the alloy slurry and injection speed on mechanical properties have been clarified.

scholarly journals The Influence of Casting Defects on Fatigue Resistance of Elektron 21 Magnesium Alloy

2013 ◽  
Vol 13 (2) ◽  
pp. 103-106
Author(s):  
I. Pikos ◽  
A. Kiełbus ◽  
J. Adamiec
Keyword(s):  
Magnesium Alloy ◽  
Fatigue Resistance ◽  
Automotive Industry ◽  
Detrimental Effect ◽  
Sine Wave ◽  
Resistance Test ◽  
Wave Form ◽  
Casting Defects ◽  
Cast Material ◽  
Heat Treated

Abstract The Mg-RE alloys are attractive, constructional materials, especially for aircraft and automotive industry, thanks to combination of low density, good mechanical properties, also at elevated temperature, and good castability and machinability. Present paper contains results of fatigue resistance test carried out on Elektron 21 magnesium alloy, followed by microstructural and fractographical investigation of material after test. The as-cast material has been heat treated according to two different procedures. The fatigue resistance test has been conducted with 106 cycles of uniaxial, sine wave form stress between 9 MPa and 90 MPa. Fractures of specimens, which ruptured during the test, have been investigated with scanning electron microscope. The microstructure of specimens has been investigated with light microscopy. Detrimental effect of casting defects, as inclusions and porosity, on fatigue resistance has been proved. Also the influence of heat treatment's parameters has been described.

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