Effect of process parameters on mechanical properties of high pressure die cast magnesium AZ91 components

Okcu, Işık Yılmaz
Before beginning the experimental work of this study, a magnesium high pressure die casting facility is set up to manufacture magnesium cast parts for defence industry. In this thesis two components are cold chamber high pressure die casted using magnesium alloy AZ91 as raw material, and one component was manufactured using both aluminium alloy A.413, and magnesium alloy AZ91. Mechanical properties of high pressure die casting parts depend on various parameters such as, thickness of the cast part, position of the cast part in the cavity, molten metal temperature, die temperature, piston speeds, and injection pressure. The aim of this study is to investigate the effects of section thickness of the cast part, position of the cast part in the die cavity, piston speeds, and molten metal temperature on mechanical properties of magnesium die cast parts. Tensile properties of products from Al A.413 and Mg AZ91 alloys are also compared. Casting analysis software is used to simulate filling and temperature evolution of three different casting components. Piston speeds are first calculated from equations in the literature and then verified by using the software. Specimens for microstructural investigation, and mechanical tests are machined directly from the mass produced parts. Optical microscopy, and scanning electron microscopy investigations are carried out for grain size and porosity determination. Tensile tests are conducted for yield strength, ultimate tensile strength, and % elongation values. The results of casting analysis software simulations, grains size investigations, porosity investigations, and tensile tests are correlated to each other. Optimum piston speeds, optimum molten metal temperatures are observed, effect of grain size and porosity concentrations on the effect of mechanical properties are vi compared. Weight of cast parts produced from Mg AZ91 are 35 % lower than that of Al A.413 parts. However, ultimate tensile strength of the cast parts produced from Mg AZ91 are found to be similar to the aluminium parts.


Effect of swaging on microstructure and tensile properties of W-Ni-Fe alloys
DURLU, NURİ; Caliskan, N. Kaan; Bor, Sakir (Elsevier BV, 2014-01-01)
The objective of this study was to investigate the effect of swaging on the microstructure and tensile properties of high density two phase alloys 90W-7Ni-3Fe and 93W-4.9Ni-2.1Fe. Samples were liquid phase sintered under hydrogen and argon at 1480 degrees C for 30 min and then 15% cold rotary swaged. Measurement of microstructural parameters in the sintered and swaged samples showed that swaging slightly increased tungsten grain size in the longitudinal direction and slightly decreased tungsten grain size i...
Effects of fabrication method on initial powder characteristics and liquid phase sintering behaviour of tungsten
Erol, Mahmut; Erdogan, Metehan; Karakaya, İshak (Elsevier BV, 2018-12-01)
Direct electrochemical production of tungsten involves removal of oxygen in solid state from an important tungsten compound, calcium tungstate, in molten salts. A detailed experimental study was performed to characterize the liquid phase sintering behaviour of the tungsten powder (WE), which was produced by the direct electrochemical reduction technique. All of the tungsten heavy alloy (WHA) compositions covered in this study, contained four parts nickel, one part cobalt and over 90 wt% tungsten. The pellet...
Effects of SiC particulates on the fatigue behaviour of an Al-alloy matrix composite
Kaynak, Cevdet (2006-01-01)
In this study, the fatigue behaviour of aluminium matrix-silicon carbide (SiC) particulate reinforced composite specimens was investigated in comparison to the matrix aluminium alloy containing 12 wt% Si. Three different weight percentages of SiC particulates: 5, 10, and 15 in the size range of 40-60 gm were injected into the melt. Mg was also added to improve the wettability of Al-alloy matrix over SiC particulates resulting in better interfacial bonding. Test specimens were machined from squeeze casting b...
Effect of lithium doping on the properties of Tl-based superconductors
Kayed, TS; Ozkan, H; Hasanlı, Nızamı (IOP Publishing, 2001-09-01)
The effects of lithium doping on the formation and properties of the T1-based superconductors have been studied. Lithium atoms up to around 3 mol.% have been added to the oxides of nominal composition Tl1.8Ba2Ca2.2Cu3Ox, and the usual solid-state reaction method has been applied. Lithium additions in the range 0.23-0.29 mol.% increase the fraction of the Tl-2223 phase and significantly improve the critical temperature of the samples. Higher amounts of lithium additions diminish the Tl-2223 phase, reduce the...
Effects of additives on mechanical milling and hydrogenation of magnesium powders
Guvendiren, M; Bayboru, E; Öztürk, Tayfur (2004-04-01)
A study is carried out on the role of additives for structural refinement of magnesium powders in mechanical milling. Additives, namely Al2O3, SiC, V and graphite are chosen so as to cover a wide hardness range. Structural refinement after milling is studied both metallographically and in terms of X-ray line broadening. It is found that for efficient structural refinement, the additives should be chosen not on the basis of their hardness but rather whether or not they are preserved with an acceptable size d...
Citation Formats
I. Y. Okcu, “Effect of process parameters on mechanical properties of high pressure die cast magnesium AZ91 components,” M.S. - Master of Science, Middle East Technical University, 2011.