scholarly journals Comparison of the Heat Treatment Response of SSM-HPDC 6082 and 6004 Wrought Alloys with A356 and F357 Casting Alloys

2011 ◽  
Vol 690 ◽  
pp. 53-56 ◽  
Author(s):  
Heinrich Möller ◽  
Gonasagren Govender ◽  
Waldo Stumpf
Keyword(s):  
Heat Treatment ◽  
Artificial Aging ◽  
Die Casting ◽  
Natural Aging ◽  
Solid Metal ◽  
Casting Alloys ◽  
Aging Response ◽  
Semi Solid ◽  
Si Content ◽  
Pressure Die Casting

Semi-solid metal high pressure die casting was used to produce plates from traditional wrought Al-Mg-Si alloys 6082 and 6004, as well as from traditional casting Al-Si-Mg alloys A356 and F357. The high Si-content of the casting alloys offer several advantages, including a faster artificial aging response, higher strength for comparable Mg contents and less sensitivity to prior natural aging on peak strength. However, over-aging occurs earlier in the casting alloys than in the wrought alloys.

The T5 Heat Treatment of Semi-Solid Metal Processed Aluminium Alloy F357

2009 ◽  
Vol 618-619 ◽  
pp. 365-368 ◽  
Author(s):  
Heinrich Möller ◽  
Gonasagren Govender ◽  
Waldo Stumpf
Keyword(s):  
Heat Treatment ◽  
Aluminium Alloy ◽  
Tensile Properties ◽  
Cooling Rate ◽  
Quality Index ◽  
Artificial Aging ◽  
Natural Aging ◽  
Solid Metal ◽  
Semi Solid

The T5 heat treatment of semi-solid metal (SSM) processed alloy F357 was investigated by considering the effects of cooling rate and natural aging after casting, as well as artificial aging parameters on tensile properties. In addition, the tensile properties of SSM-HPDC F357 in different temper conditions (F, T4, T5 and T6) are compared. The Quality Index (QI) is used to compare the influence of different T5 heat treatment parameters and different temper conditions.

scholarly journals The Influence of Prior Natural Aging on the Subsequent Artificial Aging Response of Aluminium Alloy A356 with Respective Globular and Dendritic Microstructures

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Heinrich Möller ◽  
Gonasagren Govender ◽  
Pierre Rossouw ◽  
Waldo Stumpf
Keyword(s):  
Heat Treatment ◽  
Metal Forming ◽  
Artificial Aging ◽  
Natural Aging ◽  
Casting Technique ◽  
Casting Alloys ◽  
Aging Response ◽  
Dendritic Microstructures ◽  
The Difference ◽  
Linear Correlations

Alloy A356 is one of the most popular alloys used for semisolid metal forming. The heat treatment cycles that are currently applied to semisolid processed components are mostly those that are in use for dendritic casting alloys. The assumption has been made that these heat treatments are not necessarily the optimum treatments, as the difference in solidification history and microstructure of SSM processed components should be considered. The objective of this study is to determine whether dendritic A356 behaves in a similar way to globular A356 in terms of its response to artificial aging with or without prior natural aging. The results indicate that the differences in microstructures (globular or dendritic) do not have a noteworthy effect on the heat treatment response. It is also shown that strong linear correlations are found between T4 and T6 hardness and wt% Mg of A356, regardless of the casting technique used.

The Natural and Artificial Aging Response of Semi-Solid Metal Processed Alloy A356

2008 ◽  
Vol 141-143 ◽  
pp. 737-742 ◽  
Author(s):  
Heinrich Möller ◽  
Gonasagren Govender ◽  
Waldo Stumpf
Keyword(s):  
Artificial Aging ◽  
Natural Aging ◽  
Peak Hardness ◽  
Time To Peak ◽  
Casting Alloys ◽  
Aging Period ◽  
Aging Response ◽  
Hardness Peak ◽  
Dendritic Microstructures ◽  
Semi Solid

The heat treatment cycles that are currently applied to semi-solid processed components are mostly those that are in use for dendritic casting alloys. These heat treatments are not necessarily the optimum treatments for non-dendritic microstructures. For rheocast alloy A356, it is shown that natural aging prior to artificial aging causes the time-to-peak-hardness to be longer compared to the time when only artificial aging is used. Furthermore, a hardness plateau is maintained during artificial aging at 180oC between 1 and 5 hours without any prior natural aging. A natural aging period as short as 1 hour results in a hardness peak (rather than a plateau) to be reached during artificial aging after 4 hours at 180oC.

Effects of Physical Melt Treatments on Microstructural Evolution and Anodizing Characteristics of Al-Si Casting Alloys

2011 ◽  
Vol 695 ◽  
pp. 243-246 ◽  
Author(s):  
Je Sik Shin ◽  
Bong Hwan Kim ◽  
Sang Mok Lee
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Aluminum Alloys ◽  
Die Casting ◽  
Microstructural Feature ◽  
Casting Alloys ◽  
Melt Treatment ◽  
Twin Screw ◽  
A356 Aluminum ◽  
Pressure Die Casting

In order to investigate the effects of physical melt treatment on microstructural feature and anodizing characteristics of Al-Si system casting alloys, A380 and A356 aluminum alloys were chosen and a twin-screw melt-shearing process was utilized before high pressure die casting. In order to refine and homogenize the microstructure of the diecast Al-Si alloys, the melt-shearing process parameters were controlled and T6 heat treatment was carried out.

Comparison of the Heat Treatment Response of Wrought and SSM-HPDC Alloy 6082

2011 ◽  
Vol 690 ◽  
pp. 242-245 ◽  
Author(s):  
Heinrich Möller ◽  
Gonasagren Govender ◽  
Waldo Stumpf
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
Treatment Response ◽  
Artificial Aging ◽  
Natural Aging ◽  
Aging Response ◽  
Unfavourable Effect

The natural and artificial aging responses of wrought and SSM-HPDC alloy 6082 are compared. It is shown that the heat treatment response of this Al-Mg-Si alloy is not influenced by differences in microstructures produced by different processing routes. Wrought alloy 6082 is known to experience an unfavourable effect of prior natural aging on the subsequent artificial aging response, which was also found for SSM-HPDC 6082 in this study. The tensile properties of SSM-HPDC 6082-T6 agree well with those specified for wrought 6082-T6, except for a much lower ductility of the SSM-HPDC variant.

Fusion Welding of Rheocast Semi-Solid Metal (SSM) Processed Aluminium Alloy 7017

2012 ◽  
Vol 192-193 ◽  
pp. 161-166 ◽  
Author(s):  
Madeleine du Toit ◽  
Patronica Letsoalo ◽  
Heinrich Möller
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Aluminium Alloy ◽  
Die Casting ◽  
Solid Metal ◽  
Hot Tearing ◽  
High Pressure Die Casting ◽  
Near Net Shape ◽  
Semi Solid ◽  
Pressure Die Casting

Near-net shape casting of wrought aluminium alloys has proven to be difficult due to a tendency towards hot tearing during cooling. Rheocasting, or semi-solid metal (SSM) processing followed by high pressure die casting (HPDC), has recently been shown to be an effective alternative to conventional die casting, yielding near-net shape wrought aluminium alloy castings with less risk of hot tearing. This casting process involves pouring the liquid metal into a processing cup, which is then transferred into a coil for induction stirring and simultaneous forced air cooling. When the metal reaches the semi-solid casting temperature, the resultant slurry is transferred to a high pressure die casting machine and cast to near-net shape. This modifies the as-cast microstructure, yielding a more globular primary phase and results in mechanical properties in the -T6 condition closely approaching those of wrought material in the same condition. Little information is currently available on the response of SSM-HPDC material to welding. This project investigated the influence of autogenous laser and gas tungsten arc welding on the microstructure and mechanical properties of aluminium 7017 after rheocasting. It is possible to successfully weld this material without solidification or liquation cracking. The effect of welding on the rheocast microstructure in the heat-affected zone and weld metal was shown, and the hardness and tensile properties of the resulting joints in the as-welded condition were tested and related to the microstructures achieved.

Influence of Intermetallics Modification by Melt-Shearing Treatment on Mechanical Properties of Iron-Containing Al-Si-Mg Casting Alloy

2011 ◽  
Vol 383-390 ◽  
pp. 4683-4687
Author(s):  
Bong Hwan Kim ◽  
Sang Hwan Lee ◽  
Sang Mok Lee
Keyword(s):  
Mechanical Properties ◽  
Die Casting ◽  
Mg Alloy ◽  
Casting Alloys ◽  
Solid Region ◽  
Formation Behavior ◽  
Morphological Modification ◽  
Semi Solid ◽  
Globular Form ◽  
Pressure Die Casting

This study aims to investigate the influence of intermetallics morphological modification on mechanical properties of iron-containing Al-Si-Mg casting alloys. The modification of the intermetallics was performed by using melt-shearing treatment prior to commercial high pressure die casting. The process parameters of the melt-shearing treatment were controlled and optimized based on the theoretical consideration of the intermetallics formation behavior. It was found that the mechanical properties of low-iron containing Al-Si-Mg alloy was improved due to the modification of primary α-Al from dendritic to globular form by the melt-shearing. Regarding to high-iron containing Al-Si-Mg alloy, harmful morphology of intermetallics was successfully modified by the melt-shearing at semi-solid region, which results in the improvement of mechanical properties such as elongation.

Weldability of SSM Rheo Processed Aluminum Alloy A356

2008 ◽  
Vol 141-143 ◽  
pp. 773-778 ◽  
Author(s):  
Gonasagren Govender ◽  
L. Ivanchev ◽  
H.P. Burger ◽  
R.D. Knutsen ◽  
G. Kunene
Keyword(s):  
Die Casting ◽  
Casting Machine ◽  
Solid Metal ◽  
Hardness Profile ◽  
Liquid Alloys ◽  
Heat Treated ◽  
Technology Process ◽  
Metal State ◽  
Semi Solid ◽  
Pressure Die Casting

CSIR-Rheo technology process which involves the preparation of metal slurry direct from liquid alloys by stirring and cooling was applied for treatment of Al-7%Si-0.35%Mg alloy, A356, to the Semi-Solid Metal state. Plates were cast in steel moulds with a 50 Ton High Pressure Die Casting machine. Heat treatments T4 and T6 were given to the samples. Butt laser welding was performed on the heat treated and as fabricated plates (F). Tensile properties, hardness profile, microstructure of the weld, heat affected zone and base metal were examined. Some comments on outcomes of the research are included.

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