Natural and artificial aging response of semisolid metal processed Al–Si–Mg alloy A356

Möller, Heinrich; Govender, Gonasagren; Stumpf, Waldo E.

doi:10.1179/136404608x286156

Cited by 40 publications

(57 citation statements)

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“…In Al-7Si-Mg casting alloys, natural pre-ageing causes a sluggish age-hardening response during subsequent artificial ageing, but interestingly, the extent of the loss in hardness is fully recovered 5 upon further artificial ageing [17][18][19]. To date, there is a lack of detailed research revealing precipitate micro-and nanostructural evolution during ageing of Al-Si-Mg casting alloys.…”

Section: Introductionmentioning

confidence: 99%

Solute nanostructures and their strengthening effects in Al–7Si–0.6Mg alloy F357

et al. 2012

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The solute-nanostructures formed in the primary α-Al grains of a Semi-Solid Metal cast Al-7Si-0.6Mg alloy (F357) during ageing at 180°C, and the age-hardening response of the alloy have been systematically investigated using transmission electron microscopy, atom probe tomography and hardness testing. A 120-h natural pre-ageing led to the formation of solute clusters and GP zones. The natural pre-ageing slowed down the precipitation kinetics six-fold during 1 h ageing at 180°C, but this effect diminished after 4 h when the sample reached the same hardness as that without the pre-ageing treatment. It reduced the number density of β″-needles to approximately half of that formed in samples without the treatment, and postponed the peak hardness occurrence to 4 h, 4 times that of the as-quenched sample. A hardness plateau developed in the as-quenched sample between 1 h and 4 h ageing corresponds to the growth of 2 the β″ precipitates and a significant concurrent decrease of solute clusters and GP zones. The average Mg:Si ratio of early solute clusters is < 0.7 while that of GP zones changes from 0.8 to 0.9 with increasing in their size, and that of β″-needles increases from 0.9 to 1.2. β″-needles, GP zones and solute clusters are important strengthening solute nanostructures of the alloy. The partitioning of solutes and precipitation kinetics of the alloy are discussed in detail.

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Section: Introductionmentioning

confidence: 99%

Solute nanostructures and their strengthening effects in Al–7Si–0.6Mg alloy F357

et al. 2012

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“…In the first set of experiments, the applicability of shorter heat treatment cycles on SSM-HPDC automotive brake calipers was investigated. The authors have investigated the use of shorter cycles on relatively small plates before [6][7][8][9][10], but not on larger, more complex castings such as the automotive brake calipers (with approximate size of 150x90x50mm 3 ). Vickers hardness (2 kg) profiles (average of at least three measurements per position) through a cross section of the side-arm of the SSM-HPDC calipers were measured (see Figure 1 for the position of the cross section).…”

Section: Methodsmentioning

confidence: 99%

“…The assumption is 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 [4][5][6][7][8]. However, very little information is available in the literature where the heat treatment response of globular and dendritic A356 components is compared.…”

Section: Introductionmentioning

confidence: 99%

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Application of shortened heat treatment cycles on A356 automotive brake calipers with respective globular and dendritic microstructures

Möller

Govender

Stumpf

2010

Transactions of Nonferrous Metals Society of China

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Abstract:The conventional casting alloy A356 is probably one of the most popular alloys used for semi-solid metal (SSM) forming. This is due to its high fluidity and good "castability". This alloy can be heat treated alternatively to the T4, T5 or T6 temper conditions. Previous work by the authors has shown that shorter heat treatment cycles can be applied for SSM processed A356 rather than the more costly traditional cycles (that were originally developed for liquid cast dendritic A356). The previous work was performed on relatively small rectangular plates (4×80×100mm 3 ) that were cast in steel moulds with a 50 ton high pressure die casting (HPDC) machine. This work determined whether these short heat treatment cycles (T4, T5 and T6) can be applied successfully to a larger (and more complex) casting too. Since the automotive industry has many possible applications for SSM-HPDC parts, the newly developed heat treatment cycles, as well as the traditional heat treatment cycles, were applied to A356 brake calipers cast using a 630 ton HPDC machine. Vickers hardness measurements at a cross section of the brake calipers were performed, indicating that similar values can be obtained when using the significantly shorter heat treatment cycles. Finally, the typical tensile properties that can be obtained for SSM-HPDC A356 brake calipers are compared with those manufactured by gravity die casting. These results indicate that the differences in microstructures (globular or dendritic) do not have a noteworthy effect on the heat treatment response. This implies that the short heat treatment cycles originally developed for globular SSM-HPDC A356 castings can be successfully applied to dendritic liquid A356 castings too.

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“…The largest part of fundamental research at the CSIR was focused on the Al-Si-Mg alloy system, investigating topics including various heat treatment conditions [23][24][25][26], heat treatment time and temperature response [27,28], the effect of elevated impurity levels [29], comparing dendritic and globular microstructures [30]. The Al-Si-Mg casting alloy system was compared to the Al-Mg-Si wrought alloy system for which the strengthening mechanism is similar [31,32].…”

Section: Component Productionmentioning

confidence: 99%

R-HPDC in South Africa

Curle¹,

Möller²,

Govender³

2012

SSP

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Abstract. The history of semi-solid metal forming and in particular rheo-high pressure die casting at the Council for Scientific and Industrial Research in South Africa is discussed. Processing flexibility is demonstrated on the Al-Si-Mg, Al-Mg-Si, Al-Cu-Mg and Al-Zn-Mg-Cu casting and wrought alloy systems as well as on high purity aluminium, unmodified Al-Si binary eutectic, metal matrix composites and magnesium alloys. Material properties are highlighted.

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Natural and artificial aging response of semisolid metal processed Al–Si–Mg alloy A356

Cited by 40 publications

References 0 publications

Solute nanostructures and their strengthening effects in Al–7Si–0.6Mg alloy F357

Solute nanostructures and their strengthening effects in Al–7Si–0.6Mg alloy F357

Application of shortened heat treatment cycles on A356 automotive brake calipers with respective globular and dendritic microstructures

R-HPDC in South Africa

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