Comparison of heat treatment response of semisolid metal processed alloys A356 and F357

Möller, Heinrich; Govender, Gonasagren; Stumpf, Waldo E.; Pistorius, Petrus Christiaan

doi:10.1179/174313309x451252

Cited by 33 publications

(54 citation statements)

References 11 publications

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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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“…1 for (a) The globular primary α-Al structure is retained in all the samples during heat treatment with spheroidisation of the eutectic silicon occurring during solution treatment in the casting alloys as shown in Fig. 2 [4,7]. Fig.…”

Section: Resultsmentioning

confidence: 96%

“…Fig. 3 shows artificial aging curves, where, for the casting alloys, only A356 is shown as the behaviour of A356 and F357 is similar [4,7]. It can be seen that the same maximum hardness can be achieved in A356 regardless of the natural aging time period [7].…”

Section: Resultsmentioning

confidence: 96%

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

Möller¹,

Govender²,

Stumpf

2011

MSF

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Semi-solid metal high pressure die casting was used to produce plates from traditional wrought AlMg-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. IntroductionThe Al-Si-Mg alloys that constitute the 6000 series wrought alloys and 300 series casting alloys are heat treatable and depend on age-hardening to develop enhanced strength properties [1]. The main difference between the 300 series and 6000 series is the Si content, with the casting alloys containing a significantly higher quantity [1]. Silicon promotes castability mainly because of the high fluidity imparted by the presence of large volumes of the Al-Si eutectic [1]. The lack of research on the precipitation sequence in Al-Si-Mg casting alloys compared with the Al-Mg-Si wrought alloys has recently been highlighted [2]. In Al-Si-Mg alloys in general, the decomposition of the supersaturated solid solution (SSS) is believed to occur as follows [3]: SSS → (Mg + Si) clusters / GP(I) spherical → β″ / GP (II) needles → β rods ′ → β plates , where GP = Guinier-Preston zones, β = equilibrium Mg 2 Si, β′ and β″ = metastable precursors of β. Semi-solid metal (SSM) processing is a unique manufacturing method to produce near-net shape products for various industrial applications. The aim is to obtain a semi-solid structure which is free of dendrites and with the solid constituent present in a near spherical form. Casting alloys A356/7 are probably the most popular alloys used for SSM forming [4], but one of the main advantages of SSM processing is that it is also possible to produce near net-shape components from alloys that are conventionally wrought such as the 6000 series [5]. The purpose of this paper is to compare the aging response of 6000 series wrought alloys with A356/7 casting alloys produced with the same processing technique with the advantage of having comparable globular primary α-Al microstructures.

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“…The CSIR-RCS demonstrates its flexibility by the ability to process a number of different types of material including aluminium casting alloys [6,7], aluminium wrought alloys [8,9], high purity aluminium [10], unmodified aluminium-silicon binary eutectic [11], metal matrix composites [12] and magnesium casting alloys [13,14].…”

Section: Alloy Processingmentioning

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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Comparison of heat treatment response of semisolid metal processed alloys A356 and F357

Cited by 33 publications

References 11 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

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

R-HPDC in South Africa

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