On the effect of additions of Cu and Mg on the ductility of AlSi foundry alloys cast with a cooling rate of approximately 3K/s

Dons, Anne Lise; Heiberg, G.; Voje, Jorunn; Mæland, Jorunn Snøan; Løland, Jan Ove; Prestmo, A.

doi:10.1016/j.msea.2005.09.053

Cited by 27 publications

(13 citation statements)

References 12 publications

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“…Cu, and Mg are added to increase the strength of the alloy, but this also lead to a reduction in ductility [7,15]. The strength and ductility obtained are affected by factors such as if the Cu and Mg are present as coarse phases after solidification, as atoms in solid solution, as GP zones formed at room temperature, or as precipitates formed during artificial ageing [7].…”

Section: Alloy Compositionmentioning

confidence: 99%

“…The highest strength contribution is obtained when Cu and Mg are present as small precipitates after a heat treatment, but a reduction in ductility also results. Additions of Cu and Mg also leads to the formation of bands of coarse Si particles and an increased risk for shrinkage porosity due to an increased solidification interval, which may decrease the elongation to fracture [15].…”

Section: Alloy Compositionmentioning

confidence: 99%

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The heat treatment of Al–Si–Cu–Mg casting alloys

Sjölander

Seifeddine

2010

Journal of Materials Processing Technology

447

223

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Environmental savings can be made by increasing the use of aluminium alloys in the automotive industry as the vehicles can be made lighter. Increasing the knowledge about the heat treatment process is one task in the direction towards this goal. The aim of this work is to investigate and model the heat treatment process for Al-Si casting alloys. Three alloys containing Mg and/or Cu were cast using the gradient solidification technique to achieve three different coarsenesses of the microstructure and a low amount of defects.Solution treatment was studied by measuring the concentration of Mg, Cu and Si in the α-Al matrix using wavelength dispersive spectroscopy (WDS) after various times at a solution treatment temperature. A diffusion based model was developed which estimates the time needed to obtain a high and homogenous concentration of alloying elements for different alloys, temperatures and coarsenesses of the microstructure. It was shown that the yield strength after artificial ageing is weakly dependent on the coarseness of the microstructure when the solution treatment time is adjusted to achieve complete dissolution and homogenisation.The shape and position of ageing curves (yield strength versus ageing time) was investigated empirically in this work and by studying the literature in order to differentiate the mechanisms involved. A diffusion based model for prediction of the yield strength after different ageing times was developed for Al-Si-Mg alloys. The model was validated using data available in the literature. For Al-Si-Cu-Mg alloys further studies regarding the mechanisms involved need to be performed.Changes in the microstructure during a heat treatment process influence the plastic deformation behaviour. The Hollomon equation describes the plastic deformation of alloys containing shearable precipitates well, while the Ludwigson equation is needed when a supersaturated solid solution is present. When non-coherent precipitates are present, none of the equations describe the plastic deformation well. The evolution of the storage rate and recovery rate of dislocations was studied and coupled to the evolution of the microstructure using the Kocks-Mecking strain hardening theory.

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Section: Alloy Compositionmentioning

confidence: 99%

Section: Alloy Compositionmentioning

confidence: 99%

The heat treatment of Al–Si–Cu–Mg casting alloys

Sjölander

Seifeddine

2010

Journal of Materials Processing Technology

447

223

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“…The plastic deformation behaviour will be depending upon factors such as whether the Cu and Mg are found as coarse intermetallic compounds, the level of Cu and Mg in solid solution, or if Cu and Mg are found as GP zones formed at room temperature and/or as precipitates due to a post solidification treatment. Cu and Mg present in Al-Si cast alloys lead also to the formation of bands of coarse Si particles as they also enlarge the solidification interval, leading to an increased risk in forming shrinkage porosity, leading to premature failures [3].…”

Section: Introductionmentioning

confidence: 99%

On the Role of Copper and Cooling Rates on the Microstructure, Defect Formations and Mechanical Properties of Al-Si-Mg Alloys

Seifeddine¹,

Sjölander²,

Bogdanoff³

2013

MSA

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This paper aims to assess the role of Cu on Al-Si-Mg alloys, in a range of 0 -5 wt%, qualitatively on microstructure, defect formation, in terms of porosity, and strength in the as-cast conditions. The ternary system of Al-Si-Mg, using the A356 alloy as a base material, were cast using the gradient solidification technique; applying three different solidification rates to produce directional solidified samples with a variety of microstructure coarsenesses. Microstructural observations reveal that as the Cu levels in the alloys are increased, the amounts of intermetallic compounds as well as the Cu concentration in the α-Al matrix are increased. Furthermore, the level of porosity is unaffected and the tensile strength is improved at the expense of ductility.

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“…Small additions of Na or Sr can "modify" the morphology of the eutectic silicon from its acicular form to a fine fibrous form which improves the mechanical properties. 34 ' 35> 36 Magnesium and copper are the other major alloying elements that may be present in cast aluminum-silicon alloys.…”

Section: Objectivesmentioning

confidence: 99%

use of fluidized sand bed as an innovative technique for heat treating aluminum based castings /

Ragab¹

2012

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The current study was carried out to arrive at a better understanding of the influences of the fluidized sand bed heat treatment on the tensile properties and quality indices of A356.2 and B319.2 casting alloys. For the purposes of validating the use of fluidized sand bed furnaces in industrial applications for heat treatment of 356 and 319 castings, the tensile properties and the quality indices of these alloys were correlated with the most common metallurgical parameters, such as strontium modification, grain refining, solutionizing time, aging parameters and quenching media. Traditional heat treatment technology, employing circulating air convection furnaces, was used to establish a relevant comparison with fluidized sand beds for the heat treatment of the alloys investigated, employing T6 continuous aging cycles or multi-temperature aging cycles. Quality charts were used to predict and/or select the best heat treatment conditions and techniques to be applied in industry in order to obtain the optimum properties required for particular engineering applications.The results revealed that the strength values achieved in To-tempered 319 and 356 alloys are more responsive to fluidized bed (FB) heat treatment than to conventional convection furnace (CF) treatment for solution treatment times of up to 8 hours. Beyond this solution time, no noticeable difference in properties is observed with the two techniques. A significant increase in strength is observed in the FB heat-treated samples after short aging times of 0.5 and 1 hour, the trend continuing up to 5 hours. The 319 alloys show signs of overaging after 8 hours of aging using a conventional furnace, whereas with a fluidized bed, overaging occurs after 12 hours. Analysis of the tensile properties in terms of quality index charts showed that both modified and non-modified 319 and 356 alloys display the same, or better, quality, after only a 2-hr treatment in an FB compared to 10 hours when using a CF. The quality values of the 356 alloys are more responsive to the FB technique than 319 alloys through long aging times of up to 5 hours. The 319 alloys heat-treated in an FB, however, show better quality values after 0.5 hour of aging and for solution treatment times of up to 5 hours than those treated using a CF. With regard to the quality charts of 319 alloys, heat-treated samples show that increasing the aging time up to peakstrength, i.e. 8 and 12 hours in a CF and an FB, respectively, results in increasing in the alloy strength with a decrease in the quality values, for each of the solution heat treatment times used. The statistical analysis of the results reveals that modification and heating rate of the heat treatment technique have the greatest positive effects on the quality values of the 356 alloys. Analysis of the interaction plots and of the main effects plots confirmed that the quality values of 356 alloys, as compared to 319 alloys, are more responsive to the FB than to the CF heat treatment technique. The silicon particle characteristics of th...

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On the effect of additions of Cu and Mg on the ductility of AlSi foundry alloys cast with a cooling rate of approximately 3K/s

Cited by 27 publications

References 12 publications

The heat treatment of Al–Si–Cu–Mg casting alloys

The heat treatment of Al–Si–Cu–Mg casting alloys

On the Role of Copper and Cooling Rates on the Microstructure, Defect Formations and Mechanical Properties of Al-Si-Mg Alloys

use of fluidized sand bed as an innovative technique for heat treating aluminum based castings /

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