Strain induced macrosegregation in squeeze cast AlMg and AlSi alloys

Rølland, Tone; Flatval, R; Arnberg, L.

doi:10.1016/0921-5093(93)90227-6

Cited by 12 publications

(9 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The cooling rate was then relatively high until the LM25 liquidus temperature of ϳ615 ЊC [14] solidification shrinkage. With the direct squeeze cast billets, previous studies [12,13] have shown that squeeze casting leads was reached, where the evolution of latent heat caused a thermal arrest in the cooling curves. A second thermal arrest to the macrosegregation of a eutectic constituent toward the center of the casting, and the tensile test specimens were, then occurred at the Al-Si eutectic temperature of ϳ577 ЊC.…”

Section: Introductionmentioning

confidence: 98%

The effect of Sr and Fe additions on the microstructure and mechanical properties of a direct squeeze cast Al-7Si-0.3Mg alloy

Dong

Karnezis

Durrant

et al. 1999

Metall Mater Trans A

View full text Add to dashboard Cite

This article describes the results of an investigation into the microstructure and mechanical properties of a gravity die cast and direct squeeze cast LM25 alloy (Al-7Si-0.3Mg-0.3Fe). The direct squeeze cast LM25 alloy has superior mechanical properties compared to the gravity die cast LM25 alloy, especially with regard to ductility, which is increased from ϳ1.7 pct for the gravity die cast LM25 alloy to ϳ8.0 pct for the direct squeeze cast LM25 alloy in the T6 heat-treated condition. This increase in ductility is due to (1) the removal of porosity, (2) a decrease in Si particle size, and (3) a refinement of the Fe-Si-aluminide particles. High cooling rates in direct squeeze casting result in quench modification of the Si particles, such that chemical modification with Sr or Na may not be required. In addition, direct squeeze casting is more tolerant of Fe impurities in the alloy, due to the formation of smaller Fe-Si-aluminide particles than those in gravity die cast material. The direct squeeze cast LM25 ϩ Fe alloy (Al-7Si-0.3Mg-1.0Fe) has a ductility of ϳ6.5 pct, compared to that of ϳ0.5 pct for the gravity die cast LM25 ϩ Fe alloy in the T6 heat-treated condition. This increase in tolerance to Fe impurities can lead to a substantial reduction in manufacturing costs due to (1) reduced raw-material costs, (2) reduced die sticking, and (3) improved die life.

show abstract

Section: Introductionmentioning

confidence: 98%

The effect of Sr and Fe additions on the microstructure and mechanical properties of a direct squeeze cast Al-7Si-0.3Mg alloy

Dong

Karnezis

Durrant

et al. 1999

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…of this fascinating technology field. [1,2,3] Extensive efforts have been made to overcome this weakness, and several suggestions have emerged from numerous investigations. [4-II.…”

Section: Introductionmentioning

confidence: 99%

Prevention of macrodefects in squeeze casting of an Al-7 wt pct Si alloy

Hong

Lee

Shen

2000

Metall Mater Trans B

View full text Add to dashboard Cite

The squeeze casting of an Al-7 wt pct Si alloy was carried out in order to investigate the conditions for the formation and the prevention of macrosegregation. The effects of process parameters such as applied pressure, die temperature, pouring temperature, delay time, degassing, and inoculation on the formation of macrosegregation were investigated, in correlation with the evolution of macrostructure and shrinkage defects. Three critical applied pressures were defined, based on the experimental results for the squeeze-cast Al-7 wt pct Si. The first is the critical applied pressure under which shrinkage defects form (P SC ). The second is the critical applied pressure above which macrosegregates form (P MS ). The third is the critical applied pressure above which and under which minor segregation forms. (P m and P MS , respectively). With the concept of these three critical pressures, an experimental diagram describing the optimum process conditions was proposed for obtaining sound squeeze castings. It was concluded that sound castings without macrosegregation and shrinkage defects can only be obtained when the applied pressure is in the range where P SC Ͻ P Ͻ P m (ϽP MS ). Both degassing and inoculation treatments greatly enhanced the soundness of the castings. It was also found that the pouring temperature and the delay time should not exceed T D-critical and t D-critical , respectively, in order to achieve sound castings.

show abstract

“…Although several prior investigations have identified deformation-driven melt flow as a possible mechanism of such defects [1,7,12], the influence of stress on a semi-solid alloy and the melt flow through the equiaxed microstructure are not clearly understood. Many models have been developed to predict the formation of those defects, based on the proposition of the mushy zone as a sponge saturated with liquid [2,7,13,14].…”

mentioning

confidence: 97%

“…In solidification processing, deformation in the semisolid can induce a range of defects, including extrusion segregation in squeeze-casting [1] and surface exudation in direct-chill casting [7]. Although several prior investigations have identified deformation-driven melt flow as a possible mechanism of such defects [1,7,12], the influence of stress on a semi-solid alloy and the melt flow through the equiaxed microstructure are not clearly understood.…”

mentioning

confidence: 98%

“…Understanding liquid migration through a deforming semi-solid medium is critical for a wide range of processes from metal casting [1,2] to volcanology [3][4][5]: during casting, deformation of semi-solid alloys can influence liquid flow, resulting in macrosegregation, which can degrade the mechanical properties of the final product [2,[6][7][8][9][10]; semi-solid magma is deformed by convection and/or tectonic plate spreading, inducing melt migration and segregation [3,4,11].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Time-resolved synchrotron tomographic quantification of deformation-induced flow in a semi-solid equiaxed dendritic Al–Cu alloy

et al. 2015

View full text Add to dashboard Cite

The rheology of semi-solid alloys has been studied by a novel in situ tomographic technique. Via extruding an equiaxed Al-15 wt.%Cu alloy, the inhomogeneous coherent compression of the a-Al grains was quantified, including the interdendritic channel closure and formation of a liquid extrudate. This investigation not only provides important insights into the microstructural changes occurring during semi-solid deformation, but also offers a validation benchmark for segregation and rheological models.Understanding liquid migration through a deforming semi-solid medium is critical for a wide range of processes from metal casting [1,2] to volcanology [3][4][5]: during casting, deformation of semi-solid alloys can influence liquid flow, resulting in macrosegregation, which can degrade the mechanical properties of the final product [2,6-10]; semi-solid magma is deformed by convection and/or tectonic plate spreading, inducing melt migration and segregation [3,4,11].In solidification processing, deformation in the semisolid can induce a range of defects, including extrusion segregation in squeeze-casting [1] and surface exudation in direct-chill casting [7]. Although several prior investigations have identified deformation-driven melt flow as a possible mechanism of such defects [1,7,12], the influence of stress on a semi-solid alloy and the melt flow through the equiaxed microstructure are not clearly understood. Many models have been developed to predict the formation of those defects, based on the proposition of the mushy zone as a sponge saturated with liquid [2,7,13,14]. However, currently there are no direct validation techniques that capture the kinetics incorporated in this hypothesis; in situ synchrotron tomography is one possible solution.Recently, high speed X-ray tomography has been utilized to perform four dimensional imaging (4D, i.e. 3D plus time) of the pore-scale fluid flow [15], solidification [16][17][18], and the influence of deformation on semi-sold alloys [19][20][21]. Tensile and uniaxial compression tests have been used previously with the help of 4D imaging to study semi-solid deformation; these were mainly focused on the formation of damage (hot tearing) as a result of the granular response of the mushy zone [19,21,22]. In this paper, we describe the application of an indirect extrusion cell to study the rheological behavior of the mushy zone and the mechanisms responsible for the liquid migration induced by deformation. Such an indirect extrusion cell can also be used to study how extrusion segregation and exudation form, since it mimics their forming conditions.The sample was semi-solid, equiaxed dendritic Al-15 wt.%Cu; a cylindrical specimen 2.9 mm in diameter by 2.9 mm long was prepared using wire electro-discharge machining, and then inserted in a boron nitride holder with an inner diameter (ID) of 3 mm and outer diameter (OD) of 5 mm. An alumina tube (1.5 mm ID and 3 mm OD) was placed on top of the specimen forming an indirect extrusion cell (Fig. 1). The entire extrusion set-up was enclose...

show abstract

Strain induced macrosegregation in squeeze cast AlMg and AlSi alloys

Cited by 12 publications

References 3 publications

The effect of Sr and Fe additions on the microstructure and mechanical properties of a direct squeeze cast Al-7Si-0.3Mg alloy

The effect of Sr and Fe additions on the microstructure and mechanical properties of a direct squeeze cast Al-7Si-0.3Mg alloy

Prevention of macrodefects in squeeze casting of an Al-7 wt pct Si alloy

Time-resolved synchrotron tomographic quantification of deformation-induced flow in a semi-solid equiaxed dendritic Al–Cu alloy

Contact Info

Product

Resources

About