Iron-related porosity in Al–Si–(Cu) foundry alloys

Dinnis, C. M.; Taylor, J. A.; Dahle, A. K.

doi:10.1016/j.msea.2006.03.045

Cited by 80 publications

(48 citation statements)

References 16 publications

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“…Another interesting fact is that the cooling curve in figure 2 does not register the typical 319.0 alloy plateau, related to the formation of needles of the β-Al 5 FeSi phase between 3-4 points as described in the literature 6,10,11,13 . This suggests that the formation of needles of the β-Fe 5 AlSi phase occurs just before the eutectic Al-Si phase.…”

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confidence: 86%

“…This subject is not yet completely exhausted considering that solidification of commercial alloys is complex and behaves far from the equilibrium conditions 1 . In the design of cast components, it is necessary to monitor the solidification of alloys under different cooling conditions corresponding to different cross sections of the castings 1,2,[8][9][10][11] . In the present work, we studied the microstructural behavior of iron containing intermetallic compounds in the 319.2 aluminum alloy as a function of cooling rate, through 9,12 .…”

Section: Introductionmentioning

confidence: 99%

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Effects of Solidification Rate in the Microstructure of Al-Si5Cu3 Aluminum Cast Alloy

et al. 2017

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Aluminium alloy Al-Si5Cu3 (319) is one of the most commonly used casting alloys for automobile components, due to its casting characteristics. Iron is the major impurity element that influences the detrimental β-phase formation in secondary aluminum alloys. In the present study, we investigated the influence of the cooling rate on the formation of iron compounds, α-Al 15 (Mn,Fe) 3 Si 2 and β-Fe 5 AlSi phases, in Al-Si5Cu3 containing 1.0% Fe, 0.5% Mn and 0.2% Mg, by thermal analysis and metallography. The results show that the high cooling rates, between 10-10 3 K/s, are able to reduce and nullify the formation of needle-like β-Al5FeSi phase, and help the formation of the Chinese scripts α-Al 15 (Fe,Mn) 3 Si 2 phase. The analysis of the curves reveals that the increase of the cooling rate increases the temperature of nucleation of the α-Al dendrite and decrease the eutectics Al-Si and Al-Cu phases.

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confidence: 86%

Section: Introductionmentioning

confidence: 99%

Effects of Solidification Rate in the Microstructure of Al-Si5Cu3 Aluminum Cast Alloy

et al. 2017

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“…10 The coarse /?-Fe phase platelets interfere with liquid flowing into interdendritic channels; this reduces feeding during solidification and consequently promotes the formation of porosity. 63 ' 64 Increasing the Fe content also adversely affects machinability. It has been reported that the abrasive Fe-rich phases abrade cutting tools, even at Fe contents of less than 0.6%.…”

Section: Effects Of Iron Intermetallic Phasesmentioning

confidence: 99%

Effect of additives on the mechanical properties and machinability of a new aluminum-copper base alloy /

Elgallad¹

2010

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The present dissertation is aimed at investigating the effects of additives on the mechanical properties and machinability of the 220 alloy which is a new Al-2%Cu-1.3%Si-0.4%Mg casting alloy intended for automotive applications. The research involved here was accomplished through two types of study: (i) study of mechanical properties; (ii) and study of machinability. The study of mechanical properties was proposed to examine the effects of Sr, Ti, Zr, Fe, Mn, and Ag as well as of free-cutting elements, specifically Sn and Bi, on the mechanical properties of the 220 alloy in both the as-cast and heat-treated conditions. The mechanical properties in question include tensile, hardness, and impact properties which were all evaluated at room temperature. The study of machinability was devoted to examining the drilling and tapping performance of four 220 based-alloys as well as of A206 alloy which was selected for a comparative study on the machinability of this particular alloy and that of 220 alloy. The four 220 based-alloys were selected from amongst the alloys prepared in the first study and include: (i) 220 alloy; (ii) 220 alloy + Ti + Zr; (iii) 220 alloy + Ti + Zr + Sn; and (iv) 220 alloy + Ti + Zr + Bi. The machining performance was evaluated based on the calculation of the cutting force, cutting moment, and tool life, as well as on the investigation of chip characteristics. Tool life was expressed as the number of holes drilled/tapped up to the point of tool breakage.An assessment of the microstructure reveals that A^Cu, AlsMggSiôC^, and the Chinese script-like a-Ali5(Fe,Mn)3Si2 phases are the main microstructural constituents of the 220 alloy. The absence of free Si in the microstructure implies that the Si-content was consumed in the formation of the Al-Fe-Si and Al-Cu-Mg-Si intermetallic phases. The platelet-like /?-AlsFeSi phase was not in evidence because of the higher Mn:Fe ratio (~1) of the 220 alloy which promotes the formation of the a-Fe phase at the expense of the /?-Fe phase. The addition of Sr refines the morphology of the ct-Fe Chinese script phase to a certain extent, resulting in the even distribution of the particles of this phase within the aluminum matrix. The combined addition of Ti and Zr causes a reduction in the grain size by about 68% compared to the non-grain-refined base 220 alloy. This reduction may be ascribed to the formation of Zr-Ti particles which act as nucleation sites for small equiaxed grains of cc-Al. Tin precipitates in the form of /?-Sn particles which appear as small non-uniformly distributed clusters usually solidified within the AbCu phase network. Bismuth and /?-Sn particles were found undissolved in the Almatrix after heat treatment, thereby making it possible to induce their free-cutting action during machining.Results from the evaluation of the mechanical properties show that, because of the low Si content, the effects of Sr on the mechanical properties with respect to the modification of silicon eutectic do not come into play. The role of Sr in refining th...

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“…Precipitates of this phase are associated with porosity [5,6] and reduced fluidity, [7] and they act as stress concentrators, [8,9] promoting crack initiation and shortening fatigue life. The presence of b-Al 5 FeSi intermetallics increases hardness and reduces impact strength and machinability, but also lowers the soldering of the casting in permanent molds and high pressure die casting.…”

Section: Introductionmentioning

confidence: 99%

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

Mikołajczak

Ratke

2014

Metall Mater Trans A

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The presence of Fe aids in establishing the mechanical and physical properties of AlSi alloys and is also one of the main impurities leading to formation of b-Al 5 FeSi intermetallics. This study aims to understand the effect of fluid flow on the dendritic microstructure with intermetallics in Al-5/7/9 wt pct Si-0.2/0.5/1.0 wt pct Fe alloys that are directionally solidified under defined thermal and fluid flow conditions. We made extensive use of 3D X-ray tomography to obtain a better insight into the morphology and formation of the intermetallics. Three-dimensional (3-D) distribution of intermetallics presented here shows that the growth of large b-Al 5 FeSi due to forced flow occurs in the eutectic specimen center and together with an increase in the number density of b precipitates. The 3D reconstructions have verified the b shaped to be curved, bent with twining, branched, and to have imprints, holes, and propeller-shaped platelets. The 3D views showed that hole-shaped b arose from the lateral growth around a-Al dendrites. These views also confirmed the phenomenon of shortening of b as an effect of flow in the dendritic region, where b could be fragmented or completely remelted, and ultimately resulting in microstructures with shorter b-Al 5 FeSi and increases in number density. The analysis revealed an interaction between melt flow, 3D distribution, and the morphology of b-Al 5 FeSi. The growth of a large and complex group of b intermetallics can reduce the melt flow between dendrites and strengthen pore nucleation and eutectic colonies nucleation, leading to lower permeability of the mushy zone and increased porosity in the castings.

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Iron-related porosity in Al–Si–(Cu) foundry alloys

Cited by 80 publications

References 16 publications

Effects of Solidification Rate in the Microstructure of Al-Si5Cu3 Aluminum Cast Alloy

Effects of Solidification Rate in the Microstructure of Al-Si5Cu3 Aluminum Cast Alloy

Effect of additives on the mechanical properties and machinability of a new aluminum-copper base alloy /

Interplay Between Melt Flow and the 3D Distribution and Morphology of Fe-Rich Phases in AlSi Alloys

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