Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
  • B22D21/002—Castings of light metals
  • B22D21/007—Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
  • C22C21/04—Modified aluminium-silicon alloys

Definitions

• Inexpensive die-casting alloys can be obtained from scrap aluminum, for example, but generally contain undesirably high levels of contaminants in the form of iron, copper, and zinc alloy components, in disadvantageous manner (EP1111077A1). This not only leads to reduced ductility potential, but rather can also have negative influences on strength as well as quenching sensitivity of the die-casting alloy. The most varied measures for reciprocal weighting of the alloy elements, as well as diverse suggestions for additives are known from the state of the art—particularly in order to thereby compensate for the negative influences of the contaminants.
• a die-casting alloy having 5 to 13 wt.-% Si, having maximally 0.5 wt.-% Mg, having 0.1 to 1.0 wt.-% Mn, and having 0.1 to 2.0 wt.-% Fe is known from JP9-003610.
• Mn is supposed to suppress the formation of Al—FeSi needle crystals, for example, in order to prevent a reduction in strength.
• Mg is supposed to be kept to a content as low as possible, maximally 0.5 wt.-%.
• Cu and Zn contaminants, as these usually occur in significant amounts in the case of secondary aluminum, are not taken into consideration by the die-casting alloy in JP9-003610.
• DE102004013777B4 proposes a die-casting alloy having 5 to 18 wt.-% Si, having 0.15 to 0.45 wt.-% Mn, having 0.2 to 0.6 wt.-% Fe, having 0.3 to 0.5 wt.-% Mg, possibly having 0.1 to 0.5 wt.-% Cu, and having 4 to 5 wt.-% Zn.
• the content of maximally 0.5 wt.-% magnesium is supposed to prevent the formation of Mg—Fe “pi” phases, in order to thereby obtain stretchability.
• Cu is supposed to improve the heat strength of the alloy, whereby the content of zinc is supposed to be restricted to 4 to 5 wt.-%, in order to thereby adjust the strength and quenching sensitivity of the alloy.
• the content of zinc is supposed to be restricted to 4 to 5 wt.-%, in order to thereby adjust the strength and quenching sensitivity of the alloy.
• it is disadvantageous that such a composition of alloy elements can demonstrate low corrosion resistance, particularly because of the comparatively high zinc content, and this can lead to restrictions of the die-cast parts produced from it, in terms of safety technology.
• a die-casting alloy having 9 to 11 wt.-% Si, having maximally 0.6 wt.-% Fe, having 0.2 to 0.6 wt.-% Mn, having 0.05 to 0.4 wt.-% Cu, having 0.2 to 0.35 wt.-% Mg, and having maximally 0.35 wt.-% Zn is known from DE102009012073A1. It is true that DE102009012073A1 concerns itself with secondary aluminum—because of the lower limits of permissible Cu and Zn contents, which are set to be comparatively low, the bandwidth of secondary aluminum that can be used is comparatively restricted.
• the invention accomplishes the stated task in that the die-casting alloy contains
• a cost-advantageous die-casting alloy on the basis of Al—Si can be made available, because essentially, the proportion of primary aluminum is reduced or actually dispensed with, and thereby secondary aluminum can be used to a greater extent for the production of cast parts.
• the alloy components of the casting alloy are forced to remain within certain content limits, according to the invention, in order to thereby approach the parameters known for primary aluminum (for example strength values, ductility values, chemical reaction resistance, processability and/or castability).
• a quotient of weight percents of Fe and Mn of 0.35 to 1.5 can lead to the result that despite a comparatively high iron content, the formation of the ⁇ phase (for example Al 5 FeSi/Al 8.9 Fe 2 Si 2 ) in the structure, which precipitates in the form of fine needles, can be clearly reduced.
• An increasing occurrence of the ⁇ phase can be expected, which can be present due to the manganese content, according to the invention, of at least 0.25 wt.-%, as Al 15 (FeMn) 3 Si 2 .
• This a phase crystallizes in globulite form, and because of its compact structure can have a clearly more advantageous influence on the ductility than is known for the needle-shaped ⁇ phases.
• a die-casting alloy having comparatively great ductility can be ensured in this way.
• the total proportion of Fe and Mn in the die-casting alloy is restricted to maximally 1.5 wt.-%, the formation of coarse a phases can also be further reduced, even if the high cooling speeds that are usually carried out in die-casting methods are applied.
• the concentration provisions regarding Fe and Mn can therefore be beneficial for the ductility of the die-casting alloy, in particular.
• the copper present can essentially be bound in the Q phase (Al 5 Cu 2 Mg 8 Si 6 ) that preferentially forms.
• This concentration provision can therefore prevent the formation of phases susceptible to corrosion, such as, for example, the tao phase (Al 5 Cu 4 Zn) or the theta phase (Al 2 Cu) in the structure, so that despite comparatively high weight percents of Cu, which fact is utilized, according to the invention, for improving the heat hardening of the die-casting alloy, great corrosion resistance can also be maintained. Furthermore, because of this magnesium excess, the hardening mechanism of the alloy can be improved, because part of the Mg is bound in the Q phase (Al 5 Cu 2 Mg 8 Si 6 ), and thereby limits known in this regard, which occur as the result of excessive precipitation of Mg 2 Si pre-phases, can be overcome.
• phases susceptible to corrosion such as, for example, the tao phase (Al 5 Cu 4 Zn) or the theta phase (Al 2 Cu) in the structure, so that despite comparatively high weight percents of Cu, which fact is utilized, according to the invention, for improving the heat hardening of the die-casting alloy
• the concentration provisions concerning Cu and Mg can therefore satisfy particularly great demands of the die-casting alloy with regard to strength and chemical reaction resistance. Furthermore, improved processability, for example with regard to the weldability and rivetability of components composed of this die-casting alloy, can be achieved by means of the proposed concentration ratio of Cu and Mg.
• the introduction and/or adjustment of the aforementioned magnesium excess with regard to Cu can also be utilized to bind the increased Fe content of the die-casting alloy in a pi phase (Al 8 FeMg 3 Si 6 ).
• the ⁇ phase for example Al 5 FeSi/Al 8.9 Fe 2 Si 2
• the Mn content in the die-casting alloy because the pi phase (for example Al 8 FeMg 3 Si 6 ) can be used for absorption of Fe.
• the strength of the alloy determined, for example, by means of an interaction of the pre-phases Mg 2 Si and the Q phase (Al 5 Cu 2 Mg 8 Si 6 ), can be further improved by means of mixed crystal hardening, using embedded zinc.
• zinc must be adjusted within the content limits of 0.40 to 1.5 wt.-%.
• this can be beneficial for the ductility of the die-casting alloy. In this way, a possible negative influence of a comparatively high Mg content on the ductility of the die-casting alloy can be reduced.
• the content limits of Zn can distinguish themselves in the improvement in castability of the die-casting alloy, thereby making it possible to compensate impairments, in this regard, to a great extent, on the basis of the proposed content limits of Mn in the die-casting alloy.
• the die-casting alloy on the basis of Al—Si which is balanced in terms of the alloy components Fe, Mn, Cu, Mg, and Zn, can therefore combine comparatively great ductility, corrosion resistance, strength, castability, and processability with one another, and thereby overcome parameter limits known from the state of the art, even if the die-casting alloy contains secondary aluminum and/or the latter is added to it, or comparatively high contents of contaminants are brought about thereby.
• the die-casting alloy can contain 50 to 300 ppm strontium (Sr) and/or 20 to 250 ppm sodium (Na) and/or 20 to 350 ppm antimony (Sb).
• Sr strontium
• Na sodium
• SB antimony
• maximally 0.2 t.-% titanium (Ti) and/or maximally 0.3 wt.-% zirconium and/or maximally 0.3 wt.-% vanadium (V) can prove to be advantageous for grain refinement of the die-casting alloy.
• the die-casting alloy can be supplemented to 100 wt.-%, in each instance, with Al, whereby this die-casting alloy can also contain process-related unavoidable contaminants. In general, it should be mentioned that the die-casting alloy can contain contaminants at maximally 0.1 wt.-% per contaminant, and at most 1 wt.-% in total.
• secondary aluminum is understood to be aluminum or an aluminum alloy obtained from scrap aluminum.
• measurement unit ppm is understood to mean weight ppm.
• Strength, ductility, processability, and chemical reaction resistance of the die-casting alloy can be further improved if this alloy contains 0.3 to 1.0 wt.-% iron (Fe), 0.25 to 1.0 wt.-% manganese (Mn), and 0.1 to 0.6 wt.-% copper (Cu).
• the die-casting alloy can be further improved with regard to the ductility, strength, and corrosion resistance that can be achieved for it if the total proportion of Fe and Mn in the die-casting alloy, together, amounts to maximally 1.2 wt.-%, the quotient of the weight percents of Fe and Mn amount to 0.5 to 1.25, and the quotient of the weight percents of Cu and Mg amounts to 0.2 to 0.5.
• the die-casting alloy contains 9.5 to 11.5 wt.-% silicon (Si) and/or 0.35 to 0.6 wt.-% iron (Fe) and/or 0.3 to 0.75 wt.-% manganese (Mn) and/or 0.1 to 0.4 wt.-% copper (Cu) and/or 0.24 to 0.5 wt.-% magnesium (Mg) and/or 0.40 to 1.0 wt.-% zinc (Zn), narrower limit ranges for a die-casting alloy on the basis of Al—Si, which is improved in terms of its mechanical strength and/or chemical resistance, occur.
• the alloy 1 is a die-casting alloy composed of primary aluminum with a low degree of contamination.
• Alloy 2 in contrast, demonstrates a significant degree of contaminants of iron and copper alloy components, which can be introduced by secondary aluminum, for example.
• the alloys or the die-cast parts or test bodies produced from them were subjected to T7 heat treatment with one hour at 460° C., solution annealing, quenching with water, and two hours of hot aging at 220° C.
• the finished test bodies were finally investigated with regard to their mechanical properties.
• the tensile strength R m , the yield strength R p0.2 , and the elongation to rupture A 5 were determined in a tensile test.
• the measurement values obtained are summarized in Table 2.
• the die-casting alloy No. 2 showed that the formation of an undesirable beta phase during solidification can be avoided by means of the adjusted iron component and manganese content.
• the copper component can also be completely bound in the Q phase by means of a magnesium component, thereby achieving comparatively great corrosion resistance.
• increased strength and elongation to rupture of 13.8% can be achieved, despite the iron content of 0.5 wt.-%.
• the comparatively high zinc content leads to an increase in strength, without any negative influence on the mechanical properties.

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• 2012
  • 2012-04-26 EP EP12165829.8A patent/EP2657360B1/de active Active
  • 2012-04-26 PL PL12165829T patent/PL2657360T3/pl unknown
  • 2012-04-26 SI SI201230032T patent/SI2657360T1/sl unknown
  • 2012-04-26 ES ES12165829.8T patent/ES2466345T3/es active Active
• 2013
  • 2013-04-10 WO PCT/EP2013/057521 patent/WO2013160108A2/de active Application Filing
  • 2013-04-10 CA CA2871260A patent/CA2871260C/en active Active
  • 2013-04-10 CN CN201380022231.6A patent/CN104350165B/zh active Active
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