Classifications

• • 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
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/62—Quenching devices
  • C21D1/667—Quenching devices for spray quenching
• • 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
  • C22C21/12—Alloys based on aluminium with copper as the next major constituent
• • 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
  • C22C21/12—Alloys based on aluminium with copper as the next major constituent
  • C22C21/14—Alloys based on aluminium with copper as the next major constituent with silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
  • C22F1/057—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with copper as the next major constituent

Definitions

• the invention relates to a method for producing complex shaped castings from an AlCu alloy.
• AlCu alloys of the type in question existing castings have particularly high strengths, especially at elevated temperatures of more than 250 ° C. However, this is offset by poor casting properties, which complicate the casting-technical production of components that are characterized by a complex shape.
• Typical examples of such castings are cylinder heads intended for internal combustion engines, which on the one hand are exposed to high temperatures in practical use and, on the other hand, have a compact design in which filigree shaped mold elements, such as cooling and oil passages, recesses, lands, guides and the like, are molded.
• a significant problem in the processing of essentially Si-free AlCu alloys results from their high susceptibility to hot cracking and a refilling behavior that is significantly worse than with conventional AlSi alloys.
• a method of making complex shaped castings from an AlCu alloy which consists of (in wt%) 2 - 8% Cu, 0.2 - 0.6% Mn, 0.07 - 0.3% Zr , up to 0.25% Fe, up to 0.3% Si, 0.05-0.2% Ti, up to 0.04% V and the remainder being Al and unavoidable impurities, the sum of the contents being Impurities is not more than 0.1%.
• the presence of Zr is attributed a special significance with regard to the production of a fine microstructure with particle sizes of at most 100 ⁇ m.
• a grain refining agent such as, for example, TiC in a dosage of typically 2 kg per ton of melt, may additionally be added prior to casting in carrying out the known method of a correspondingly composed melt.
• the casting obtained after casting and solidification is subjected to a heat treatment, in which it is first solution-annealed at 530-545 ° C. From the solution annealing temperature, the casting is accelerated by means of water or in the air stream accelerated, in particular, the quench with water is considered to be advantageous in terms of the desired high strength, but the cooling in the air stream is recommended in the case that the casting, due to its complex shape tends to crack during faster cooling. After quenching, the casting is held at a temperature of 160-240 ° C over a period of 3 to 14 hours to increase the hardness of the structure.
• the object was to provide a method which allows in a practical, reliable manner, the production of castings from an AlCu alloy of the known type.
• the invention has achieved this object in that in the production of castings made of an AlCu alloy, the steps specified in claim 1 are completed.
• the inventive method is based on that of the already mentioned WO 2008/072972 A1 known AlCu alloy and provides a casting that meets the highest demands on its performance in practical use.
• Copper is present in the inventively processed alloy in contents of 6-8 wt .-%, in order to achieve the required heat resistance of the casting to be produced. Optimum properties in this respect are achieved when the Cu content of the alloy processed according to the invention is 6.5-7.5% by weight.
• Manganese in contents of 0.3-0.55% by weight supports the diffusion of Cu in the Al matrix of the structure of a component produced according to the invention and thus stabilizes the strength of the alloy according to the invention even at high operating temperatures. This effect is achieved particularly reliably when the Mn content is 0.4-0.55% by weight.
• Zirconium has a special significance for the heat resistance of castings produced according to the invention.
• Zr contents of 0.15-0.25% by weight favor the formation of disperse precipitates which ensure that the castings cast from casting alloys according to the invention have a fine microstructure which is optimally uniform over the casting volume Distribution of mechanical properties and a minimized tendency to crack has.
• Iron is undesirable in an alloy according to the invention because it tends to form brittle phases.
• the Fe content is limited to a maximum of 0.25 wt .-%, preferably 0.12 wt .-%.
• the content limit prescribed for the Si content according to the invention is at most 0.125% by weight, because with higher contents of Si the risk of the formation of hot cracks increases. Negative effects of Si on the properties of an alloy according to the invention can be safely excluded by limiting the Si content to at most 0.06% by weight.
• the sum of the contents of impurities due to melting and production unavoidable impurities should be kept low as in the prior art, in particular not exceed 0.1 wt .-%.
• the invention is based on the recognition that it is necessary for the production of reliable defect-free complex shaped castings, such as cylinder heads for gasoline or diesel-powered internal combustion engines, from an AlCu alloy to modify the parameters of the manufacturing process over the already known measures. Only in this way can be produced reliably according to the invention composite castings, the have a particle size of less than 100 ⁇ m, ideally less than 80 ⁇ m, over their entire volume.
• the melt must be kept warm for a sufficiently long duration in a suitable temperature range.
• step b) of the method according to the invention could not yet be conclusively clarified.
• the presence of Zr, Ti and optionally V in the quantities provided according to the invention seems to have a decisive influence.
• step d) the actual casting operation begins with step d).
• the working steps d) -i) of the method according to the invention are then repeated until the number of castings intended for the respective casting campaign has been produced.
• the mixing between two portion withdrawals can be repeated.
• the thorough mixing carried out, for example, as intensive stirring can be carried out in the course of a conventional degassing treatment, as is customarily used in the production method of the type in question before the start of the actual casting operation starting with the first removal of a melt portion.
• the formation of a particularly fine structure in the castings produced according to the invention can be further supported by the fact that the respective melt portion, for example, on its way to the casting mold, is optionally subjected to a grain refining treatment prior to casting to the casting.
• a grain refining treatment can be used in the application of the method according to the invention produce castings in which the structure of an average grain size of less than 60 microns can be guaranteed.
• Grain refining agents optionally added according to the invention are suitable for this purpose already known compounds, such as TiC or TiB, which can be added in each case in a dosage of 1 - 10 kg per ton of melt.
• TiC or TiB which can be added in each case in a dosage of 1 - 10 kg per ton of melt.
• step e of the method according to the invention is in principle any conventional casting process. This includes the possibility of conventional gravity casting.
• a common characteristic of the dynamic casting process which is also known by the term "tilt casting method" is that the casting mold is filled via a melt container docked to it by a melt container from a starting position, in which the melt container is filled with the melt to be cast, around a Swivel axis is rotated to an end position, so that flows as a result of this pivotal movement, the melt in the mold.
• Examples of such methods are in the EP 1 155 763 A1 , of the DE 10 2004 015 649 B3 , of the DE 10 2008 015 856 A1 , of the DE 10 2010 022 343 A1 and the hitherto unpublished German patent application DE 10 2014 102 724.8 described.
• steps a) - e) and additionally performed if necessary grain refining treatment is already a casting after casting and solidification, the structure of which meets the requirement of its fine grain requirement (average particle size ⁇ 100 microns).
• the casting according to the invention now undergoes a heat treatment in which it first undergoes solution heat treatment at a solution annealing temperature of 475-545 ° C. over a solution annealing time of 1-16 hours.
• the solution temperature can be set to 515-530 ° C.
• the duration of solution heat treatment has no significant influence. It is to be set within the framework according to the invention so that the copper content present is optimally dissolved in the Al matrix. In practice, it is typically possible here to dissolve at least 60% of the existing Cu content, with the aim of dissolving the highest possible proportions, for example at least 70% or more, of the Cu content present. For this purpose, a solution annealing time of 2 to 6 hours can be provided in practice in the casting production of components for internal combustion engines.
• the respective casting is accelerated from the solution annealing temperature to a quench stop temperature of at most 300 ° C.
• the quenching rate is of decisive importance.
• the quench rate is limited at the bottom by the fact that too slow cooling results in too low strengths. It can thus be seen that with conventional air quenching, the tensile strength and yield strength of castings consisting of the alloy processed according to the invention are lower than those of castings consisting of standard alloys. Therefore, in step g), the invention provides a quench rate of at least 0.75 K / s on average over the entire casting.
• the deterrent with a spray.
• the cooling is so gentle that it does not crack even when the spray is applied at room temperature.
• the upper limit of quenching rate achieved over the entire casting in the inventively made deterrent in step g) of the inventive method is limited to 15 K / s to avoid cracking.
• Ideal is an average cooling rate of 1.5 - 7.5 K / s achieved over the entire casting.
• a water quenching with 90 ° C warm water gives a cooling rate of about 7.5 K / s and led to the best results in the trial of the method according to the invention.
• the quenching agent as mentioned, for example, be applied as a wave or spray.
• spray mist cooling it is possible to cool the parts by pressurizing their outside or inside by passing the quencher through channels in the casting, such as a cylinder head through the water jacket.
• measures are, for example, in the DE 102 22 098 B4 described. Cooling from the outside results a cooling rate of approx. 2 - 2.5 K / s, with an internal quenching the quenching rates are 1.5 - 3.75 K / s.
• step g) the casting is quenched to a temperature that is less than or equal to the subsequent aging temperature.
• the aging according to the invention lasts 1 - 10 hours at a 150 - 300 ° C, in particular 200 - 260 ° C, amounting Wärmauslagerungstemperatur.
• the thermal aging is thus based on the conventional procedure, unlike there, however, the invention expressly does not provide for aging.
• the duration of artificial aging has no significant effect on the treatment outcome. In order to achieve a stable condition of the casting, however, it has proved expedient to carry out the aging for at least 2 hours. In practice-oriented design, the duration provided for hot aging is typically 2 to 4 hours.
• Castings produced according to the invention are thus characterized in that they consist of an AlCu alloy with (in% by weight) 6 - 8% Cu, 0, 3 - 0.55% Mn, 0, 15 - 0.25% Zr, up to 0.25% Fe, up to 0.125% Si, 0.05-0.2% Ti, up to 0.04% V and as consisting of balance Al and unavoidable impurities and having a structure which has a mean grain size of less than 100 microns, especially less than 80 microns, has.
• manufactured and manufactured castings have minimized susceptibility to cracking even after at least 400 h use at temperatures of at least 250 ° C, as are typical for applications in internal combustion engines for automobiles, at a test temperature of 250 ° C, a tensile strength of at least 160 MPa , typically at least 200 MPa, and a yield strength of at least 100 MPa, typically at least 150 MPa.
• the melts S1, S2, S3 have been kept at a holding temperature TH in the melting furnace for a duration tH in each case.
• the castings G1-G4 (melt S1), G5 (melt S2) and castings G6, G7 (melt S3) have been cast from the melts S1, S2, S3.
• castings G1 - G5 were cylinder heads for diesel internal combustion engines, whereas cast parts G6, G7 were cylinder heads for gasoline internal combustion engines.
• the melt portion contained in the ladle has been added to each TiB in a dosage of DKF.
• the resulting castings After solidification and demolding, the resulting castings have been solution annealed at a solution annealing temperature TLG for a solution annealing time tLG.
• the castings After the end of the solution annealing, the castings have been quenched from the respective solution annealing temperature TLG to a quench stop temperature TAS at a cooling rate dAS.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Cylinder Crankcases Of Internal Combustion Engines (AREA)
• Continuous Casting (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Priority Applications (12)

Applications Claiming Priority (1)

Publications (2)

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• 2015
  • 2015-01-21 PL PL15151960T patent/PL3048179T3/pl unknown
  • 2015-01-21 ES ES15151960.0T patent/ES2633026T3/es active Active
  • 2015-01-21 EP EP15151960.0A patent/EP3048179B1/de active Active
• 2016
  • 2016-01-13 TW TW105100900A patent/TWI583803B/zh not_active IP Right Cessation
  • 2016-01-21 BR BR112017014023-3A patent/BR112017014023B1/pt active IP Right Grant
  • 2016-01-21 US US15/545,062 patent/US10081856B2/en active Active
  • 2016-01-21 RU RU2017129447A patent/RU2670627C1/ru active
  • 2016-01-21 KR KR1020177020538A patent/KR101891226B1/ko active IP Right Grant
  • 2016-01-21 WO PCT/IB2016/000036 patent/WO2016116805A1/de active Application Filing
  • 2016-01-21 MX MX2017009062A patent/MX2017009062A/es unknown
  • 2016-01-21 CN CN201680006763.4A patent/CN107208199B/zh active Active
  • 2016-01-21 JP JP2017538321A patent/JP6359778B2/ja active Active

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