EP1546421A2 - Procede de coulage de metal semi-solide et produit coule - Google Patents

Procede de coulage de metal semi-solide et produit coule

Info

Publication number
EP1546421A2
EP1546421A2 EP03759315A EP03759315A EP1546421A2 EP 1546421 A2 EP1546421 A2 EP 1546421A2 EP 03759315 A EP03759315 A EP 03759315A EP 03759315 A EP03759315 A EP 03759315A EP 1546421 A2 EP1546421 A2 EP 1546421A2
Authority
EP
European Patent Office
Prior art keywords
alloy
casting process
ssm
hypereutectic
hypoeutectic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP03759315A
Other languages
German (de)
English (en)
Inventor
Deepak Sha
Diran Apelian
Rathindra Dasgupta
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SPX Technologies Inc
Original Assignee
SPX Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by SPX Corp filed Critical SPX Corp
Publication of EP1546421A2 publication Critical patent/EP1546421A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/007—Semi-solid pressure die casting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/12—Making non-ferrous alloys by processing in a semi-solid state, e.g. holding the alloy in the solid-liquid phase
    • 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

Definitions

  • the present invention relates generally to the process of casting metal alloys. More particularly, the present invention relates to a method of casting aluminum-silicon alloys for semi-solid metal rheocasting.
  • SSM Semi-solid metal
  • Al hypereutectic aluminum
  • thixocasting is the most common approach.
  • Thixocasting involves the heating of a metal alloy to the liquid state and then the electromagnetic stirring of the melt during solidification/freezing. These billets are subsequently cut into slugs, and re-heated to a semi- solid state before being injected for casting.
  • rheocasting which is also known as "slurry” or “slurry-on-demand” casting, eliminates several steps required by thixocasting techniques. This process involves singularly heating a metal to a liquid state and then cooling the molten metal to the required SSM phase, before injecting the semi-solid metal into the mold/die cavity.
  • the mechanical and metallurgical properties of hypereutectic SSM castings are predicated, in part, by the microstructures of primary Si in the final part.
  • the size and morphology of these particles can be controlled by the cooling rate of the hypereutectic alloy to the required temperature and the isothermal hold time at the SSM temperature.
  • solid primary phase particles are a part of the semi-solid metal being injected into a mold die cavity
  • the microstructure of the primary phase of an aluminum alloy prior to injection into a mold/die is indicative of the microstructure of the primary phase of the resulting aluminum alloy casting.
  • the mechanical properties of a casting can be predicted before a casting is even produced. Accordingly, many attempts have been made to improve methods to achieve the requisite microstructure. Known strategies including electromagnetic stirring and addition of grain refiners.
  • FIG. 1 is a phase diagram of the composition versus temperature of the alloys used in the mixing experiments.
  • FIG. 2 shows the time versus temperature plot for various experiments.
  • FIG. 3 shows representative microstructures from the castings produced from the experiments outlined in Figure 2.
  • the present invention provides a method for controlling the composition, temperature and microstructure of Al-Si alloys prior to SSM casting to control the mechanical properties of the final cast product. Generally, this is accomplished by mixing a hypereutectic Al-Si alloy with a hypoeutectic Al-Si alloy. By definition, aluminum alloys with less than about 12.6 percent Si are considered hypoeutectic whereas those with greater than about 12.6 percent Si are considered hypereutectic ( Figure 1).
  • the metallic composition of alloys used in current methods for SSM casting are limited to the availability and composition of the starting materials.
  • a broad range of metallic compositions are achievable from the same starting materials. This is because the combination of a hypereutectic solution into a hypoeutectic allows for the manipulation of the final concentration of Si in the Al-Si alloy by controlling the composition and mass of the two liquids or semi-solid slurries.
  • the final concentration of Si present in the alloy determines many of its mechanical properties. For example, increasing amounts of Si provides greater wear-resistance and strength with lower expansion rates.
  • the final, mixed alloy composition is about 17 percent to about 18 percent Si in aluminum, formed by combining a hypereutectic aluminum alloy comprising about 23 percent to about 25 percent Si and a hypoeutectic aluminum alloy comprising about 7 percent to about 8 percent Si.
  • a hypereutectic alloy can contain about 12.6 percent to over 25 percent Si in aluminum.
  • a hypoeutectic alloy can contain about 12.6 percent or less Si in aluminum.
  • One example of a hypoeutectic alloy with about 7% Si is developed by Elkem (under the trademark of SIBLOY®), and is preferable for SSM processing of hypoeutectic Al-Si alloys because the alpha aluminum formed in the melt is independent of the hold time.
  • Figure 1 is a phase diagram showing the composition of alloys as varied by temperature. According to Figure 1, about 12.6 percent Si in aluminum defines the eutectic point, which is defined as the lowest melting point possible between two substances in an alloy or solution.
  • the phase diagram also indicates the temperature to which the alloys need to be raised in order to be entirely in the liquid state; this consists of the area designated above the liquidus line 1.
  • the shaded areas 2, 3 indicate the temperature and composition where the alloy is in a semi-solid phase, containing both liquid and solid matter.
  • the semi-solid phase is where deposits of one of the metals in the alloy begin to form.
  • hypereutectic Al-Si alloys begin to develop large Si particles as they begin to cool below the liquidus and into the SSM range.
  • the instant invention teaches a method of mixing two Al-Si alloys at different temperatures together so that the amount of time the mixture spends in the transitional semi-solid phase is minimized.
  • Temperature control of the alloys can also be achieved by mixing a hypereutectic alloy with a hypoeutectic alloy as in the present invention. Generally, one alloy is heated to a liquid state and then mixed with an alloy of cooler temperature to bring the combined melt within the SSM range. The hypoeutectic alloy is generally maintained at a lower temperature than the hypereutectic alloy. Preferably, the hypereutectic alloy is generally poured into the hypoeutectic alloy, however, it is also possible to pour the hypoeutectic alloy into the hypereutectic alloy.
  • the hypereutectic alloys are heated to a range of about 800°C to about 900°C and combined with hypoeutectic alloys which are heated in the range of 350°C to about 580°C.
  • the hypereutectic alloy is raised to about 800°C and the hypoeutectic alloy to about 500°C. This large temperature gradient allows for a quicker extraction of heat from the parent hypereutectic alloy and decreases the time necessary for the liquid alloy to drop in temperature to a semi-solid/slurry processing temperature.
  • the growth of Si particles in the semi-solid phase is directly correlated to the time in addition to the temperature of the alloy. Longer time periods in the semi-solid phase is conducive for undesirable growth of large Si particles. Alternatively, shortening that period minimizes the growth of large Si particles by maximizing the number of nucleating events, producing more Si particles of smaller size.
  • Al- Si alloys can spend a defined length of time in the casting machinery/device in addition to the imposed cooling times. Therefore, in addition to temperature control, it is preferable to define the time parameters (i.e. cooling rates) within which the desirable properties of the alloy are realized.
  • Figure 3 shows the microstructure of the alloys from the experiments described after they had been quenched.
  • Microanalysis of the casting from experiment 7 (Figure 3A) shows that the primary Si particles range in size from about 60 microns to about 100 microns in diameter.
  • the primary Si are also relatively evenly distributed with minimal aggregate formation as compared with controls.
  • Figure 3B shows the morphology of primary Si from experiment 6 to be radiating from a given point (star-shaped). This is generally observed when the cooling rates are slow and were controlled by elevating the temperature of the hypoeutectic solution to about 570°C.
  • the star shaped primary Si structures were reduced by decreasing the temperature of the hypoeutectic alloy from 570°C to 500°C as shown in Figure 3A from experiment LM # 7.
  • Results from experiment 5 show that the amount of dissolved aluminum can be controlled by regulating the temperature of the hypoeutectic solution.
  • Figure 3C shows the structures obtained when the hypoeutectic alloy is heated to 350°C and then mixed into the hypereutectic alloy.
  • Figure 3D similarly shows results from experiment 4 where undissolved primary aluminum of the hypoeutectic alloy remain in the final casting. In this case, the final temperature was 615°C. Small primary Si can be seen on the primary aluminum, indicating that the heat extracted by the primary aluminum provided local undercooling and assisted in the nucleation of the primary Si.
  • Figure 3E is a representative example of the microstructure from experiments LM # 1-3 and shows the dissolution of primary aluminum as the melts were held at a higher temperature (ranging from about 625°C to about 636°C).
  • SSM cast hypereutectic alloys can be attained by controlling the temperatures of the hypo- and hypereutectic solutions and the hold times at the SSM temperature during casting.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Continuous Casting (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Silicon Compounds (AREA)

Abstract

L'invention concerne un procédé d'affinage de silicium primaire dans des alliages hypereutectiques, qui consiste à mélanger un alliage hypereutectique et un alliage hypoeutectique solide/semi-solide. Le procédé permet de régler la morphologie, la taille et la distribution de Si primaire dans un moulage Al-Si hypereutectique par le mélange d'un liquide hypoeutectique Al-Si et d'un liquide hypereutectique en vue d'obtenir des propriétés mécaniques voulues.
EP03759315A 2002-09-20 2003-09-22 Procede de coulage de metal semi-solide et produit coule Withdrawn EP1546421A2 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US293694 1994-08-19
US41187202P 2002-09-20 2002-09-20
US411872P 2002-09-20
US10/293,694 US20040055724A1 (en) 2002-09-20 2002-11-14 Semi-solid metal casting process and product
PCT/US2003/029552 WO2004027101A2 (fr) 2002-09-20 2003-09-22 Procede de coulage de metal semi-solide et produit coule

Publications (1)

Publication Number Publication Date
EP1546421A2 true EP1546421A2 (fr) 2005-06-29

Family

ID=31996870

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03759315A Withdrawn EP1546421A2 (fr) 2002-09-20 2003-09-22 Procede de coulage de metal semi-solide et produit coule

Country Status (4)

Country Link
US (1) US20040055724A1 (fr)
EP (1) EP1546421A2 (fr)
AU (1) AU2003275047A1 (fr)
WO (1) WO2004027101A2 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6880613B2 (en) * 2003-05-01 2005-04-19 Spx Corporation Semi-solid metal casting process of hypoeutectic aluminum alloys
US20050103461A1 (en) * 2003-11-19 2005-05-19 Tht Presses, Inc. Process for generating a semi-solid slurry
SE528376C2 (sv) * 2004-12-10 2006-10-31 Magnus Wessen Förfarande och anordning för framställning av en flytande- fast metallkomposition
CN100415908C (zh) * 2006-10-14 2008-09-03 重庆工学院 一种用于亚共晶铸造铝硅合金热处理强化的固溶处理方法
CN102864350A (zh) * 2012-10-15 2013-01-09 兰州理工大学 免变质过共晶铝硅合金的制备方法
CN103381472B (zh) * 2013-07-30 2016-03-02 上海交通大学 过共晶铝硅合金半固态浆料或坯料的制备方法
CN111763837B (zh) * 2020-06-29 2021-07-09 东南大学 一种细化过共晶铝硅合金初生硅相的方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2788788B1 (fr) * 1999-01-21 2002-02-15 Pechiney Aluminium Produit en alliage aluminium-silicium hypereutectique pour mise en forme a l'etat semi-solide
WO2000043152A1 (fr) * 1999-01-26 2000-07-27 Spx Corporation Alliage pour procede de moulage semi-solide

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2004027101A2 *

Also Published As

Publication number Publication date
US20040055724A1 (en) 2004-03-25
WO2004027101A2 (fr) 2004-04-01
AU2003275047A1 (en) 2004-04-08
AU2003275047A8 (en) 2004-04-08
WO2004027101A3 (fr) 2004-06-03

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