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
• • 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
  • C22C21/10—Alloys based on aluminium with zinc as the next major constituent

Definitions

• the invention relates to the field of metallurgy, namely, to aluminium-based alloys, and can be used in the production of castings of complex shapes by casting into a metal mould, mainly by injection moulding.
• Well-known thermally non-hardenable Al-Si base alloys such as A413.2 or AlSi11 alloys, are noted for their high castability and good corrosion resistance. Disadvantages of this group of alloys include low level of strength properties, in particular, yield strength typically in the as-cast state does not exceed 80 MPa. A higher level of strength properties of castings in the as-cast state is provided by the addition of copper, in particular, alloys of the AA383.1 or AlSi12Cu2 type are known. Disadvantages of these alloys include a significant reduction in corrosion resistance and a poor elongation of no more than 1-2%.
• thermally non-hardenable casting alloys based on the Al-Mg system such as AMg6L, AMg5K, AMg5Mz (GOST1583), Magsimal ® 59 (Rheinfelden Alloys), among others, distinguished by satisfactory castability, good corrosion resistance and decent strength properties and elongation. High linear shrinkage and insufficiently good tightness of thin-walled castings should be highlighted among the disadvantages of the alloys of this system.
• alloys of the Al-Si system with an addition of 0.2-0.5 wt.% magnesium.
• Alloys of the AK9 type (GOST 1583), Silafont ® 36 (Rheinfelden Alloys), trimal ® 37 (Trimet), etc. are particularly known. Quenching significantly complicates the technological cycle of obtaining castings, since it can cause warping of castings (especially when using quenching in water), changes in overall dimensions and the appearance of cracks.
• a casting alloy of the Al-Ni-Mn system is as known intended for the production of structural components for automotive and aerospace applications, as well as an alternative to branded silumins, developed by Alcoa and disclosed in patent US 6,783,730 B2 (publication date: August 31, 2004 ).
• This alloy can be used to produce castings with a good combination of casting and mechanical properties in the case of (wt. %) 2-6% Ni, 1-3% Mn, 1% Fe, less than 1% silicon, as well as in the case of other unavoidable impurities.
• the disadvantages of the proposed alloy include the fact that the high level of casting and mechanical properties is ensured by using high-purity aluminium grades and with a high nickel content, thus significantly increasing the cost of the castings produced.
• the material proposed is thermally non-hardenable in the entire concentration range, thus limiting its use, while the corrosion resistance of castings is significantly reduced in the area of high nickel concentration.
• Cast aluminium alloys based on Al-Ni and Al-Ni-Mn systems and a method of producing cast parts from them are known, which are described in Alcoa invention US8349462 (published on January 8, 2013 ) and application EP2011055318 of Rheinfelden Alloys GmbH & Co. KG .
• the invention proposes alloy compositions for casting applications. Common in the proposed inventions is a high nickel content of 1-6%, which determines the main disadvantage - a significant decrease in corrosion resistance. With relatively poor nickel and manganese content, casting alloys show a low level of strength properties.
• the alloy most closely analogous to the proposed alloy is invented by the Institute of Lightweight Materials and Technology, disclosed in claim RU 2745595 .
• the material for use in the as-cast state contains, wt.%: 1.5-5.1% calcium, 0.1-1.8% zinc, up to 1.0% silicon and up to 0.7% iron.
• Disadvantages of the proposed alloy include poor yield strength in the as-cast state due to poor solubility of alloying elements, except for zinc, in solid solution and as a consequence insufficient solid-solution hardening.
• the invention is intended to provide a new aluminium casting alloy for producing castings mainly by high pressure, but not limited thereto, to be used without heat treatment, with good casting processability, good mechanical properties, including yield strength of no less than 100 MPa and high corrosion resistance.
• the key application is casting for automotive engineering, electronic enclosures, etc. Parts for critical applications can be manufactured from this material.
• This invention is technically aimed at ensuring high strength properties while maintaining plasticity, castability and high corrosion resistance.
• the technical result is achieved by using an aluminium-based casting alloy containing calcium, silicon, iron, zinc, magnesium and, optionally, at least one element from the group including copper, manganese, chromium, titanium, and zirconium, with concentrations of alloying elements by weight, as specified below.
• Magnesium 0.01-2.0 preferably 0.05-0.5).
• the alloy contains at least one alloying element from the group: Copper 0.01-1.4 (preferably 0.02-0.5) Manganese 0.01-1.5 (preferably 0.5-1.0) Chromium 0.01-0.2 (preferably 0.05-0.1) Titanium 0.01-0.2 (preferably 0.05-0.1) Zirconium 0.01-0.2 (preferably 0.05-0.1)
• the rest is aluminium and unavoidable impurities.
• magnesium is arranged in an aluminium matrix and copper is bonded to calcium and forms a eutectic phase, thus providing enhanced strength properties without compromising ductility.
• the alloy is applied for producing castings that exhibit the following tensile properties in the as-cast state: yield strength of no less than 100 MPa.
• concentrations (wt.%) of calcium (2.0-5.2), silicon (0.05-0.8), iron (0.05-1.0), zinc (0.01-5.0) and copper (optionally 0.01-1.4) are limited to the specified limit to ensure forming a structure representing an aluminium solid solution and the corresponding eutectic phases containing calcium and the following elements: silicon, iron, zinc and optionally copper.
• Calcium, silicon, iron, zinc, and optionally copper influence the overall amount of eutectic phase in the alloy.
• the eutectic content is approximately 2.5 vol.%.
• magnesium 0.01-2.0
• at least one element from the group including manganese (0.01-1.5), chromium (0.01-0.2), titanium (0.01-0.2), and zirconium (0.01-0.2) allow, when combined with the above elements (calcium, silicon, iron, zinc and, if present, copper), to form a structure representing an aluminium solid solution as a primary crystallising phase and a eutectic that contains at least one alloying element including manganese, chromium, titanium and zirconium.
• Magnesium and, optionally, at least one of the elements including manganese, chromium, titanium and zirconium within the specified limits can enhance hardening through dissolution in the aluminium solid solution (solid solution hardening), while also increasing the crystallisation interval, adversely affecting casting properties.
• Figure 1 illustrates a typical alloy structure in the as-cast state, featuring the primary aluminium solid solution and the eutectic phases.
• the structure in the as-cast state is represented by an aluminium solid solution containing zinc, magnesium and eutectic phase particles that include compounds of aluminium, calcium with zinc, aluminium, calcium with iron and aluminium, calcium with silicon, in relation to the presence of certain elements in the alloy.
• the structure in the as-cast state is qualitatively similar and consists of an aluminium solid solution containing zinc, magnesium manganese, chromium, titanium and zirconium, as well as eutectic phase particles with compounds of aluminium, calcium with zinc, aluminium, calcium with iron, aluminium, calcium with silicon and aluminium, calcium with copper.
• Calcium content below 2.0 wt.% results in poor casting properties, failing to ensure the binding of elements such as silicon, iron, zinc and optionally copper with calcium. Calcium content above 5.2 wt.% results in the formation of coarse inclusions of the primary phase Al 4 Ca, thus reducing mechanical properties.
• Silicon content between 0.05 and 0.8 wt.% with calcium provides good elongation in the as-cast state, as silicon aids in dispersing the eutectic.
• silicon content above 0.8 wt.% coarse intermetallics containing silicon form, consequently reducing mechanical properties.
• Below 0.05 wt.% silicon is not enough to form a eutectic with favourable morphology, resulting in inadequate elongation in the as-cast state.
• Iron content between 0.05 and 1.0 wt.% with calcium enhances casting properties while maintaining an acceptable elongation level.
• Iron content below 0.05 wt.% worsens the alloy casting processability, as manifested by increased adhesion of the casting to moulds.
• Iron content above 1.0 wt.% forms coarse intermetallics of crystallisation origin containing iron and calcium, thereby reducing mechanical properties.
• Zinc content between 0.01 and 5.0 wt.% enhances corrosion resistance and boosts casting properties. At zinc content below 0.01 wt.%: no beneficial impact of zinc on strength properties observed. From 0.01 wt.% onwards, there is a modification effect manifested as a change in the calcium-containing eutectic morphology. Zinc content above 5.0 wt.% forms coarse crystallisation-origin phases containing zinc and calcium, adversely affecting the alloy's mechanical properties.
• Copper content (optionally) between 0.01 and 1.4 wt.% enhances strength properties without compromising casting performance and maintains corrosion resistance at an acceptable level. Satisfactory corrosion resistance with copper content is maintained by binding copper in a phase with calcium. At copper content below 0.01 wt.%: no positive impact of copper on mechanical or other properties observed. At low copper content starting from 0.01 wt.%, there is modification effect changing the morphology of eutectic phases containing calcium by forming phases with copper and calcium.
• Magnesium content between 0.01 and 2.0 wt.% enhances the strength properties in the as-cast state. At magnesium content exceeding 2.0%, the crystallisation interval is significantly widened, thus unacceptably worsening casting properties, in particular, the hot-tearing tendency. At magnesium content below 0.01 wt.%: no positive impact on strength properties together with other elements within the specified chemical composition observed.
• Chromium content between 0.01 and 0.2 wt.% facilitates solid solution hardening in the as-cast state. With higher content, primary crystals of Al 7 Cr phase are significantly more likely to form, reducing mechanical properties.
• Titanium content between 0.01 and 0.2 wt.% aids in modifying primary precipitates of the aluminium solid solution during crystallisation.
• a higher titanium content in the structure may result in the appearance of primary crystals to reduce the overall level of mechanical properties, while a lower titanium content will not achieve the positive effect of this element.
• boron or carbon may be found in the alloy proportionally to their content in the master alloy. Boron and carbon, as independent elements, have no significant effect on the mechanical and casting properties for the range in question.
• Zirconium content between 0.01 and 0.2 wt.% facilitates solid solution hardening in the as-cast state. Larger quantities require casting temperatures to rise above typical levels, thus reducing the durability of casting moulds and enhancing the hot cracking tendency.
• the structure may contain up to 0.3 vol.% of primary crystals including manganese, chromium, zirconium or titanium, thus reducing the casting adhesion to the mould walls.
• Phase composition in particular, the number of eutectic phases, the number of primary crystals was quantitatively assessed in at least one of the two following ways: 1) by Thermo-calc calculation; 2) metallographically.
• Alloys were prepared in either an induction or resistance furnace in graphite crucibles using primary aluminium with a minimum content of 99.8 wt.% and 99.99 wt.%, zinc no less than 99.90 wt.%, copper no less than 99.9 wt.% and magnesium no less than 99.9 wt.% (the purity of the base metals is specified for use in the melt), along with master alloys: AlCa10, AlFe10, AlMn20, AlSi10, AlTi5, AlCr10, AlZr10. Other elements and unavoidable impurities in the alloy did not totally exceed 0.05 wt.% found in primary aluminium and master alloys and not regulated for melt preparation.
• alloys were crystallised in a metal mould, 'separately cast cylindrical sample', with an operating part diameter of 10 mm and a mould temperature of up to 150 °C. Casting properties of the alloys were determined by hot-tearing tendency by using the ⁇ ring sample', with the best indicator as the ring having the minimum wall thickness at a constant outer diameter of 40 mm, crystallised without cracking in the row of 3, 7 and 10 mm.
• the mechanical properties were evaluated under uniaxial tension of separately cast samples in the as-cast state. The test speed was 10 mm/min, with a working part length of 50 mm, as per GOST 1583-93. Adhesion was tested based on the material's ability to be separated from the surface of the metal mould without mechanical impact.
• compositions 2-5 and 8-26 according to the claimed concentration range provide an acceptable level of hot cracking resistance.
• Compositions 1, 6, 7 are not applicable because composition 1 is more likely to adhere to the mould walls.
• Composition 6 is distinguished by a high hot cracking tendency and composition 7 by the realisation of an unsatisfactory structure with unacceptable primary crystals containing calcium, iron, silicon, and zinc, significantly reducing the elongation.
• Table 4 Chemical composition, wt.% No Ca Si Fe Zn Mn Mg Cr Zr Al 30 4.5 0.7 0.2 1.4 0.8 0.1 0.08 0.12 Base metal 31 3.3 0.75 0.2 1.4 0.8 0.02 0.05 0.05 Base metal 32 4.0 0.5 0.3 1.4 0.8 0.02 0.04 0.08 Base metal Table 5: Mechanical properties No Ultimate tensile strength, MPa Yield strength, MPa Elongation, % 30 270 205 6.1 31 235 110 11.5 32 250 125 8.5

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• Continuous Casting (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)

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• 2023
  • 2023-09-07 CN CN202380067940.XA patent/CN119998476A/zh active Pending
  • 2023-09-07 WO PCT/RU2023/050210 patent/WO2024072262A1/fr not_active Ceased
  • 2023-09-07 KR KR1020257013188A patent/KR20250076581A/ko active Pending
  • 2023-09-07 JP JP2025517894A patent/JP2025534295A/ja active Pending
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