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
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
  • C22C21/08—Alloys based on aluminium with magnesium 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
  • C22F1/04—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
  • C22F1/047—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 magnesium 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

Definitions

• the invention refers to the non-ferrous metallurgy, in particular to non-heat-treatable workable aluminium alloys based on the aluminium-magnesium-scandium system used as materials for elements of structures including welded structures, which are fabricated also using the shaping operation.
• a non-heat-treatable workable aluminium alloy based on the aluminium-magnesium-scandium system, which is widely used at present, is AMg5 grade alloy (as per GOST 4784-2019) with the following composition, % wt: Magnesium 4.8-5.8 Manganese 0.3-0.8 Titanium 0.02-0.1 Beryllium 0.0002-0.005 Aluminium Balance
• the alloy is widely used in various industries, such as ship building, aerospace engineering, construction, and transport machine building.
• the alloy is weldable using all welding procedures and highly corrosion-resistant.
• the main disadvantage of this alloy is its unsatisfactory strength.
• Non-heat-treatable wrought alloy designed for application in cold-moulded products with irregular shape, such as vessels, tanks, cans, etc. including welded structures ( WO 2018/187406A1 , C22C3/00, B32B15/01 published on October 11th, 2018).
• the alloy is designed for products, such as home appliance parts, construction elements, and vehicle body parts, which can be anodised.
• the alloy has the following composition, % wt: Silicon 0-0.1 Iron 0-0.2 Copper 0-0.3 Manganese 0-0.5 Magnesium 2.0-5.0 Chromium 0-0.2 Zinc 0-0.2 Titanium 0-0.1 Aluminium Balance
• a disadvantage of this alloy is its insufficient strength due to low contents of elements readily-soluble in aluminium, which ensure solid-solution hardening, and low quantity of transition metal additives, which ensure hardening through formation of dispersoids.
• This alloy has the following chemical composition, % wt: Magnesium 5.0-6.0 Scandium 0.06-0.16 Beryllium 0.0002-0.005 Manganese 0.15-0.6 Zirconium 0.01-0.12 Zinc 0.1-0.6 Iron 0.02-0.15 Silicon 0.01-0.1
• This alloy is negative impact from hardening elements on cold sheet stamping, in particular, with magnesium. Contents of scandium and other lanthanides in the selected range result in low cost effectiveness of this alloy application due to their high cost, as well as limited availability of lanthanides for batch production of semi-finished products made of this alloy.
• Joint doping with scandium in quantity from 0.01% wt to 0.045% wt and zirconium in quantity from 0.03% wt to 0.14% wt ensures higher strength properties through formation of nano-sized dispersoids upon process heating during production of semi-finished products.
• these elements have a modifying effect on both cast and deformed structures of the material. Lesser recrystallised grain size facilitates deformation through sliding of grain boundaries and consequently has a positive effect on the material mouldability.
• Doping with yttrium in quantity from 0.005% wt to 0.02% wt further increases strength, as well as improves corrosion resistance and mouldability thanks to modification of particle shapes of iron-containing phases to more favourable shapes.
• the natural material ageing process further improves hardening by precipitates.
• Al 8 Mg 5 ⁇ -phase precipitates in large quantity at boundaries of grains in alloys with high magnesium content, which makes these alloys more susceptible to intercrystalline corrosion.
• Zinc precipitates serve as sites for initiation of Al 8 Mg 5 deposition. This promotes deposition of Al 8 Mg 5 phase both at boundaries and inside grains thereby reducing tendency to intercrystalline corrosion.
• At least one element of the group including boron and carbon is added in quantity from 0.0001% wt to 0.005% wt.
• the added elements form compounds with each other and aluminium being crystallisation centres during casting, which ensure fine-grained structures in ingots.
• the provided Si ⁇ Zr + 2Sc ratio allows excluding precipitation of triple phases with silicon and scandium and/or zirconium, formation of which may result in reduction of the dispersion hardening effect.
• the offered alloy is not additionally doped with chromium in order to exclude formation of coarse intermetallic compounds, which deteriorate stampability.
• beryllium is not added as distinct from alloys with similar applications.
• the slabs were homogenised in the three-stage mode. First stage at temperature of 310-320°C for 2 h. Second stage at temperature of 380-390°C for 4 h. Third stage at temperature of 420-440°C for 4 h. Blanks 100x340x320 mm in size for rolling were cut from the slabs after homogenisation. Hot rolling of the flat blanks was performed at temperatures of 400-440°C to thickness of 6 mm. After that, their intermediate annealing was performed at temperature of 290-330°C followed by cold rolling to thickness of 1.0 mm. The rolled sheets were annealed at temperature of 280-320°C.
• the tensile tests were performed on the flat specimens according to GOST 1497-84.
• the process tests with the Erikson sheet extrusion method were performed according to GOST 10510-80.
• the intercrystalline corrosion tests were performed on the specimens 10x20 mm in size according to GOST 9.021-74 in solution 1 for 24 h.
• the offered alloy ensures higher strength properties versus the prototype, whilst keeping percentage elongation, mouldability, and corrosion resistance.
• the most significant advantage of the alloy is higher strength, which will allow reducing wall thickness of products made of it and thereby increasing weight efficiency of structures made of it.
• the kept percentage elongation and results of the Erikson extrusion tests guarantee high workability of the material during moulding.
• An example of an extruded dimple before failure in the developed alloy composition is given in Fig. 1 .
• the billets were homogenised in the two-stage mode. First stage at temperature of 350°C for 4 h. Second stage at temperature of 450°C for 6 h. Profiles #1 with wall thickness of 6 mm were extruded from the billets. The billets were heated to temperature of 440-460°C before extrusion. The extrusion speed for all alloy compositions including the prototype was 0.3 mm/s. The surface quality and geometry of all extruded profiles met the required parameters, which in turn indicated the comparable workability of the alloys.
• the tensile tests were performed on the flat specimens according to GOST 1497-84 made from the profiles in the hot-extruded state.
• the offered alloys ensure higher strength properties versus the prototype, whilst keeping percentage elongation and workability during extrusion.
• the most significant advantage of the alloy is higher strength, which will allow reducing wall thickness of products made of it and thereby increasing weight efficiency of structures made of it.
• the slabs were homogenised in the three-stage mode. First stage at temperature of 370-380°C for 3 h. Second stage at temperature of 450-460°C for 6 h. Blanks 100x340x320 mm in size for rolling were cut from the slabs after homogenisation. Hot rolling of the flat blanks was performed at temperatures of 440-460°C to thickness of 6 mm. After that, their intermediate annealing was performed at temperature of 290-330°C followed by cold rolling to thickness of 1.0 mm. The rolled sheets were annealed at temperature of 280-320°C.
• the tensile tests were performed on the flat specimens according to GOST 1497-84.
• the process tests with the Erikson sheet extrusion method were performed according to GOST 10510-80.
• the intercrystalline corrosion tests were performed on the specimens 10x20 mm in size according to GOST 9.021-74 in solution 1 for 24 h.

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• Chemical & Material Sciences (AREA)
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• Extrusion Of Metal (AREA)
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• 2023
  • 2023-10-20 WO PCT/RU2023/050246 patent/WO2024117936A1/fr not_active Ceased
  • 2023-10-20 KR KR1020257020975A patent/KR20250117802A/ko active Pending
  • 2023-10-20 EP EP23898427.2A patent/EP4628610A1/fr active Pending
  • 2023-10-20 CN CN202380082555.2A patent/CN120283070A/zh active Pending

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