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

Definitions

• the invention relates to the field of laminated or extruded products, such as sheets, profiles, wires or tubes, of aluminum alloy of the AlMgMn type at Mg> 3% by weight, intended for welded constructions having a high elastic limit, a good resistance to fatigue and good toughness for structural applications, such as, for example, boats, industrial vehicles or welded bicycle frames.
• Japanese patent application JP 06-212373 proposes, in order to minimize the reduction in mechanical resistance due to welding, to use an alloy containing from 1.0 to 2.0% of M from 3.0 to 6.0% of Mg and less than 0.15% iron.
• an alloy with such a high manganese content leads to a reduction in the fatigue strength and toughness.
• the object of the invention is, under determined welding conditions, to significantly improve the mechanical strength and the fatigue life of the structures welded in AlMgMn alloy, without adverse consequences on other parameters such as toughness, resistance to corrosion and cutting deformation due to internal stress.
• the subject of the invention is products intended for welded constructions of AlMgMn alloy of composition (e weight%):
• Zn ⁇ 0.40 optionally at least one of the elements Cr, Cu, Ti, Zr such that:
• the Mn content must be> 0.5%, and preferably> 0.8%, to have sufficient mechanical characteristics, but must not exceed 1%, if we want to avoid degradation of the toughness and the resistance to fatigue.
• the addition of zinc in combination with manganese has been shown to have a beneficial effect on the mechanical characteristics of the sheets and welded joints. However, it is better not to exceed 0.4%, as this can cause problems with welding.
• Magnesium is preferably maintained> 4.3%, because it has a favorable effect on the elastic limit and the resistance to fatigue, but above 5% the corrosion resistance is less good.
• the addition of Cu and Cr are also favorable to the elastic limit, but Cr is preferably maintained ⁇ 0.15% to maintain good resistance to fatigue.
• the mechanical resistance of the sheets depends on both the content of magnesium in solid solution and the manganese dispersoids. It has been found that the volume fraction of these dispersoids, which is linked to the iron and manganese contents, should preferably be maintained above 1.2%. This volume fraction is calculated from the average of the surface fractions measured on polished sections made in the 3 directions (length, width and thickness) by scanning electron microscopy and image analysis.
• the products according to the invention can be rolled or extruded products such as hot or cold rolled sheets, wires, profiles or optionally re-drawn extruded tubes.
• the sheets according to the invention assembled by butt welding using a MIG or TIG process and with a chamfer of the order of 45 e over approximately 2/3 of the thickness, present in the welded zone an elastic limit R 2 which can be at least 25 MPa higher than that of a conventional alloy having the same magnesium content, ie a gai of around 20%.
• the width of the heat affected zone is reduced by around a third compared to a usual 5083 alloy, and the hardness of the welded joint increases from around 75 Hv to more than 80 Hv.
• Welded joints also have a breaking strength which exceeds the minimum imposed by the inspection bodies for raw sheets of unwelded rolls.
• the sheets according to the invention have a resistance to fatigue, measured in planar bending with a stress ratio R * 0.1 on test pieces taken in the transverse section, greater than:
• the sheets according to the invention are most often thicker than 1.5 mm. For thicknesses greater than 2.5 mm, they can be obtained directly by hot rolling, without the need for subsequent cold rolling, and, moreover, these hot rolled sheets exhibit less distortion on cutting than the cold rolled sheets.
• the products according to the invention have a corrosion resistance as good as the usual alloys with the same magnesium content, for example 5083 of common composition. widely used in shipbuilding.
• the reference 0 corresponds to a conventional composition of 5083 and the reference 1 has a composition slightly outside the invention.
• the other 11 (ref. 2 to 12) have a composition according to the invention.
• the compositions were as follows (% by weight):
• the samples all have, after rolling, an elastic limit Ro, 2 > 220 MPa in the direction L.
• the mechanical resistance of the welded joints was measured from these sheets under the following conditions: automatic continuous butt MIG welding, with a symmetrical chamfer of slope 45 * relative to the vertical over a thickness of 4 mm and wire 5183 alloy intake.
• the mechanical characteristics (tensile strength R m , elastic limit Q, 2) orvt been obtained by traction on test pieces standardized by the Norwegian inspection body DNV for shipbuilding, length 140 mm, width 35 mm, the weld bead width 15 mm being the center and the length of the narrow part of the test piece being 27 mm, the sum of the width of the bead and times the thickness (15 + 12 mm).
• the elastic limit of the welded samples according to the invention has, compared to the reference sample, an increase of between 15 and 35 MPa.
• the sheets according to the invention have a resistance to fatigue at least as good as that of conventional 5083 sheets.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Heat Treatment Of Steel (AREA)
• Conductive Materials (AREA)
• Laminated Bodies (AREA)
• Arc Welding In General (AREA)
• Butt Welding And Welding Of Specific Article (AREA)
• Heat Treatment Of Articles (AREA)
• Compositions Of Macromolecular Compounds (AREA)

Priority Applications (1)

Applications Claiming Priority (5)

Related Child Applications (1)

Publications (2)

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Citations (1)

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• 1995
  • 1995-10-09 FR FR9512065A patent/FR2731019B1/fr not_active Expired - Lifetime
• 1996
  • 1996-02-21 US US08/875,113 patent/US6444059B2/en not_active Expired - Lifetime
  • 1996-02-21 CA CA002211433A patent/CA2211433C/fr not_active Expired - Lifetime
  • 1996-02-21 DK DK96904891T patent/DK0804626T3/da active
  • 1996-02-21 PL PL96321887A patent/PL321887A1/xx unknown
  • 1996-02-21 EP EP96904891A patent/EP0804626B1/de not_active Revoked
  • 1996-02-21 RU RU97115807/02A patent/RU2156319C2/ru active
  • 1996-02-21 UA UA97094747A patent/UA49823C2/uk unknown
  • 1996-02-21 TR TR97/00843T patent/TR199700843T1/xx unknown
  • 1996-02-21 EP EP98123582A patent/EP0909828A3/de not_active Ceased
  • 1996-02-21 WO PCT/FR1996/000279 patent/WO1996026299A1/fr not_active Ceased
  • 1996-02-21 CN CN96192103A patent/CN1078622C/zh not_active Expired - Lifetime
  • 1996-02-21 DE DE0804626T patent/DE804626T1/de active Pending
  • 1996-02-21 AU AU49305/96A patent/AU690433C/en not_active Expired
  • 1996-02-21 ES ES96904891T patent/ES2161347T3/es not_active Expired - Lifetime
  • 1996-02-21 NZ NZ302706A patent/NZ302706A/en not_active IP Right Cessation
  • 1996-02-21 DE DE69613812T patent/DE69613812T2/de not_active Revoked
  • 1996-02-21 AR ARP960101464A patent/AR001000A1/es unknown
  • 1996-02-21 JP JP8525458A patent/JPH11500783A/ja active Pending
  • 1996-02-22 UY UY24172A patent/UY24172A1/es not_active IP Right Cessation
  • 1996-08-23 FI FI963290A patent/FI121471B/fi not_active IP Right Cessation
• 1997
  • 1997-08-11 NO NO973681A patent/NO973681D0/no not_active Application Discontinuation

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Non-Patent Citations (4)

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