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US4186034A Expired / Lapsed US ⏱️ 0.0 years remaining

Method of manufacturing aluminum alloy sheets containing magnesium and zinc

Assignee: Rio Tinto Switzerland AG
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Filing: 1978-12-06
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Granted: 1970-01-29
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Expires: 1998-12-06
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Abstract

Abstract The present invention resides in the manufacture of an AlMg alloy sheet with zinc addition which is readily deformable in the soft condition and especially suited for shaping into motor vehicle body components. The alloy sheet has a strength of at least 250 N/mm2, a grain size of less than 50 mu m and, after deformation has occurred, remains free of surface defects such as orange peel effect and Luders bands and also, after a possible influence of heat, remains insensitive to stress corrosion cracking. The zinc addition produces a widening of the working range so that after the last cold rolling operation the alloy can be soft annealed above the recrystallization temperature without coarse grains or Luders band appearing. The zinc addition produces an insensitivity with respect to stress corrosion cracking after a heterogenization annealing subsequent to the soft annealing, even after a sensitization at 150 DEG C. on a sheet which has been deformed with a cold reduction of 20% and more.

Inventors

  • 👤 Rudolf Akeret

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-05 09:21
CPC Classifications
C; C22; C22F; C22F1/00; C22F1/04; C22F1/047

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 133 words
A process for producing fine-grained, high strength, good formability sheet characterized by superior stress corrosion cracking properties upon subsequent cold deformation by deep and stretch drawing comprising: A. casting an aluminum alloy melt consisting essentially of 4.0 to 7.0% magnesium, 0.5 to 2.0% zinc, balance essentially aluminum into a rolling ingot; B. hot rolling to an intermediate thickness; C. cold rolling to a final thickness; D. annealing above the recrystallization temperature of said alloy so as to produce a grain size of less than 50 μm; and E. cooling from said annealing temperature to a stabilization temperature of between 200° and 260° C. at a rate of less than 100° C. per hour, said alloy sheet being free from flow patterns and characterized by superior stress corrosion cracking properties upon subsequent cold deformation.
Claim 2
Dependent Claim 133 words
A process for producing fine-grained, high strength, good formability sheet characterized by superior stress corrosion cracking properties upon subsequent cold deformation by deep and stretch drawing comprising: A. casting an aluminum alloy melt consisting essentially of 4.0 to 7.0% magnesium, 0.5 to 2.0% zinc, balance essentially aluminum into a rolling ingot; B. hot rolling to an intermediate thickness; C. cold rolling to a final thickness; D. annealing above the recrystallization temperature of said alloy so as to produce a grain size of less than 50 μm; and E. cooling from said annealing temperature to a stabilization temperature of between 200° and 260° C. at a rate of less than 100° C. per hour, said alloy sheet being free from flow patterns and characterized by superior stress corrosion cracking properties upon subsequent cold deformation.
Claim 3
Dependent Claim 14 words
The process of claim 1 wherein said alloy melt comprises 0.7 to 1.5% Zn.
Claim 4
Dependent Claim 15 words
The process according to claim 1 wherein said alloy melt comprises 0.9 to 1.1% Zn.
Claim 5
Dependent Claim 37 words
The process according to claim 1 wherein said alloy melt further comprises 0 to 0.6% Si, 0 to 0.8% Fe, 0 to 1.0% Mn, 0 to 1.0% Cu, 0 to 0.3% Cr and 0 to 0.05% Bi.
Claim 6
Dependent Claim 65 words
The process according to claim 1 wherein said cold rolling comprises the steps of: A. cold rolling to a reduction of at least 20%, preferably 30 to 70%; B. annealing said cold rolled strip above the recrystallization temperature of the alloy; and C. cold rolling to final thickness to a further reduction of at least 12%, preferably 15 to 30% and ideally 15 to 22%.
Claim 7
Dependent Claim 24 words
The process according to claim 1 further including the step of holding said sheet at said stabilization temperature for from 1 to 24 hours.
Claim 8
Dependent Claim 20 words
The process according to claim 1 further including the step of manufacturing motor vehicle bodies by drawing from said sheet.

References Cited (Backward Citations)

US4081294A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1973-01-28 1973-07-30 1974-01-29 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1977-01-28 1977-07-30 1978-01-29 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1981-01-28 1981-07-30 1982-01-29 $7700.00 Window Closed / Lapsed

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