Al-si-mg alloy sheet metal for motor car body outer panel
Abstract
A metal sheet for a motor vehicle body outer panel, having a thickness ranging between 0.8 and 1.2 mm, containing, in wt. %, Fe 0.25-0.40 and preferably 0.25-0.35; Si 0.90-1.20 and preferably 0.95-1.10; Cu 0.10-0.25 and preferably 0.15-0.20; Mg 0.35-0.50 and preferably 0.40-0.50; Mn 0.05-0.20 and preferably 0.08-0.15; other elements<0.05 each and <0.15 in total, the rest being aluminum. The sheet has, after solution heat treatment, quenching, pre-tempering or reversion, and maturation at room temperature for 3 weeks to 6 months, an L R 0.2 direction yield strength less than 160 MPa, and preferably less than 150 MPa. A yield strength>180 MPa can be obtained on the body stamping part after the paint has been cured. The sheet of the invention enables a reduction in the thickness of parts while satisfying all the other required properties.
Claims
exact text as granted — not AI-modified1 . Sheet for an automobile body outer panel part between 0.8 and 1.2 mm thick, havinq a composition consisting essentially of (% by weight):
Fe: 0.25-0.40 and preferably: 0.25-0.35
Si: 0.90-1.20 and preferably: 0.95-1.10
Cu: 0.10-0.25 and preferably: 0.15-0.20
Mg: 0.35-0.50 and preferably: 0.40-0.50
Mn: 0.05-0.20 and preferably: 0.08-0.15
other elements<0.05 each and <0.15 total, the remainder being aluminum,
presenting a yield strength R 0.2 in the L direction less than 160 MPa after solution heat treatment, quenching, pre-ageing or reversion and ageing at ambient temperature for between 3 weeks and 6 months.
2 . Sheet according to claim 1 , presenting a yield strength R 0.2 in the L direction less than 150 MPa after solution heat treatment, quenching, pre-ageing or reversion and ageing at ambient temperature for between 3 weeks and 6 months.
3 . Sheet according to claim 1 , characterised in that solution heat treatment is made such that the peak area is less than 1 J/g in the 565-580° C. range in a differential enthalpy analysis diagram, the test being carried out at a temperature rise rate of 20° C./min.
4 . Sheet according to claim 1 , characterised in that pre-ageing is made at a temperature and time such that the equivalent time teq defined by the formula:
T
(
eq
)
=
∫
exp
(
-
6000
/
T
)
ⅆ
t
∫
exp
(
-
6000
/
T
ref
)
ⅆ
t
where T (in °K) is the temperature and t is the preageing time, and T ref =373° K, is between 1 and 10 h.
5 . Sheet according to claim 4 , characterised in that t eq is between 3 h and 6 h.
6 . Sheet according to claim 1 , with a formability anisotropy LDH 0 between the rolling direction and the perpendicular direction less than 1 mm.
7 . Sheet according to claim 6 , with a formability anisotropy LDH 0 between the rolling direction and the perpendicular direction less than 0.6 mm.
8 . Sheet according to claim 1 , characterised in that it has a yield strength measured at 160° C. more than 140 MPa.
9 . Sheet according to claim 1 , with a grain size smaller than 50 μm.
10 . Sheet according to claim 1 , with a textured surface.
11 . Sheet according to claim 1 , coated with a dry lubricant.
12 . Body outer panel part made from a sheet according to claim 1 , presenting a yield strength R 0.2 (L or TL direction) in the solution heat treated temper and quenched, naturally aged, drawn and artificially aged by paint baking, greater than 180 MPa.
13 . Body outer panel part according to claim 12 , presenting a yield strength R 0.2 (L or TL direction) in the solution heat treated temper and quenched, naturally aged and artificially aged by paint baking, greater than 200 MPa.
14 . Body outer panel part made from a sheet according to claim 1 , characterised in that it is assembled on a steel structure before the paint baking treatment.Join the waitlist — get patent alerts
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