Wrought aluminium-magnesium alloy product
View Patent ↗A method of making a wrought aluminium-magnesium alloy rolled product, having a composition (in wt. %) of: 3.1<Mg<4.5; 0.4<Mn<0.85; 0.4<Zn<0.8; 0.06<Cu<0.35; 0.06<Cr<0.2; Fe<0.35; Si<0.2; Zr<0.05; Ti<0.3; impurities≦0.05 each up to a total of max. 0.15, and balance aluminium.
1. Method of producing a wrought aluminium alloy rolled product comprising the steps of:
(i) providing an intermediate alloy product, having a composition (in wt. %) consisting of:
Mg 4.05 to 4.31
Mn 0.5 to 0.6
Zn 0.4 to 0.6
Cu 0.085 to 0.18
Cr 0.11 to 0.2
Fe<0.2
Si<0.12
Zr<0.01
Ti at most 0.02
impurities each ≦0.05, total of max. 0.15,
and balance aluminium;
(ii) homogenization annealing a slab of the alloy;
hot rolling the homogenization annealed slab to form an intermediate alloy product;
cold working the intermediate alloy product by cold rolling to a final gauge of 0.7 to 4 mm to obtain an intermediate wrought product; and
(iii) continuously annealing the intermediate wrought product by heating the product at a heating rate in the range of 80 to 200° C./sec, holding the product at a soaking temperature in the range of 520 to 550° C. for a duration of at most 40 sec,
followed by a cooling rate in the range of 10 to 500° C./sec to below a temperature of 150° C. to arrive at plates in H111-temper;
wherein the product after annealing has a weight loss after sensitising for 100 hours at 100° C. of less than 15 mg/cm 2 when tested against intergranular corrosion in accordance with ASTM G67.
2. Method according to claim 1 , wherein the final gauge of the aluminium product is in a range of 0.7 to 2.4 mm.
3. Method according to claim 1 , wherein the product after annealing has a weight loss after sensitising for 100 hours at 100° C. of less than 10 mg/cm 2 when tested against intergranular corrosion in accordance with ASTM G67.
4. Method according to claim 1 , wherein the amount of Mn in the alloy product is more than 0.52 wt. %.
5. Method according to claim 1 , wherein the amount of Cu in the alloy product is at least 0.12 wt %, wherein the product after annealing has a weight loss after sensitising for 100 hours at 100° C. of less than 15 mg/cm 2 when tested against intergranular corrosion in accordance with ASTM G67.
6. Method according to claim 1 , wherein the amount of Cu in the alloy product is more than 0.1 wt. %.
7. Method according to claim 1 , wherein the amount of Cu in the alloy product is less than 0.15 wt. %.