5XXX SERIES H32 HIGH MAGNESIUM ALUMINUM ALLOY SHEET AND METHOD FOR ITS PRODUCTION

Claims

1. An aluminum alloy sheet, wherein the aluminum alloy sheet contains the following chemical components in percentage by weight: Si: 0-0.15%, Fe: 0.20-0.30%, Cu: 0-0.05%, preferably 0.01-0.05%, Mn: 0.41-0.49%, Mg: 4.0-4.9%, Cr: 0.06-0.14%, Zn: 0-0.05%, preferably 0.01-0.05%, Ti: 0.01-0.03%, and the remainder is Al and unavoidable impurities; wherein the content of each of the unavoidable impurities as a percentage by mass is greater than or equal to 0 and less than or equal to 0.05%, and the total content of unavoidable impurities as a percentage by mass is greater than or equal to 0 and less than or equal to 0.15%; and wherein the following formula is satisfied: (Si+Fe) / Mn≤1, wherein the symbols of the elements in the formula respectively represent the numerical values ​​preceding the symbol % of the mass percentage content of the corresponding elements.

2. A sheet of aluminum alloy according to item 1, the remainder of which consists of Al and unavoidable impurities.

3. A sheet of aluminum alloy according to claim 1, in which Si: 0-0.12%; and / or Fe: 0.20-0.25%; and / or Mn: 0.43-0.47%.

4. An aluminum alloy sheet according to any one of claims 1 to 3, wherein the microstructure of the aluminum alloy sheet includes an iron-rich phase with a volume fraction of ≤3%, wherein the iron-rich phase has a maximum grain size of ≤5 μm; preferably, the aluminum alloy sheet has an equiaxed grain morphology with an average grain size of ≤20 μm, preferably ≤15 μm.

5. An aluminum alloy sheet according to any one of claims 1 to 4, wherein the aluminum alloy sheet has a yield strength of ≥260 MPa, a relative elongation of ≥12%, a minimum bending radius at 90° of ≤1.0 x the sheet thickness, where the sheet thickness is expressed in mm; preferably, the aluminum alloy sheet has a tensile strength of ≥318 MPa.

6. A method for producing a sheet of aluminum alloy according to any of paragraphs 1-5, comprising the following stages, performed sequentially: (1) Melting and casting: melting and casting according to the composition of aluminum alloy sheet to obtain slab; (2) conducting homogenizing heat treatment of the slab at a heating temperature of 500-540°C for a holding time of 6-10 hours; (3) hot rolling to obtain hot-rolled blank: the intermediate stage of hot rough rolling is performed with a per-pass reduction of ≥15%, hot finish rolling is performed with a per-pass reduction of ≥30% and a winding temperature of 300-350°C, and the thickness of the obtained hot-rolled blank is determined based on the thickness of the finished aluminum alloy sheet product and the degree of deformation in cold rolling; (4) the first cold rolling to obtain cold rolled coil: the total reduction in the first cold rolling is 40% or more; (5) intermediate annealing of cold-rolled coil: intermediate annealing is carried out in an air-cushion furnace, with the target sheet temperature of 450-550°C, preferably 480-530°C, and the holding time of 0-20s, and after being discharged from the furnace, the sheet is air-cooled to room temperature; (6) Second cold rolling: The reduction in the second cold rolling is 5-15%.

7. The production method according to paragraph 6, wherein at stage (2) the homogenizing heat treatment is carried out at a heating temperature of 530-540°C with a holding time of 8-10 hours.

8. The production method according to paragraph 6, in which at stage (3) the intermediate stage of hot rough rolling is carried out with a reduction per pass of ≥20%, hot finish rolling is carried out with a reduction per pass of ≥35% and a winding temperature of 310-330°C, and the thickness of the resulting hot-rolled blank is 3-4 times greater than the thickness of the finished product made from an aluminum alloy sheet.

9. The production method according to claim 6, wherein at step (4) the total reduction during the first cold rolling is 60-80%.

10. The production method according to claim 6, wherein at stage (6) the reduction during the second cold rolling is 8-10%.