Aluminum sheets GOST 21631-76

Aluminum sheets manufactured according to GOST 21631-76 "The sheets of aluminum and aluminum alloys". This standard has a fairly large amount of, as well as a very "loose", difficult to grasp summary. Below is a fact-finding review of GOST 21631-76 with the release of the most important moments. The professional activity need to apply a full and updated text of the standard.

1 Classification of aluminum sheets according to GOST 21631-76

1.1 Method of making aluminum sheets:
1) unclad - no additional designation;
2) clad:
with technological plating – B;
with normal plating - A;
with thicker plating - I.

1.2 Material condition of aluminum sheets:
1) without heat treatment - without additional designation;
2) annealed - M;
3) semi-standard – H2;
4) cold-worked - H;
5) hardened and naturally aged - T;
6) hardened and artificially aged - T1;
7) hard-worked after hardening and natural aging - ТН.

1.3 Surface finish quality of aluminum sheets:
1) high finishing - B;
2) high finishing - P;
3) normal finishing - no designation.

1.4 Manufacturing accuracy of aluminum sheets:
1) increased accuracy in thickness, width, length, or one or two of these parameters;
2) normal thickness accuracy, width and length - without any additional symbol.

2 Gauge aluminum sheet according to GOST 21631-76

2.1 The standard specifies a nominal thickness of aluminum sheet 0,3 to 10,5 mm increments from 0,1 mm 0,5 mm. Tolerances are dependent on the thickness and width of the sheets and their manufacturing accuracy.

2.2 examples

1) Limit deviations in sheet thickness 0,3 mm and a width 1000 mm:
– increased accuracy: – 0,07 mm;
– normal precision: – 0,10 mm.

2) Limit deviations in sheet thickness 10,5 mm and a width 1000 mm:
– increased accuracy: – 0,48 mm;
– normal precision: – 0,50 mm.

3 Aluminum and aluminum alloys sheets GOST 21631-76

Aluminum sheets are made:
1) made of aluminum grades A7, a6, A5, A0 GOST 11069-74;
2) from aluminum grades AD00, AD0, AD1, AD GOST 4784-97;
3) from aluminum alloys in accordance with GOST 4784-97:
– AMC, AMCs, MM, D12;
– AMg2, AMg3, AMg5, АМг6;
– АВ;
– D1, D16;
– B95, 1915;
4) from aluminum alloys in accordance with GOST 1131-76: B95-1, AKM, B-95-2, VD1.

4 Plating aluminum sheets according to GOST 21631-76

4.1 For plating the sheets of aluminum alloy D1, D16, AMg6, VD-1 and AKM use aluminum with the following chemical composition:
aluminum – no less 99,30;
iron - no more 0,30 %;
silicon - not more 0,30 %;
copper - no more 0,02 %;
manganese - not more 0,025 %;
Zinc - no more 0,1 %;
Titanium - no more 0,15 %;
magnesium - less than 0,05 %;
other impurities, each - no more than 0,02 %.

4.2 For plating the sheets of aluminum alloys B95, V95-2, B95-1 use an aluminum alloy with the following chemical composition:
aluminum is the main component;
zinc - 0,9-1,3 %;
iron - no more 0,3 %;
silicon - not more 0,3 %;
copper - not controlled;
manganese - not more 0,025 %;
Titanium - no more 0,15 %;
maniy - is not controlled;
other impurities, each - no more than 0,05 %.

4.3 The thickness of the clad layer on aluminum sheets according to GOST 21631-76

4.3.1 Sheets of a thickness 0,5 to 1,9 mm:
1) technological plating: no more 1,5 % from the thickness of the sheet;
2) normal plating: not less 4,0 % from the thickness of the sheet;
3) thick plating: not less 8,0 % the sheet thickness.
4.3.2 Sheets thicker than 1,9 to 4,0 mm:
1) technological plating: no more 1,5 % from the thickness of the sheet;
2) normal plating: not less 2,0 % from the thickness of the sheet;
3) thick plating: not less 4,0 % the sheet thickness.
4.3.3 Sheets thicker than 4,0 to 10,5 mm:
1) technological plating: no more 1,5 % from the thickness of the sheet;
2) normal plating: not less 2,0 % from the thickness of the sheet;

5 The flatness of the aluminum sheets according to GOST 21631-76

5.1 Requirements to deviations from planarity of aluminum sheets according to GOST 21631-76 depend on:
– chemical composition of aluminum alloys;
– the state of the sheet material;
– sheet width;
– sheet length;
– rolling method - hot or cold.
5.2 The deviation from the flatness of the sheet is controlled with its free laying (by each side) on the plane of the surface plate:
1) over the entire surface of the sheet, including long sides;
2) on short sides, including the long sides up 300 mm from the sheet corners.
5.3 First group of sheets:
aluminum alloy AB, D1, B95, D16, 1915, V95-1, V95-2, AKM, VD1:
– annealed and
– in quenched and aged states.
This group of sheets has the most stringent tolerances for flatness.
for instance, for an "average" thickness of the sheet 5 mm, width 1500 mm and length 4000 mm deviation 1) should be no more 22 mm, and the deviation 2) - no more 40 mm.
5.4 Second group of sheets:
from aluminum of all grades and all aluminum alloys in:
– in semi-hardened and cold-worked states;
– annealed condition (other than those listed in 6.3).
This group of sheets has moderate tolerances for deviations from planarity.
for instance, for the same "average" thickness of the sheet 5 mm, width 1500 mm and length 4000 mm deviation 1) should be no more 25 mm, and the deviation 2) - no more 40 mm.
5.5 The third group of sheets:
from aluminum and aluminum alloys:
– thick in the annealed condition above 4 mm, manufactured by hot rolling;
– without thermal treatment.
The third group has the widest tolerances flatness.
for instance, for the same "average" thickness of the sheet 5 mm, width 1500 mm and length 4000 mm deviation 1) should be no more 30 mm, and the deviation 2) - no more 45 mm.

6 The surface quality of aluminum sheets according to GOST 21631-76

6.1 The surface of the sheets of all finishing groups should be:
glossy or matte, crack-free, Rvanina, bundles, bubbles, burnout, plaque nitrate, spots of corrosion origin, diffusion spots, slag inclusions, plots without cladding (on clad sheets), blurred whitish spots on the quenching, and nonmetallic inclusions metallurgical production.
6.2 The standard also sets special requirements for the surface quality of aluminum sheets and high elevated finishing.