GB/T 3880.3-2024Wrought aluminium and aluminium alloy plates, sheets and strips for general engineering - Part 3: Dimensional tolerances (English PDF)

6.1.1.2 Hot-rolled plates and strips

6.1.2 Thickness range The thickness range of plates and strips in the same batch (the difference between the maximum and minimum measured thickness) shall comply with the provisions of Table

8.When the purchaser has special requirements for the thickness range, it shall be determined by negotiation between the supplier and buyer and indicated in the order (or contract).

6.2.1 Width deviation of plates

6.2.1.1 The width deviation of plates is divided into ordinary grade and high-precision grade. When the purchaser requires high-precision grade, it shall be determined by negotiation between the supplier and buyer and indicated in the order form (or contract).

6.2.2 Width deviation of strip

6.2.2.1 The width deviation of strip is divided into ordinary grade and high precision grade. When the purchaser requires high precision grade, it shall be determined by negotiation between the supplier and buyer and indicated in the order (or contract). If not indicated, it shall be ordinary grade.

6.2.2.2 The width deviation of strip of finished product secondary trimming shall comply with the provisions of Table

10.When the purchaser requires positive or negative symmetrical deviation, it shall be indicated in the order (or contract); the allowable deviation value is half of the value in Table 10.

6.3 Length

6.3.1 The length deviation of the plate is divided into ordinary grade and high precision grade. When the purchaser requires high precision grade, it shall be determined by negotiation between the supplier and buyer and indicated in the order (or contract). If not indicated, it shall be based on ordinary grade.

6.3.2 The length deviation of the plate shall comply with the provisions of Table 11. When the purchaser requires positive and negative symmetrical deviations, it shall be

6.4 Unevenness

6.4.1 The unevenness of the plate is divided into ordinary grade and high-precision grade. When the purchaser requires high-precision grade, the supplier and buyer shall negotiate and determine, meanwhile indicate it in the order form (or contract). If it is not indicated, the ordinary grade shall be used. The ordinary grade unevenness of the plate shall comply with the provisions of Table 12; the high-precision grade unevenness shall comply with the provisions of Table 13.

6.5 Side curvature

6.6 Diagonal The diagonal deviation of the plate is divided into ordinary grade and high-precision grade. When the buyer requires high-precision grade, it shall be determined by negotiation between the supplier and buyer and indicated in the order form (or contract). If not indicated, the ordinary grade shall be used. The diagonal deviation of the plate shall comply with the provisions of Table 18 for ordinary grade and Table 19 for high- precision grade.

6.7 Center convexity When the buyer has requirements for the center convexity of plates and strips, the supplier and buyer shall negotiate and determine, meanwhile indicate in the order (or contract). The convexity of the mother plate or mother strip of the plate or strip shall be 0% ~ 1.5%.

6.8 Roughness When the purchaser has requirements for the surface roughness of cold-rolled plates and strips, the supplier and the purchaser shall negotiate and determine, meanwhile indicate it in the order (or contract). The surface roughness (Ra) of cold-rolled plates and strips shall not exceed 0.50 µm.

6.9 Staggered layers and tower shapes The staggered layers of strips shall not exceed 3 mm; the tower shape shall not exceed 10 mm (except for the inner 5 circles and the outer 2 circles). When the purchaser has special requirements for the staggered layers and tower shapes of strips, the supplier and the purchaser shall negotiate and determine, meanwhile indicate it in the order (or contract).

6.10 Others Where there are other requirements for the dimensional deviation of plates and strips, the supplier and the purchaser shall negotiate and determine, meanwhile indicate it in the order (or contract).

7.4.1.3 Multiple waves

7.4.2 Unevenness of strip Cut a specimen from the strip; the specimen length is 1000 mm ~ 2000 mm, which contains at least one wave; measure the unevenness of the strip according to 7.4.1.

7.5 Side curvature Draw a straight line (preferably a polyamide line) between the two ends of the plate side, or any two points on the side of the strip 2000 mm (or specified length) apart; then use a ruler (or triangle ruler) to measure the maximum vertical distance between the plate or strip side and the straight line, which is the side curvature (d1), as shown in Figure 7.

7.6 Diagonal The allowable deviation of the diagonal of the plate is to measure the length of the two diagonals AA and BB using a steel tape measure at an accuracy of 1 mm and then calculate the difference, as shown in Figure 8.

7.7 Center convexity Use an outside micrometer, which has an accuracy of 0.001, to measure the center thickness and the thickness of both sides of any cross section of the mother plate or mother strip of the plate or strip, as shown in Figure

9.The center convexity (Cw) of plates and strips is calculated according to formula (1); the value is expressed as a percentage. The calculation result is expressed to one decimal place; the value is rounded according to the provisions of GB/T 8170.

7.8 Roughness Measure the surface roughness perpendicular to the rolling direction according to the provisions of GB/T 1031.Take not less than 1 sample from each batch, to make measurement at the two sides, the center, the two ribs (a total of 5 positions, as shown in Figure 10); take the average value. The calculation result is expressed to two decimal places; the value is rounded according to the provisions of GB/T 8170.If there is obvious color difference visible to the naked eye, the measurement result shall include the uneven color.

7.9 Staggered layer, tower shape

7.9.1 Staggered layer Use a steel ruler, which has an accuracy of 1 mm, to measure the maximum distance of the shift between the strip layers.