GB/T 14978-2008Continuously hot-dip aluminum-zinc alloy coated steel sheet and strip (English PDF)

4.1 Designation naming method

The code of steel sheets and strips consist of product use code, steel grade character (or serial number), steel grade characteristic (if any), hot-dip code (D) and coating type code; hot-dip code (D) and coating type code are connected with "+". Detailed provisions are as follows.

4.1.1 Use code

a) DX. the first letter D represents flat steels for cold forming; if the second letter is

X, it represents that there is no requirement for the rolled condition of base-plate;

if the second letter is C, it represents that cold-rolled base-plate is required; if the second letter is D, it represents that hot-rolled base-plate is required;

b) S. represents structural steels.

4.2 Designation naming examples

4.3 The designation of steel sheets and strips AND the steel grade characteristic

shall be in accordance with those specified in Table 1.

4.4 The surface quality classification of steel sheets and strips shall be in accordance with those specified in Table 2.

7.1 Chemical composition

Reference values of chemical composition (smelting analysis) are detailed in

Appendix C. If the Purchaser has any requirement for chemical composition, it shall be negotiated in ordering.

7.2 Smelting method

The steels for steel sheets and strips shall be smelted by oxygen converter or electric furnace; unless otherwise specified, the smelting method shall be chosen by the

Supplier.

7.4 Mechanical property

7.4.1 The mechanical property of steel sheets and strips shall be in accordance with those specified in Tables 5 and Table 6.Unless otherwise specified, the tensile sample shall be coated.

7.5 Tensile strain marks

For DX51D+Z, DX51D+ZF, DX52D+Z and DX52D+ZF steel sheets and strips in Table

5, it shall be guaranteed that no stretcher strain marks appear in use within 1 month after manufacturing; for steel sheets and strips with other designations in Table 5, it shall be guaranteed that no tensile strain marks appear in use within 6 months after manufacturing. For steel sheet and strip specified in Table 6, its tensile strain marks shall not be required.

7.6 The coating adhesiveness shall be tested by proper test method which is subject to the choice of the Supplier.

7.7 Coating weight

7.7.1 The scope of supplied nominal coating weight is 60g/m2~200g/m2.After negotiation between the Supplier and the Purchaser, other coating weight can also be provided.

7.8 Coating surface structure

7.8.1 The coating surface structure of steel sheets and strips shall be in accordance with those specified in Table 8.

7.9 Surface treatment

7.10 Surface quality

7.10.1 The surface of steel sheets and strips shall be free from defects such as skip plating, fall-off coating and visible cracks that affect their use. Tiny zinc coating cracks and white edges are allowed to exist on the sides of non-trimmed steel strips.

8.1 The inspection item, sample quantity, sampling method, sampling position and

test method of each batch of steel sheets and strips shall be in accordance with those specified in Table 10.

8.2 The surface quality of steel sheets and strips shall be inspected by naked eyes.

8.5 The re-inspection of steel sheets and strips shall be in accordance with those specified in GB/T 17505.