GB/T 30068-2025Cold rolled steel sheet and strip for appliances (English PDF)

4.1 Classification

4.1.1 The designations of steel sheets and strips are classified according to steel type characteristics, as shown in Table 1.

Table 1 -- Classification of steel designations and steel type characteristics 4.1.2 Steel sheets and strips are classified according to surface quality in Table 2.

1 - A numerical serial number.

5.2 Unless otherwise specified in the order contract regarding dimensions, unevenness

tolerance, surface quality grade, surface finish, edge condition, packaging method, and other details, the products covered by this document shall be supplied as steel sheets or strips featuring standard dimensional tolerance, enhanced flatness tolerance, premium surface quality, a matte finish, slit edges, and a light oil coating. Furthermore, they shall be packaged in accordance with the packaging method provided by the supplier. If the inner diameter of the steel coils is not specified, it shall be supplied at 610 mm.

6.1 Smelting method

The steel shall be smelted in a converter or an electric furnace. Unless the purchaser has specific requirements expressly stipulated in the contract, the smelting method shall be selected by the supplier.

6.2 Delivery condition

6.2.1 Steel sheets and strips shall be delivered in an annealed and flattened condition.

6.2.2 Steel sheets and strips are typically supplied with an oil coating. The applied oil film shall be removable using an alkaline aqueous solution or common solvents. Under standard conditions of packaging, transportation, handling, and storage, lightly oiled steel sheets and strips shall remain free of rust for a period of three months from the date of manufacture; medium-oiled and heavily oiled steel sheets and strips shall remain free of rust for a period of six months from the date of manufacture. For the oil coating weights corresponding to each coating type, please refer to Annex B.

NOTE 1.For products requested by the purchaser to be supplied either uncoated or treated with DOS oil, rust formation may occur. Furthermore, during the processes of transportation, handling, storage, and usage, the surface is susceptible to minor scratches.

NOTE 2.Typically, the issuance date specified in product inspection documents is designated as the date on which the product's manufacturing was completed.

7.1 Chemical composition

7.1.1 Reference values for the chemical composition (ladle analysis) of steel are

provided in Annex C.

7.1.2 If specific requirements regarding chemical composition exist, they may be agreed

upon at the time of order placement. The allowable deviations for the chemical composition of the finished steel shall comply with the provisions of GB/T 222.

7.2 Mechanical properties

7.2.1 The tensile properties of steel sheets and strips shall comply with the requirements specified in Table 6.

7.2.2 Reference hardness values for steel sheets and strips are shown in Table 6. ......