1. The silicon content of boiling steel is not more than 0.07%; The silicon content of semi-killed steel is not more than 0.17%; The lower limit of silicon content of the killed steel is 0.12%.

2. Grade D steel should contain enough elements to form a fine grain structure, such as the acid-soluble aluminum content of steel is not less than 0.015% or the total aluminum content is not less than 0.020%.

3. The content of residual elements chromium, nickel and copper in steel should be no more than 0.30%, and the nitrogen content of oxygen converter steel should be no more than 0.008%. If the supplier can guarantee, no analysis will be performed

With the consent of the demander, the copper content of grade A steel shall not be greater than 0.35%. At this time, the supplier should do an analysis of the copper content and indicate its content in the quality certificate.

4. The residual content of arsenic in steel should not be greater than 0.080%. The arsenic content of steel smelted by smelting pig iron from arsenic-containing ore shall be stipulated by agreement between the supply and demand parties. If there is no arsenic in the raw material, the arsenic content in the steel can not be analyzed.

5. To ensure that the mechanical properties of steel comply with the provisions of this standard, the carbon, silicon, manganese content of each grade A steel and the lower limit of carbon and manganese content of other grades of steel of each grade may not be used as a delivery condition, but the content (melting analysis) shall be indicated in the quality certificate.

6. When supplying commercial ingot (including continuous casting billet) and billet, the supplier shall ensure that the chemical composition (melting analysis) conforms to the requirements of Table 1. However, in order to ensure that the properties of rolled steel meet the requirements of this standard, the chemical composition of grade A and B steel of each grade may be adjusted appropriately according to the requirements of the demander.

● The permissible deviation of the chemical composition of finished steel and commercial billet shall comply with the provisions of Table 1 in GB222.

The chemical composition deviation of finished steel and commercial billet is not guaranteed.

● Smelting method

Steel is smelted by oxygen converter, open furnace or electric furnace, unless the demander has special requirements and indicated in the contract, the smelting method is generally determined by the supplier.

● Delivery status

Steel is generally delivered in hot rolled (including controlled rolling) condition. According to the requirements of the demander, by mutual agreement, can also be delivered in normalizing condition (except for grade A steel).