GB/T 700-2006Carbon structural steels (English PDF)

Foreword

The consistent degree between this Standard and ISO 630:1995 “Structural Steels” is not equivalent. The main differences are as follows:

- Designations of yield strength levels of 185N/mm2 and 355N/mm2 are not defined;

- Designations Q195 and Q215 are specified to corresponding levels 195N/mm2 and 215N/mm2;

- For Q235 class B steel of which the thickness is smaller than 25mm, it may be exempted from inspection, with the consent of the buyer, and if the supplier can ensure that the impact absorbed energy is qualified;

- Cold bending test is added;

- Detailed group-batching rules are specified according to the situation of China.

This Standard replaces GB/T 700-1988 “Carbon Structural Steels”. Compared with GB/T 700-1988, the main changes are as follows:

- Semi-killed steel is deleted in “deoxidization method”;

- Designation E275 in ISO 630:1995 is newly added, and is changed to new designation Q275;

- “The upper limit of the tensile strength of wide strip steel (including sheared steel plate) is not used as delivery condition” and “Q235 class B steel of which the thickness is smaller than 25mm may be exempted from inspection, with the consent of the buyer, and if the supplier can ensure that the impact absorbed energy is qualified” are added in the footnotes of Table 2;

Annex A of this Standard is normative.

This Standard was proposed by China Iron and Steel Association.

This Standard shall be under the jurisdiction of National Technical Committee for Steel Standardization.

Drafting organizations of this Standard: China Metallurgical Information & Standardization Institute, Capital Iron and Steel Company, and Handan Iron & Steel Group and Benxi Iron & Steel Group Co., Ltd.

The main drafters of this Standard: Tang Yifan, Luan Yan, Wang Liping, Sun Ping, Zhang Xianfeng, and Dai Qiang.

This Standard was first-time issued in January 1965; first revised in October 1979; and revised for the second-time in June 1988.

1 Scope

This Standard specifies the designation, dimension, shape, weight, permissible deviation, technical requirements, test methods, inspection rules, packing, marking, and quality certificate of carbon structural steel.

This Standard is applicable to the structural hot rolled steel sheets, steel strips, sectional steels, and bar steels that are generally used for welding, riveting and bolting engineering in delivery state.

The chemical composition specified by this Standard is also applicable to steel ingots, continuous casting billets, steel billets and their products.

2 Normative references

The following normative documents contain provisions which, through reference in this text, constitute provisions of this Standard. For dated references, subsequent amendments (not including corrections) to, or revisions of, any of these publications do not apply. However parties to agreements based on this Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.

3 Designation denotation and symbols

4 Dimension, shape, weight and permissible deviation

The dimension, shape, weight and permissible deviation of steel sheets, steel strips, sectional steels and bar steels shall meet the specification of the corresponding standards respectively.

5 Technical requirements

6 Test methods

6.2 In tensile and cold bending tests, the longitudinal axis of the samples of steel sheets and steel strips shall be perpendicular to the rolling direction, while the longitudinal axis of the samples of sectional steels, bar steels and narrow steel strips limited by the width shall be parallel to the rolling direction.

7 Inspection rules

7.1 The inspection and acceptance of the steel products shall be carried out by the technical supervision department of the supplier. The buyer has the right to carry out inspection and acceptance on any inspection item specified in this Standard or in the contract.

7.2 The steel products shall be accepted in batches Each batch shall be comprised of the steel products of the same-designation, same-furnace number, same-quality grade, same-variety, same-dimension, and same-delivery state. The weight of each batch shall not be greater than 60t.

For the steel products rolled with the steels smelted in the steel-making furnaces of which the nominal capacity is small, the Class A or Class B steels of the same furnace number, same designation, and manufactured by the same-smelting, pouring and deoxidization methods, they are allowed to form a mixed batch. However, the carbon content difference between the various furnace numbers of each batch shall not be bigger than 0.02%, the manganese content difference shall not be bigger than 0.15%.

7.3 If the Charpy (V-notch) impact test result of the steel product does not meet the specification of 5.4.6, the sampling product shall be rejected. Take another two sampling products from the remaining part of this inspection batch, and select a new group of three samples from each sampling product. The retest results of these two groups of samples shall be qualified. Otherwise, this batch of products shall not be delivered.

8 Packing, marking and quality certificate

The packing, marking and quality certificate of the steel product shall meet the specifications of GB/T 247 and GB/T 2101.

Annex A Impact absorbed energy of small-sized impact sample