GB/T 699-2015Quality carbon structure steels (English PDF)

Foreword

This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This Standard replaces GB/T 699-1999 Quality Carbon Structural Steels.

Compared with GB/T 699-1999, the main technical changes are as follows:

- Deleted steel bar classification according to metallurgical quality; added classification according to surface type (see Clause 3 of this Standard; Clause 4, Table 2 & Table 4 in GB/T 699-1999);

- Deleted rimmed steel and semi-killed steel (see Table 1 of this Standard;

- Modified chemical composition of the Steel 08Al (see footnote c in Table

- Specified “yield point” as “lower yield strength Rel or specific plastic extension strength Rp0.2” (see Table 2 of this Standard; Table 3 in GB/T 699-1999);

- Increased allowable adjustment range of heat treatment temperature (see footnote c in Table 2 of this Standard);

wrought (rolled) (see setting in Table 2 of this Standard; Sub-clause 6.4.2 in GB/T 699-1999);

- Specified requirements for forging steel (see Sub-clause 6.5.1 of this

- Increased macrostructure requirements for continuously cast steel (see Table 3 of this Standard);

- Subdivided surface imperfection into imperfection and defect (see Sub-

- Added that surface quality shall comply with provisions of GB/T 28300 (see Sub-clause 6.8.4 of this Standard).

- Modified sampling number of impact test, microstructure inspection, etc.

(see Table 7 of this Standard);

- Added requirements that steel bar test results use numerical rounding rules (see Sub-clause 8.4.3 of this Standard).

This Standard was proposed by China Iron and Steel Association.

This Standard shall be under the jurisdiction of the Technical Committee on Steel of Standardization Committee of China (SAC/TC 183).

The main drafting organizations of this Standard: Information Standard Institute of the Ministry of Metallurgical Industry, Shijiazhuang Iron and Steel Co., Ltd., Fujian Province Sanming Steel (Group) Co., Ltd., Tianjin Iron and Steel Group Co., Ltd., Daye Special Steel Co., Ltd., Shougang Group, Qingdao Iron and Steel Co., Ltd.

Main drafters of this Standard: Luan Yan, Dai Qiang, Meng Ruiying, Liu Jianfeng, Liu Guihua, Sun Zhicheng, Gong Cui, Hu Haiping, Liu Junhui, Yan Chengming, Deng Zhiyong.

1 Scope

This Standard specifies classification and code, order information, size, appearance and weight, technical requirements, test methods, inspection rules, packaging, marks and quality certificate of quality carbon structural steel bars.

This Standard is applicable to hot-rolled or forged quality carbon structural steel bars of which nominal diameter or thickness is not greater than 250 mm. Hotrolled or forged quality carbon structural steel bars of which nominal diameter or thickness is greater than 250 mm shall also be supplied, as agreed between the buyer and the supplier (hereinafter referred to as steel bars) The designations and chemical composition specified in this Standard are also applicable to steel ingots, steel billets, steels and its products of other crosssections.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Classifications and Code

3.1 Steel bar is classified into two categories according to the processing method used:

3.2 Steel bar is classified into five categories according to the type of surface:

4 Order Information

The contracts or purchase orders ordered according to this Standard shall contain the following contents:

c) Designations or unified numerical code;

e) Dimension, appearance and allowance (see Clause 5);

g) Heat treatment delivery or special surface state delivery (see 6.3.2 and h) Impact test (if required, see 6.4.2);

i) Upsetting (if required, see 6.5);

j) Decarburized layer (if required, see 6.7);

k) Special requirements (if required, see 6.9).

5 Size, Appearance and Weight

6 Technical Requirements

7 Test Methods

Test items and test methods of steel bar are shown in Table 7.

15 Size, appearance Piece by piece On whole steel bar Calipers, micrometer, etc.

a Group I: For U-type notch, take 2 specimens; for V-type notch, take 3 specimens.

8 Inspection Rules

9 Packaging, Marks and Quality Certificate

Packaging, marks and quality certificates of the steel bar shall comply with the provisions of GB/T 2101.