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GB/T 700-1988 English PDF (GBT700-1988)

GB/T 700-1988 English PDF (GBT700-1988)

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GB/T 700-1988: Carbon structural steels

This Standard specifies the technical specification of the carbon structural steels. This Standard is applicable to the general structural steels, hot rolled steel sheets, steel strips, sectional steels, and bar steels that are generally used for welding, riveting and bolting member engineering in delivery state.
GB 700-1988
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
UDC 669.14.018.29
H 40
GB 700-88
Carbon Structural Steels
ISSUED ON. JUNE 29, 1988
IMPLEMENTED ON. OCTOBER 1, 1988
Issued by. National Standardization Bureau
Replaced
Table of Contents
1 Theme Contents and Applicable Scope ... 3
2 Normative References ... 3
3 Designation Denotation, Codes and Symbols ... 3
4 Dimension, Shape, Weight and Permissible Deviation ... 4
5 Technical Requirements ... 4
6 Test Methods ... 8
7 Inspection Rules ... 9
8 Packing, Marking and Quality Certificate ... 9
Appendix A Designation Comparison between New and Old GB 700 Standards
(Reference) ... 11
Additional Explanation... 12
No.1 Amendment of GB/T 700-1998 Carbon Structural Steels ... 13
Carbon Structural Steels
This standard references to and adopts ISO 630 Structural Steels.
1 Theme Contents and Applicable Scope
This Standard specifies the technical specification of the carbon structural steels. This Standard is applicable to the general structural steels, hot rolled steel sheets, steel strips, sectional steels, and bar steels that are generally used for welding, riveting and bolting member engineering in delivery state.
The chemical composition specified by this Standard is also applicable to steel ingots (including continuous casting billets), steel billets and their products. 2 Normative References
GB 222 Method of Sampling Steel for Determination of Chemical Composition and Permissible Variations for Product Analysis
GB 223 Methods for Chemical Analysis of Iron, Steel and Alloy
GB 228 Methods for Tensile Testing of Metals
GB 232 Methods for Bend Testing of Metals
GB 247 General Rule of Acceptance, Package, Mark and Certification for Steel Plates (Sheets) and Strips
GB 2101 General Requirement of Acceptance, Packaging, Marking and
Certification for Section Steel
GB 2106 Method for Metal Charpy (V-Notch) Impact Test
GB 2975 Steel and Steel Products - Location and Preparation of Test Pieces for Mechanical Testing
GB 4159 Metallic Materials - Charpy Impact Test at Low Temperature
GB 6397 Metallic Materials - Test Pieces for Tensile Testing
3 Designation Denotation, Codes and Symbols
3.1 Denotation of the designation
The designation of steel is composed of the letter representing yield strength, value of yield strength, symbol of quality grade, and symbol of deoxidization method in sequence. For example. Q235-A?€?F.
3.2 Symbols
Q - First letter of Chinese phonetic spelling for the ?€?Qu?€? word of steel yield strength; A, B, C, D - are respectively quality grade;
F - First letter of Chinese phonetic spelling for the ?€?Fei?€? word of rimmed steel; b - First letter of Chinese phonetic spelling for the ?€?Ban?€? word of semi-killed steel Z - First letter of Chinese phonetic spelling for the ?€?Zhen?€? word of killed steel; TZ - First letters of Chinese spelling for the ?€?Tezhen?€? word of special killed steel. In the denotation of designation components, symbols ?€?Z?€? and ?€?TZ?€? can be omitted. 4 Dimension, Shape, Weight and Permissible
Deviation
The dimension, shape, weight and permissible deviation of steels shall conform to the provisions of corresponding standards.
5 Technical Requirements
5.1 Designation and chemical composition
5.1.1 The designation and chemical composition (heat analysis) of the steel shall conform to Table 1.
However, their contents shall be indicated in the quality certificate.
5.1.1.6 When supplying commercial products of steel ingots (including continuous casting billets) and steel billets, the suppler shall guarantee the chemical composition (melting analysis) conforms to the provisions of Table 1; in order to ensure properties of rolled steel meet the requirements of this Standard, the chemical composition of Class-A and B steel of each designation shall be adjusted as per the buyer?€?s demands, and another agreement shall be concluded.
5.1.2 The permissible deviation of the chemical composition of finished steel products and commercial steel billets shall meet the specification of Table 1 in GB 222.
The chemical composition deviation of the finished products and commercial billets of rimmed steel is not guaranteed.
5.2 Smelting method
The steel is smelted in oxygen converter, open-hearth furnace or electric furnace. The smelting method is generally selected by the supplier, unless the buyer has special requirements and they are noted in the contract.
5.3 Delivery state
The steels are generally delivered in hot rolled (including controlled rolled) state. According to the buyer demand, and through the agreement between two parties, it can also be delivered in normalized state (except the Class-A steel).
5.4 Mechanical properties
5.4.1 The results of tensile and impact tests of the steel shall meet the specification of Table 2. The result of bending test shall meet the specification of Table 3. specimen is not planed, the bending diameter shall be increased one specimen thickness a compared with the value listed in Table 3.
6.1.2 The longitudinal axis of the impact specimen shall be parallel to the rolling direction.
6.1.3 When conducting impact test against the steel sheets, strips and section steel with thickness no less than 12mm, or against bar steel with diameter no less than 16mm, the specimen with dimension of 10mm ?? 10mm ?? 55mm shall be used; when conducting impact test against the steel sheets, strips and section steel with thickness from 6mm to less than 12mm, or against bar steel with diameter from 12mm to less than 16mm, the specimen with small dimension of 5mm ?? 10mm ?? 55mm shall be used. Impact test can reserve a rolling surface.
7 Inspection Rules
7.1 The inspection and acceptance of the steel products shall be carried out by the technical supervision department.
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 smelted in the steel-making furnace with nominal capacity no more than 30t, or the steel rolled by continuous casting billets, the Class-A and B steels of the same designation, the same smelting and pouring methods, different furnace number are allowed to form a mixed batch; however, each batch shall contain less than 6 furnace number; while the difference of carbon content in each furnace number shall be no more than 0.02%; and the difference of manganese content shall be no more than 0.15%.
7.3 If the Charpy (V-notch) impact test result of the steel does not meet the specification of 5.4.2, then take another three specimens per group from the same batch of steel to test; the average value of the six specimens shall be no less than the specified value; however, the values of two specimens are allowed to be less than specified value, whereof only one specimen value is allowed to be less than 70% specified value.
7.4 The retest and inspection rules of other inspection items of steel shall meet the specifications of GB 247 and GB 2101.
8 Packing, Marking and Quality Certificate
The packing, marking and quality certificate of the steel shall meet the specifications Additional Explanation.
This Standard was proposed by Intelligence Standard Research Institute of the Ministry of Metallurgical Industry.
This Standard was drafted by Shanghai No.3 Iron and Steel Works, and Intelligence Standard Research Institute of the Ministry of Metallurgical Industry.
The chief drafting staff of this Standard includes Wang Hansheng, and Tang Yifan. Since October 1, 1991, the previous national standard GB 700-79 (Technical Requirements for Ordinary Carbon Structural Steels) was abolished.
The level of this Standard shall be marked as GB 700-88 I.
No.1 Amendment of GB/T 700-1998 Carbon Structural
Steels
This amendment was approved by State Bureau of Technical Supervision in JJGBF [1992] No.148 document on July 31, 1992; and it has been implemented since October 1, 1992.
I. For the deoxidization method column in Table 1, the deoxidization method of Q255 shall be changed from Z to F, b, Z; while that of Q275 shall be changed from Z to b, Z. II. In 5.1.1.5, change ?€?guarantee the mechanical properties of steel..., the carbon and manganese contents of Class-A steel for each designation...?€? into ?€?guarantee the mechanical properties of steel..., the carbon, silicon and manganese contents of Class-A steel for each designation...?€?
III. In Table 2. the upper limit of Q195 tensile strength (??b) shall be changed from 390 to 430 (MPa)
the upper limit of Q215 tensile strength (??b) shall be changed from 410 to 450 (MPa)
the upper limit of Q235 tensile strength (??b) shall be changed from 460 to 500 (MPa)
the upper limit of Q255 tensile strength (??b) shall be changed from 510 to 550 (MPa)
the upper limit of Q275 tensile strength (??b) shall be changed from 610 to 630 (MPa)
NOTE. through the above modification, the level of this Standard is still Level-I.

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