Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 3078-2008 Quality structural steel cold drawn bars, with respect to which, the following main technical changes have been made:
——the "Terms and definitions" is added (see Clause 3);
——the symbols of delivery condition codes are added (see 7.3.1);
——the steel hardness requirements are modified and three designations, i.e., 20SiMnVB, 20CrV and 45CrVA are canceled (see 7.4; 6.4 of Edition 2008);
——the unit of tensile strength is modified to "MPa" (see 7.5; 6.5 of Edition 2008);
——the requirements for macrostructure is revised as shall meet the requirements of GB/T 699 and GB/T 3077 (see 7.7; 6.7 of Edition 2008);
——the test methods are specified (see Clause 7; Clause 7 of Edition 2008);
——the batching rules are regulated (see Clause 8; Clause 8 of Edition 2008);
——the requirements for surface roughness grade of cold drawn polish steel are added (see 7.9.4).
This standard was proposed by China Iron and Steel Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of this standard are as follows:
——GB 3078-1982, GB/T 3078-1994 and GB/T 3078-2008.
Quality structural steel cold drawn bars
1 Scope
This standard specifies the classification, order contents, dimensions, shapes and permissible deviations, technical requirements, test methods, inspection rules, and packaging, marking and quality certificate of structural steel cold drawn bars and cold drawn polish steel.
This standard is applicable to quality carbon structural steel and alloy structural steel cold drawn bars (round steel, square steel and hexagonal steel) and cold drawn polish round steel (hereinafter collectively referred to as "steel").
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.
GB/T 222 Permissible tolerances for chemical composition of steel products
GB/T 224 Determination of depth of decarburization of steel
GB/T 225 Steel - Hardenability test by end quenching (Jominy test)
GB/T 226 Test method for macrostructure and defect of steel by etching
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method
GB/T 341-2008 Steel wire - Classification and terminology
GB/T 699 Quality carbon structure steel
GB/T 905-1994 Dimension, shape, weight and tolerance for cold-drawn round, square and hexagonal steels
GB/T 1814 Inspection method for steel work fractures
GB/T 1979 Standard diagrams for macrostructure and defect of structural steels
GB/T 2101 General requirement of acceptance, packaging, marking and certification for section steel
GB/T 2975-2018 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
GB/T 3077 Alloy structure steels
GB/T 3207-2008 Bright steel
GB/T 4162 Forged and rolled steel bars - Method for ultrasonic testing
GB/T 6394 Determination of estimating the average grain size of metal
GB/T 7736 Ultrasonic inspecting method for macro-structure and imperfection of steel
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 10561 Steel - Determination of content of nonmetallic inclusions - Micrographic method using standards diagrams
GB/T 13298 Inspection methods of microstructure for metals
GB/T 17505 Steel and steel products - General technical delivery requirements
GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition
GB/T 34474.1 Determination of banded structure of steel - Part 1: Micrographic method using standards diagrams
YB/T 5293 Metallic materials - Forging test
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 341-2008 and GB/T 3207-2008 apply. For the convenience of application, some terms and definitions in GB/T 341-2008 and GB/T 3207-2008 are listed again.
3.1
cold drawing
processing through pressure forming methods such as die drawing and roller drawing
[GB/T 341-2008, Definition 3.1.6]
3.2
polish steel
round steel polished after drawing or peeling
[GB/T 3207-2008, Definition 3.3]
4 Classification
Steels are classified as follows according to their use and processing purposes:
a) steel for pressure processing (UP);
1) steel for hot pressure processing (UHP);
2) steel for cold forging (UCF);
3) steel for hot forging (UHF).
b) steel for cutting (UC).
5 Order contents
Order contracts made based on this standard shall cover the following contents:
a) No. of this standard;
b) product name;
c) steel designation or uniform numerical code;
d) delivery weight (or quantity);
e) dimension, shape and permissible deviation (see Clause 6);
f) use and processing purposes (deemed as steel for cutting unless otherwise indicated);
g) delivery condition (see 7.3.1);
h) mechanical properties (see 7.5);
i) cold or hot forging (see 7.6 if required);
j) decarburized layer (see 7.8 if required);
k) special requirements (see 7.10 if required).
6 Dimensions, shapes and permissible deviations
6.1 The dimension, shape and permissible deviation of cold drawn steel bars shall meet the requirements of GB/T 905-1994, and the specific requirements shall be indicated in the contract; otherwise the requirements of Grade h11 shall be met.
6.2 The dimension, shape and permissible deviation of cold drawn polish round steel shall meet the requirements of GB/T 3207-2008, and the specific requirements shall be indicated in the contract; otherwise the requirements of Grade h11 shall be met.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Classification
5 Order contents
6 Dimensions, shapes and permissible deviations
7 Technical requirements
8 Test methods
9 Inspection rules
10 Packaging, marking and quality certificate
