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 6725-2008 Cold Forming Steel Sections; the following changes have been made with respect to GB/T 6725-2008 (the previous edition):
——The standard name is modified;
——The strength grade is modified;
——The requirements on designation and composition are modified;
——The delivery conditions are modified;
——The requirements of mechanical property are modified;
——The relevant requirements on plating are added.
This standard was proposed by China Iron and Steel Industry Association.
This standard is under the jurisdiction of SAC/TC 183 National Technical Committee on Iron and Steel of Standardization Administration of China.
The previous editions of this standard are as follows:
GB/T 6725-1986, GB/T 6725-1992, GB/T 6725-2002 and GB/T 6725-2008.
General Requirements of Cold Forming Steel Sections
1 Scope
This standard specifies order contents; classification and code; dimension, shape, weight and permissible deviation; technical requirements; test methods; acceptance rules as well as packaging, marking and quality certificate of cold forming steel sections.
This standard is applicable to cold forming steel sections produced on consecutive roller cold forming units by using cold-rolled, hot-rolled or coated (plated) steel plates and strips which are deformed through cold working.
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 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 699 Quality Carbon Structure Steels
GB/T 700 Carbon Structural Steels
GB/T 714 Structural Steel for Bridge
GB/T 1591 High Strength Low Alloy Structural Steels
GB/T 2101 General Requirement of Acceptance, Packaging, Marking and Certification for Section Steel
GB/T 2518 Continuously Hot-dip Zinc-coated Steel Sheet and Strip
GB/T 2650 Impact Test Methods on Welded Joints
GB/T 2651 Tensile Test Method on Welded Joints
GB/T 2975 Steel and Steel Products - Location and Preparation of Test Pieces for Mechanical Testing
GB/T 3280 Cold Rolled Stainless Steel Plate, Sheet and Strip
GB/T 3524 Hot-rolled Carbon and Low Alloy Structural Steel Strips
GB/T 4171 Atmospheric Corrosion Resisting Structural Steel
GB/T 6723 Cold forming Sectional Steel - Open Sectional Steel for General Structure
GB/T 6726 Cold Forming Sectional Steel for Vehicles - Dimensions Shape Weight and Tolerances
GB/T 6728 Cold Formed Steel Hollow Sections for General Structure
GB/T 12754 Prepainted Steel Sheet
GB/T 33162 Continuously Hot-rolled Steel Sheet and Strip for Cold-forming Steel Sections
YB/T 081 Rule for Rounding Off of Numberical Values and Judgement of Testing Values for Technical Standards of Metallurgy
3 Order Contents
The contract or order ordered according to this standard shall cover the following contents:
a) Standard No.;
b) Product specification;
c) Material designation and corresponding product yield strength grade;
d) Delivery weight (or quantity) and delivery length;
e) Plating type and thickness (if any);
f) Other special requirements.
4 Classification and Code
4.1 Classification and code of cold forming steel sections shall be made according to the product cross sectional shape
Classify according to product cross sectional shape; generally, the initials of Chinese phonetic alphabet to indicate the product appearance feature are adopted. For example:
For cold-formed circular hollow section (circular tube for short), the code is Y (or φ).
For cold-formed square hollow steel (square tube for short), the code is F.
For cold-formed rectangular hollow section (rectangular tube for short), the code is J.
For cold-formed special-shaped hollow section (special tube for short), the code is YI.
For cold-formed opening section steel (opening section steel for short), depending on the cross sectional shapes, the codes are as follows: JD (equal angle steel), JB (unequal angle steel), CD (equal channel steel), CB (unequal channel steel), CN (interior crimping channel steel), CW (exterior crimping channel steel), Z (zee steel), ZJ (crimping zee steel) and YX (cold-formed special-shaped section steel).
4.2 Cold forming steel sections classified by yield strength grade
The cold forming steel sections are generally classified by yield strength grade into Q195, Q215, Q235, Q345, Q390, Q420, Q460, Q500, Q550, Q620, Q690 and Q750.
5 Dimension, Shape, Weight and Permissible Deviation
Dimension, shape, weight and permissible deviation of cold forming steel sections shall meet the requirements of corresponding product standards like GB/T 6723, GB/T 6726, GB/T 6728, etc.
Foreword i
1 Scope
2 Normative References
3 Order Contents
4 Classification and Code
5 Dimension, Shape, Weight and Permissible Deviation
6 Technical Requirements
7 Test Methods
8 Acceptance Rules
9 Packaging, Marking and Quality Certificate
