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GB/T 3078-2019 (GB/T3078-2019)

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GB/T 3078-2019: PDF in English (GBT 3078-2019)

GB/T 3078-2019
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.60
H 44
Replacing GB/T 3078-2008
Quality structural steel cold drawn bars
ISSUED ON: AUGUST 30, 2019
IMPLEMENTED ON: JULY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Terms and definitions ... 5 
4 Classification ... 6 
5 Order content ... 6 
6 Size, shape and allowable deviation ... 7 
7 Technical requirements ... 7 
8 Test method ... 12 
9 Inspection rules ... 14 
10 Packaging, marking and quality certificate ... 15 
Quality structural steel cold drawn bars
1 Scope
This Standard specifies the classification, ordering content, size, shape and
allowable deviation, technical requirements, test methods, inspection rules,
packaging, marking and quality certificates of structural steel cold drawing and
cold drawing polish steels.
This Standard applies to quality carbon structural steel and alloy structural steel
cold drawing bars (round steel, square steel and hexagonal steel) and cold
drawing polish round steel (hereinafter collectively referred to as "steel").
2 Normative references
The following documents are indispensable for the application of this document.
For dated references, only the dated version applies to this document. For
undated references, the latest edition (including all amendments) applies to this
document.
GB/T 222, Permissible tolerances for chemical composition of steel products
GB/T 224, Determination of depth of decarburization of steels
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 structural steels
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
Terms and definitions determined by GB/T 341-2008 and GB/T 3207-2008 are
applicable to this document. For ease of use, some of the terms and definitions
in GB/T 341-2008 and GB/T 3207-2008 are repeated below.
3.1 Cold drawing
A process in which it is formed by pressure processing methods such as die
drawing or roll drawing at normal temperature.
[GB/T 341-2008, Definition 3.1.6]
it is not specified, perform according to the provisions of level 2. If the supplier
can guarantee, it may not be tested.
Table 5 -- Surface roughness of the cold drawing polish round steel
Roughness level Code Surface roughness Ra/μm
Level 1 FB ≤ 1.6
Level 2 FA ≤ 3.2
7.9.5 The steel that is straightened by a slanting roll is allowed to have threaded
roll marks on the surface.
7.9.6 The surface quality of cold drawing square steel and hexagonal steel shall
be in accordance with the provisions of steel for cutting.
7.10 Special requirements.
According to the requirements of the buyer, if it is negotiated between the
supplier and the buyer, and specified in the contract, steels of the following
special requirements can be supplied:
a) reduce the chemical composition range;
b) impact absorption energy of the steel in the delivery state;
c) specify upper and lower limits of mechanical properties;
d) inspect the layered fracture;
e) inspect the banded structure;
f) inspect the grain size;
g) inspect the end hardenability;
h) inspect the non-metallic inclusions;
i) perform a non-destructive testing;
j) others.
8 Test method
The inspection items and test methods of each batch of steels shall comply with
the requirements of Table 6.
Table 6 -- Inspection item, sampling quantity, sampling position and test
method of steels
Inspection item Sampling quantity Sampling portion Test method
a For round steel and hexagonal steel, respectively perform according to Figure A.4 and a),
b) and d) of Figure A.6 of GB/T 2975-2018; for square steel, perform according to a), c),
e), f) of Figure A.8 of GB/T 2975-2018.
b For round steel and hexagonal steel, respectively perform according to Figure A.5 and a),
b) and d) of Figure A.7 of GB/T 2975-2018; for square steel, perform according to Figure
A.9 of GB/T 2975-2018.
9 Inspection rules
9.1 Inspection and acceptance
9.1.1 The delivery inspection and acceptance of steels shall be carried out by
the supplier's quality and technical supervision department.
9.1.2 The supplier shall ensure that the delivered steel meets the requirements
of this Standard or the contract. If necessary, the buyer has the right to inspect
and accept according to any inspection item that is specified in this Standard or
the contract.
9.2 Batch rules
the steels shall be inspected and accepted in batches. Each batch shall consist
of steels of the same designation, the same heat number, the same processing
method, the same size, the same delivery state, and the same heat treatment
system (heating). For steels that are remelted and smelted by electroslag
(excluding aluminum steel), under the conditions of stable process and
guaranteed requirements of this Standard, it’s allowed to be delivered in
batches of smelting master furnace number of consumable electrodes.
9.3 Sampling quantity and sampling portion
The sampling quantity and sampling portion of the steels shall comply with the
requirements of Table 6.
9.4 Re-inspection and determination rules
9.4.1 The re-inspection and determination rules of the steels shall comply with
the provisions of GB/T 17505.
9.4.2 If the supplier can ensure that the steel is qualified, for the test results of
the mechanical properties, macrostructure and non-metallic inclusions of steels
or steel billet of the same heat number, it is allowed to replace the steel with
billet, and replace the small one with the large one.
9.4.3 The test and inspection results of the steels shall be rounded off by
rounding-off value the comparison method to the number that is indicated by
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.