GB/T 702-2008 English PDF (GBT702-2008)

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GB/T 702-2008: [Newer version GB/T 702-2017] Hot-rolled steel bars -- Dimensions, shape, weight and tolerances
GB/T 702-2008
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 70.140.60
H 44
Replacing GB/T 702-2004, GB/T 704-1988, GB/T 705-1989 and GB/T 911-2004
Hot-rolled Steel Bars –
Dimensions, Shape, Weight and Tolerances
(ISO 1035-1.1980, ISO 1035-2.1980, ISO 1035-3.1980, ISO 1035-4.1980, MOD)
ISSUED ON. AUGUST 5, 2008
IMPLEMENTED ON. APRIL 1, 2009
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine (AQSIQ);
Standardization Administration (SAC) of the People's Republic
of China.
Table of Contents
Foreword ... 3 
1 Scope ... 6 
2 Cross-sectional Shape ... 6 
3 Sectional Dimension, Weight and Tolerance ... 7 
4 Length and Tolerance ... 10 
5 Shape ... 11 
6 Marking Example ... 14 
Appendix A ... 15 
Foreword 
Modification for the dimensions of round steel bars in this Standard adopts ISO
1035-1.1980 "Hot-rolled Steel Bars - Part 1. Dimensions of Round Bars"; for the
dimensions of square bars, it adopts ISO 1035-2.1980 "Hot-rolled Steel Bars--Part 2.
Dimensions of Square Bars; for the dimensions of flat bars, it adopts ISO 1035-3.1980
"Hot-rolled Steel Bars - Part 3. Dimensions of Flat Bars"; and for the dimension
tolerance of round steel bars, square bars, flat bars, hot-rolled hexagons and hot-rolled
octagon steel, it adopts ISO 1035-4.1982 "Hot-rolled Steel Bars--Part 4. Tolerances".
The main technical differences between this Standard and ISO 1035-1.1980 are as
follows.
— The international standard has two diameter series of round steel bars, while this
Standard has only one;
— For the diameter range of the round steel bars, this Standard extends it from
8mm~220mm of the international standard to 5.5mm~310mm.
The main technical differences between this Standard and ISO 1035-2.1980 are as
follows.
— The international standard has two side length series of square bars, while this
Standard has only one;
— For the side length range of the square bars, this Standard extends it from
8mm~120mm of the international standard to 5.5mm~200mm;
— This Standard does not specify the minimum diameter of the square bar fillet.
The main technical differences between this Standard and ISO 1035-3.1980 are as
follows.
— The international standard has dimension series of flat bars, while this Standard
has only one;
— As for the dimension range of the flat bars, the international standard has flat bars
in width of 20mm~150mm and thickness in 5mm~50mm; while this Standard has
flat bars in width of 10mm~200mm and thickness in 3mm~60mm.
The main technical differences between this Standard and ISO 1045-4.1982 are as
follows..
— For the application scope of this Standard, hot-rolled tool steel flat bars are
added;
— Add dimensional tolerance with hot-rolled round steel bars and square bars in
sectional dimensions of 135mm, 145mm, 155mm, 165mm, 260mm, 270mm,
280mm, 290mm, 300mm and 310mm;
— The length tolerance of the round steel bars and square bars is not classified, and
the provisions of this Standard are equivalent to L3-level of the international
standard;
— Out-of-roundness of the round steel bars is more strict in this Standard than that
specified in the international standard.
This Standard replaces GB/T 702-2004 "Hot-rolled Round and Square Steel Bars -
Dimension, Shape, Weight and Tolerance", GB/T 704-1988 "Dimensions, Shape,
Weight and Tolerances for Hot-rolled Flats", GB/T 705-1989 "Hot-rolled Hexagonal and
Octagonal Steel Bars - Dimensions, Shape, Weight and Tolerance" and GB/T 911-2004
"Dimensions, Shapes, Weight and Tolerances for Hot-rolled Tool Flat Steels".
Compared with GB/T 702-2004, GB/T 704-1988, GB/T 705-1989 and GB/T 911-2004,
this Standard has the main changes as follows.
— Add hot-rolled round and square bars in sectional dimension of 135mm, 145mm,
155mm, 165mm and hot-rolled round steel bars in sectional dimension of 260mm,
270mm, 280mm, 290mm, 300mm and 310mm;
— Add dimensional tolerance and theoretical weight for the hot-rolled round and
square bars in sectional dimension of 135mm, 145mm, 155mm, 165mm, 260mm,
270mm, 280mm, 290mm, 300mm and 310mm;
— Adjust usual length of the hot-rolled round steel bars;
— Add dimension, shape, weight and tolerance of the hot-rolled flat bars, hot-rolled
hexagons, and hot-rolled octagon steel and hot-rolled tool steel flat bars;
— The width of the hot-roll flat bars is changed from 10mm~150mm to
10mm~200mm; and the thickness of the hot-rolled tool steel flat bars is changed
from 6mm~100mm to 4mm~100mm;
— For the hot-rolled flat bars, add under-gauge length requirement and curvature
requirement for width of more than 150mm.
Appendix A of this Standard is normative.
This Standard was proposed by China Iron and Steel Association.
This Standard shall be under the jurisdiction of National Steel Standardization Technical
Committee.
>70 ≥1.0 -
4.5 In case of indicated in the contract made and entered into by and between the
parties concerned, steel bars in length unspecified in the table may also be supplied;
the cut or double length shall be indicated in the contract, and its length tolerance is
+50mm (excluding hot-rolled flat bars).
4.6 The delivery volume of the steel bars in under-gauge length shall not exceed 10%
of the total bars weight in that batch.
5    Shape 
5.1 Hot-rolled Round and Square Bars
5.1.1 The hot-rolled round and square bars are delivered in vertical bars, and they may
be delivered in pony rolls in case of negotiated by and between the parties.
5.1.2 Out-of-roundness of the round steel bars and the diagonal line length of the
square bars shall be in accordance with those specified in Table 9. The
out-of-roundness of the round steel bars hereof refers to the difference between the
maximum diameter and the minimum diameter of the same cross section.
Table 9 Out-of-roundness of Hot-rolled Round Steel Bars and Diagonal Line Length of Square
Bars In. mm
Nominal diameter d
of round steel bars
Out-of-roundness
Nominal side length a
of the square bars
Diagonal line length
≤50 50% of the nominal diameter tolerance < 50 1.33 times of the nominal side length
>50~80 65% of the nominal diameter tolerance ≥50 1.29 times of the nominal side length
>80 70% of the nominal diameter tolerance
All of the specifications
of the tool steel 1.29 times of the nominal side length
5.1.3 The out-of-squareness of the square bars shall be on the same cross section;
difference of any two sides shall not be greater than 50% of the nominal side length
tolerance; difference of any two diagonal line lengths shall not be greater than 70% of
the nominal side length tolerance.
5.1.4 The curvature of the hot-rolled round and square bar shall be in accordance with
those specified in Table 10, the curvature groups shall be indicated in the
corresponding product standard or purchase contract, and that unspecified in the
contract complies with group 2. In case of indicated in the contract made and entered
into by and between the parties concerned, the curvature not indicated in Table 10 may
also be supplied.
Table 10 Curvature of Hot-rolled Round and Square Bars in. mm
Groups
Curvature ≤
Curvature per meter Total curvature
Group 1 2.5 0.25% of the steel bar length
Group 2 4 0.40% of the steel bar length
5.1.5 The hot-rolled round and square bars shall not be significantly reversed.
5.1.6 The shearing slant on both ends of the hot-rolled round an...