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

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

This Standard specifies the cross-sectional shape, sectional dimension, weight and tolerance, length and tolerance, shape or marking illustration of the hot-rolled steel bars (round steel bars, square bars, flat bars, hexagon steel and octagon steel).
GB/T 702-2008
GB
NATIONAL STANDARD OF THE
PEOPLE 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 and square bars shall not be greater than 30% of the nominal diameter of the round steel bars and the nominal side length of the square bars, while the ends of the hot-rolled round and square bars shorn by shearing machine is allowed to be with local deformation.
5.2 Hot-rolled flat and hot-rolled tool steel flat bars
5.2.1 The curvature of the hot-rolled flat bars shall be in accordance with those specified in Table 11, the curvature of hot-rolled tool steel flat bars and hot-rolled flat bar in width >150mm per meter shall not exceed 5mm, and the total curvature shall be not greater than 0.50% of the total length. The lateral curvature (rocker) shall not exceed 5mm per meter, and the total lateral curvature shall not be greater than 0.50% of the total length.
Table 11 Curvature of Hot-rolled Flat Bars in. mm
Accuracy level
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
Note. For the flat hot rolled bar with width of >150mm, the curvature per meter is no greater than 5mm and the total curvature is no greater than 0.50% of the steel bar length.
5.2.2 The ends shall be shorn straightly, and the burr on both ends of the hot-rolled tool steel flat bars shall be removed, but burr in size of no greater than 5mm may be allowed to existing. The both ends of the hot-rolled tool steel flat bars shorn by contractor are allowed with local deformation; the shearing slant of the hot-rolled flat bar shall not be greater than those specified in the following. the hot-rolled flat bars with width of???100mm shall not be greater than 6mm, and that w...

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