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GB/T 708-2019 PDF in English


GB/T 708-2019 (GB/T708-2019, GBT 708-2019, GBT708-2019)
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GB/T 708-2019: PDF in English (GBT 708-2019)

GB/T 708-2019
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.50
H 46
Replacing GB/T 708-2006
Dimension, shape, weight and
tolerance for cold-rolled steel strip and sheet
ISSUED ON: MARCH 25, 2019
IMPLEMENTED ON: FEBRUARY 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 ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Classification and code ... 6
5 Dimensions ... 7
6 Dimension tolerances ... 8
7 Shape ... 12
8 Measurement of dimensions and shape ... 14
9 Weight ... 16
10 Rounding off of numerical values ... 17
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard replaces GB/T 708-2006 “Dimension, shape, weight and
tolerance for cold-rolled steel plates and sheets”.
Compared with GB/T 708-2006, the main technical changes of this Standard
are as follows:
- MODIFY the thickness and width ranges of steel sheets and strips (see 5.1
of this Standard, 5.1 of 2006 edition);
- MODIFY the thickness tolerance of steel sheets and strips, which is
specified respectively according to the specified minimum yield strength Re
< 260 MPa, 260 MPa ≤ Re < 340 MPa, 340 MPa ≤ Re ≤ 420 MPa, Re > 420
MPa (see Table 2, Table 3, Table 4, Table 5 of this Standard, Table 2 of
2006 edition);
- ADD the higher precision (PW.B) of width tolerance of slit wide strips and
its requirements; MODIFY the width tolerance of slit wide strips (see 6.2.3
of this Standard, 6.2.2 of 2006 edition);
- MODIFY the flatness of steel sheets and strips according to the specified
minimum yield strength Re < 280 MPa, 280 MPa ≤ Re < 360 MPa, Re < 260
MPa, 260 MPa ≤ Re < 340 MPa; MODIFY the requirements for flatness (see
7.1 of this Standard, 7.1 of 2006 edition);
- ADD the requirement that steel sheets and strips are supplied according to
general precision when the thickness tolerance, width tolerance, length
tolerance and flatness are default (see 6.1.6, 6.2.2, 6.3, 7.1.1);
- ADD the negotiation terms when the yield strength and requirements are
not specified in the thickness tolerance and flatness requirements of steel
sheets and strips in the product standard (see 6.1.5, 7.1.5);
- MODIFY the requirements for camber (see 7.2 of this Standard, 7.2 of 2006
edition);
- MODIFY the “cutting angle” to “out-of-squareness”; ADD the method and
requirements for the measurement of out-of-squareness using the diagonal
method (see 7.3 of this Standard, 7.3 of 2006 edition);
- ADD the requirements for the measurement position of flatness of steel
strips (see 8.3.3);
Dimension, shape, weight and
tolerance for cold-rolled steel strip and sheet
1 Scope
This Standard specifies terms and definitions, classification and code,
dimensions, dimension tolerances, shape requirements, measurement of
dimensions and shape, weight and rounding off of numerical values of cold-
rolled steel sheets and strips.
This Standard applies to cold-rolled wide strips, slit wide strips and sheets cut
from strip of which the rolling width is not less than 600 mm (hereinafter referred
to as steel sheets and strips). Steel plates may also refer to this Standard.
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 8170 Rules of rounding off for numerical values & expression and
judgement of limiting values
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
3.1
wide strip
Steel strips with a width of not less than 600 mm and delivered in rolls.
3.2
slit wide strip
Slit from wide strips and delivered in rolls.
3.3
sheet cut from strip
Cut form steel strips and delivered in sheets.
3.4
plate
Cold-rolled flat steel that is directly rolled and does not have fixed edge
deformation.
4 Classification and code
4.1 Classification according to edge state is as follows:
a) cut-edge, EC;
b) mill-edge, EM.
4.2 Classification according to dimension precision and code is as follows:
a) general precision of thickness, PT.A;
b) higher precision of thickness, PT.B;
c) general precision of width PW.A;
d) higher precision of width, PW.B;
e) general precision of length, PL.A;
f) higher precision of length, PL.B.
4.3 Classification according to flatness precision and code is as follows:
a) general precision of flatness, PF.A;
b) higher precision of flatness, PF.B.
4.4 Classification of dimensions and precision of flatness corresponding to
product shape and edge state is shown in Table 1.
Table 8 -- Length tolerance of steel sheets
Dimensions in millimeters
7 Shape
7.1 Flatness
7.1.1 The flatness of steel sheets shall comply with the requirements of Table
9. If the demand party requires supply according to the higher precision of
flatness (PF.B), it shall be indicated in the contract. If not indicated, supply
according to the general precision of flatness (PF.A).
7.1.2 The flatness of steel sheets, of which the minimum yield strength Re is
specified to be not less than 340 MPa, shall be agreed upon between the supply
and demand parties.
7.1.3 For steel sheets with a specified minimum yield strength Re less than 260
MPa, when supplied according to the higher precision of flatness (PF.B), the
side waves shall be inspected in the case of arbitration. The side waves shall
meet the following requirements:
a) When the wave length is not less than 200 mm, for steel sheets with a
nominal width of less than 1500 mm, the wave height shall be less than
1.0 % of the wave length; for steel sheets with a nominal width of not less
than 1500 mm, the wave height shall be less than 1.5 % of the wave length.
b) When the wave length is less than 200 mm, the wave height shall be less
than 2 mm.
7.1.4 When the user has requirements for the flatness of steel strips, after the
user has fully flattened the steel strips, the values specified in Table 9 are also
applicable to steel sheets cut by the user from the steel strips.
7.1.5 When the yield strength is not specified in the product standard and the
flatness is not specified, the flatness of steel sheets and strips shall be agreed
upon between the supply and demand parties and shall be indicated in the
contract.
Nominal length Length tolerance General precision PL.A Higher precision PL.B
+ 0.3 % × nominal length
+ 0.15 % × nominal length
8 Measurement of dimensions and shape
8.1 Thickness
8.1.1 For mill-edge steel sheets and strips, it is measured at a distance of not
less than 40 mm from the rolling side. For cut-edge steel sheets and strips, it is
measured at a distance of not less than 25 mm from the cutting side.
8.1.2 When the width of the slit wide strip is less than 50 mm, it is measured at
the center along the width direction.
8.2 Width
The width shall be measured at where perpendicular to the centerline of steel
sheets and strips.
8.3 Flatness
8.3.1 Place the steel sheet freely on a platform. Except for the weight of the
steel sheet itself, do not apply any pressure. Measure the maximum distance
between the lower surface of the steel sheet and the platform, as shown in
Figure 1.
Key:
1 - flatness.
Figure 1 -- Measurement of flatness
8.3.2 If limited by the length of the test platform, for steel sheets with a length
greater than 2000 mm, it may arbitrarily take 2000 mm for the measurement of
flatness instead of measuring the flatness of full length.
8.3.3 For steel strips, the flatness shall be measured at a distance of more than
5000 mm from the head or tail of the steel strip.
8.4 Camber
The camber of steel sheets and strips refers to the maximum distance between
the side and the straight line connecting the two ends of the measuring portion.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.