Q/BQB 401-2018 PDF in English
Q/BQB 401-2018 (Q/BQB401-2018, QBQB 401-2018, QBQB401-2018)
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Dimension, shape, weight and tolerances for cold-rolled steel sheet and strip
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Dimension,shape,weight and tolerances for cold-rolled steel sheet and strip
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Newer version: Q/BQB 401-2023 Standards related to: Q/BQB 401-2023
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Q/BQB 401-2018: PDF in English (QBQB 401-2018) Q/BQB 401-2018
BQB
ENTERPRISE STANDARD OF BAOSHAN
IRON & STEEL CO., LTD.
Replacing Q/BQB 401-2014
Dimension, shape, weight and tolerances
for cold-rolled steel sheet and strip
ISSUED ON. JANUARY 15, 2018
IMPLEMENTED ON. APRIL 10, 2018
Issued by. Baoshan Iron & Steel Co., Ltd.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Classification and code ... 5
4 Dimension ... 6
5 Dimension tolerances ... 7
6 Shape ... 10
7 Measurement of dimension and shape ... 12
8 Weight ... 13
9 If the user has other special requirements for dimension, shape, weight, and
tolerances, it can be negotiated when ordering; and shall be indicated in the
contract... 13
10 Rules of rounding off for numerical values ... 13
Appendix A (Normative) Weight calculation method for theoretical weight ... 15
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009
“Directives for standardization - Part 1. Structure and drafting of standards”.
This Standard is developed with reference to EN 10131.2006, EN 10143.2006,
JIS G 3141.2017.
This Standard replaces Q/BQB 401-2014, Appendix A of Q/BQB 420-2014,
Appendix A of Q/BQB 425-2014, Appendix A of Q/BQB 427-2015.
As compared with Q/BQB 401-2014, Appendix A of Q/BQB 420-2014, Appendix
A of Q/BQB 425-2014, and Appendix A of Q/BQB 427-2015, the main changes
of this Standard are as follows.
- INTEGRATE the requirements of tolerances for the dimension and shape
of cold-rolled uncoated and coated products. The scope of application
covers cold-rolled uncoated and coated products;
- ADD the classification of slitting steel strip and related technical
requirements;
- REVISE the product supply nominal width range of Table 2;
- ADD technical requirements for special thickness tolerances PT.AQ and
PT.AD;
- ADD thickness tolerance requirement for the weld of steel strips which are
delivered with welds;
- ADD thickness tolerance requirement for hot-dip products with a combined
weight of double-sided plating of not less than 450g/m2;
- TIGHTEN the thickness tolerance requirements of Table 4; and ADD the
requirement for thickness tolerances of thickness ≤0.3mm;
- COORDINATE and UNIFY the minimum yield strength grading specified in
Table 4 and Table 5;
- OPTIMIZE the nominal thickness grading for the specified minimum yield
strength below 360MPa in Table 5; and ADD a PT.C thickness tolerance
requirement for the specified minimum yield strength above 420MPa;
- REVISE width tolerances of Table 6;
- REVISE the provisions of Table 9 for the length general precision tolerance;
Dimension, shape, weight and tolerances
for cold-rolled steel sheet and strip
1 Scope
This Standard specifies the classification and code, dimension, shape, weight,
and their tolerances for cold-rolled steel sheet and strip.
This Standard applies to the cold-rolled steel strip produced by Baoshan Iron &
Steel Co., Ltd. with a thickness of 0.17mm ~ 3.50mm and a rolling width of
700mm ~ 2080mm, as well as the steel sheet which is crosscut therefrom, and
the steel strip which is slit therefrom; hereinafter known as steel sheet and strip
for short.
Note. The cold-rolled products referred to in this Standard include cold-rolled uncoated
products and cold-rolled coated products.
2 Normative references
The following documents are indispensable for the application of this Standard.
For the dated references, only the editions with the dates indicated are
applicable to this Standard. For the undated references, the latest edition
(including all the amendments) are applicable to this Standard.
GB/T 8170-2008 Rules of rounding off for numerical values & expression and
judgement of limiting values
3 Classification and code
According to different product forms, the classification and code of the edge
state and dimensional precision of steel sheet and strip shall comply with the
requirements of Table 1.
5 Dimension tolerances
5.1 Thickness tolerances
5.1.1 The thickness tolerances of steel sheet and strip shall comply with the
provisions of Table 4. For the slitting steel strip, the thickness tolerances shall
comply with the provisions for the steel strip before slitting. If the user has higher
requirements on thickness precision, it can also be ordered according to the
PT.C super high thickness precision given in Table 5.
5.1.2 With the agreement of the supplier and the purchaser, users with special
requirements for thickness precision can also use asymmetric tolerance for
ordering.
5.1.2.1 PT.AQ mode. The target thickness of steel sheet and strip is the nominal
thickness minus 2%. The upper and lower tolerances of steel sheet and strip
are still controlled according to the PT.A requirement of nominal thickness in
Table 4.
5.1.2.2 PT.AD mode. Only for steel sheets and strips with a minimum yield
strength of less than 260MPa. When the upper tolerance requirement is 0, the
lower tolerance is controlled according to the PT.A requirement of nominal
thickness in Table 4.
5.1.2.3 If the user has other special thickness precision requirements, it can be
negotiated when ordering.
5.1.3 When in the PT.C, PT.AQ, and PT.AD ordering modes, the thickness
tolerance within the total length of 30m at both ends of steel strip (within 15m
on one side end) is allowed to exceed 20% of the specified value.
5.1.4 For steel strips delivered with welds, the thickness tolerance in the range
of 10m near the weld can exceed 50% of the specified value.
5.1.5 For hot-dip products with a combined weight of double-sided plating of
not less than 450g/m2, the thickness tolerance shall be increased by ±0.01mm.
camber shall be no more than 0.2% of the actual measured length of the steel
sheet.
6.3 Flatness
6.3.1 The flatness of steel sheet refers to the maximum distance between the
lower surface of steel sheet and the platform measured by freely placing the
steel sheet on the platform.
6.3.2 The flatness regulations apply only to steel sheets. If the steel sheet is not
flattened, only general flatness precision is applied.
6.3.3 The flatness of steel sheet shall comply with the values specified in Table
10.
6.3.4 For steel sheets with a specified minimum yield strength of less than
260MPa, if the user has special requirements for the flatness precision, it can
also be ordered according to the super high precision given in Table 11.
6.3.5 If the user has special requirements for the L-warp produced by delivery
in rolls, it can be agreed separately.
Note. According to the shape and location, the strain type of steel sheet can be divided into
the following categories.
Bow
Residual curving along all directions of the steel sheet, either longitudinal (in the rolling
direction) or transverse (perpendicular to the rolling direction);
Wave
Wave along the longitudinal direction of steel sheet, rippling;
Edge wave
It refers to the wave along the edge of steel sheet;
Center buckle, center fullness; full center
It refers to the wave which appears in the middle of steel sheet, also known as the
middle fold.
6.3.6 For steel sheets with a specified minimum yield strength of less than
260MPa, when supplying according to high flatness precision or super high
flatness precision, in the arbitration case, the edge wave shall also be inspected.
The edge wave shall meet the following requirements.
7.2.3 When measured by the diagonal method, the two diagonal lengths of steel
sheet shall be measured. 1/2 of the difference in the diagonal lengths is
calculated; that is, u=|X1-X2|/2, as shown in Figure 2.
7.3 Edge camber
7.3.1 The measuring part of edge camber of steel strip shall be no less than
5000mm from the head or tail of the steel strip.
7.3.2 For steel sheets with a length of not more than 2000mm, the length of the
steel sheet is equal to the measured length of edge camber. For steel sheets
with a length greater than 2000mm, any 2000mm length can be taken for
measurement of edge camber.
7.4 Flatness
7.4.1 For steel sheets with a length of not more than 2000mm, the length of
steel sheet is the measured length of flatness.
7.4.2 For steel sheets with a length greater than 2000mm, the steel sheet with
a length of 2000mm can be arbitrarily cut for flatness measurement.
8 Weight
Steel sheets are usually delivered according to the theoretical weight; and can
also be delivered according to the actual weight. The calculation method of
theoretical weight is as specified in Appendix A. Steel strips are usually
delivered according to the actual weight.
9 If the user has other special requirements for
dimension, shape, weight, and tolerances, it can be
negotiated when ordering; and shall be indicated in the
contract.
10 Rules of rounding off for numerical values
Rules of rounding off for numerical values shall comply with the provisions of
GB/T 8170.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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