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Q/BQB 408-2023 (QBQB408-2023)

Q/BQB 408-2023_English: PDF (QBQB 408-2023, QBQB408-2023)
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Q/BQB 408-2023English480 Add to Cart 0--9 seconds. Auto-delivery Low carbon cold-rolled steel sheet and strip for cold forming Q/BQB 408-2023


Standards related to: Q/BQB 408-2023

Q/BQB 408-2023
BQB
ENTERPRISE STANDARD OF BAOSTEEL CO., LTD.
Replacing Q/BQB 408-2021
Low carbon cold-rolled steel sheet and strip for cold forming
ISSUED ON: APRIL 09, 2023
IMPLEMENTED ON: JULY 01, 2023
Issued by: BaoSteel Co., Ltd.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Classification and code ... 6
5 Information required for ordering ... 7
6 Dimensions, appearance, weight, allowable deviations ... 8
7 Technical requirements ... 8
8 Inspection and testing ... 13
9 Packaging, marking, inspection documents ... 15
10 Numerical rounding rules ... 15
11 Comparison of similar designations ... 15
Appendix A (Normative) Hard material ... 16
Appendix B (Informative) Hardness reference value of SPCC-X series specific
designation ... 19
Appendix C (Informative) Comparison of similar designations between this document
and relevant domestic and foreign standards ... 20
Low carbon cold-rolled steel sheet and strip for cold forming
1 Scope
This document stipulates the classification and code, size, shape, weight, technical
requirements, inspection and testing, packaging, marking and inspection documents of
low carbon cold-rolled steel sheet and strip for cold forming.
This document applies to low carbon cold-rolled steel sheet and strip for cold forming
(hereinafter referred to as steel plates and strips), which have a thickness of 0.17 mm ~
3.5 mm, as produced by Baoshan Iron & Steel Co., Ltd.
2 Normative references
The contents of the following documents constitute essential provisions of this
document through normative references in the text. Among them, for dated reference
documents, only the version corresponding to the date applies to this document; for
undated reference documents, the latest version (including all amendments) applies to
this document.
GB/T 222 Permissible tolerances for chemical composition of steel products
GB/T 223 Chemical analysis methods for steel and alloys
GB/T 228.1-2021 Metallic materials - Tensile testing - Part 1: Method of test at room
temperature
GB/T 230.1 Metallic materials - Rockwell hardness test - Part 1: Test method
GB/T 232 Metallic materials - Bend test
GB/T 2523 Measuring method of surface roughness, peak count and waviness for
cold-rolled metal sheet and strip
GB/T 2975 Steel and steel products - Location and preparation of samples and test
pieces for mechanical testing
GB/T 4336 Carbon and low-alloy steel - Determination of multi-element contents -
Spark discharge atomic emission spectrometric method (routine method)
GB/T 4340.1 Metallic materials - Vickers hardness test - Part 1: Test method
GB/T 5027 Metallic materials - Sheet and strip - Determination of plastic strain ratio
GB/T 5028 Metallic materials - Sheet and strip - Determination of tensile strain
hardening exponent
GB/T 8170 Rules of rounding off for numerical values & expression and judgement
of limiting values
GB/T 20066 Steel and iron - Sampling and preparation of samples for the
determination of chemical composition
GB/T 20123 Steel and iron - Determination of total carbon and sulfur content
Infrared absorption method after combustion in an induction furnace (routine
method)
GB/T 20125 Low-alloy steel - Determination of multi-element contents -
Inductively coupled plasma atomic emission spectrometric method
GB/T 20126 Unalloyed steel - Determination of low carbon content - Part 2: Infrared
absorption method after combustion in an induction furnace (with preheating)
Q/BQB 400 Package, mark and inspection document for cold-rolled product
Q/BQB 401 Dimension, shape, weight and tolerances for cold-rolled steel sheet and
strip
3 Terms and definitions
There are no terms or definitions to be defined in this document.
4 Classification and code
4.1 Steel sheets and strips shall comply with the requirements in Table 1, when divided
according to their uses.
4.2 Steel sheets and strips shall comply with the requirements in Table 2, when divided
according to surface quality.
4.3 Steel sheets and strips shall comply with the requirements in Table 3, when divided
according to surface structure.
4.4 Codes for distinguishing types of tempering degrees of steel sheets and strips with
SPCC designation.
8.3 The tensile test shall be in accordance with Method B of GB/T 228.1-2021. In order
to improve the reproducibility of the measurement results, it is recommended to use the
beam displacement rate control method. The beam displacement rate for determining
the yield strength is 0.00083 × Lc (mm/s) (where Lc is the parallel length of the tensile
specimen, in mm, the same below) or 0.05 × Lc (mm/min). After the yield strength is
measured, the beam displacement rate is 0.0067 × Lc (mm/s) or 0.4 × Lc (mm/min).
8.4 The r value is calculated at 15% plastic strain. When the maximum force plastic
elongation Ag is less than 15%, the value of the plastic strain at the end of Ag is
calculated. The n value is calculated in the range of 10% ~ 20% plastic strain. When Ag
is less than 20%, the calculated strain range is 10% to Ag.
8.5 Steel sheets and strips shall be inspected and accepted in batches. Each inspection
batch shall be composed of steel sheets and strips of the same designation, specification,
processing state, at not exceeding 30 tons. For steel strips weighing more than 30 tons,
each coil forms an inspection lot.
8.6 The inspection items, number of samples, sampling methods, test methods for each
batch of steel sheets and strips shall comply with the provisions of Table 15.
8.7 The supplier may use different inspection and test methods for acceptance testing.
In the event of a dispute, it shall use the inspection and test methods and relevant
technical requirements specified in this document for testing.
8.8 Reinspection
For tensile test, strain hardening index (n value), plastic strain ratio (r value), Rockwell
hardness or Vickers hardness, bending test, if any test result does not meet the
requirements of this document, it shall take double quantity of specimens randomly
from the same batch, to carry out reinspection for this unqualified item. If the re-
inspection results (including all indicators required for the test of item) are qualified,
the whole batch will be qualified. If even one index in the reinspection results (including
all indicators required for the test of the item) fails, the reinspection will fail. If the re-
inspection fails, the individual pieces that have been tested and have inconsistent test
...