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This standard is developed 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 by reference to JIS G3113: 2006 (2016), JIS G3134: 2006 (2016), EN 10149-2: 2013, YB/T 4151-2015, and GB/T 3273-2015, and in combination with the actual situation of Baoshan iron and steel.
This standard replaces Q/BQB 310-2014.
The following main changes have been made with respect to Q/BQB 310-2014:
—— Editions of normative references are updated;
—— Designation and corresponding requirements are added for SPFH780, B530CL, and B610L;
—— The lower limit of thickness in Table 1 is canceled, the nominal thickness ranges of some designations are expanded and the corresponding technical requirements are added;
—— Hot-rolled flat steel strip is added to the product category;
—— The thickness tolerance PT.B regulation of B330CL to B650CL is deleted and changed to default;
—— The regulation is added that the High precision PT.C may be selected as thickness precision;
—— The upper limit of Mn for some designations is expanded and the contents of chemical compositions P and S for some designations are tightened;
—— The lower limit of tensile strength of B600L is increased;
—— The width of bending specimens of some designations is adjusted;
—— The yield strength range of B450CL ~ B600CL is adjusted, and the bending indenter diameters of B450CL ~ B650CL and B510L are adjusted;
—— The regulation is deleted that the specified minimum tensile strength of B380CL, B450CL to B650CL is allowed to decrease by 10 MPa if the thickness is no less than 10mm;
—— The regulation is added that the upper limit of yield strength or the upper limit of tightening tensile strength may be stipulated through negotiation for designation of QStE series;
—— The regulations are tightened for defective parts of steel strip.
Annex A of this standard is informative.
This standard was proposed by manufacturing management department of Baoshan Iron & Steel Co., Ltd.
This standard is under the jurisdiction of manufacturing management department of Baoshan Iron & Steel Co., Ltd.
The previous editions of this standard are as follows: Q/BQB 310-1989, Q/BQB 310-1994, Q/BQB 310-1999, Q/BQB 310-2003, Q/BQB 310-2009, Q/BQB 310-2014.
Continuously hot-rolled steel sheet and strip for automobile structural use
1 Scope
This standard specifies the dimension, shape, technical requirements, inspection and testing, as well as package, mark and inspection documents of continuously hot-rolled steel sheet and strip for automobile structural use.
This standard is applicable to the continuously hot-rolled steel strip of carbon and micro-alloyed steel with good cold-forming performance produced by Baoshan iron and steel Co., Ltd., as well as the steel sheet cut horizontally and the slit wide strip cut vertically therefrom, hereinafter referred to as steel sheet and strip. The products are used for the manufacturing of automobile girders, crossbeams, roll-forming wheels, automobile transmission shaft pipes, automobile axle housings and other structures.
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 222-2006 Permissible tolerances for chemical composition of steel products
GB/T 223 Methods for chemical analysis of iron, steel and alloy
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 232 Metallic materials - Bend test
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 8170 Rules of rounding off for numerical values & expression and judgment 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
Q/BQB 300 General rules of package, mark and inspection document for continuously hot rolled steel sheet and strip
Q/BQB 301 Dimension, shape, weight and tolerance for continuously hot rolled steel sheet and strip
3 Classification and code
3.1 The designation, nominal thickness and application of steel sheet and strip are shown in Table 1.
3.2 Steel sheet and strip classification by surface treatment method:
Pickled surface
Rolled surface
3.3 Steel sheet and strip classification by surface quality classes:
General grade surface FA
Superior grade surface FB
3.4 Steel sheet and strip classification by product category:
Hot-rolled steel strip
Hot-rolled steel sheet
Hot-rolled flat steel strip
Hot-rolled slit wide steel strip
Hot-rolled pickled steel strip
Hot-rolled pickled steel sheet
Table 1
Designationa Nominal thicknessb mm Application
SAPH310 ≤16.0 Used for automobile structural members with forming performance requirements, such as automobile frameworks and wheels
SAPH370, SAPH400, SAPH440 ≤14.0
SPFH540, SPFH590 ≤14.0 Used for automobile structural members with good forming performance and high strength requirements, such as automobile frameworks and wheels
SPFH780 ≤8.0
QStE340TM, QStE380TM,
QStE420TM, QStE460TM,
QStE500TM, QStE550TM ≤14.0 Used for structural members with good cold-forming performance and higher or higher strength requirements, such as automobile frame, square tubes, and round tubes
QStE600TM, QStE650TM, QStE700TM ≤12.0
B330CL, B380CL, B420CL, B450CL, B500CL, B530CL, B550CL, B600CL, B650CL ≤14.0 Has good cold forming performance, used for the rims and spokes of roll-forming wheels
B320L, B420L, B510L, B510DL, B550L, B610L (B600L), B650L, B700L, B750L ≤14.0 Used for the manufacturing of automobile frames and cross beams
B440QZR, B480QZR ≤8.0 Used for the manufacturing of automobile transmission shaft tubes
B440QK ≤8.0 Used for the manufacturing of automobile axle housing
a Upon requirements of the purchaser, orders may be made according to the designations in brackets.
b For steel sheet and strip with hot-rolled pickled surface, the nominal thickness t ≤ 8.0 mm.
4 Information necessary for ordering
4.1 The user shall provide the following information when ordering:
a) No. of this company standard;
b) Product category;
c) Designation, surface treatment method and surface quality class;
d) Specification and dimension (thickness, width, unevenness) precision;
e) Edge condition;
f) Application;
g) Types of inspection documents.
4.2 Omissions in order contract
4.2.1 Where surface treatment mode is not specified, the products shall be delivered with rolled surface.
4.2.2 For hot-rolled steel sheet and strip, if dimension precision is not specified, except those specified in this standard, B330CL to B650CL shall be delivered with higher thickness precision PT.B of Q/BQB 301, and as for other dimensions, the products will be delivered with general precision. If the edge condition is not specified, the steel strip will be delivered in the uncut state and the steel sheet will be delivered in the trimmed state.
4.2.3 For hot-rolled pickled steel sheet and strip, if the dimension precision is not specified, the products will be delivered with higher thickness precision, and as for other dimensions, the products will be delivered with general precision. If the edge state, surface quality class and oil-coated are not specified, the products will be delivered in the trimming state, with superior grade surface and in oil-coated status. If the inner diameter of the steel coil is not specified, the products will be delivered with the inner diameter of steel coil being 610 mm.
Foreword i
1 Scope
2 Normative references
3 Classification and code
4 Information necessary for ordering
5 Dimension, shape, weight and tolerance
6 Technical requirements
7 Inspection and test
8 Packaging, marking and inspection documents
9 Rules of rounding off
10 Annex
Annex A (Informative) Tables on comparison between similar designations in this standard and relevant standards