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Q/BQB 600-2018: General technical requirements for steel plates
Q/BQB 600-2018
ENTERPRISE STANDARD OF
BAOSHAN IRON and STEEL CO., LTD.
Replacing Q/BQB 600-2013
General Technical Requirements for Steel Plates
ISSUED ON: JANUARY 15, 2018
IMPLEMENTED ON: APRIL 10, 2018
Issued by: BAOSHAN IRON and STEEL CO., LTD.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative References ... 5 
3 Ordering Information ... 5 
4 Smelting Method ... 6 
5 State of Delivery ... 6 
6 Thermal Treatment ... 7 
7 Chemical Analysis ... 7 
8 Appearance ... 8 
9 Dimension, Appearance, Weight and Permissible Tolerance ... 9 
10 Additional Requirements ... 11 
11 Inspection and Testing ... 15 
12 Acceptance Check ... 17 
13 Rounding-off of Numerical Value ... 18 
14 Signs ... 18 
15 Inspection Documents ... 18 
16 Others ... 19 
Appendix A (normative) Weight Calculation Method and Additional Value of
Thickness for Various Thickness Precisions in Theoretical Weight ... 20 
Appendix B (informative) Steel Weldability ... 22 
Foreword
This Standard was drafted in accordance with the rules in GB/T 1.1-2009 Directives
for Standardization - Part 1: Structure and Drafting of Standards.
The formulation of this Standard takes GB/T 709-2006, EN 10029-2010 and ASTM
A6M-2017, and the practical situation of manufacture in Baoshan Iron and Steel as a
reference.
This Standard serves as a replacement of Q/BQB 600-2013 General Technical
Requirements for Steel Plates. In comparison with the previous standard, there are
several main changes as follows:
---In Normative References, the reference of GB/T 14977-2008 is added; the year
of issuance of GB/T 18253 and GB/T 2975 is added;
---The default mode of the surface state of non-heat-treated steel plate during
delivery is clarified;
---The stipulation that appearance quality may implement in accordance with GB/T
14977 through negotiation is added;
---It is clarified that quenching includes offline quenching and online quenching;
---The permissible tolerance of length that is over 10,000 mm becomes more
rigorous;
---The stipulation of permissible tolerance of unevenness of untrimmed steel plate
is added;
---The common unevenness precision tolerance of steel plate whose width is more
than 3,000 mm becomes more rigorous;
---In the rounding-off of numerical value, it is clarified that the determination of
numerical value adopts rounded-off value comparison method.
In this Standard, Appendix A is normative; Appendix B is informative.
This Standard was proposed by the Manufacturing Management Department of
Baoshan Iron and Steel Co., Ltd.
This Standard shall be under the jurisdiction of the Manufacturing Management
Department of Baoshan Iron and Steel Co., Ltd.
This Standard was drafted by the Manufacturing Management Department of Baoshan
Iron and Steel Co., Ltd.
General Technical Requirements for Steel Plates
1 Scope
1.1 This Standard stipulates a group of general technical requirements for thick steel
plates. The content includes ordering information, smelting method, state of delivery,
thermal treatment, chemical analysis, surface, dimensions, appearance, weight,
additional requirements, inspection and testing, acceptance check, rounding-off of
numerical values, signs and inspection documents, etc.
1.2 This Standard is applicable to thick steel plates (hereinafter referred to as steel
plates) manufactured by Baoshan Iron and Steel Co., Ltd.
1.3 When product standards or contract stipulations are inconsistent with the
stipulations in this Standard, product standards and contract stipulations shall prevail.
2 Normative References
The following documents are indispensable to the application of this Standard. In terms
of references with a specified date, only versions with a specified date are applicable
to this Standard. In terms of references without a specified date, the latest version
(including all the modifications) is applicable to this Standard.
GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products
GB/T 8170 Rules of Rounding-off For Numerical Values and Expression and
Judgement of Limiting Values
GB/T 14977-2008 General Requirement for Surface Condition of Hot-rolled Steel
Plates
GB/T 18253-2000 Steel and Steel Products - Types of Inspection Documents
GB/T 2975-1998 Steel and Steel Products - Location and Preparation of Test
Pieces for Mechanical Testing
3 Ordering Information
3.1 In accordance with demands, during ordering, users need to provide the following
information that is sufficient to illustrate necessary documents:
a) Standard No. and nameplates;
b) Specifications, tolerances and weights;
c) The state of edges, the state of delivery and the state of surface;
d) Purposes, and types of inspection documents;
e) Others (such as additional requirements, requirements of weld repairs).
3.2 When the grade of thickness tolerances, the state of edges and the grade of
unevenness tolerances are not stated in the order contract, products shall be delivered
in accordance with the grade of thickness tolerances - PT.N, the state of edges - EC,
and the grade of common unevenness precision PF.N. When the state of delivery is
not stated, the supply-side shall determine. In terms of non-heat-treated steel plates,
when the surface state is not stated, products shall be delivered in the state of black
surface. When the type of inspection documents is not appointed, comply with Type
5.1 B in GB/T 18253-2000.
NOTE: the type of inspection documents: Type 5.1 B in GB/T 18253-2000 is equivalent to
Type 3.1 in EN 10204-2004.
4 Smelting Method
Steel shall be killed steel smelted through oxygen converter or electric furnace.
5 State of Delivery
5.1 Steel plates may be delivered in the state of rolling, normalized rolling, thermo-
mechanical controlled rolling and/or thermal treatment, unless it is otherwise stipulated
in product standards or contracts.
5.2 When the delivery state of steel plates is not stipulated in product standards or
contracts, the supply-side shall determine.
5.3 The classification and code of the delivery state of steel plates is shown in Table 1.
c) Before welding and repairing, adopt appropriate methods, such as evening out
or polishing to completely remove detrimental defects on steel plates. The
depth of the removed parts shall be within 20% of the nominal thickness of steel
plates. The total of a single-sided grinded area shall be within 2% of the area
of steel plates.
d) On the edges of steel plates’ welded parts, there shall be no undercuts or
overlaps. Stack height shall be more than 1.5 mm higher than the rolled surface;
then, use methods like evening out or polishing to remove the stack height.
e) In terms of heat-treated steel plates, after welding and repairing, they shall
receive thermal treatment again.
f) The welding and repairing of products whose minimum tensile strength is
stipulated to be not less than 690 MPa shall be negotiated through the demand-
side and the supply-side.
8.2.2 If the demand-side demands, through the negotiation between the demand-side
and the supply-side, and indication in the contract, surface quality may implement in
accordance with GB/T 14977. Under this circumstance, if classification or grade is not
indicated in the contract, comply with Class-B, Grade-1 requirements in GB/T 14977.
9 Dimension, Appearance, Weight and Permissible
Tolerance
9.1 Classification and Code
9.1.1 In accordance with the state of edges, steel plates shall be divided into:
Trimmed: EC
Untrimmed: EM
9.1.2 In accordance with the grade of thickness tolerance, steel plates shall be divided
into:
PT.N: symmetrical tolerance;
PT.A: negative tolerance is stipulated in accordance with nominal thickness;
PT.B: asymmetric tolerance whose negative tolerance is 0.30 mm;
PT.C: fixed negative tolerance is 0; positive tolerance is stipulated by nominal thickness.
9.1.3 In accordance with the grade of unevenness tolerance, steel plates shall be
divided into:
9.4.4 Untrimmed steel plates’ out-of-squareness
9.4.4.1 Steel plates’ out-of-squareness (u) may adopt projection method in
measurement, or, it may also adopt diagonal method in measurement. When
projection method is adopted in measurement, the measured out-of-squareness
(oblique cutting) u shall be not more than 1% of the actual width of steel plates. When
diagonal method is adopted in measurement, the out-of-squareness (u), which is
obtained through calculation, shall be not more than 0.7% of the actual width of steel
plates.
9.4.4.2 When there is any dispute, the projection method measurement shall be
adopted for arbitration.
9.4.5 In terms of untrimmed steel plates’ camber and out-of-squareness, if the
demand-side has demands, the demand-side and the supply-side may negotiate and
determine them during ordering.
9.5 Weight
When steel plates are delivered in accordance with theoretical weight, the thickness
adopted in theoretical weight is the average value of the maximum allowable thickness
and the minimum allowable thickness (in other words, nominal thickness plus the
additional value of thickness); width and length shall adopt the nominal dimensional
value. Unless it is otherwise stipulated in product standards, steel’s density shall adopt
7.85 g/cm3 (in other words, the basic weight is 7.85 kg/(mm.m2)). Please refer to
Appendix A (normative) for the calculation method for the theoretical weight and the
additional value of thickness for various thickness precisions.
9.6 Others
In accordance with the demand-side’s demands, through the negotiation between the
demand-side and the supply-side, and indication in the contract, dimension,
appearance, weight and permissible tolerance may be otherwise stipulated.
10 Additional Requirements
In accordance with the demand-side’s demands, through the negotiation between the
demand-side and the supply-side, and indication in the contract, other inspection items,
such as analysis of finished products, mechanical test, process test, metallographic
examination, non-destructive testing (ultrasonic flaw detection UT, magnetic particle
inspection MT, penetrant flaw detection PT) and welding test may be supplemented.
qualified, then, the whole batch shall be deemed as qualified. Even if one of the
indicators is disqualified in the re-inspection result (including all the indicators
requested in the item), then, the whole batch shall be deemed as disqualified.
12.4 Re-classification and rework
Before or after re-inspection, disqualified steel plates may receive re-classification and
rework. Please see the specific methods as follows:
a) Single-piece of steel plate which already receives the inspection and is
disqualified in the inspection result shall not be accepted. However, steel plates that
do not receive the inspection in the batch may be re-submitted piece by piece for
inspection and acceptance check.
b) Disqualified steel plates shall re-receive thermal treatment, then, be re-grouped
and submitted for inspection and acceptance check.
13 Rounding-off of Numerical Value
The determination of numerical value shall adopt rounded-off value comparison
method. Rounding-off of numerical value shall comply with the stipulations in GB/T
8170.
14 Signs
14.1 Steel plates’ signs shall be distinct.
14.2 Generally speaking, steel plates shall be delivered piece by piece. Each piece of
steel plate shall spray-print or engrave certain signs, such as the supply-side’s
trademark, standard No., nameplate, furnace No., dimensions, steel plate No., weight,
and symbols of special requirements.
15 Inspection Documents
15.1 Each batch of steel plates being delivered must issue inspection documents. In
accordance with demands, inspection documents shall indicate: the supply-side’s
name and trademark, product-ordering and product-receiving organization, contract
No., product name, standard No., nameplate, delivery state, dimensions and
specifications, furnace No., steel plate No., delivery weight, various test results
stipulated in the standards, date of issuance, signature of the principal of quality
management department.
15.2 The type of inspection documents shall comply with the stipulations in GB/T
18253.
Appendix B
(informative)
Steel Weldability
B.1 Steel’s weldability refers to the relative difficulty of steel being shaped through
welding under the traditional welding methods (manual arc welding, submerged arc
welding, melting gas shielded welding, non-melting gas shielded welding, electric
resistance welding, plasma arc welding, electron beam welding and laser welding).
B.2 During the welding thermal cycle process of steel, in welded joints and base metal,
certain brittle and unfavorable organizational structure might be generated, which
leads to brittle cracking of welded joints and base metal. In terms of steel, the primary
welding question is cold crack.
B.3 Generally speaking, steel’s cold crack sensitivity is known as hardenability.
Hardenability may be determined through many methods. The most common method
is carbon equivalent method.
B.4 In steel, carbon is the primary hardening element. The calculation of carbon
equivalent is to convert the influence of carbon content and main alloy elements in
steel (such as manganese and vanadium) on hardenability into corresponding carbon
content, then, accumulate it.
B.5 The most commonly used carbon equivalent formula is the carbon equivalent
formula by International Institute of Welding. It has been proved by a lot of production
practices that it is applicable to the majority of commonly used carbon manganese
steel and low-alloy steel.
The following is the method for the calculation of carbon equivalent. Where, the mass
percentage of chemical composition is based on the result of smelting analysis.
B.6 In terms of low-carbon steel and low-alloy steel, when steel is mainly reinforced
through the means of microalloying and thermal treatment, other formulas may also be
adopted to more-accurately deter...