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This standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 709-2006 Dimension, shape, weight and tolerances for hot-rolled steel plates and sheets.
In addition to editorial changes, the following main technical changes have been made with respect to GB/T 709-2006:
—— terms and definitions of “slit wide strip” and “plate/sheet cut from strip” are added (see 3.3 and 3.4);
—— "positive deviation" is modified to "upper deviation" and "negative deviation" to "lower deviation" (see 4.2 of this standard and 4.2 of Edition 2006);
—— the classification of and technical requirements for average precision of flatness (PF.A) and higher precision of flatness (PF.B) are added (see 4.4 and 7.1.1.2);
—— the dimension ranges of steel plate/sheet and strip are modified (see Table 1 of this standard and 5.1 of Edition 2006);
—— classes N, A, B and C deviations of plate are combined into one table, the thickness deviation requirement for plate with a thickness greater than 400 mm is added, and the upper limit of nominal width is adjusted to 5,300 mm (see Table 2 of this standard, and Tables 1, 2, 3 and 4 of Edition 2006);
—— the negotiation clause is added for thickness tolerance of steel plates with a thickness greater than 200 mm (see 6.1.1.3);
—— the requirement is added that the products may be supplied according to the tolerance given in Annex A upon negotiation between the supplier and the demander (see 6.1.1.4);
—— in Edition 2006, the thickness tolerance of steel strips (including plates/sheets cut from strip) are classified based on a specified minimum yield strength less than 345 MPa, which is modified to 360 MPa in this standard, and a separate table is given for thickness tolerance of steel strips (including plates/sheets cut from strip) with a specified minimum yield strength Re not less than 360 MPa (see Tables 3 and 4 of this standard, and Table 5 of Edition 2006);
—— the thickness tolerance of the steel strip, plate/sheet is added, so is the requirement that the steel strip, plate/sheet shall be supplied with PF.A unless otherwise specified (see 6.1.2 and 7.1.2);
—— the negotiation clauses on the thickness tolerance and flatness requirements are added when the yield strength and requirements are not specified in the product specification (see 6.1.2.3 and 7.1.3);
—— the length tolerance of plates is modified (see Table 8 of this standard, and Table 10 of Edition 6);
—— the length tolerance of plates/sheets cut from strip is modified (see Table 9 of this standard, and Table 11 of Edition 6);
—— the flatness requirements for plates are modified (see 7.1.1 of this standard, and Table 12 of Edition 2006);
—— the flatness requirements for plates/sheets cut from strip are modified (see Table 11 of this standard, and Table 13 of Edition 2006);
—— the "oblique cutting" is modified to "out-of-squareness", and diagonal measuring method and requirements for out-of-squareness with are added (see 7.3 of this standard and 7.3 of Edition 2006);
—— the schematic diagram for measuring flatness of plates is added (see Figure 2);
—— the schematic diagram for measuring the out-of-squareness with diagonal method is added (see Figure 6);
—— the provision is added that for a piece of steel plate/sheet of greater than 1,000 kg, the value shall be rounded to an integer in kg (see Table 14).
This standard was proposed by the China Iron and Steel Association.
This standard is under the jurisdiction of SAC/TC 183 National Technical Committee on Iron and Steel of Standardization Administration of China.
The previous editions of this standard are as follows:
—— GB 709-1965, GB 709-1988, and GB/T 709-2006.
Dimension, shape, weight and tolerance for hot-rolled steel strip, plate and sheet
1 Scope
This standard specifies the terms and definitions, classifications and codes, dimensions, dimensional tolerance, shape, measurement of dimensions and shape, weight, and rounding off for numerical values in connection with hot-rolled steel strip, plate and sheet.
This standard is applicable to single rolled steel plates (hereinafter referred to as plates) and wide steel strips with a rolling width of not less than 600 mm, slit wide strips and plates/sheets cut from strip.
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 judgment of limiting values
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
plate
hot-rolled flat steel subject to direct rolling without fixed edge deformation
3.2
wide strip
steel strip with a rolled width of not less than 600 mm and delivered in rolls
3.3
slit wide strip
steel strip formed by slitting the wide strip and delivered in rolls
3.4
plate/sheet cut from strip
steel plate/sheet formed by cutting the wide strip or slit wide strip and delivered in plates
4 Classifications and codes
4.1 The classification based on the edge state and corresponding codes are as follows:
a) trimmed, EC;
b) untrimmed, EM.
4.2 The classification based on the thickness deviation types and corresponding codes are as follows:
a) Class N deviation: upper deviation equals to lower deviation;
b) Class A deviation: the lower deviation is specified as the nominal thickness;
c) Class B deviation: the fixed lower deviation is -0.30 mm;
d) Class C deviation: the fixed lower deviation is 0.00 mm.
4.3 The classification based on the thickness precision and corresponding codes are as follows:
a) average precision of thickness, PT.A;
b) higher precision of thickness, PT.B.
4.4 The classification based on the flatness precision and code are as follows based on the flatness precision:
a) average precision of flatness, PF.A;
d) higher precision of flatness, PF.B.
5 Dimensions
5.1 Range of nominal dimension
The range of nominal dimension of steel strip, plate and sheet shall meet the provisions specified in Table 1.
Table 1 Range of nominal dimension In: mm
Product name Nominal thickness Nominal width Nominal length
Plate 3.00~450 600~5,300 2,000~25,000
Wide strip ≤25.40 600~2,200 -
Plate/sheet cut from strip ≤25.40 600~2,200 2,000~25,000
Slit wide strip ≤25.40 120~900 -
5.2 Recommended nominal dimension
5.2.1 The nominal thickness of the plate shall be within the range specified in Table 1, and for the steel plate/sheet with a thickness less than 30 mm, the recommended nominal thickness shall be a multiple of 0.5 mm; for the steel plate/sheet with a thickness of not less than 30 mm, the recommended nominal thickness shall be of a multiple of 1 mm.
5.2.2 The nominal width of the plate shall be within the range specified in Table 1, and the recommended nominal width shall be a multiple of 10 mm or 50 mm.
5.2.3 The nominal thickness of the steel strip (including plate/sheet cut from strip) shall be within the range specified in Table 1, and the recommended nominal thickness shall be a multiple of 0.1 mm.
5.2.4 The nominal width of steel strip (including plate/sheet cut from strip) shall be within the range specified in Table 1, and the recommended nominal width shall be a multiple of 10 mm.
5.2.5 The length of the steel plate/sheet shall be within the range specified in Table 1, and the recommended nominal length shall be a multiple of 50 mm or 100 mm.
5.2.6 As required by the demander, the steel strips, plates and sheets with other dimensions may be supplied subject to negotiation between the supplier and demander.
6 Dimensional tolerance
6.1 Thickness tolerance
6.1.1 Thickness tolerance of the plate
6.1.1.1 The thickness tolerance of the plate shall meet the requirements specified in Table 2 (Class N).
6.1.1.2 As required by the demander, the supplier may supply plates of other deviation classes (such as Classes A, B and C) with the tolerance values equal to those specified in Table 2, and it shall be noted in the contract; the supplier may also supply plates subject to upper deviation with a tolerance value equal to those specified in Table 2, and the upper and lower deviation shall be specified by the supplier and the demander through negotiation.
6.1.1.3 For the steel plate/sheet with a thickness greater than 200 mm, the thickness tolerance may be determined by both supplier and demander through negotiation and shall be noted in the contract.
6.1.1.4 The products may be supplied according to the tolerance given in Annex A subject to negotiation between the supplier and the demander.
6.1.2 Thickness tolerance of the steel strip (including plate/sheet cut from strip)
6.1.2.1 The thickness tolerance of the steel strip (including plate/sheet cut from strip) with specified minimum yield strength Re less than 360 MPa shall meet the provisions specified in Table 3. If the demander requires that the products shall be supplied with the higher precision of thickness (PT.B), it shall be noted in the contract; otherwise, the products may be supplied with the average precision of thickness (PT.A). As required by the demander, the upper and lower deviations of the steel strip may be adjusted properly within the tolerance range specified in Table 3.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Classifications and codes
5 Dimensions
6 Dimensional tolerance
7 Shape
8 Measurement of dimension and shape
9 Weight
10 Rounding of numerical values
Appendix A (Informative) Thickness tolerance of the plate
