GB/T 28300-2012 in English

《GB/T 28300-2012热轧棒材和盘条表面质量等级交货技术条件》由TC183（全国钢标准化技术委员会）归口，TC183SC2（全国钢标准化技术委员会基础分会）执行，主管部门为中国钢铁工业协会。

Surface quality classes for hot-rolled bars and rods—Technical delivery conditions

1 Scope

This standard specifies the terms and definitions, codes, requirements, tests, repairs and
other contents of surface quality for hot-rolled bars and rods.

This standard is applicable to the surface quality classes for hot-rolled bars and rods with nominal dimensions of 5 mm to 150 mm. It may also be used for hot-rolled bars and rods with nominal dimensions of greater than 150 mm after negotiation by the purchaser and the supplier.

This standard is applicable to engineering steel, and may also to structural steel or tool steel after negotiation by the purchaser and the supplier.

This standard does not include any requirements for the permissible depth of surface decarburization.

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 239 Metallic materials wire torsion test (GB/T 239-1999, eqv ISO 7800: 1984; ISO 9649: 1990)
YB/T 5293 Metallic materials—Forging test

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1
delivery lot
unless otherwise specified in the order or in the appropriate product standard, a quantity of steel of the same type and the same diameter ordered with the same requirements for the surface quality, delivered at the same time
 
3.2
bar

3.2.1
rounds
bar with circular cross section and diameter generally 8 mm or above
[GB/T 15574-1995, Definition 6.2.1.2.1.1]

3.2.2
squares
bar with square cross section and side length generally 8 mm or above
[GB/T 15574-1995, Definition 6.2.1.2.1.2a)]

3.2.3
hexagons
bar with hexagonal cross section and opposite side length generally 8 mm or above
[GB/T 15574-1995, Definition 6.2.1.2.1.2b)]

3.2.4
octagons
bar with octangle cross section and opposite side length generally 14 mm or above
[GB/T 15574-1995, Definition 6.2.1.2.1.2c)]

3.3
rod
finished products delivered in coils after hot rolling. The cross section is usually round, elliptical, square, rectangular, hexagonal, octagonal, semicircular or other shape, and the nominal dimension of rod is not less than 5 mm. The surface of rod shall be smooth and may be used for further machining deformation

Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Code
5 Requirements
6 Test
7 Repairs
Annex A (Informative) Description of common discontinuities of hot rolled bars and rods
Annex B (Informative) Comparison between this standard and EN 10221: 1995 in clause/subclause number
Annex C (Informative) Technical deviations between this standard and EN 10221: 1995 and their justifications
Bibliography