YB/T 4003-2016Standard diagrams for macrostructure and defect in continuous casting slab (English PDF)

Foreword

This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This Standard is a revision of YB/T 4003-1997 Standard diagrams for macrostructure

and defect in continuous casting slab.

Compared with YB/T 4003-1997, the major technical changes of this Standard are as

follows.

-- Expand the scope of application;

-- Add morphological characteristics and cause, as well as schematic diagram, of the

��white band��;

-- Add the evaluation details for some defects (see Appendix A), and modify the

standard diagrams accordingly (see Appendix B and Appendix C).

This Standard was proposed by China Iron and Steel Industry Association.

This Standard shall be under the jurisdiction of National Technical Committee 183 on

Iron and Steel of Standardization Administration of China (SAC/TC 183).

The drafting organizations of this Standard. Wuhan Iron and Steel Company Limited,

Shougang Group Co., Ltd., Hebei Iron and Steel Co., Ltd. Tangshan Branch, China

Metallurgical Information and Standardization Institute.

The drafters of this Standard. Han Rongdong, Chen Shihua, Luan Yan, Wang Zhifen,

Zhou Yigui, Ju Xinhua, Zhang Ping, Wu Lixin, Guo Jian, Deng Cuiqing.

The previous versions �C replaced by this Standard �C of the standard are.

-- YB/T 4003-1991, YB/T 4003-1997.

Standard diagrams for macrostructure and defect in

continuous casting slab

1 Scope

This Standard specifies the samples used in the testing of macrostructure and defect in

continuous casting slab by etching and sulfur print, as well as the morphological

characteristics, cause and evaluation principle of defects.

This Standard applies to the evaluation for macrostructure and defect in slabs such as

carbon steel and alloy steel produced by continuous casting process.

The qualification grade of various defects in this Standard and the defects that are not

allowed to exist shall be stipulated in the corresponding technical conditions and the

agreement between the two parties.

2 Normative references

The following referenced documents are indispensable for the application of this

document. For dated references, only the dated version applies to this document. For

undated references, the latest edition (including all amendments) applies to this

document.

GB/T 226, Test method for macrostructure and defect of steel by etching

GB/T 4236, Steel examination by sulphur print (Baumann method)

3 Sampling and sample corrosion methods

The sample cut-out and display methods shall comply with the provisions of GB/T 226

or GB/T 4236.

4 Defect classification and evaluation

5 Inspection report

The inspection report shall include the following contents.

a) entrusting unit;

b) test steel designation;

c) melting number of the test sample;

d) sample number;

e) specifications of the continuous casting slab;

Appendix A

(Informative)

Evaluation details for macrostructure and defect in continuous casting slab

A.1 Center segregation

A.1.1 The segregation of class A is distributed continuously; the segregation of class B

is distributed discontinuously (strip segregation with a length of more than 3 mm); the

segregation of class C is distributed in point form. The schematic diagram is shown in

Figure A.1.

A.1.2 When there are two classes of center segregation in the field of view, the

evaluation shall be made based on the principle that the length of the segregated band

with the higher class (class A > class B > class C) exceeds a quarter of the length of the

entire sample. When class A does not exceed 1/4 of the total length of the sample, but

Classes A+B exceed 1/4 of the total length of the sample, evaluate it as class B. See

Table A.1 for the relationship between class and segregation thickness. The thickness

is the average value of 5 points at the most serious part of segregation defects.

A.2 Standard for internal cracks

Class A Class B Class C

Grade Class A segregation thickness t Class B segregation thickness t Class C segregation thickness t

Intermediate cracks, triangular cracks and corner cracks are rated based on the largest

single crack length (see Table A.2). The crack length is the length of a straight line or a

curve.

A.3 Bubbles and Al2O3 inclusions

The evaluation of pinhole bubbles, honeycomb bubbles and Al2O3 inclusions is mainly

based on the size and distribution of the bubbles. The pinhole bubbles and inclusions

are rated by the maximum diameter; the honeycomb bubbles are rated by the maximum

bubble width (Table A.3).

Appendix B

(Normative)

Standard diagrams for macrostructure and defect in continuous casting slab by

etching

Appendix C

(Normative)

Standard diagrams for macrostructure and defect in continuous casting slab by

sulphur print

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