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GB/T 30834-2022 English PDF (GBT30834-2022)

GB/T 30834-2022 English PDF (GBT30834-2022)

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GB/T 30834-2022: Rating and classifying of inclusions in steel - Scanning electron microscope method
GB/T 30834-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.99
CCS H 24
Replacing GB/T 30834-2014
Rating and classifying of inclusions in steel - Scanning
electron microscope method
ISSUED ON: OCTOBER 12, 2022
IMPLEMENTED ON: FEBRUARY 01, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Overview ... 7
5 Equipment ... 9
6 Calibration and verification of equipment ... 10
7 Sampling ... 10
8 Specimen preparation ... 10
9 Test steps ... 11
10 Inclusion classification, rating and statistics ... 13
11 Inspection report ... 16
12 Precision and bias ... 18
Annex A (informative) Typical acquisition conditions for SEM ... 19
Annex B (informative) Typical examples for test results of Method 1 ... 21
Annex C (informative) Typical examples for test results of Method 3 ... 23
Annex D (informative) Typical examples for test results of 80CL rare earth treated steel
... 25
Annex E (informative) Typical examples for test results of X80 pipeline steel ... 27
Annex F (informative) X-ray counting and chemical classification statistics ... 29
Rating and classifying of inclusions in steel - Scanning
electron microscope method
1 Scope
This document specifies the equipment for evaluating and classifying non-metallic
inclusions in steel by scanning electron microscope (SEM), calibration and verification
of equipment, sampling, specimen preparation, test procedures, inclusion classification,
rating and statistics, test reports, precision and bias.
This document recommends three inspection methods. Method 1 mainly classifies
inclusions according to their morphology. Method 2 mainly classifies inclusions
according to their chemical composition. Method 1 and Method 2 are suitable for
microscopic evaluation of non-metallic inclusions larger than 2μm in rolled or forged
steel with a compression ratio greater than or equal to 3. Method 3 is used to determine
the specific details of a certain type of inclusion such as volume fraction, number
fraction and other stereological parameters. It is suitable for the statistical classification
of inclusions of all sizes (including below 2μm) in various slabs or steel products.
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 10561, Steel - Determination of content of nonmetallic inclusions -
Micrographic method using standards diagrams
GB/T 13298, Inspection methods of microstructure for metals
GB/T 17359, Microbeam analysis - Quantitative analysis using energy dispersive
spectrometry
GB/T 18876.1, Standard practice for determining the metallographic constituent
and inclusion content of steels and other metals by automatic image analysis - Part
1: Determining the inclusion or second-phase constituent content of steels and other
metals by automatic
GB/T 18876.2, Standard practice for determining the metallographic constituent
and inclusion content of steels and other metals by automatic image analysis - Part
2: Determining the inclusion ratings of steels by automatic image analysis and
stereology
GB/T 27788, Microbeam analysis - Scanning electron microscopy - Guidelines for
calibrating image magnification
GB/T 30067, Standard terminology relating to metallography
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T 30067 as
well as the followings apply.
3.1 acquisition analysis rules
The conditions for terminating X-ray acquisition (count, time or both), the list of
elements to be analyzed, the number of fields or particles to be analyzed, the shape of
particles to be analyzed, and so on.
NOTE: Typical acquisition conditions for SEM (see Annex A).
3.2 post-acquisition analysis rules
The elemental composition that identifies the chemical classification of the inclusions.
NOTE: For Method 1 and Method 2, in addition to setting the elemental composition of the
chemical classification of inclusions, it is also necessary to set the type of inclusion (class A, class
B or class C) to which each chemical classification belongs.
3.3 chemical classification
Set the category to which inclusions belong based on elemental composition.
NOTE: It can be broadly classified, such as sulfide, alumina, and silicates. It can also be finely
classified, such as calcium sulfide, calcium silicate, and anorthite.
3.4 aspect ratio; AR
The ratio of the longitudinal and transverse directions of the extension of the inclusions.
3.5 stringer
A single inclusion that is highly extended in the direction of deformation. Two or more
type A or type C inclusions, three or more type B inclusions, and these two or more
inclusions must be arranged in a row, parallel to the direction of the thermal processing
axis. The center line of offset stringer inclusions is less than or equal to 15μm. The
distance between any two adjacent inclusions is less than or equal to 40μm.
3.6 Feret's diameter
chemical classification should be indicated in the inspection report.
4.4 Method 1 and Method 2 provide a quantitative evaluation method for each type of
inclusion and each width series of inclusion levels (level 0~5) in half-level increments.
4.5 Method 3 specifies procedures for analyzing and counting inclusions by size and
chemical classification. Method 3 is used to determine and record some basic
stereological parameters of inclusions, such as the area fraction of sulfides and oxides,
the number of sulfides or oxides per square millimeter. Method 3 is not used for rating.
5 Equipment
5.1 The scanning electron microscope should be equipped with the following
accessories:
- Image acquisition software: It can acquire images.
- Sample stage: Computer control, X-Y direction motor drive. Automatic sample
stage is recommended. Manual operation is also possible. Pay attention to the
continuity of the field of view when operating manually.
- Energy spectrometer: Its resolution should meet the requirements of GB/T 17359.
According to the set parameters, the electron beam and sample stage can be
controlled, and images and spectra can be collected. The chemical composition
analysis of inclusions can be carried out.
- Backscattered electron detector: One or more thresholds can be set to distinguish
between matrix and inclusions.
5.2 The requirements for automatic feature analysis software are as follows:
- It should be possible to set analysis conditions for chemical classification. It should
be possible to characterize by elemental composition, size and morphology.
- It should be able to distinguish stringer and single spherical oxide. Then distinguish
stringer oxides according to different forms (type B or type C). It can measure the
length of various stringer inclusions in each field of view. Classify all spherical
oxides separated from type B or type C stringer inclusions into type D or type DS
oxides. After separation of various types of inclusions (type A, type B, type C, type
D), the automatic feature analysis software should also be able to measure the
diameter of a single inclusion or the width of a stringer incl...
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