GOST R ISO 4967-2009

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  ГОСТ Р ИСО 4967-2009

GOST R ISO 4967−2009 Steel. Determination of content of nonmetallic inclusions. Metallographic method using standard reference scales (adjusted)

GOST R ISO 4967−2009

Group B09

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

Steel

DETERMINATION OF CONTENT OF NONMETALLIC INCLUSIONS. METALLOGRAPHIC METHOD USING STANDARD REFERENCE SCALES

Steel. Determination of content of nonmetallic inclusions. Micrographic method using standard diagrams

OKS 77.080.20
AXTU 0709

Date of introduction 2011−01−01

Preface

The objectives and principles of standardization in the Russian Federation established by the Federal law of 27 December 2002 N 184-FZ «On technical regulation», and rules for the application of national standards of the Russian Federation — GOST R 1.0−2004 «Standardization in the Russian Federation. The main provisions"

Data on standard

1 PREPARED AND SUBMITTED by the Technical Committee for standardization TC 145 «monitoring Methods of steel products» on the basis of an authentic translation of the standard referred to in paragraph 3

2 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology of December 11, 2009 N 728-St

3 this standard is identical to international standard ISO 4967:1998 «Steel. Determination of content of nonmetallic inclusions. Metallographic method using standard reference scales» (ISO 4967:1998 «Steel — Determination of content of nonmetallic inclusions — Micrographic method using standard diagrams»)

4 INTRODUCED FOR THE FIRST TIME


Information about the changes to this standard is published in the daily published information index «National standards», and the text changes and amendments — in monthly indexes published information «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in a monthly information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet

AMENDED, published in IMS No. 2, 2012

An amendment made by the manufacturer of the database

1 Scope

This standard specifies the metallographic method for determination of content of nonmetallic inclusions in rolled or forged steel with a degree of compression of not less than 3, using the reference scales.

For free-cutting steels and steels with a controlled shape sulfides at the reference scale given in this standard (Annex a) not applicable.

Allowed determination of content of nonmetallic inclusions using the methods of automatic image analysis (Annex D).

2 the essence of the method

The method consists in comparing the observed field of view with a reference scale, shown in Appendix A, and assessing each type of inclusions separately. In the case of using image analysis fields are assessed in accordance with the dependencies given in Appendix D.

On the reference image correspond to square fields of view with an area of 0.5 mmeach, is observed on the longitudinal polished plane at a magnification x 100.

In accordance with the shape and distribution of inclusions in the reference image are divided into five major groups, denoted by the letters A, b, C, D, and DS.

These five groups characterize the most frequently observed types and morphological characteristics of the inclusions:

— Group a (inclusions of sulphides) — a severely deformed individual particles gray color, with a wide range of shape factor (ratio length/width) and usually with rounded ends;

— Group b (inclusions aluminates) — numerous non-deformable particles (at least three), polygonal in shape, with low aspect ratio (less than three), black or bluish color, oriented in the warp direction;

— Group C (inclusions of silicates) is strongly deformed individual black or dark grey particles with a wide range of shape factor (not less than three) and, as a rule, acute ends;

— Group D (inclusions globular oxides) — rigid, angular or round, black or blue, randomly distributed particles with a low aspect ratio (less than three);

— Group DS (on single globular oxides) — round or almost round single particles with a diameter of at least 13 microns.

According to the above reference scales can also be estimated other (non-traditional) types of inclusions, provided similarities in their morphology (shape, size, distribution and quantity) with the above five types of inclusions, and indicate their chemical nature. For example, globular sulfides should be assessed as to the inclusion of the type indicated in the test report should indicate the composition using subscript (for example ). The designation means that the sulphides of calcium, and the designation of globular inclusions of sulfides of rare earth elements.  — globular two-phase inclusions, such as aluminate, surrounded by sulphide of calcium.

Compounds such as borides, carbides, nitrides and carbonitrides, can also be evaluated by these scales provided the similarity of their morphology with the above five types of inclusions, and indicate their chemical nature, as described in the previous paragraph.

Note — To establish the nature of unconventional inclusions before the test is advisable to carry out their research by increasing more x 100.


Each main group of inclusions shown on the scale is composed of two subgroups, each of which contains six reference images, characterizing the increase in the content of inclusions. A subdivision carried out in order to give examples of the different thickness of non-metallic inclusions.

The reference scale for different groups of inclusions are given in Appendix A.

To the left of each reference image specified point inclusions increasing from 0.5 to 3 with increasing length of the enable lines or inclusions (group A, b and C) or the number of inclusions (group D), or their diameter (group DS), as shown in table 1, and thickness as indicated in table 2. For example, the designation of the reference image A2 indicates that the shape of the inclusions observed in the microscope corresponds to group A, and their distribution and the number corresponds to the score 2.


Table 1 — minimum values for scoring

Table 2 — thickness Parameters of the inclusions

3 Sampling

The shape of the inclusions substantially depends on the degree of deformation of steel; therefore, a comparative measurement can be carried out only on the samples selected from products with the same degree of deformation. The polished surface of the sample used for the determination of inclusions should be approximately 200 mm(20x10 mm). It should be parallel to the longitudinal axis of the product and located in the middle of the distance between its outer surface and the centre.

The method of sampling must be specified in standards and technical documents for products. In the case of sheet metal, the polished surface of the sample should be at a distance equal to approximately ¼ the width of the sheet from the edge.

In the absence of such instructions should be used the following methods of sampling:

— for bar or billet with a diameter of over 40 mm are exploring the surface of a part diametrical cross section, located in the middle between the outer surface and the center (figure 1);

for rod with diameter of 25 to 40 mm inclusive examine the surface of the diametrical half section (from the center to the edge of the sample) (figure 2);

for rod with a diameter of not more than 25 mm the surface of exploring the full diametrical cross section, whose length is sufficient to obtain an area of about 200 mm(figure 3);

for sheets with a thickness of not more than 25 mm explore the entire surface of the longitudinal section located at a distance equal to ¼ of the width of the sheet from its edge (figure 4);

for sheets thicker than 25 to 50 mm inclusive examine the surface of half the sheet thickness from outer surface to centre is at a distance equal to ¼ of the width of the sheet from its edge (figure 5);

for sheets with a thickness of over 50 mm are exploring the surface of ¼ sheet thickness, located at half the distance between the outer surface and mid-thickness and at a distance equal to ¼ of the width of the sheet from its edge (figure 6).

The number of core samples is determined in accordance with a product standard or agreement.

For any other products the method of sampling should be specified in the agreement between the parties.

Figure 1 — Sample from bar stock or billets with a diameter or a side length of more than 40 mm

Figure 1 — Sample from bar stock or billets with a diameter or a side length of more than 40 mm

Figure 2 — a Sample from bar stock or billets with a diameter or a side length of more than 25 to 40 mm inclusive

Figure 2 — a Sample from bar stock or billets with a diameter or a side length of more than 25 to 40 mm inclusive

Figure 3 — a Sample rod with a diameter of not more than 25 mm

Figure 3 — a Sample rod with a diameter of not more than 25 mm

Figure 4 — a Sample sheet with a thickness of not more than 25 mm

Figure 4 — a Sample sheet with a thickness of not more than 25 mm

Figure 5 — a Sample sheet with a thickness of more than 25 to 50 mm inclusive

Figure 5 — a Sample sheet with a thickness of more than 25 to 50 mm inclusive

Figure 6 — a Sample from a sheet thickness of over 50 mm

Figure 6 — a Sample from a sheet thickness of over 50 mm

4 Preparation of samples

The sample is cut in such a way to obtain the required surface for the study. To get a flat surface and to exclude the rounding of specimen edges during polishing, the sample can be mounted in a clamping fixture or subjected to a crowbar.

During polishing of samples it is important to avoid chipping or deformation of inclusions and contamination of the polished surface. The sample surface should be clean, and the shape of the inclusions should not change. These requirements are particularly important when the estimated inclusion are small in size. For polishing it is recommended to use diamond pastes. In some cases, may require heat treatment of the sample before polishing to give it the maximum hardness.

5 Determination of inclusions

5.1 observation Method

Research on the microscope is carried out using one of two methods:

— projecting an image on frosted glass;

— observation through the eyepiece.

The method chosen should be used throughout the test.

If the image is projected on a frosted glass or a similar device, the increase of the frosted glass must be within x (100±2). Printed on transparent plastic overlay (figure 7) a square with side equal to 71 mm (the area of which corresponds to the true area of 0.5 mm), placed on the projection screen of frosted glass or behind the screen. The image observed within the square compared to the images on the reference scale (Appendix A).

Figure 7 — Measuring grid for transparent overlays or ocular inserts

Figure 7 — Measuring grid for transparent overlays or ocular inserts

In the case of inclusions through the microscope eyepieces should be installed in the microscope eyepiece insert with a measuring grid is shown in figure 7, positioning it so that the square area of 0.5 mmwas located in the image plane.

Note — In some cases can be used an increase of more x 100, provided that the same increase was used for the reference scales, as indicated in the test report.

5.2 evaluation Methods

To evaluate inclusions apply two methods.

5.2.1 Method A

Explore the entire polished surface of the sample and for each type of inclusions, thin and thick, determine the worst box, i.e. the box that corresponds to the highest score of the reference scale.

5.2.2 Method In

Explore the entire polished surface of a sample and each field is compared with a reference scale. Record the score for each type of inclusions, both thin and thick (specified to the left of the reference images), which corresponds to the studied field.

Permitted by agreement with the consumer to carry out a partial examination of the sample by evaluating a reduced number of fields, distributed in a specific pattern. As the number of the studied fields and their distribution needs to be specified in the agreement between the parties.

5.2.3 General rules for methods A and b

Every observed field is compared with a reference image. If the evaluation of inclusions in the observed field is located between the two reference images, then it is rounded up to a lower score.

If there are individual enable lines or inclusions, the length of which exceeds the field width (0.71 mm), and if the width or the diameter of the inclusions exceeds a maximum value for thick inclusions (table 2), such inclusion should be assessed as oversize in length, width or diameter. The size of such inclusions or lines should be indicated in the test report separately. However, these inclusions should be taken into account in the overall assessment of the field.

The reproducibility of the measurements improved when carrying out the actual measurements (length of the inclusions of types A, b and C, the diameter of the inclusions of type DS) and counts inclusions (type D). For such measurements it is necessary to use a transparent overlay or ocular insert (see figure 7), the limit values given in tables 1 and 2, as well as morphological descriptions under section 2.

Non-traditional types of inclusions is evaluated by reference to the images of the group (A, b, C, D, DS), which corresponds to their morphology. The length, number, width, or diameter of the inclusions are compared with reference images each group of inclusions is given in Appendix A, or determine the total length, number, thickness or diameter of inclusions and use of tables 1 and 2 for determining the score, characterized by a content of inclusions, and thickness class (thin, thick, or oversize). Then indicate the unconventional nature of the inclusions by the subscript in the designation of the type of inclusions. The definition of the subscript is given in the test report.

For inclusions of types A, b and C, two separate switching or two lines of inclusions in length and located or not located on the same line, considered as one inclusion, or one line, if the distance is less than or equal to 40 microns, and the distance (distance between the centers of the inclusions or lines) is less than or equal to 10 µm (figures 8 and 9).

Figure 8 — Inclusion types A and C

Figure 8 — Inclusion types A and C

Figure 9 — type included In

Figure 9 — type included In

In case the lines that contain inclusions of different width, the width of the line is considered to be equal to the width of the largest inclusion.

6 Presentation of results

6.1 General

If standards for products not specified otherwise, the test results can be presented as follows.

The results are expressed by the numbers of points belonging to each sample, based on which it calculates the arithmetic mean value of the score for the smelting for each type and each thickness of the inclusions. This method is used in combination with the method As given in 5.2.1.

6.2 Method A

Lead score corresponding to the worst field of each type and each thickness of the inclusions (Appendix C).

After the standard indicate the type of inclusions indicate the worst score of the field. The presence of thick inclusions indicate by the letter , and the presence of oversize inclusions (5.2.3) is marked .

Examples: And 2; 1E; 3; D 1; 2s; DS of 0.5.

For each subscript used to identify non-traditional types of inclusions in the test report needs to be given definition.

6.3 Method In

The total number of fields evaluated by each grade, for each type and each thickness of the inclusions for a given number of investigated fields .

By agreement of the parties for the presentation of the results can be used the complete set of values the number of fields that correspond to each score for the various types of inclusions, such as the total extent of inclusions , or of the average content of inclusions .

An example For inclusions of type A are:

— the number of fields evaluated by 0,5 points;

— the number of fields evaluated by 1 point;

— the number of fields evaluated a score of 1.5;

— the number of fields evaluated score 2;

— the number of fields evaluated a score of 2.5;

— the number of fields evaluated score of 3;

then

; (1)

, (2)

where is the total number of investigated fields.

Typical examples of the presentation of the results is given in Annex C.

7 test report

The test report shall contain:

a) reference to this standard;

b) grade of steel and the melting number;

c) product and its size;

d) sample type and location investigated in a plane;

e) the selected methods (method of observation, method of evaluation, method of processing results);

f) the increase, if it is more than x 100;

g) the number of the studied fields or total investigated area;

h) the results of the study (including the number, size and type oversize inclusions or lines);

i) of the definition of subscripts used to non-traditional types of inclusions.

Annex a (mandatory). The reference scale ISO for inclusions of types A, b, C, D, and DS

Appendix A
(required)

Group a (inclusions of sulphides)

Group b (inclusions aluminates)

Group (inclusions of silicates)

Group D (inclusions globular oxides)

Group DS (on single globular oxides)

Diameter from 13 to 76 µm inclusive

The minimum diameter

Annex b (informative). Field evaluation and oversize inclusions or lines

The App
(reference)

B. 1 Example evaluation field

Figure B. 1 — field Evaluation

The upper left drawing in figure B. 1 shows the field observed at magnificationof 100, which can distinguish four types of non-metallic inclusions. Depending on their shape and distribution of these inclusions klassificeret as the following four types:

— type a sulfides;

— type b aluminates (destroyed enable);

— type C silicates;

— type DS, one globular inclusion.

The observed field estimate by comparing it for each type of inclusions with the closest reference image, without considering other types of inclusions. This assessment gives the following scores: 2, 2, 1 and DS is 2.5.

Figure B. 1 — field Evaluation

B. 2 Example of evaluation of oversize inclusions or lines

If the enable or line are oversize only length, by using the method In part on or lines within a field, and when using the method And 0.71 mm added to the length of all the other inclusions of the same type and the same thickness are present in this field (figure V. 2a).

Figure B. 2 — field Evaluation with oversize inclusions or lines

Figure B. 2 — field Evaluation with oversize inclusions or lines

If the enable or line are oversize in width or diameter (inclusions of type D), then this inclusion should be assessed as the fat inclusion for this field (figure V. 2b).

If the number of inclusions of type D, more than 49, then the score should be calculated from the expression given in Appendix D.

For inclusions of type DS with a diameter of more 0,107 mm score can be calculated by the expression given in Appendix D.

Application (reference). A typical example of presentation of results (total number of fields evaluated by each score for each type of inclusions, the number of investigated fields)

Application
(reference)

C. 1 Points corresponding to each field and type of inclusions

Table C. 1 shows an example of the results of such evaluation for the 20 studied field. Usually examine at least 100 fields.


Table C. 1 — Points

C. 2 total number of fields of each score for each type of inclusions

From the above results the total number of fields evaluated by each grade, for each type of inclusions. These values are the total number of fields is given in table C. 2.


Table C. 2 — total number of fields

C. 3 Calculation of total contamination with inclusions and the average of pollution

Using the full number of fields shown in table C. 2, calculate the corresponding values of the full and average contamination for each type of inclusions and each thickness.

P.3.1 For the inclusions of type A

and the Subtle inclusion of

; (P. 1)

(S. 2)

where is the total number of investigated fields (see p.2).

b — Thick inclusion

; (P. 3)

indicating the 1s. (P. 4)

P.3.2 For type inclusion In

and the Subtle inclusion of

; (P. 5)

. (P. 6)

b — Thick inclusion

; (P. 7)

. (P. 8)

P.3.3 For inclusions of the type

and the Subtle inclusion of

; (P. 9)

. (P. 10)

b — Thick inclusion

; (P. 11)

. (P. 12)

P.3.4 For inclusions of type D

and the Subtle inclusion of

; (C. 13)

. (P. 14)

b — Thick inclusion

; (C. 15)

indicating the 1s. (P. 16)

P.3.5 For inclusions of type DS

; (P. 17)

. (P. 18)

C. 4 Weighting factor

With the aim of obtaining increased General cleanliness of steel based on the number of inclusions, it is recommended to use a weighting factor for each score.

Can be used the weights given in table C. 3.


Table C. 3 — weights

A measure of the purity calculated by the following formula

(S. 19)

where is a weighting factor;

 — the number of field points ;

 — complete investigated area of the specimen, mm.

Annex D (informative). Dependencies between points of the reference scale and the measurement of inclusions

Appendix D
(reference)

Dependencies between points of the reference scale and the measurement of inclusions (length or diameter in microns, or the number on the box) for inclusions of groups A, b, C, D, and DS are shown in the graphs below. To calculate the score from the measurement result or the measured characteristics of points, for example, if you want to evaluate the inclusion of higher than third grade, use the following expression.

D. 1 Calculation of points the measurement results

For sulfides of the group And the length , µm

. (D. 1)

For aluminates groups In the length , µm

. (D. 2)

For silicate groups by length , µm

. (D. 3)

For globular oxides of group D by number on the field

. (D. 4)

For single globular oxide type DS diameter, µm

. (D. 5)

Except for the inclusions of type DS to realise you should use antilogarithm.

D. 2 Calculation of the measured characteristics.

For sulfides of the group And the length , µm

. (D. 6)

For aluminates groups In length , µm

. (D. 7)

For silicate group With length , µm

. (D. 8)

For globular oxides of the group D on the field

. (D. 9)

For single globular oxide type DS diameter , µm

. (D. 10)

To obtain the measured values should be used antilogarithm.

For all the above equations the linear regression values exceed 0,9999.

Group a (inclusions of sulphides)

Group b (inclusions aluminates)

Group (inclusions of silicates)

Group D (inclusions globular oxides)

Group DS (on single globular oxides)