GOST 1763-68

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  ГОСТ 1763-68

GOST 1763−68 (ST SEV 477−77, ISO 3887−77) Steel. Methods for determining the depth bezoperatsionnogo layer (with Amendments No. 2, 3, 4, as amended)

GOST 1763−68
(ST CMEA 477−77,
ISO 3887−77)

Group B09

STATE STANDARD OF THE USSR

STEEL

Methods for determining the depth
bezoperatsionnogo layer

Steel. Methods for determination
of decarbonized layer depth

Valid from 01.01.70
to 01.01.95*
_______________________
* Expiration removed by Protocol No. 4−93
The interstate Council for standardization,
Metrology and certification
(IUS N 4, 1993). -
Note the manufacturer’s database.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED Tsniichermet of MISI USSR

DEVELOPERS

B. A. Klypyn, G. E. Sharonov, I. V. Armagnac, L. G. Polovnikova

2. APPROVED AND put INTO EFFECT by decision of the Committee of standards, measures and measuring devices under Council of Ministers of the USSR from 27.11.68 N 165

3. The standard fully complies ST SEV 477−77, ISO 3887−77

4. INTRODUCED FOR THE FIRST TIME

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. Validity extended until 01.01.95 by the resolution of Gosstandart of the USSR from 28.09.89 N 2969

7. The re-release (may 1992) with Changes in N 2, 3, 4, approved in November 1978, February 1980 September 1989 (IUS 12−78, 3−80, 1−90)


AMENDED, published in IMS No. 5, 2002

An amendment made by the manufacturer of the database


This standard covers wrought steel: structural carbon and alloy with a carbon content of not less than 0.3%, tool steels carbon, alloyed and high speed; spring, bearing, supplied in the form of hot rolled and forged bars and billets with a diameter or a side of a square to 150 mm, hot rolled strips, tubes, sheets, strips and wire rods, cold rolled sheet and strip and cold-drawn bars, wires, pipes, and establishes methods for determining the depth bezoperatsionnogo layer.

By agreement of the parties methods for determining the depth bezoperatsionnogo layer spread on the steel for other purposes, steel with carbon content less than 0.3%, and other products.

Depth bezoperatsionnogo layers define:

metallographic methods M, M1, M2,

method of measurement of thermoelectric power T. E. D. S.,

method of measurement of hardness — T,

chemical method — X

method of measurement of microhardness — MT.

The use of the methods provided in standards and specifications for steel products, which establishes technical requirements for it.

If the standards or technical conditions, the method of determining the number of samples is not specified, the determination of decarburization is produced by the method adopted by the manufacturer, not less than two samples from the party. For the party adopted a metal one melting, one profile, the last heat treatment in a single tank furnace.

Recommendations on the choice of the method specified in Annex 1.

The standard fully complies ST SEV 477−77, ISO 3887−77.

(Changed edition, Rev. N 2, 4).

METALLOGRAPHIC METHODS

1.1. General instructions

1.1.1. The essence of metallographic methods is to determine the depth bezoperatsionnogo layer structure under the microscope.

1.1.2. Samples for making thin sections taken from random bars, tubes, sheets, tapes and strips.

The specimens shall be cut cold in a mechanical way, not causing changes in the structure of the metal (cutter, cutter, saw, stone, etc.), and cut across the direction of fiber.

Note. For forgings, the direction of cutting of the samples is set by the manufacturer. At the request of the consumer the cutting direction can be set by agreement of the parties.

1.1.3. Sections to determine the depth bezoperatsionnogo layer should meet the following requirements:

a) the plane of the cone must be perpendicular to the examined surface;

b) recommended area of the cone is up to 10 cm;

b) on the ground littered with the edges of the depth bezoperatsionnogo layer do not determine.

1.1.4. The etching of the thin section except for the method M1, is produced in a 2−4% solution of nitric or picric acid in ethyl alcohol and other reagents and should ensure clear identification of the structural components.

The etching of the cone in 4% strength solution of nitric acid in methyl alcohol needed to dry wet cone warm air.

1.1.5. There are two zones of decarburization: the zone of complete decarburization and partial decarburization zone.

The zone of complete decarburization is characterized by the structure of pure ferrite. Area of partial decarburization is characterized by a structure different from the structure of the base metal.

The total depth of decarburization involves the zone of complete decarburization and partial decarburization area and is measured from the edge of the cone to the main metal structure.

In the absence of a zone of complete decarburization zone of partial decarburization is measured from the edge of the cone to the main metal structure.

Distribution decarburization distinguish uniform around the perimeter of the sample and local decarburization portions of the perimeter of the sample.

Depth bezoperatsionnogo layer is defined as the maximum depth for a given sample or as an average value of five measuring points the most significant decarburization indicating maximum depth.

Method is specified in the product standards. If such an indication is not, the depth of decarburization is defined as the maximum depth for this sample.

Decarbonisation is not measured at the place of detection of surface defects on thin-section. The test results indicate the presence of a surface defect according to GOST 21014−88.

(Changed edition, Rev. N 2, 4).

1.2. Method M

1.2.1. The essence of the method

A method M consists in determining the depth of bezoperatsionnogo layer structure under a microscope on cross sections etched in the delivery condition.

For samples of steels with trudnoperevarimoy structure bezoperatsionnogo layer additional heat treatment (normalizing or annealing) without decarburization or carburization, must be carried out after cold working, quenching, vacations, quenching with vacation as well as after annealing.

By agreement of the parties, the boundary zones of decarburization may be fixed by standards.

Note. If they are not clearly identifying bezoperatsionnogo layer in the annealed steel with a structure of granular pearlite is allowed to expose the samples normalization to prevent additional decarburization or carburization.

(Changed edition, Rev. N 4).

1.1.2. Preparing for the test

Cutting samples with a length of 30−40 mm for the determination of depth of decarburization by the method M is performed according to the schemes specified by the devil. 2−5.

Notes:

1. To facilitate the manufacture of thin sections of samples cut according to the specified schema, it is allowed to cut into pieces.

2. If they are not clearly identifying bezoperatsionnogo layer in the annealed steel with a structure of granular pearlite is allowed to expose the samples normalization to prevent additional decarburization or carburization.


Samples for making thin sections cut out:

a) from bars, rods, wires, and billets of round, square and hexagonal.

diameter or thickness up to 30 mm of cross-section (Fig. 2A);

diameter or thickness greater than 30 to 60 mm half section (Fig. 2B);

diameter or thickness greater than 60 to 100 mm from the fourth side of the perimeter (Fig. 2B);

diameter or thickness of over 100 to 150 mm — from the sixth of the perimeter of the circle or the corner of a square (Fig. 2G).

Drawing 2

Damn. 2*

___________________
* Hell. 1 — is excluded. Izm. N 3.

b) pipes:

with external diameter up to 20 mm from the entire cross-section of the pipe (DWG. 3A);

with an outside diameter of more than 20 to 40 mm half-section of the tube (Fig. 3b);

with external diameter over 40 up to 100 mm — quarter-section of the pipe (DWG. 3b);

with an external diameter over 100 to 140 mm of one-twelfth of the cross section of the pipe (DWG. 3G);

with an external diameter of 140 to 200 mm from one-sixteenth part of a section of a pipe (Fig. 3D).

Figure 3

Damn. 3

C) strip and ribbon:

width up to 60 mm from the entire section of the strip (Fig. 4A);

width in excess of 60 to 120 mm — half section of the strip (Fig. 4B);

of a width > 120 mm — hell. 4B.

Note. For strip thickness more than 30 mm is permitted for fillet samples from the upper and lower surfaces of the strip.

Figure 4

Damn. 4

g) from the list:

from two mutually perpendicular sides at a distance of 40 mm from the sheet edge (Fig. 5A);

from a sheet thickness up to 30 mm inclusive, through the entire thickness of the sheet (Fig. 5B);

from a sheet thickness of over 30 mm from the upper and lower surfaces of the sheet (Fig.5B).

Figure 5

Damn.5

(Changed edition, Rev. N 4).

1.2.3. Testing

The depth of decarburization is determined when viewing specimens cut according to the diagrams on the devil. 2, 3, 4B, 5, along the perimeter corresponding to the surface of the rental. For samples cut from a strip or tape according to the schemes given on features. 4A, b, the view is on the wide side at a distance of not less than 2 mm from the edge.

For spring spring and strips, and by agreement of the parties and for other cases, the determination of decarburization is produced across the wide side of the sample.

1.2.4. Evaluation of test results

Depth bezoperatsionnogo layer is determined in millimeters. Determination is made under a microscope at magnification (100±10)*. May be increased to 200−500. Determination is made with an accuracy of ±0.02 mm. if necessary, the depth of decarburization () is determined as a percentage and is calculated by the formula

,

where

 — the depth of decarburization in unilateral dimension, mm;

 — the thickness of rolled or semi-finished product, mm.

(Changed edition, Rev. N 4).

1.2.5. The zone of complete decarburization is characterized by the structure indicated in section 1.1.5. Area of partial decarburization is characterized by: for zaevtektoidnoj steel ferrite-pearlite structure, the ferrite content is greater than in the main structure; for hypereutectoid steel — area ferrite-pearlite structure, the pearlite area of the plate as the primary structure of the granular perlite, or zone of granular pearlite, carbides depleted. Examples of typical structures are given in Appendix 3 (Fig. 1−9, 14, 16).

1.3. Method M1 (carbide mesh)

1.3.1. The essence of the method

Method M1 is to determine the depth bezoperatsionnogo layer structure under a microscope on cross etched thin sections made on samples subjected to special heat treatment and coloring etching.

1.3.2. Preparing for the test

To determine the depth of decarburization, the samples are cut in accordance with the requirements of section 1.1.2 8−12 mm in length, according to the scheme given on features. 6;

from bars with diameter up to 25 mm of the total cross section of the rod. To cut the ground off the sample area (the flats), ensuring the complete removal of bezoperatsionnogo layer (Fig. 6A);

from bars with a diameter of more than 25 to 40 mm of the half-section of the rod (to hell. 6b);

from bars with diameter over 40 mm according to the diagram (DWG. 6b).

Figure 6

Damn. 6

For bars other sizes and profiles cutting samples produced by the schemes of the manufacturer, or by agreement of the parties.

(Changed edition, Rev. N 4).

1.3.3. Testing

The samples are heated to 950° C without decarbonisation, for example in the molten salt with the addition of activated charcoal (0,5−2,0%). The compositions of the bath used for heating samples, are given in Annex 2. The samples are incubated for 5−7 min, cooled at a speed of 15−30° C per minute to a temperature of 30−50° below , and then cooled in air. Sections etched for 5−30 min in one of the following boiling of the reagents, staining carbide mesh: picrate sodium (1 g picric acid plus 15 g Koh per 100 ml of water); potassium hydroxide or sodium hydroxide (20 g of NaOH or Koh per 100 ml of water); red blood salt in alkali (60 grams of KFe (CN)plus 30 g NaOH to 30 ml of water).

1.3.4. Evaluation of test results

The zone of complete decarburization is characterized by the structure indicated in section 1.1.5.

Area of partial decarburization is characterized by a ferrite-pearlitic structure without dark-colored carbide mesh.

Examples of typical structures are given in Appendix 3 (Fig. 10, 15). The estimation of the depth of decarburization is produced according to claim 1.2.4.

1.4. Method M2 method (Sadovsky)

1.4.1. The essence of the method

Method M2 is to determine the depth bezoperatsionnogo layer structure under a microscope on cross etched thin sections made on samples subjected to a special heat treatment.

1.4.2. Preparing for the test

Preparation of the test produce, as specified in paragraph 1.3.2.

1.4.3. Testing

Heat treatment of samples are recommended for the modes indicated in the table.

(Changed edition, Rev. N 1, 4).

The samples preheated to 820−840° C, then transferred to well raskolennuyu corbarieu a bath in which they stand 1−3 min after download.

Cooling of samples produced within 10 min in an oil or salt bath (the first bath).

After exposure the sample is immediately transferred into a salt or lead bath (second bath), which stand for 10 min, and then cooled in air.

The bath volume should be sufficient to maintain the temperature within specified limits.

1.4.4. Evaluation of test results

The zone of complete decarburization is characterized by the structure indicated in section 1.1.5. Area of partial decarburization is characterized by dark travadas troostite or needle toastmastering structure. Examples of typical structures are given in Appendix 3 (Fig. 11−13).

The estimation of the depth of decarburization is produced according to claim 1.2.4.

2. METHOD OF MEASUREMENT OF THERMOELECTRIC POWER

2.1. The essence of the method

This method of determining depth of decarburization is to measure thermoelectric power (T. E. D. S.) obesplozhennym and neobespechenie surfaces of the sample.

2.2. Preparing for the test

2.2.1. Samples selected as specified in clause 1.1.2. The scheme of cutting out of samples given on features. 2−5. Length samples of 60−100 mm.

2.2.2. For products in which the decarburization is not allowed, with one side of each sample of the abrasive wheel or another method of preparing a flatted длиной10−15 mm for removal bezoperatsionnogo layer. The surface of the sample purified from the residue of the emulsion and the abrasive cloth soaked in alcohol.

2.2.3. For products with an acceptable amount of depth of decarburization initially removed tolerance for decarburization, and then the sample prepared as described in section 2.2.2.

2.3. Equipment

Installation diagram to determine the T. E. D. S. (fuck. 7).

Your installation includes:

the ammeter in accordance with GOST 8711−78;

auto-transformer and ammeter M95 (10−100 µa) with a shunt R-4.

Drawing 7

1 — heating copper core; 2 — copper base;
3 — investigated sample; 4 — a measuring instrument.

Damn. 7

Installation turn to the AC network. The temperature of the rod must be maintained in the range of 150−160° C.

Work installation check according to the standards. Standards are samples for which pre-determined by metallographic methods the presence or absence of decarburization and the difference in the readings.

2.4. Testing

For the test, the specimen is mounted on the copper base of the device so that the plain was located just below the working part of the heated rod. Produce 3−5 measurements along the flats and record the average readings. The same measurements (5−10) are produced in different points of the sample surface (outside flats) and record the average value.

2.5. Evaluation of test results

The sample is considered niebezpiecznym, if the difference in readings on the plain and on the surface of the sample does not exceed the reference value.

3. THE METHOD OF MEASURING HARDNESS

3.1. The essence of the method

This method of determining depth of decarburization is to measure hardness of specimens subjected to heat treatment.

3.2. Preparing for the test

3.2.1. Samples selected as specified in clause 1.1.2.

Scheme of cutting out of samples given on features. 2−5.

Length samples of 20−50 mm.

3.2.2. Specimens test after heat treatment. Heat treatment of samples produced according to the regimes prescribed by the relevant standards or specifications for steel this brand in conditions that exclude the possibility of additional decarburization (for example, heating in the salt bath).

3.3. The hardness measurement is carried out according to GOST 9013−59.

(Changed edition, Rev. N 4).

3.4. Evaluation of test results

The sample is considered niebezpiecznym if its hardness is consistent with the standards of hardness for the steel this brand established in relevant standards or technical conditions.

4. CHEMICAL METHOD

4.1. The essence of the method

This method of determining depth of decarburization is to determine the carbon content in chips, in layers taken from the sample.

4.2. Preparing for the test

4.2.1. Samples selected as specified in clause 1.1.2, in the state of delivery. Length of samples should ensure the removal of chips in the quantity needed for chemical analyses (at least 2 g of chips).

4.2.2. Before removing the chip to determine the depth of decarburization samples of products, which is not allowed decarburization, cleansed from dross, and product samples on which it is allowed decarbonisation, machined to remove the surface layer to a depth of tolerance for decarburization.

4.3. Testing

To determine the depth of decarburization chemically remove the layer of chip thickness of 0.1 mm.

Removal of chips and determination of the carbon content in each removed layer is produced to obtain a chemical composition corresponding fine.

The carbon content determined according to GOST 22536.1−88 and GOST 12344−88, GOST 28473−90.

4.4. Evaluation of test results

The sample is considered niebezpiecznym, if the carbon content corresponds to the fine composition, specified in relevant standards or technical conditions.

5. METHOD OF MEASUREMENT OF MICROHARDNESS — MT

5.1. The essence of the method

The method consists in the determination of the microhardness over the cross-section of hardened specimen from the surface to the center.

5.2. Preparing for the test

5.2.1. Samples selected as specified in clause 1.1.2. Scheme of cutting out of samples given on features. 2−5.

Length samples of 10−25 mm.

5.2.2. Preparation of thin sections produced as described in section 1.1.3.

5.3. Testing

5.3.1. Microhardness testing on netravlenoy cross sections produced with a load no more than 2 N (~ 200 g) according to GOST 9450−76.

The distance between the prints must exceed the diagonal of the print is not less than 2.5 times. Measurements to produce consistent results of the microhardness.

The cone carried out a series of tests in at least two locations distant from each other.

5.4. Evaluation of test results

5.4.1. The depth of decarburization in the measured place take distance from the edge of the cone to the point at which the resulting stable microhardness.

Depth bezoperatsionnogo layer on the sample is defined as the arithmetic average of the depth measurements.

Sec. 5 (Introduced later, Rev. N 2).

6. TEST REPORT

The test report should indicate:

the designation of the sample;

test method; the method MT — load;

the magnification of the microscope;

the depth of decarburization;

the presence of a surface defect.

(Changed edition, Rev. N 2, 4).

APPENDIX 1. RECOMMENDATIONS FOR APPLICATION OF METHODS FOR THE DETERMINATION OF DECARBURIZATION

ANNEX 1

APPENDIX 2. THE COMPOSITION OF THE BATH USED FOR HEATING SAMPLES DURING HEAT TREATMENT

ANNEX 2

APPENDIX 3. EXAMPLES OF THE MICROSTRUCTURE BEZOPERATSIONNOGO LAYER DEFINED BY METHOD M OF VARIOUS GRADES OF STEEL

APPENDIX 3

(magnification 100 times)