GOST 5657-69

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  ГОСТ 5657-69

GOST 5657−69 (ST SEV 475−88) Steel. Method for testing the hardenability (with Amendments No. 1, 2)

GOST 5657−69
(CT CMEA 475−88)

Group B09

STATE STANDARD OF THE USSR

STEEL

Method for testing the hardenability

Steel. Methods for the determination of hardenability

Valid from 01.07.70
to 01.01.95*
______________________________
* Expiration removed
Protocol N 4−93 inter-state Council
for standardization, Metrology and certification
(IUS N 4, 1994). — Note the CODE.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED TSNIICHERMET OF MISI USSR

DEVELOPERS

R. I. L. Kolesnikova, E. V. Kruchinina, S. N. Misurina, K. G. Popov, V. N. Zikeev

2. APPROVED AND put INTO EFFECT by Decision of the Committee of standards, measures and measuring instruments under the USSR Council of Ministers N 750 from 27.06.69

3. The standard fully complies ST SEV 475−88, ISO 642−79 in part test method, equipment, sampling

4. INTRODUCED FOR THE FIRST TIME

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. REPRINT (January 1993) with additions 1, 2, approved in January 1980 and October 1989 (ICS 3−80, 2−90)


This standard specifies the determination of the hardenability of carbon and alloyed structural, tool and bearing steels (with the exception of steels, sabaliauskas in the air, and steels with very low hardenability) by the method of mechanical hardening (Jomini).

Test hardenability of steel by end quenching is that one end of a cylindrical sample heated to the quenching temperature, cooled with water in a special installation under the conditions given in PP.4.1−4.5.

After quenching the hardness is measured along the length of the sample from water-cooled end face to the soft head and according to the obtained results build a graph of hardness (PP.5.1−5.6; 6.1−6.3).

Application of the method of hardenability provided for in the standards and specifications that establish technical requirements for products.

1. BASIC DEFINITIONS AND NOTATION

1.1. Under the hardenability understand the depth of penetration of the hardened zone. When determining hardenability by the method of mechanical hardening the hardenability of steel is characterized by a single melting curve in the coordinates: hardness (y-axis) — distance from the cooled end face (x-axis).

Hardenability of steel is characterized by fine stripe hardenability determined by the boundary curves established for several heats of the steel grade (Fig.1).

Damn.1

Damn.1

1.2. The hardenability of steel can be expressed by the indices (numerical values) hardenability (instead of the curve or band hardenability).

The index of the hardenability is expressed by the hardness (HRC) at this distance from the cooled end face (in mm) on one of the following options (see the devil.1):

a) hardness maximum or minimum at a predetermined distance ;

b) minimum and maximum value of hardness at a given distance from the cooled end face (points and ) — ;

C) minimum and maximum distance from the cooled end with a certain hardness (points and ) — ;

g) the maximum hardness values at different distances from the cooled end (points and ) — ; ;

d) the maximum hardness values at different distances from the cooled end (point and

) — ; .

1.3. Designation of parameters and their values are given in the informational Appendix 1A.

(Added, Rev. N 2).

2. THE SELECTION OF SAMPLES FOR THE DETERMINATION OF HARDENABILITY

2.1. The sample for the testing of steel hardenability should be cylindrical shape with a diameter of (25±0,25) mm and a length of (100±0,5) mm.

The end of the sample which is not subjected to hardening, must be provided with a shoulder or flange (Fig.2).

Damn.2

Damn.2

(Changed edition, Rev. N 2).

2.2. From bars with cross section from 28 to 50 mm the sample machined from center in accordance with the requirements of GOST 7564−73, and bars cross-section 50 mm and more — from the forge and perekatnoe samples on the circle-square size 30mm. On the surface of the sample is not allowed traces of decarburization.

2.2.1. When the diameter or thickness of wire more than 150 mm, the sample is allowed to take away a notch so that its axis was located at a distance of 20 mm from the surface of the rod.

2.2.2. Allowed the use of the samples made from cast samples.

2.2.3. If the size of the hardware does not allow to prepare a standard sample for testing, it must be made of prefabricated, which further is suitable for manufacture the products.

2.2.1−2.2.3. (Added, Rev. N 2).

2.3. Before manufacture of sample preparation must be subjected to a heat treatment:

the normalization — processing of structural steel;

annealing the billet of tool steel and bearing (in case of production samples of the untreated steel).

Structure of steel after annealing shall conform to the requirements of the relevant standard for the steel in the annealed condition.

Exposure time began when the normalization should be from 30 to 60 min.

(Changed edition, Rev. N 2).

2.4. At the end of the sample (from the shoulder) should be marked heat number and number of sample.

2.5. The number of samples for tests for hardenability is established by standards or specifications for products. If such instructions are absent, tests are carried out on one sample from melting.

2.6. The sample surface and edges should be sanded.

(Added, Rev. N 2).

3. INSTALLATION FOR HARDENING

3.1. Quenching of the sample must be performed with water as a special unit, consisting of a sample holder and nozzle for supplying water (Fig.3).

Damn.3

1 — holder; 2 — sample; 3 — nozzle

Damn.3

3.2. The installation must comply with the following basic requirements:

a) the specimen shall be mounted vertically: machined surface on the nozzle. The axis of the specimen and end must match.

b) nozzle diameter, height of free water jet on the nozzle and the distance from the nozzle to the end of the sample should conform to the standards given in table.1.

Table 1

C) the height of the jet in the cooling process, the sample should be constant;

g) water shall only apply to the end of the sample, not washing its cylindrical surface.

3.3. Installation for testing must be protected from air currents (drafts) during the hardening process.

(Added, Rev. N 2).

4. TEMPERING OF SAMPLE

4.1. When heating the end of the sample subject to water cooling, must be protected from oxidation and decarburization. If heating is carried out in a furnace without controlled atmosphere, the sample is placed in a steel cylindrical Cup with a lid. End intended for cooling, the sample is put on a graphite plate or a layer of spent graphite (Fig.4).

Damn.4

1 — a box;

2 — cover; 3 — sample; 4 — graphite plate

Damn.4

4.2. The sample is heated to the quenching temperature of steel of the brand adopted in the standards for technical requirements. If hardening is specified in temperature range, the heating of the sample under tempering choose the maximum temperature.

4.3. Warm-up time of the sample to the quenching temperature is 30−50 min. Deviation from the set temperature quenching must not exceed ±5 °C. Exposure of the sample at a temperature of quenching after heating 30 min.

Note. By agreement of the parties warm up time and holding time can be specified.

4.4. The time from the moment of extraction of the sample from the furnace before cooling does not exceed 5 s.

4.5. The sample should be under running water until completely cooled (at least 10 min). The water temperature should be in the range of 5 to 25 °C.

Note. The valve should open quickly.


(Changed edition, Rev. N 2).

5. HARDNESS MEASUREMENT

5.1. For measuring the hardness along the entire length of the tempered sample is ground off two opposite platforms at a depth of (0,5±0,10) mm.

5.2. Sites should zashlifovyvayutsya with abundant cooling water or a special emulsion. The surface roughness of pads on the base length of 0.8 mm should be not more than 1.25 µm according to GOST 2789−73. Not allowed burn marks, causing structural changes in the metal.

The recommended method of detecting burn marks metal given in the Appendix.

Notes:

1. Burn marks obtained by grinding, prior to measurement of hardness must be removed to re-grinding to a depth of 0.1 mm. If after re-sanding burn marks remain, then the plane for the measurement of hardness are made again.

2. Traces of measurements of hardness must be removed before the measurement on the opposite surface.


(Changed edition, Rev. N 1).

5.3. To construct the curve hardenability steel hardness measurements begin at a distance of 1.5 mm from the hardened end face in the axial direction. The first 16 measurements from the end of the sample carried out with an interval of 1.5 mm and then 3 mm. If at a certain distance from the end of the hardness is not changed, the measurement can be made through single interval or to finish the test. Place of measurement of hardness must be carefully applied to the area for measuring the hardness with a special device, or ruler.

5.4. For the expression of hardenability using indexes (without curve plotting) hardness measured at the distance from the hardened end in accordance with the requirements of standards or technical conditions.

However, you can include or not include the first point set out in clause 5.3 (1.5 mm from the hardened end).

(Changed edition, Rev. N 2).

5.5. In case you need to re-measure the hardness at the site where measurements were taken, the site must be refaced. Depth of metal removal when re-grinding should be 0.1−0.2 mm.

5.6. Hardness is determined by Rockwell (HRC) in accordance with the requirements of GOST 9013−59.

Measurement of Rockwell hardness «C» can be replaced by measuring hardness Vickers. When measuring hardness should ensure reliable fastening of the sample.

(Changed edition, Rev. N 2).

5.7. If the sample cracks or other defects, leading to distortion of results of measurement of hardness, the samples to test are not allowed.

6. EVALUATION OF TEST RESULTS

6.1. For each pair of points at the same distance from the end of the sample at two opposite sites calculate the mean value of hardness that is applied on a graph or expressed as an index.

6.2. The graphical image hardenability in addition to the chart enter the following data:

a) the number of melt;

b) chemical composition;

C) the pre-heat treatment of steel or billets to the manufacture of the mechanical design;

g) the size of the austenitic grain, if it is provided by the standard or specifications;

d) the temperature of the quenching end of the sample.

6.3. When expressing the hardenability of steel index the need to specify additional information, except as provided in paragraph 6.2, it is specified in the technical specifications or standards for the metal.

APPENDIX 1. THE RECOMMENDED METHOD OF DETECTING BURN MARKS ON THE PADS OF THE SAMPLES AFTER GRINDING

ANNEX 1

Ground plane is washed with warm water and etched in a 5% aqueous solution of nitric acid (according to GOST 4461−77) until then, until the surface becomes black (30−60).

After etching, the surface is washed with warm water and then the sample is immersed for 3 with a 50% aqueous solution of hydrochloric acid (according to GOST 3118−77) and washed with warm water.

Changes of hardness and structure occurring during the grinding after such treatment, are identified in the form of bright and dark spots.

APP 1A (reference). Designation of parameters and their values

ANNEX 1A
Reference

(Added, Rev. N 2).