GOST 11878-66
GOST 11878−66 Steel austenitic. Methods for the determination of the content of ferritic phase in the bars (with Amendments No. 1, 2)
GOST 11878−66
Group B09
STATE STANDARD OF THE USSR
STEEL AUSTENITIC
Methods for the determination of the content of ferritic phase in the bars
Austenitic steel bars.
Methods for the determination of the ferrite-phase
AXTU 1909
Date of introduction 1967−07−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of ferrous metallurgy of the USSR
DEVELOPERS I. N. Golikov, I. A. Piterova, G. K. Semin, G. P. Kazakov, A. V. Gorgievska
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 15.03.66
3. INTRODUCED FOR THE FIRST TIME
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
The number of the paragraph, subparagraph, enumeration, applications |
| GOST 8.518−84 |
4.1 a |
| GOST 26364−90 |
3.4, 4.1 and |
5. Limitation of actions taken by the decision of the Interstate Council for standardization, Metrology and certification (ICS 2−93)
6. REPRINT (August 1995) with Amendments No. 1, 2 approved in October 1974, December 1987 (IUS 10−74, 3−88)
This standard applies to the austenitic stainless steel grades 17H18N9, 12KH18N9, 12KH18N9T, 04Х18Н10Т, 12X18H10T, 08X18H10, 04KH18N10, 02Х18Н10, 06KH18N11, 12Х18Н12Т, 08KH18N12T and 08KH18N12B and sets metallographic and magnetic methods of determining the content of the ferritic phase (SFF).
The control of the content of SFF is subjected to forged and rolled bars with a diameter or with a thickness of 80 to 270 mm.
By agreement of the parties specified methods of determining the SFF can be applied to austenitic steels other brands.
The choice of method and its application required in the standards and technical conditions for steel products, which establishes technical requirements for it.
(Changed edition, Rev. N 1, 2).
1. SAMPLING AND CUTTING OF THIN SECTIONS
1.1. The number of samples for the determination of the content of the SFF in the steel smelting establish standards and specifications for products; they must be at least two.
1.2. Samples taken from a controlled melting of any rods in random places:
a) when controlled on two or three thin sections from different rods;
b) when control over a greater number of sections, the samples must be selected from at least three rods.
The place of sampling from the weights corresponding to a particular height of the ingot, may be set by agreement of the parties.
1.3. In the metallographic method for determining SFF samples for making thin sections are cut from round or square cross-section with a diameter or with a thickness of 80 to 270 mm from center to mid-radius or one quarter of the thickness (see drawing).
Cerci.
1.4. The length of the sample in the direction of the axis of the rod set at least 10−12 mm Allowance
for grinding shall be greater than or equal to 0.5 mm (see drawing).
1.5. Deleted, Rev. N 2.
1.6. Samples should be cut by cold mechanical method. Autogenous cutting is allowed provided that the cone will be made from the cutting place at a distance of not less than 25 mm.
1.7. The definition of the content of SFF metallographic and magnetic methods is carried out on the samples in the delivery condition.
2. THE DEFINITION OF THE CONTENT OF THE FERRITIC PHASE BY METALLOGRAPHIC METHODS
2.1. Using the specimens cut along fibers, manufactured thin section on a plane extending from the centre to the mid radius of the rod (see drawing).
2.2. Microsection is subjected to electrolytic or chemical etching. Electrolytic pickling is carried out in a 10% aqueous solution of oxalic acid at room temperature and a current density of 0.03−0.08 a/cmat 20−40 C.
Chemical etching is carried out in the reagent of the following composition: 20 ml of water, 20 ml of concentrated hydrochloric acid and 4 g of copper sulfate. Etching is carried out at room temperature for 8−10 S.
Allowed etching in the reagent of a different composition, providing fast and high quality etching (sections must not be oxidized, and their borders should be thin and sharp).
2.3. The content of the SFF began to appreciate viewing the entire area of the etched microsection.
2.4. At each cone with the increase of 280−320and the diameter of the field of view of the microscope of 0.38−0.43 mm determine the place with the highest content of SFF, which is visually evaluated in points or in percent by comparison with fotoatteli the attached scale.
Arbitration the determination of the content of SFF is carried out by the photo taken by increasing 280−320, with the diameter of the prints, respectively, equal to 115−130 mm.
2.5. Annexed to this standard scale for the determination of the content of SFF — five and has the added poliatlonu the 0.5, 1.5 and 2.5 points.
The scale is represented by two rows of poliatlonu, which differ in terms of the number of sites (see tabs).
2.4, 2.5 (Revised edition, Edit. N 2).
2.6. (Deleted, Rev. N 2).
2.7. The SFF content in melt estimated in two ways:
a) by the maximum score or percentage of the estimates of the two samples;
b) at average score or percentage of the estimates of two or more samples.
Method of assessment established by the standards and technical requirements for products.
2.8. Rate the content of SFF depending on the purpose are established standards and technical specifications for products.
If the results of the tests are unsatisfactory, re-conduct tests on samples taken from other rods; in the evaluation of melting in paragraph 2.7 and the same amount in the assessment bottoms on p. 2.7 b — at twice the number of samples. The results of repeated tests are final.
3. THE DEFINITION OF THE CONTENT OF THE FERRITIC PHASE MAGNETIC METHOD
3.1. For the magnetic method for the determination of SFF samples cut from bars in the form of transverse templates of not less than 10 mm.
3.2. The determination is carried out on the polished surface of the macrosections made on the samples. Allowed determination carried out on macrosections used to control the macrostructure before etching.
3.3. The main magnetic method for high precision is the method of magnetic saturation.
3.4. Working means of measurement are ferritometer according to GOST 26364−90 when measuring the content of ferritic phase in the range of 0−20%. In the measurement of SFF more than 20% is allowed using other devices with the appropriate calibration.
3.5. Calibration of working measuring instruments must be carried out by standard models SFF, certified by the method of magnetic saturation or by metallographic methods.
3.6. To determine SFF at macrolife spend at least 40 measurements equally spaced along two or three diameters (diagonals). When establishing macrolife areas with the highest SFF conduct a smaller number of dimensions, but not less than 20.
3.7. SFF on macrolife determine the average of the three maximum readings in different places of the cone then the expression for the calibration curve in points or percent.
3.8. SFF in the melt estimated in two ways:
a) at the maximum reading from the two samples;
b) by the average reading from two or more samples.
Method of assessment established by the standards or specifications for products.
3.9. If the results of the tests are unsatisfactory, re-conduct tests on samples taken from other rods; in the evaluation of melting at the maximum rate on the same amount, in the assessment of melting on average — twice the number of samples. The results of repeated tests are final.
Sec. 3 (Revised edition, Edit. N 2)
4. TESTING
4.1. Before operating the new device is calibrated.
4.1. The methodology for initial and periodic calibration of ferritometer (GOST 26364−90) is set in accordance with GOST 8.518−84.
(Added, Rev. N 2).
4.2. The calibration of an instrument, i.e., obtaining the calibration curve of the readings from the content of the SFF, carried out on reference samples with different concentrations of SFF. It is recommended that the construction of one calibration curve for rods ranging from 80 to 180 mm and the second is 180 mm or more.
4.3. The standards necessary to produce bars of a controlled grades of steel.
It is possible to produce benchmarks for steel grades 17H18N9, 12KH18N9, 12KH18N9T, 04Х18Н10Т, 08X18H10, 04KH18N10, 02Х18Н10, 06KH18N11, 12Х18Н12Т, 08KH18N12T, 08KH18N12B, made of steel 12X18H10T.
(Changed edition, Rev. N 1).
4.4. As template we used the micro-sections, carved and manufactured in accordance with the PP. 1.3 and 2.1. One side of the microsection, located across the axis of the rod, prepared as microslip in accordance with clause 3.2.
4.5. The content of the SFF in the standard metallographic method was determined by scoring according to the method described in sect. 2.
4.6. The content of the SFF references in the magnetic method is determined in accordance with the method described in sec. 3.
4.7. According to the relevant standards with different concentration of SFF, build a calibration curve of the instrument in the coordinates of the «reading device — a point SFF». Every 5−6 points on the curve should be determined not less than 10 results obtained on various reference samples.
Note. Allowed calibration of the instrument in the coordinates of the «reading device — the volume content of the SFF». In this case, the content of SFF reference samples define one of the methods of quantitative metallography, such as point and expressed as a percentage.
4.8. The correct operation of the device during operation and after repair to check periodically for two or three reference samples with a pre-fixed readings corresponding to different portions of the calibration curve of the instrument.
SCALE TO DETERMINE THE MAGNIFICATION 300X
MAGNIFICATION 300X
Points (percent)
0,5 (1−2%)
1,0 (2,5−3,5%)
and
b
1,5 (4−5%)
2,0 (5,5−6,5%)
and
b
2,5 (8,5−9,5%)
3 (11,5−12,5%)
and
b
4 (23,5−24,5%)
5 (47,5−48,5%)
and
b
