GOST 22838-77
GOST 22838−77 high-temperature Alloys. Methods of monitoring and evaluation of the macrostructure (Change No. 1)
GOST 22838−77
Group B09
STATE STANDARD OF THE USSR
HIGH-TEMPERATURE ALLOYS
Methods of control and estimation of macrostructure
Heat-resistantalloys.
Methods of testing and estimation of macrostructures
AXTU 0909*
_______________
* Introduced later. Izm. N 1.
Valid from 01.01.1979
to 01.01.1984*
______________________________
* Expiration removed
Protocol N 7−95 Interstate Council
for standardization, Metrology and certification.
(IUS N 11, 1995). — Note the CODE.
DEVELOPED by the research Institute of metallurgy (niim)
Director A. N. Morozov
Director and responsible officer Z. M. Kalinina
INTRODUCED by the Ministry of ferrous metallurgy of the USSR
Zam. Minister A. F. Borisov
The draft all-Union scientific research Institute of standardization (VNIIS)
Director A. V. Gichev
APPROVED AND promulgated by the Decree of the State Committee of standards of the USSR Council of Ministers dated December 5, 1977 N 2805
The Change N 1, approved by Decree of the USSR State Committee for standards from
Change No. 1 entered the law office of «Code» in the text IUS N 8 1987
This standard applies to the rental of high-temperature alloys on Nickel and iron-Nickel basis, in the form of bars and billets with thickness or diameter from 20 to 220 mm, obtained by hot deformation, and establishes methods of control and evaluation of the macrostructure.
Allowed to apply the methods of monitoring and evaluation rental of other alloys and sizes.
1. SAMPLING METHODS
1.1. Samples are taken:
in the smelting alloy open method and plasma arc melting and casting the top bars of the first and last ingot;
the casting of siphon — bars from the ingot of the first and last siphon;
vacuum-induction smelting from bars podperevalny part of the ingot;
when vacuum-arc, electron beam, plasma, and when you double-remelting — from rods of the respective top and bottom parts of the ingot.
In the absence of marking of the location of the ingot on the casting (first, last) or bar height of the ingot (top, middle, bottom), a sample taken from any rod.
When the supply of rods with a machined or polished surface samples are taken after turning or grinding.
1.2. The number of samples and place the clippings is set by standards and other normative-technical documentation on the alloys, approved in the prescribed manner.
1.3. To control the macrostructure of the samples, cut samples:
from bars with diameter or thickness of 20−140 mm in full cross-section across the grain;
from bars with diameter or thickness of 20−60 mm, it is allowed to cut the samples along the fiber;
from bars with diameter or thickness greater than 140 mm across the grain; sample pre-peroxide on a square 90−100 mm, unless a section is not specified in the normative-technical documentation.
1.4. Samples should be cut in such a way that the controlled section was at a distance, precluding the influence of the processing conditions: from the heat of cutting, crumpling from the press or saws, chipping hammers, etc.
1.5. Under the control of the macrostructure on the transverse sample cut perpendicular to the direction of rolling (forging) through the entire cross section of the rod (sample). The height of the sample should be 15−30 mm.
1.6. Longitudinal samples cut parallel to direction of rolling with the conservation of the axial zone. Length of specimens 50−70 mm.
1.7. Samples for testing the fracture is made by applying a cut on the center line through all of the cross-section. The depth and shape of the cut shall provide a straight fracture, without contortion and high enough of a break: not less than 10 mm for bars with diameter or thickness of 140 mm or more, not less than 6 mm for bars with diameter or thickness greater than 60 to 140 mm and at least 4−5 mm for bars with diameter or thickness of 20−60 mm.
2. EQUIPMENT AND REAGENTS
2.1. For etching the samples should be used baths (vessels), made of materials that do not react with the applied Etchant.
3. PREPARATION FOR CONTROL
3.1. Samples subjected to heat treatment in the case of the macrostructure on scales 3, 4, 5, 6 and drawing 4, 5.
Heat treatment regime must meet regulatory and technical documentation for the supply of bars and billets.
It is allowed to apply a protective atmosphere.
3.2. The surface of the samples before etching should be subjected to cold mechanical processing: beveling, planing, milling, grinding.
Grinding of samples should be performed according to modes, precluding the formation of grinding cracks using umagaeshi heat treatment for alloys with high hardness.
The differences in the evaluation of the macrostructure of steel surface roughness of the samples should be not more than 10 µm according to GOST 2789−73.
3.3. Recommended reagents and etching modes listed in the recommended Annex 1. Allowed to use other reagents, subject to obtaining the identical etching results. The reagents used must be clean, free of suspended particles and foam.
3.4. Before etching, the samples shall be cleaned of dirt and grease. Samples of the pickling bath must not touch controlled planes with each other and with the walls of the bath (the vessel).
In front of a hot etching, the samples should be heated up to the temperature of the solution.
If you reuse the etching solution, the concentration of acid is reduced to the density established during the preparation of fresh solution.
3.5. Etching must be performed to obtain a clearly identified macrostructure, which allows to evaluate it in comparison with scales and drawings. With a strong rastravleniya alloy (surface Browning, the appearance of false porosity throughout the cross section, surface roughness) etching is repeated on the same samples after removing the surface layer to a depth of at least 2 mm.
4. CONTROL
4.1. Evaluation of the macrostructure of the etched samples and breaks to produce a visually. To clarify the classification of defects may be two-, fourfold increase.
4.2. Determination of the type and degree of development of defects of a macrostructure is produced by comparing svezheprigotovlennyj samples with scales and drawings.
The scales assess the following types of macrostructures and defects:
Central porosity — scale N 1 and 1A GOST 10243−75;
exudation square — scale N 5 and 5A GOST 10243−75;
podnasadochnogo liquation — scale N 6 and 6A GOST 10243−75;
subcortical bubbles — scale N 7 GOST 10243−75;
intergranular cracks — scale N 8 and 8A GOST 10243−75;
pinstripe (outline) — N scale 10A GOST 10243−75;
dot spotted heterogeneity — scale N 1 of Annex 2;
the layered structure of the fracture in the alloy brand ЭИ437БУ-VD — N scale 2 of Annex 2;
common banded heterogeneity — scale N 3 of Annex 2;
various-grained macrostructure in the longitudinal direction between the boundary and the axial area — scale N 4 of Annex 2;
various-grained macrostructure stripped heterogeneity — scale N 5 of Annex 2;
size macrocera — scale N 6, Appendix 2.
For God. 1−14 evaluate the defects listed in the recommended Annex 3.
Description of the macrostructure and faults, illustrated scales and drawings, given in the recommended Appendix 3 of this standard and in appendices 2 and 3 to GOST 10243−75.
4.3. The amount of defects allowed to estimate a score and a half (0.5, 1.5, and so on). A score of 0.5 with regard to the structure of samples having defects with the degree of development and a half-two times less than the first scores of their respective scales.
In the absence of defects set the score to 0; the rough development of the defect indicates the maximum score of the scale with the word «more» (e.g. more than 5). With the simultaneous presence of several defects evaluation and classification of each defect are produced separately.
4.4. The differences in the assessment of quality alloy evaluation of the macrostructure of samples produced by the photos that need to be made in full size or with the scale.
ANNEX 1 (recommended)
ANNEX 1
Recommended
| Nome- RA reactions tivov |
The composition of the reagent |
Tempe temperatures of solution, °C |
The time of etching, min. |
Method of etching |
| 1 |
Hydrochloric acid by the GOST 3118−77 — 100 ml |
The etching is produced by immersing samples in a solution | ||
| Nitric acid GOST 4461−77 — 100 ml |
||||
| Water — 100 ml |
60−70 |
5−10 |
||
| 2 |
Hydrochloric acid by the GOST 3118−77 — 500 ml |
20 |
15−25 |
For complete dissolution of copper sulphate in hydrochloric acid reagent in the manufacture of heated to 40−50 °C. |
| Sulfuric acid GOST 4204−77 — 35 ml |
||||
| Copper sulfate according to GOST 4165−78 — 150 g (or copper sulphate, anhydrous — 100 g) | 60−70 |
5−15 |
The etching is produced by immersing samples in a solution or RUB them for 5−10 minutes with a swab dipped in the solution. | |
| . |
Samples were washed with water and then a solution of 100 ml of sulfuric acid, 5 g of potassium dichromate, 1000 ml of water | |||
| 3 |
Hydrochloric acid by the GOST 3118−77 — 1000 ml |
20 |
15−25 |
The etching is produced by immersing samples in a solution |
| Nitric acid according to GOST 4461−77−100 ml |
||||
| Potassium dichromate according to GOST 4220−75 — 100 g |
60−70 |
30−40 |
||
| Water — 1000 ml |
||||
| 4 |
Hydrochloric acid by the GOST 3118−77, 50% solution |
2−8 |
Samples heated to 50 °C. Etching is produced by rubbing a swab or dip | |
| Hydrogen peroxide (perhydrol) according to GOST 177−77 |
||||
| Five |
Nitric acid GOST 4461−77 — one piece |
20 |
- |
After producing the reagent is kept one day at room temperature. The etching is produced by wiping or by immersion for 1−2 min. |
| Hydrochloric acid by the GOST 3118−77 three parts |
Notes:
1. After etching the samples are thoroughly washed in running water and dried.
2. Samples intended for storage, well-dried and coated with varnish.
Annex 2 (mandatory)
Annex 2
Mandatory
N scale 1 Point-spotted the heterogeneity in the macrostructure of the alloys after refining remelting. Bars the size of 60−220 mm and reforged sample.
A (in the form of points-spots) B (in the form of brackets, short strips)
Scale N 2, the layered Structure of the fracture of bars of size 200−220 mm from alloy grade ЭИ437БУ-VD
The layered structure of the fracture of bars of size 200−220 mm
of alloy grade ЭИ437БУ-VD
N scale 3 Total banded heterogeneity in the macrostructure of bars with a size of 20−60 mm
N scale 4 various-grained macrostructure in bars the size of 20−60 mm
The depth of the zone with a large grain as a percentage of the section: for score 1 to 10−15; for score 2 to 17−21;
for points 3 to 23 to 27; for the score of 4 over 30
Notes:
1. The second numbers refer to the smaller grains in the area.
2. In case of unilateral raznozernistoy assessed for the deeper zone.
Scale N 5 various-grained macrostructure with a shared banded heterogeneity in bars in size of 20−60 mm
N scale 6 grain Size in the macrostructure
Score a 3.5*
_____________
* Introduced later. Izm. N 1.
Dot spotted heterogeneity in high-temperature alloys open
and vacuum-induction melting.
Damn.1 Bars the size of 60−220 mm and reforged samples
Damn.1
Damn.2 Layered fibrous structure breaks rods size 200−220 mm from alloys of ЭИ698-VD, ЭП199-VD
Damn.2
Damn.3 Total banded heterogeneity in the fracture of bars with a size of 20−60 mm
Damn.3
Damn.4 various-grained macrostructure, various-grained fracture
a — rods of size 20−60 mm; b — bars and rods, hot machining;
in — forged samples
Damn.4
Damn.5 various-grained structure of the fracture forgings
Damn.5
Damn.6 Bundle
Damn.6
Damn.7 Particles of the crown
(cast as)
Damn.7
Damn.8 the Remains of the burning from cutting
Damn.8
Damn.9 Remnants of ligatures and other additives in fracture
Damn.9
Damn.10 Cracks in the upsetting of the blanks in the end
Damn.10
Damn.11 Forging cracks in the longitudinal sample
Damn.11
Damn.12 Cracks by cutting
Cracks from felling (cutting)
Damn.12
Damn.13 Slivovice-etching cracks
Damn.13
Damn.14 Crack shift
Damn.14
APPENDIX 3 (recommended). Description of macrostructure and defect
APPENDIX 3
Recommended
1. Point-spotted the heterogeneity of the superalloy is characterized by different size, shape and arrangement of the phase separation volumes, a metal which is different from the primary high content livermush elements or released during crystallization stable and redundant phases. The development of the heterogeneity is due to a chemical composition of the alloy, mould and mold, the cooling rate of the metal. there are two types of heterogeneity:
a) dot-spotted heterogeneity in alloys the open and vacuum induction melting is characterized by a symmetric arrangement of a large number of dots, small spots on the transverse templet. In assessing the macrostructure is not taken into account (hell. 1 of Annex 2);
b) point-spotted the heterogeneity in the alloys after refining remelting is characterized by a rounded or u — (a twist of) a form of phase separation volume, located generally asymmetrical. Heterogeneity in the form of rounded points characteristic of the two-phase alloys with a wide area and takes place during remelting with a deep bath of liquid metal (scale No. 1 ). Heterogeneity in the form of brackets, twist the strips is formed by high-speed rotation of the metal in the mold (scale No. 1
).
2. Layered fracture. For alloy grade ЭИ437БУ-VD (N scale 2 of Annex 2) is characterized by the alternation of a regular grain structure with a more fine-grained light strips. The structure of bands of light caused by the separation and coagulation of chromium carbides at the grain boundaries brittle due to violations of technology of heating and metal deformation. The points in the scale increases with increasing brightness, length and number of light strips, as well as the area of the fracture with non-uniform structure: the points 1, 2 evaluate the heterogeneity, located in the regional areas: grade 3 — heterogeneity to a depth of ½ of the radius (side of square); score 4 — inhomogeneity over the entire cross section of the rod. For alloys other brands, the structure of the kink can be different and on a scale of 2 — the assessment is not subject.
3. Laminated fibrous fracture. For grades ЭИ698-VD, ЭП199-VD characteristic alternating bands of layered and visco-fibrous structure along the entire cross section of the rod (to hell. 2 Annex 2). Laminated fibrous structure of the fracture due to the high microstructural heterogeneity of high-alloyed alloys, particularly bars of size 200−220 mm, obtained after a small degree of deformation of the cast structure.
4. Common banded heterogeneity (phase separation banding). In the longitudinal samples taken from rods with a size of 20−60 mm, in the form of dark stripes due to increased travismathew metal in segregated quantities. Score in the scale N 3 applications 2 increases with increasing number of narrow discontinuous bands or by increasing the length and width of one segregated lane.
When establishing the rules on banded heterogeneity it is recommended that additional samples be tested to fracture along the fiber. When the degree of development of the stripe inhomogeneity, the corresponding features. 3 b of Annex 2 (type of separation) is considered invalid.
5. Various-grained macrostructure in longitudinal samples taken from rods with a size of 20−60 mm, is characterized by the location of the strips with a large grain along the edges or over the entire cross section of the rod.
Krupnoporistoj in regional areas due to the modes of heating and the conditions of deformation, work hardening curves for straightening rods, etc. Such description raznozernistoy metal bars does not affect raznozernistoy and properties in forgings and components produced by hot deformation.
Krupnoporistoj in the form of separate strips along the section of the rod due to the presence of the zones off-axis inhomogeneity.
Depending on the purpose of the alloys specified in normative and technical documentation for metal products, evaluation of the macrostructure of longitudinal samples can be made:
when administered in a cold mechanical processing — scales N 4 and 5 of Annex 2;
when administered in hot machining — scale N-5. N 4 in the scale score increases with the increase in the width of the boundary zone with a large grain, increasing grain size and with increasing difference between the size of grains in the axial and marginal zones. In N scale 5 score increases with increasing the number of lanes, their width and the grain size in the bands.
6. Various-grained macrostructure in cross-sectional samples taken from bars larger than 60 mm, and forged samples — in the form of uniformly distributed individual coarse grains, due to insufficient exposure of the samples during quenching (Fig. 4 and Annex 2) or in separate sections with a large grain, randomly placed in the section bars (Fig. 4, b, 4), reflecting recent deformation.
If the alloy is assigned in the hot mechanical processing, are forms of raznozernistoy in assessing macrostructure not taken into account.
7. Various-grained macrostructure and structure of the fractures of finished forgings in a single brilliant coarse grains or individual sections with a large grain on the background of fine-grained structure (Fig. 5 Annex 2). The validity of various-grained macrostructure in the finished forgings (products) defined on the results of extensive testing: ultrasonic testing, mechanical properties, etc.
8. Grain size in the macrostructure — uniform distribution of grains of equal size (scale N 6 Annex 2). Score 1 evaluates alloy with fine grain structure. The size of grains in each subsequent score of the scale compared with the previous, increased by approximately two times.
The scale is recommended for use with additional metal features in determining mechanical properties and heat resistance, including forged samples.
9. Stratification in the fracture is represented as a single, wide or several narrow strips with a ground and a finer surface structure than the basic structure of the fracture of the alloy. Longitudinal microtemplate (damn. 6 a and 6 b of Appendix 2) detected by the discontinuity of the metal. Stratification in the turn a rejection defect.
10. The particles of the corona are presented in the form of small, single plots of heterogeneity, the dark shade in the shape of a snail, loops, spirals, comma, strips (form found increase). The microsection is detected in the form of clusters of small nitrides and oxides of the alloying and accompanying elements (Fig. 7 of Annex 2).
11. The remains of the burning from cutting presented in the form of single spots of small size, rounded shape, arbitrary location, high travelmasti. Alloy in a spot that has almost cast, badly overheated microstructure (Fig. 8 Annex 2). The defect is formed when cutting alloys for anode-mechanical saws or under intensive cutting abrasives, accompanied by strong heating, and is associated with insufficient removal of the molten layer during the preparation microtemplate. The test is repeated after removing the metal layer with the deformation microstructure.
12. Remnants of the ligatures and other additives presented in the form of inclusions with different structure of the fracture (Fig. 9 see Appendix 2) and microstructure. These defects are unacceptable.
13. Precipitation is cracked or internal deformation cracks. In the break have the form of rounded, ellipsoid sites with slightly different crystal structure, sometimes with an oxide film different tint (damn. 10 and Annex 2) or sections of the superheated structure and raznozernistoy (damn. 10, b). Cracks located perpendicular to the direction of deforming force.
In the macrostructure of the forgings (in precipitation for disks), cracks are formed in the marginal and axial zones (Fig. 10), followed by oxidation products of the solid solution and the formation of large carbides due to local overheating of the alloy during deformation (Fig. 10, g).
Cracks formed because of exceeding the permissible stresses in deformation or cooling, are not accompanied by microstructural inhomogeneity, cracks are classified by voltage (Fig. 10, d).
14. Forging transverse cracks located parallel to the direction of the deforming force (damn. 11 Annex 2). Are formed during forging of ingots without tilting, strong common shocks, are detected by ultrasonic testing of bars.
15. Cracks from felling (cutting) by the end of the rod is represented as a single, sometimes irregular, shallow discontinuity of the metal, located at the edge, where he over the operation of the cut (Fig. 12). The test is repeated after removal of the metal layer cracked and distorted structure.
16. Slivovice-etching cracks is presented in the form of numerous (on the borders of macronema) rastrow (damn. 13 and Annex 2) or more wide, randomly placed two or more cracks (Fig. 13, b), resulting in the violation of manufacturing technology microtemplate. In the evaluation of the macrostructure are not taken into account. If necessary, repeat control, changing the mode of grinding or heat treatment.
17. Cracked shift represented as multiple of the same depth of surface gaps along the lines of the most intense shift of metal formed during deformation with a strong surface cooling of the ingot or billet (Fig. 14 Annex 2). Crack propagation is inhibited in the normal area of the heated metal.
