GOST 10243-75
GOST 10243−75 (ST SEV 2837−81) Steel. Test methods and evaluation of the macrostructure (Change No. 1)
GOST 10243−75
(ST CMEA 2837−81)
Group B09
STATE STANDARD OF THE USSR
STEEL
Test methods and evaluation of the macrostructure
Steel. Methods of test and estimation of macrostructure
Date of introduction 1978−01−01
APPROVED AND promulgated by the decree of the State Committee of standards of Ministerial Council of the USSR dated August 19, 1975 N 2176
By the decree of Gosstandart of the USSR from 03.08.82 3031 N validity extended until 01.01.88*
_______________
* Expiration removed by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification. (IUS N 4, 1994). Note the «CODE».
REPLACE GOST 10243−62
REPRINT (February 1985) with amendment No. 1, approved in August 1982 (IUS N 11−1982)
This standard applies to forged and rolled carbon, alloyed and high-alloy steels and establishes test methods and reference scale for assessment of macrostructure, as well as the classification of macrostructure defects and fractures of bars and billets with a diameter or with a thickness of 40 mm (the smallest side) to 250 mm (largest side) of the cross section.
By agreement between supplier and customer established by this standard method of fabricating microtemplates samples and the fracture is allowed to extend into billets, forgings and articles of other cross sections and sizes. Evaluation of the macrostructure in these cases may be done according to the standards of this standard, industry standards or technical conditions. By agreement between the consumer and the manufacturer standard can be used for steel produced by continuous casting.
The need for control of the macrostructure, the number and location of sampling along the length of the rumble of the ingot, the dimensions of the samples after reforging, as well as standards for allowable defects and the list-items not admitted are determined by the standards for specific types of steel products.
In the standard account of the requirements of the recommendations of the CMEA standardization 3629−72 RS.
In the method of monitoring etching standard fully complies ST SEV 2837−81.
(Changed edition, Rev. N 1).
1. GENERAL PROVISIONS
1.1. Metal macrostructure control:
etching specially prepared samples in acid solutions.
The method is based on the difference in travelmasti defect-free metal and sections with the presence of pores, phase separation, heterogeneity of structure and other defects;
break specially prepared (including advanced heat treated) samples.
The method is based on different fracture sites of metal with porosity of the flocs, overheating, a chipped without them.
Quality control of metal at the fracture produces:
instead, control of the etched samples if it is stipulated in standards for steel;
in addition to the control treated samples to verify the classification of macro defects, as well as for research purposes.
1.2. Macrostructure of carbon (with a carbon content up to 0.3%) structural steel for fracture control.
1.3. Evaluation of microtemplates and fractures produced by inspection with the naked eye. To clarify the classification of defects may be two-, fourfold increase.
2. SAMPLING AND PREPARATION OF SAMPLES
2.1. Macrostructure of metal is controlled by one of the following options.
2.1.1. Rods and billet sizes up to 140 mm in full cross section.
2.1.2. Rods and blanks larger than 140 mm at the forge or perinatalnyj samples, if the standards or specifications are not stipulated the need for control in the total cross section up to 250 mm.
2.2. The number of samples and the choice of selection of their length and the cross section of the rolled sheet ingot (cast billets) are specified in the standards and specifications for specific types of steel products.
In the absence of such instructions in the sample to control selected (in the factories-suppliers of metal) from the workpiece corresponding to the most contaminated parts of the ingot.
The marking on the samples cut off from them, the samples must comply with the specifications of the controlled blanks.
Recommended:
a) the casting of metal on top to control the workpiece from the first and last bars at the time of casting; the casting of siphon — blanks from one ingot in the first and last siphon; in the absence of mark — to control the procurement of any ingots;
b) metal is vacuum-induction melting (VI) to control one sample from podperevalny of each ingot;
metal vacuum arc (VD), electron beam (EL), plasma arc (RAP) and electroslag (W) remelting — on samples from the workpieces, the respective upper and lower parts one or two bars from the batch-melting;
C) a double metal after remelting vacuum induction + vacuum arc (ID), electroslag + vacuum arc (SM) and other control in accordance with guidelines listed for the last method of remelting.
2.3. In the control heats, separated by size into several lots, samples are taken from the workpieces with a maximum cross-section. Positive testing results can be extended to all parties of this smelting are smaller in size and also on the workpiece, the transverse dimensions of which exceed the controlled not more than 20 mm.
2.4. Samples for control of the flocs is taken from any of the blanks after the end of a full cycle of the cooling mode or heat treatment of each batch-melting. Under the same conditions of cooling of billets with different cross-sections of the samples cut off from the party of workpiece max. cross section in the melt. Fillet samples and templates across the fibre produced by the saw or blowtorch at a distance of not less than one diameter (of the square) from the edge of the workpiece.
In cases that do not allow oxyacetylene cutting (agreed standards or technical conditions), cut the sample immediately after rolling or forging in a hot condition. The length of the sample shall be not less than four diameters (sides of square). Cooling and heat treatment of the sample is produced together with the metal a controlled batch-melting. Template cut from the middle of the sample.
Control of the metal flocs are allowed to produce:
longitudinal Templeton or longitudinal fractures. In the latter case, the transverse template should be notched, quenched in water and broken;
method of ultrasonic testing.
2.5. Clipping samples to control the macrostructure is produced in compliance with the requirements and recommendations listed below.
2.5.1. Template should be cut in such a way that the controlled section was at a distance, excluding the effect of cutting conditions: heating from cutting, crumpling from the press, saws, etc.
2.5.2. When testing metal reforged samples from the monitored workpiece cut off a piece with a length of not less than one diameter (or square side) and peroxide on the size 90−140 mm, if standards are not specified other sizes. Template control should be cut from the middle part of the length of the forged samples.
2.5.3. Template cut perpendicular to the direction of rolling or forging through the entire cross section of the workpiece, and the control of macrostructure and placenow longitudinal samples is parallel to the direction of rolling, forging. In the latter case, the plane of the future section should match or be close to the axial plane of the workpiece is controlled.
The longitudinal length of the templates should be 100−150 mm.
2.5.4. Recommended height of transverse templates should be 15−40 mm.
2.5.5. If necessary, samples from billets of large cross section (more than 200 square mm and slabs) may be cut into pieces while maintaining the axial zone (Fig.1). Poison and need to evaluate all the parts of the sample.
Damn.1
2.6. The surface of the templates before the etching must be subjected to cold mechanical processing: beveling, planing, grinding. After treatment the surface should be flat and smooth, without surface hardening and preroga metal. Arbitration test, the surface roughness of the processed templates should be no more than 20 µm according to GOST 2789−73.
2.7. Grinding of templates produced with the metal hardness of not more than 388 HB (indentation diameter is not less than 3.1 mm). In the control of steel with high structural heterogeneity, as well as supply with high hardness necessary to produce a softening heat treatment of samples or templates.
2.8. A control break is performed on specimens with transverse or longitudinal direction of the fiber. When replacing the control for treated samples with control rather used the samples from the transverse direction of the fiber; in the control at fracture, in addition to the control of the macrostructure, the samples applied with the longitudinal direction of the fiber.
2.8.1. To control the fracture across the grain of the workpiece in the delivery condition (or samples from them) is incised on one of the on features.2 schemes.
Damn.2
The area of the fracture shall not be less than the sectional area of the workpiece. Failure of the specimen or the workpiece must be performed with maximum speed and a large concentrated load, eliminating crushing of the surface of the fracture and the formation of false splits.
2.8.2. To control the fracture along the fiber cut special samples or use template after etching and control of the macrostructure. Cut the templates to produce breakage along the axial line or a defective place, but on the back side relative to the plane of macrolife. The depth and shape of the incision needs to guarantee a straight cut (no shear) and sufficient water height: at least 10 mm for billets with a size of 80 mm or more and 5 mm for dimensions less than 80 mm. For the detection of very small defects template is heated to a temperature not lower than the standards or specifications for thermal treatment of samples when testing the mechanical properties or hardness and quenched in water.
3. EQUIPMENT, REAGENTS AND MODES OF ETCHING OF THE TEMPLATES
3.1. For the etching of the templates should be applied to tubs, vessels made of materials that do not react with the etching solutions used.
3.2. Before etching template must be cleaned of dirt and, if required, degrease.
Samples of the pickling bath must not touch controlled planes with each other and with the walls of the bath. The amount of etching solution should provide a small reduction in the concentration of the acid during etching.
The amount of solution should be, in cm(approximately):
10 cm |
||
100 cm | ||
2000 — 1000 cm |
Samples before etching it is recommended to heat up to 60−80 °C, i.e., to the temperature of the solution.
3.3. Recommended reagents and modes of etching are listed in Annex 1. Allowed to use other reagents, subject to obtaining the identical etching results.
The reagents used should be clean, bright, free of suspended particles and foam.
The etching conditions should exclude the occurrence of false defects.
3.4. If you use large tubs simultaneously poison samples from brands that are similar in chemical composition.
The etching time should be longer (within the range recommended in Appendix 1):
| for alloyed and acid-resistant steels; |
||
| for metal with high hardness; | ||
| the etching of the samples without heating; | ||
| when etching in a less heated solution. |
3.5. Etching of samples should provide clearly identified macrostructure, allowing to reliably assess it in comparison with scales and photographs.
3.6. In case of strong rastravleniya metal (surface Browning, the appearance of false porosity throughout the cross section, roughness) tests repeated on the same samples after removing the surface layer to a depth of at least 2 mm.
3.7. After etching in any reagent, the samples shall be carefully rinsed in running water and dried. It is recommended to use a non-metallic brush.
Samples intended for storage, it is recommended that further treated with 10% alcohol solution of ammonia or washed with alcohol and then cover with a colourless varnish.
4. EVALUATION OF THE ETCHED TEMPLATES AND FRACTURES
4.1. The definition and assessment of the degree of development of defects of a macrostructure is produced by comparing the natural look svezheprigotovlennyj samples with standard scales of this standard (see Annex 2) or still images (see Annex 4), using the descriptions in appendices 3 and 4. For the correct classification of defects in the fracture, using photographs and brief descriptions, is given in Annex 4.
4.2. Each scale consists of five points. Scale illustrate the following types of defects of a macrostructure:
| scale N 1 and 1A, the Central porosity; |
||
| the scale N 2 and 2A — point heterogeneity; | ||
| scale N 3, and 3b — the common spotted liquation; | ||
| N scale 4 and 4A — spotted boundary liquation; | ||
| scale N 5 and 5A — segregated square; | ||
| N scale 6 and 6A podnasadochnogo liquation; | ||
| N scale 7 — subcortical bubbles; | ||
| N scale 8 — intergranular cracks; | ||
| N scale 9 — layer-by-layer crystallization; | ||
| N scale 10A — pinstripe (outline). |
4.3. Samples from billets of size 90−140 mm, and from samples reforged evaluate on scales N 1, 2, 3, 3b, 4, 5, 6, 7, 8, 9; samples from billets that are larger than 140 to 250 mm on the scale N 1A, 2A, 4A, 5A, 6A, 10A.
Subcortical bubbles, intergranular cracks, layer-by-layer crystallization in the blanks in size from 140 to 250 mm assessed on scales N 7, 8, 9 (respectively). The light stripes (contour) in the blanks of size 90−140 mm is rated on a scale N 10A.
When evaluating workpieces larger than 250 mm and less than 90 mm, the area occupied by defects, compared to the scales must be appropriately increased (for workpieces of more than 250 mm) or reduced (for workpiece size at least 90 mm) in proportion to the increase or decrease in the cross sectional area of controlled harvesting. This takes into account the degree of defect development.
4.4. The amount of defects allowed to be evaluated as a whole score and a half (0.5, 1.5, and so on). A score of 0.5 with regard to the structure of the templates that have defects with the degree of development in two times less than in potatoland first points of the relevant scales.
In the absence of defects placed score 0; for gross development score more than 5.
With the simultaneous presence of several defects evaluation and classification of each defect are produced separately.
4.5. Assessment of the degree of development of defects in the fracture and longitudinal microtemplate produced by mapping their natural look with fotoatteli special scales agreed between the supplier and the consumer.
4.6. In the evaluation of the macrostructure of metals by the photographs (in arbitration tests) the latter must be completed clearly, in full size or with the scale.
4.7. When unsatisfactory results of primary control of the macrostructure of the re-test is carried out in the volume established by the standards for specific products.
In the absence of instructions the repeat test is recommended by one of the following options:
a) twice the number of samples;
b) on the samples from the defective workpieces, and when polytechnos the marking from the defective bars after additional trim defective parts of workpieces;
C) samples from adjacent blanks after sorting out defective;
g) for samples from each ingot, or each of the workpiece — in particularly important cases or defects.
5. THE RESULTS OF THE TEST
5.1. The results of the evaluation of the macrostructure recorded in the test report stating:
steel grade, heat number, designation of standard supply;
section and size-controlled of the workpiece, mm;
number and index of the workpiece;
points for defects:
CPU — Central porosity,
TN — point heterogeneity,
OPL — common spotted segregation,
KPL — spotted boundary liquation,
LK — segregated square,
PU — podsadecki segregation,
PP — subcortical bubbles;
MT — intergranular cracks;
PC layer-by-layer crystallization;
SP — light strips (contour);
defects not normalized scale, and surface defects detected on the transverse Templeton (fit note).
5.2. In the document about the quality of the metal is indicated «acceptable» or «meets the requirements».
ANNEX 1 (mandatory). RECOMMENDED REAGENTS AND MODES OF ETCHING
ANNEX 1
Mandatory
| Steel grades | The composition of the reagent | The solution temperature, °C | The time of etching, min. |
Note |
| Reagent 1 |
||||
| All steel grades, in addition to the following |
Hydrochloric acid by the GOST 3118−77, 50% aqueous solution |
60−80 | 5−45 | - |
| Reagent 2 |
||||
| Corrosion resistant, heat resistant and other steels austenitic |
Hydrochloric acid by the GOST 3118−77 — 100 cm |
60−70 | 5−10 | - |
| Reagent 3 |
||||
| Corrosion resistant, heat resistant and other steels austenitic |
Hydrochloric acid by the GOST 3118−77 — 100 cm |
60−70 | 5−10 | - |
| Reagent 4 |
||||
| Corrosion resistant, heat resistant and other steels austenitic |
Hydrochloric acid by the GOST 3118−77 — 100 cm |
20 | 5−10 | - |
| Reagent 5 |
||||
| Corrosion resistant, heat resistant and other steels austenitic and ferritic steel grade |
Hydrochloric acid by the GOST 3118−77 — 100 cm |
20 | 15−25 | Etching is recommended by wiping with cotton wool soaked in reagent. Cone washed with water and 5−10%-s ' solution of potassium bichromate (GOST 4220−75) |
ANNEX 2 (mandatory). THE SCALE OF MACROSTRUCTURES
ANNEX 2
Mandatory
SCALE N 1 CENTRAL POROSITY
SCALE N 1A CENTRAL POROSITY
N SCALE 2 POINT HETEROGENEITY
N SCALE 2A POINT HETEROGENEITY
N SCALE 3 COMMON SPOTTED LIQUATION
N SCALE 3A COMMON SPOTTED LIQUATION
SCALE N 3B SPOTTY LIQUATION CHARACTERISTIC OF THE METAL OF ELECTROSLAG AND VACUUM-ARC REMELTING
N SCALE 4 REGIONAL SPOTTY LIQUATION
N SCALE 4A REGIONAL SPOTTY LIQUATION
SCALE N 5 EXUDATION SQUARE
N SCALE 5A EXUDATION SQUARE
N SCALE 6 POUSADELA LIQUATION
N SCALE 6A POUSADA LIQUATION
N SCALE 7 SUBCORTICAL BUBBLES
N SCALE 8 INTERGRANULAR CRACKS
N SCALE 9 SUBSURFACE CRYSTALLIZATION
N SCALE 10A LIGHT STRIP (CONTOUR)
APPENDIX 3 (obligatory). DESCRIPTION OF THE MACROSTRUCTURE AND FAULTS, ILLUSTRATED SCALES
APPENDIX 3
Mandatory
1. Central porosity — small voids, not ready during hot machining of the ingot. On microtemplate porosity is detected in the form of small or some large dark spots — pores. The development of the defect (point) is determined by the number, pore size and area of the sample affected by porosity (scale N 1 and 1A).
2. Liquation is the heterogeneity of individual sections of the metal by chemical composition, structure, non-metallic and gaseous impurities.
Provides for the classification and evaluation of four types of segregation.
2.1. Point heterogeneity, liquation point — small rounded, travesias (matte) points located along the entire cross section of the sample, with the exception of the edge zones. The development of the defect (the score) is mainly determined by the number of points and restroom metal in them. Take into account the size of the dots and size of sample affected (N scale 2 and 2A). In the hardened longitudinal fracture liquation is sometimes found in the form of strips with lighter crystalline structure.
2.2. Spotty liquation separate dark spots of various sizes and shapes. The location of the samples there are two types of spotted segregation:
a) common spotted liquation — spot, located in the sample section symmetrically relatively to the axis of the workpiece (scale N 3 and Over) or asymmetrically located spots smaller, but with a big difference of their structure from the structure of the base metal (N scale 3b). The last are mostly found in the metal, melted in vacuum arc and electroslag furnaces;
b) regional spotty liquation oriented along the sides of the sample spot oval.
The development of the defect (point) is determined by the number, sharpness of manifestation, the size of spots and area of the sample stained. Account is also taken of the depth of the stains from the surface of the workpiece (scale N 4 and 4A).
2.3. Exudation exudation square or round contours of segregation are determined by the configuration of the ingot. On microtemplate detected in the form of a strip of metal (often located in the middle of the radius or the sides of the square), travesas more intense compared to the rest of the cone. With increasing travelmasti metal in the band and with the increase in closed-loop score in the evaluation increases (scale N 5 and 5A).
2.4. Pousada liquation — dark, rastravleniya portions of the metal in the center of the workpieces. The score increases with increasing size of the spots and the difference in travelmasti of the axial zone and the rest of the sample (scale No. 6 and 6A). The appearance of dark spots can also be caused by carburization of metal from insulated fillings containing carbon.
To clarify the classification of defects and detection of phase separation it is recommended that additional testing by the method of fingerprinting on the distribution of sulphur — Baumann (Appendix 5, item 1), and etching the polished samples with reagents Oberhoffer, Hein etc. for research purposes to determine the distribution of lead in steel method of imprint on Wragge (Annex 5, p.2).
3. Subcortical bubbles — small voids-pores located near or on the surface of the workpiece. The shape of the defect depends on the depth: in the form of rounded, oval or nakatannyh to thin «lines». The degree of development of the defect is evaluated. With the increase in the number of bubbles in the sample plane, and the depth from the surface point increases (scale No. 7).
4. Intergranular cracks with three or more sinuous, thin, spider-like stripes directed from the axis of the workpiece to the side (scale No. 8). The score increases with the number and size of cracks (length and width). Classification of the defect is verified by the fracture: the presence of stratification in the hardened fracture indicates the correct definition.
Rastra metal «spider» can occur due to structural heterogeneity, which is not a rejection symptom. In this case, the test should be repeated after heat treatment: normalizing or annealing samples.
5. Layer-by-layer crystallization of alternating layers of metal in the form of narrow light and dark bands, often located at the surface less frequently over the entire cross section of the sample. The score increases with travelmasti bands, their width, number and depth (scale No. 9).
6. Light strip (contour) is a relatively bright concentric strip of metal of low travelmasti. The form of bars (round, square) defined by the configuration of the mold. The score increases with increasing brightness and bandwidth for the closed loop and the number of lanes (N scale 10A).
ANNEX 4 (required). DESCRIPTION OF THE MACROSTRUCTURE AND FAULTS, ILLUSTRATED BY PHOTOGRAPHS
ANNEX 4
Mandatory
The defects in the bends
1. Rude rolled out of the pores and the gas bubbles separate, thread-like strip with a distorted crystal structure. Bubbles can be single, group located around the cross section, in the center or at the surface of the workpiece (Fig. 1A, b).
Damn. 1. Rude rolled out of the pores and the gas bubbles
and
b
Damn. 1
2. Rough spotty liquation — wide strips with a different crystal structure, often dark, randomly placed on the section of the billet (Fig. 2).
Damn. 2. Rough spotty liquation
Damn. 2
3. The remains of the shrinkage in the axial zone in the form of dark or light gray with stripes slag, non-crystalline structure or with a smoothed, honed, acid-etched surface (Fig. 3).
Damn. 3. The remains of shrinkage
Damn. 3
4. Pousada rihlat — one or more dark bands with groboclones structure, often accompanied by pores, slag inclusions.
5. Bundle — wide strips with smoothed, crystal, light (in contrast to shrinkage) structure in an axial, at least in the edge zone of the workpiece. Intercrystalline is caused by the presence of cracks in the ingot, Nezavisimaya during subsequent deformation (Fig. 4A, b).
Damn. 4. Bundle
and
b
Damn. 4
After a large degree of deformation in the fracture remain a separate light (silver) thread.
6. Intergranular layer — found in relatively little deformed metal in the form of a heterogeneous structure of the fracture of three types.
6.1. Chips — lots of different shapes and sizes, often located in the marginal zone of the blanks laminated from structural steel grades. Surface chipping has a finer structure and a bright or matte finish (damn. 5A, b) depending on the steel grade and conditions of the control sample.
6.2. Layered fractures in a more natural alternating bands of fine-grained and typical for this grade of steel structure. Vary the location of the cross section of billet: at the surface, in the axial zone, the entire section — depending on the steel grade, strain, designated sampling control (Fig. 5B, d).
Damn. 5. Intergranular layer
a — chipped with a bright hue
b — chips (platforms) with frosted shade
in the laminate fracture in the axial part of the workpiece
g — layered kink in the outer part of the workpiece
Damn. 5
7. Obesplozhennym and the carbonized layer in the fracture of bars across the grain of different grain size and shade structures: light, coarse — when decarburization (Fig. 6); matte, fine — if carburization of the metal (around the perimeter of the rod or its part).
Damn. 6. Obesplozhennym layer (after a strong overheating of the metal)
Damn. 6
8. Naphtalansky and lithoidal fractures — the result of severe overheating of the metal before deformation or at thermal processing.
Naftalinescu — classified planar fracture with a characteristic glint in the cross-section of large grains, different reflecting light (Fig. 7a).
Solid — classified matte kink on the limits of large or small grains, chiseling their cut (damn. 7b).
Damn. 7. Naphtalansky and solid breaks
and
b
Damn. 7
Unlike naftalinovogo reflectivity of faces of the grain are weakly depends on the direction of illumination. Sometimes to identify lithoidal fracture is required to determine the optimal conditions of supply-quenched samples.
9. Splitting, digging, about stratification in the form of narrow slits, protrusions and depressions («tongues») in the kink bars across, and sometimes along the fiber. Formed in the cases is not observed when the rational form of the incision of the sample, the conditions of heat treatment before the damage and speed of damage (damn. 8A, b). Splitting (tears) are not associated with the quality of the metal, as evidenced by a control macro and microstructure of the same sample in the place fission.
Damn. 8. Splitting, digging, about stratification
and
b
Damn. 8
10. Black break — a solid or in separate sections (various forms) kink with a dark gray or black color. It is found in high carbon tool steel grades (Fig. 9).
Damn. 9. Black kink
Damn. 9
Note. Defects specified in the PP. 1−6, more clearly detected in longitudinal fractures, PP. 7−10 — in the cross.
The defects in microtemplate and then rupture
11. The heterogeneity of the macrostructure (titanium, Ariva, zirconium) — local boosted rastra metal in the form of dots, brackets, spots in places where non-metallic inclusions of these elements (Fig. 10A, b). Can be located both in the axial and the marginal zone and along the entire cross section of the sample. When a large development is found in the longitudinal fracture (Fig. 10B). Takes place in steel containing titanium (0.3%), the excess percentage of the cerium, zirconium or in the wrong technologies introducing them into the metal.
Damn. 10. The inhomogeneous distribution of elements additives
and Titan
b — cerium
in Titan
Damn. 10
12. Brown (exogenous inclusion) at the edge or on the section of the workpiece — parts of various travelmasti of different shape and size. Can be dark (Fig. 11a, b) or bright (hell. 11b) depending on the location of the height of the ingot, the chemical composition, temperature of formation and degree of saturation with gas and nonmetallic inclusions.
According to rough crusts by rolling the metal may form a bundle, which is detected in the hardened a break in the form of stripes with a non-crystalline structure (Fig. 11g).
Damn. 11. Brown (exogenous inclusion)
a — dark crust (inside blank)
b — dark crust at the surface
in — light brown (bottom of ingot)
Mr. brown in fracture
Damn. 11
13. Fistula (gas bubbles, sink) — separate large and small voids, pores oval, round or elongated shape; the cross section of the specimen are usually asymmetrically (Fig. 12). Can be single and group. Formed during metal crystallization, supersaturated gases, including a breach of the conditions of pouring.
Damn. 12. Fistula
Damn. 12
14. Flocs — thin twisting cracks in length from 1 to 30 mm and more. Oriented randomly, striking all or part of section of a billet, with the exception of the edge zones (Fig. 13). For the correct classification of the defect is an additional control on the fracture of the same sample after quenching.
At the turn of the flocs are identified in the form of light spots round or oval in shape, with a crystalline surface, silvery or light shade depending on the steel grade and the time of formation of the defect (Fig. 13B, C). Flocs are not ready for subsequent compression of the workpiece, have the form of discontinuities of various sizes and shapes (Fig. 13D, e). Location placenow on length and cross section of blanks of arbitrary.
Damn. 13. The flocs
and
b
in steel with 1% carbon
Mr. nezavrsena flocs in the longitudinal microtemplate
d — nezavisna flocs in the hardened fracture
Damn. 13
15. White spots, foreign, arranged in groups, metal inclusions with a characteristic sharp structural heterogeneity (Fig. 14). From the base metal are characterized by macro — and microstructure, hardness, chemical composition (carbon and alloying elements). Meet bullion, profitable of which is filled with termite-enriched slag.
Damn. 14. White spots
Damn. 14
White spots should not be confused with light peels and non-random inclusions.
16. Foreign metal and slag inclusions — usually isolated, accidentally fell into ingots pieces of various kinds of ferroalloys undissolved, particles of oxidized metal, slag, icicles, bows, refractories, «crown», etc. Are different from the main metal travelmasti, chemical composition, microstructure and hardness (Fig. 15A, b, C, d). Sometimes found in the fracture.
Damn. 15. Foreign metal and slag inclusions
and from ferroniobium
b — slag
in — icicles
Mr. crown
Damn. 15
17. Czernowin (cracks, tears) — in the form of loose, highly travadas inner zone or separate dark spots, often accompanied by one or two cracks — breaks parallel to the faces of the ingot (Fig. 16A). In the longitudinal fracture are identified in the form of discontinuity of the metal — looseness; low degree of development — in the form of strips with a coarse-grained structure and with tears (damn. 16B). Defects burned during heating and destruction during the deformation of the internal zones of the workpieces.
Damn. 16. Czernowin (cracks, tears)
and
b
Damn. 16
18. Nesting boxes — voids, holes, of various sizes and shapes, are usually solitary along the length of roll of the ingot. Are formed by incomplete disclosure and brewing internal transverse thermal cracks (Fig. 17). When inspecting the surface of the workpiece can not be detected.
Damn. 17. Birdhouse
Damn. 17
An additional feature is the absence of segregation of carbon, sulfur, phosphorus and non-metallic inclusions around the defect.
19. Internal breaks — numerous transverse disruption of the chain along the axis of the workpiece (Fig. 18). Different from birdhouses smaller, lots, winding circuit and crystal structure of fractured surfaces. Are formed when there is insufficient pressure to deform the middle of the ingot, which is characteristic for steels with high deformation resistance and low speed of recrystallization.
Damn. 18. Internal breaks
Damn. 18
20. Forging cracks — inside of the axial zone. Can be in the form of a cross, one cracked diagonally, two or more cracks, directed from the axis of the workpiece in the hand (damn. 19). In contrast to the intergranular cracks wider and rectilinear. The length of the ingot is arbitrary. In the break have a kind of coarse oxidised wide bundles.
Damn. 19. Forging cracks
Damn. 19
21. Cracks formed in violation of the conditions of sample preparation (in the evaluation of the macrostructure are not taken into account).
21.1. Shlifovanie crack — the cracks, or a separate thin cracks in various directions and lengths. Formed when grinding metal with high hardness (more than 388 HB), significant fragility and low thermal conductivity.
21.2. Etching cracks — increased local rastrow in the form of discontinuous cracks, sometimes in the form of a grid, formed during the etching of metal, have voltages from structural transformations or hardening from deformation.
21.3. Slivovice-etching cracks — local rastra metal having cracks after grinding (Fig. 20).
Damn. 20. Slivovice-etching cracks
Damn. 20
22. A light ring or square — found in the axial zone, or within half of the radius of the workpiece. Form is determined by the contour of the mold. Compared to the bright stripe (N scale 10A) has a greater width and a closed loop (Fig. 21). A kind of the defect is light (grey) spot in the axial zone podtribunnyh blanks.
Damn. 21. Light ring
Damn. 21
Defects are detected with insufficient removal of the upper part of ingots of vacuum arc or electroslag remelting.
23. Boundary tracking (double filling) — peeling the strip of metal around the contour of the workpiece or parts of it (hell. 22). Formed due to the interruption of the jet of metal in the siphon casting, and the sudden increase in the casting speed, leading to the Gulf of metal between ingot and mold.
Damn. 22. Boundary tracking (double filling)
Damn. 22
24. Increased or reduced travelmasti of the axial zone, as well as individual sections of the investigated template — is caused by the conditions of crystallization and deformation of the ingot (Fig. 23a), uneven work hardening and recrystallization of individual harvests, raznozernistoy (damn. 23B). The difference in travelmasti disappears or decreases after high temperature treatment of the metal.
Damn. 23. Raznozernistoy and various travelmasti when cold working metal
and
b
Damn. 23
25. The remains of the cast structure in the center (Fig. 24A) or at the surface (Fig. 24B) pieces in the form of a clear pattern of dendrites or large crystals, grains.
Damn. 24. The remains of the cast structure
and
b
Damn. 24
26. Edge defects
26.1. Areas of high travelmasti metal, accompanied by the contamination of non-metallic inclusions (Fig. 25A) is formed during solidification of ingots as var, remain on the surface of the workpiece when there is insufficient depth roughing and Stripping them.
26.2. Areas of low travelmasti metal without apparent contamination (Fig. 25B) is formed by violation of the regime of crystallization of the lower part of the ingots and are detected in the blanks with the lack of trim this part of the ingots ESR and var.
26.3. Local gross irregularity (elektroprenos) is accompanied by gas bubbles, fistulas (Fig. 25V) or shape distortion other defects (Fig. 25g). In the latter case — at infringement of sequence of crystallization. Defects are formed due to the discontinuity of the slag garnissage as a result of electraprobe during electroslag remelting. It is recommended that additional control sample with the longitudinal direction of the fiber.
26.4. Corner cracks — in the form of one or more narrow strips located in the corner areas of the workpiece or slightly shifted on one of the faces (damn. 25d). Formed in violation of the conditions of deoxidation and teeming of metal, with the incorrect rounding of the corners of the molds etc.
Damn. 25. Edge defects
and — areas of high travelmasti with non-metallic inclusions
b — areas of low travelmasti without visible impurities
in local gross irregularity (elektroprenos)
g
d
Damn. 25
APPENDIX 5 (mandatory). CONTROL OF CHEMICAL INHOMOGENEITY OF STEEL BY PRINTS
ANNEX 5
Mandatory
1. Method of sulphur print (Baumann)
1.1. To imprint on the sulphur distribution in the metal template after annealing, planing or facing sanded to remove the scratches from the previous processing and polishing grains 12 and 8 according to GOST 6456−82. The samples thoroughly wipe the dust and grease (for degreasing, it is recommended to apply denaturirovannyj alcohol).
1.2. When removing fingerprints from high-sulfur (automatic) steel template pre-wipe with a cotton swab moistened with 5% strength sulfuric acid according to GOST 4204−77. With removed products of the primary reaction.
1.3. Remove fingerprints on photographic paper corresponding to the size of the investigated template (unibrom according to GOST 10752−79). Sheets of paper soaked in the light 5−8 min in 5% strength solution of sulfuric acid (GOST 4204−77). From the excess solution, the paper is dried lightly with filter paper and put the emulsion side on the surface of the investigated template. On the reverse side, avoiding shear continuously photo paper iron rubber roller or with a cotton swab to remove the gas bubbles formed during the reaction.
Remove fingerprints at a temperature of about 20 °C for 3−15 min depending on the steel alloying and the content of sulfur in it. The imprint is considered ready when the darkening of the photographic paper from light brown (on alloy steel with low sulphur content) to dark brown (on carbon steel with a high content of sulfur and phosphorus). In places where sulfur inclusions darkening of the paper will be maximized in accordance with the quantity of generated sulfur here silver.
1.4. The finished print is thoroughly washed in running water and treated with a fixer for 20−30 min (sodium thiosulfate according to ST SEV 223−75), then washed again, dried and labeling.
1.5. For removing re-imprint the sample surface is polished with the removal of the metal layer not less than 0.3 mm.
2. A method of detecting the presence and concentrations of lead (for Preggo)
2.1. The plane of the investigated template is sanded, degreased and drained a 10% solution of ammonium naternicola. Templet stand to obtain a gray color, washed in running water to remove the grey coating and dried. Bromine-silver paper (unibrom according to GOST 10752−79) to remove silver salts soaked in the dark in sodium thiosulfate according to ST SEV 223−75. After 7−10 min the paper is removed, washed in running water and dried. Before removing the imprint of the prepared photographic paper is soaked for 5−7 min in a 5% aqueous solution of caustic soda (sodium hydroxide according to GOST 4328−77), gently dried with filter paper and applied to the sample emulsion side. RUB a cotton swab for 5 minutes to provide intimate contact of the paper with a sample surface (to prevent shear).
2.2. The finished print is immersed for 10−15 with a 5% solution of sodium sulfide (sodium sulfide according to GOST 2053−77). The imprint washed, dried, label, if necessary, photographed. In the presence of steel lead the imprint turns a light brown color with dark spots in places of segregation. In the absence of lead paper color is not changed. For removing re-imprint the surface of the sample is prepared again.
2.3. Evaluation of the obtained prints (1 and 2nd methods) produce by comparison with internal standards or by description indicating the shape of the distribution of sulphur or lead. Example: uniform or nonuniform; in the form of a solid square or contour; in the axial and the marginal zone.
