GOST 6032-2003

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  ГОСТ 6032-2003

GOST 6032−2003 (ISO 3651−1:1998, ISO 3651−2:1998) Steel and alloys corrosion-resistant. Methods of test for resistance to intergranular corrosion

GOST 6032−2003
(ISO 3651−1:1998,
ISO 3651−2:1998)

Group B09

INTERSTATE STANDARD

STEELS AND ALLOYS CORROSION-RESISTANT

Methods of test for resistance to intergranular corrosion

Corrosion-resistant steels and alloys. Test methods of intercrystalline corrosion resistance

ISS 77.060
AXTU 0909

Date of introduction 2005−01−01

Preface

1 DEVELOPED by the Russian Federation, the Interstate technical Committee for standardization MTK 145 «monitoring Methods of steel», JSC «Scientific-research and design Institute of chemical machine-building (JSC «NIICHIMMASH»)

INTRODUCED by Gosstandart of Russia

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 24 dated 5 December 2003)

The adoption voted:

3 this standard is modified in relation to international standards: ISO 3651−1:1998* «Determination of resistance to intergranular corrosion of stainless steels. Part 1. Austenitic and ferritic-austenitic (two-phase) stainless steel. Corrosion tests in nitric acid by determining the mass loss (testing for Hugh)» is the essence of the method and sample preparation; ISO 3651−2:1998 «Determination of resistance to intergranular corrosion of stainless steels. Part 2. Ferritic, austenitic and ferritic-austenitic (two-phase) stainless steel. Corrosion test in media containing sulfuric acid» — components of solutions for testing, sample preparation and evaluation of resistance to intergranular corrosion
________________
* Access to international and foreign documents referred to here and hereinafter, can be obtained by clicking on the link. — Note the manufacturer’s database.

4 Resolution of the State Committee of the Russian Federation for standardization and Metrology dated 9 March 2004 No. 149-St inter-state standard GOST 6032−2003 (ISO 3651−1:1998, ISO 3651−2:1998) introduced directly as a national standard of the Russian Federation from January 1, 2005

5 REPLACE GOST 6032−89

6 REISSUE. September 2005

1 Scope

This standard establishes test methods for resistance to intergranular corrosion (hereinafter — the ICC) steel products made of corrosion-resistant steels and alloys, including two-layer austenitic, ferritic, austenitic-ferritic, austenitic-martensitic steels according to GOST 5632, as well as their welded joints and weld metal.

The ICC is due to the merging of grain boundaries in chromium as the result of deposition at the grain boundaries of the phases rich in chromium: chromium carbide -phase, intermetallic inclusions in the aging of steels or alloys at a temperature of 500 °C — 1000 °C.

Depending on the chemical composition of steel and alloy and their purpose choose one of the following methods of testing the resistance of metal to the ICC: AMA, EMUF, WU, DU, V, B.

The choice of test method is determined by the chemical composition of the metal and guidance in regulations on manufactured equipment.

Test methods for resistance to ICC B and C, listed in annexes A and B, are recommended.

The use of the methods provided in the annexes D and E, allowed along with the main methods of testing for resistance to the ICC of this standard.

All the above methods can not be used to determine the corrosion resistance of steels and alloys for different types of corrosion (solid, pitting, ulcers, stress corrosion cracking, etc.).

In the legend of AMU methods, AMWF, WU, DU, B, the letters stand for:

A, B, C, D — letter-name methods;

M — the presence in the solution for testing of metallic copper;

F — the presence in the solution for testing of fluoride ion;

U — accelerated testing.

2 Normative references

The present standard features references to the following standards:

GOST 859−2001 Copper. Brand

GOST 1381−73 Methenamine technical. Specifications

GOST 2789−73 surface Roughness. Parameters and characteristics

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3652−69 citric Acid monohydrate and anhydrous. Specifications

GOST 3769−78 Ammonium sulfate. Specifications

GOST 3776−78 Chromium (VI) oxide. Specifications

GOST 4165−78 Copper (II) sulfate 5-water. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 4463−76 Sodium fluoride. Specifications

GOST 4518−75 Ammonium fluoride. Specifications

GOST 5632−72 high-alloy Steels and alloys corrosion-resistant, heatresistant and heat-proof. Brand

GOST 6552−80 orthophosphoric Acid. Specifications

GOST 6709−72 distilled Water. Specifications

GOST 6996−66 Welded joints. Methods for determining the mechanical properties

GOST 9485−74 Iron (III) sulfate 9-water. Specifications

GOST 9940−81 seamless hot deformed Tubes made of corrosion-resistant steel. Specifications

The Tubes GOST 9941−81 seamless cold — and warm from corrosion-resistant steel. Specifications

GOST 11125−84 nitric Acid of high purity. Specifications

GOST 12601−76 zinc Powder. Specifications

GOST 14019−2003 (ISO 7438:1985) Materials of metal. Method of bend test

GOST 19347−99 copper Sulfate. Specifications

GOST 20848−75 Potassium fluoride 2 water. Specifications

GOST 22180−76 oxalic Acid. Specifications

3 Preparation of samples

3.1 Cutting blanks for samples

Blanks for samples cut out:

— from a sheet thickness of not more than 10 mm, ribbons and wires from any place in the longitudinal direction;

— from a sheet of a thickness of > 10 mm from the surface layers in the longitudinal direction. Allowed for testing methods of AMU, AMWF, WU and cut the workpiece in the cross section of metal;

— long products: round, square, hexagonal, shaped rolled — out of the axial zone in the longitudinal direction; other types of hire — from anywhere;

— from a tube blank from an axial zone in the longitudinal or transverse direction;

— from pipes — from anywhere;

— forgings from overlaps or body forging;

— casting — body casting, from tides or separately cast samples;

— from the weld metal from the surface layers;

from the weld metal from the axial zone in the longitudinal or transverse direction.

Allowed the selection of blanks for samples from the intermediate pig iron billets under the condition subsequent austenization and provoking heat or austenization without provoking heat produced from her designs.

The dimensions of the workpiece under the samples should be sufficient for manufacturing the required number of samples.

3.2 prototyping of workpieces

The samples are made of the following types:

— from a sheet, strip, long products and structural shapes, billets, forgings, castings, weld metal, weld metal — flat (table 1).


Table 1 — Samples for testing

It is possible to produce cylindrical samples of wire, cylindrical workpieces with a diameter not exceeding 10 mm and for the test according to the method of DU — from all types of steel products;

— from the pipes, segments, rings (), ports () (table 1).

Allowed to produce flat samples of thick-walled large diameter pipes and pipes with a wall thickness not exceeding 1.5 mm by flattening the ring or of the nozzle with subsequent cutting of the parties or by scanning of a ring or tube, with subsequent rectification. In the pipe nominal external diameter not exceeding 5 mm is allowed to remove on the circumference of the wall of the pipe with one of its ends or in its middle part on the length of the pipe (table 1) when tested by all methods, except do;

— dual-rolled and bimetallic tubes are the same as sheet metal and pipes, respectively.

The samples are made of a plating layer after removal machining of the main and transition layers, and to test the method do further removed, and cladding layer to a depth of not less than 0.5 mm from the side adjacent to the main layer. Completeness of removal of the metal base layer is determined, maintaining sample (3−5 min) at room temperature in solution in 4.2.2.

The required thickness of the samples from workpieces by means of mechanical processing:

— from a sheet of one of the surfaces, in the presence of the treated surface of the metal is removed from the surface;

from long products and structural shapes, forgings, castings, billets — any surfaces;

— from heat — and cold-deformed tubes — the outer surface;

— hot pipes — one or both of the surfaces;

— from the weld metal from the reverse surface of the upper rollers;

from the weld metal of the root pass.

If you have data regarding the operation of the product removal of metal is carried out from the side, not in contact with the working environment.

3.3 Manufacture of samples of welded joints

Welded butt joints produce samples of the following types (table 1):

— welded joints of sheet, long products and structural shapes, castings and forgings — flat samples of type 1 or type 2;

— electrically welded tubes — segments (type 2) with a welded seam in the center, tubes, rings;

— of circular welded joints of pipes, tubes, rings, segments, type 1;

— of welded joints of two-layer steel after removal of the primary and intermediate layers of metal are the same as that of the welded joints of sheet or pipe.

Methods AMA, EMUF, WU, experience IN welded specimens of types 1 and 2, by do the samples of a type 2.

In welded specimens of types 1 and 2, the weld reinforcement is removed mechanically, it is allowed to process the entire sample surface to a depth of not more than 1 mm, and for thin samples to a depth of no more than 0.1 mm.

Bring welded splice or weld the specimen to the desired thickness by mechanical removal of metal from the surface that is not in contact with corrosive environment; in the absence of data from the side of the surface on which the weld metal or the weld metal undergoes the least heating during welding.

Bring to desired thickness weldments of pipes — 3.2.

Covered electrodes, welding wire and welding feed control, testing metals in accordance with the regulations of their production (acceptance tests).

The weld metal test on flat specimens (table 1), cut from the top layers of multilayer welding or weld metal, made according to GOST 6996контролируемыми welding materials (unused lower layers is allowed to perform other welding materials of similar chemical composition).

3.4 Dimensions of specimens for testing

Sizes of samples for testing methods of AMU, AMWF, WU, should provide the opportunity:

— bending at an angle of 90°±5° flat sample, segment, cylinder or tube with a diameter of 10 mm, wire;

— flattening the ring;

— inspection of the surface of the bending on the lot, the width of which allows to detect intergranular cracks taking into account the likely impact of the edges.

Samples for test method DM should meet the following requirements:

the largest sample size should be in the direction of rolling;

— the length of a flat sample of the segment () or the length of the cylinder and the height of the pipe () must not be less than double width or diameter;

— the area of the smaller side surfaces for flat specimen and of a segment or the area of the ends of the ring pipe, the cylinder should be no more than 15% of the total surface of the sample.

Recommended sizes of all these types of test specimen are given in Appendix B.

3.5 Number of samples

For test methods AMA, EMUF, WU, TO produce four samples: nesvorny, weld metal and weld metal, two of which are control. For sheet and pipes of austenitic steels — two samples (control samples are not required).

Welded samples made in the amount of 8 pieces, 4 of which are control.

Control samples not subjected to boiling in solutions used in the aforementioned methods. They are designed to determine the response of a metal to bend without affecting the environment.

To test the method do produce at least two samples for all grades of steels of all of these types of steel, and of welded joints, weld metal and weld metal.

3.6 Precipitating heat

Stable steels and alloys (containing titanium and/or niobium) and unstabilized steels and alloys with a carbon content of not more than 0,030% test on samples made of blanks, subjected to further provoke the heating modes shown in table 2.


Table 2

Allowed to subject provoking heated samples.

When disagreement between the consumer and the manufacturer, provoking heating of the workpiece is subjected.

Allowed on agreement between the consumer and the manufacturer to carry out heating at provoking other modes.

Unstabilized steel (not containing titanium or niobium) with a carbon content of more than 0.030% is tested on the samples without provoking heat, if there is no further guidance in the regulations on steel products.

In the case of steel after heat treatment, different from the delivery condition, tests carried out on samples made of blanks subjected to the same heat treatment and provoke additional heat.

Steel and alloys, subjected to repeated heat treatment, different from the provocative heat, considered as a new batch of metal.

Welded joint, deposited metal and weld metal precipitating heat not subjected to.

Steel used in the cold-worked or polonikeman condition, tested on samples without provoking heat.

Permitted instead of the test samples with precipitating heat testing steels and alloys for welded samples.

When control of welded joints of equipment in the manufacturing process is subjected to heat treatment, tests carried out on welded samples subjected to the same heat treatment.

3.7 Preparation of samples for testing

When tested by the methods of AMU, AMWF, WU, oxide formed on the surface of the samples after provoking heating before grinding or sanding must be removed by chemical or electrochemical etching or mechanical processing (planing) to a depth of not more than 1.0 mm, and for thin-walled parts, to a depth of no more than 0.1 mm.

When tested by the method do the scale before grinding and remove only by chemical etching or mechanically.

Chemical etching of samples from steels austenitic, austenitic-ferritic and austenitic-martensitic steels and iron-Nickel alloys the basis is carried out at a temperature of (20±5) °C in a solution:

nitric acid according to GOST 4461 density of 1.35 g/cm — (620±3) cm;

ammonium fluoride according to GOST 4518 — (76±0,1) g;

water according to GOST 6709 — (300±3) cm.

Chemical etching of a ferritic steel is carried out at a temperature of 50 °C — 60 °C in solution:

hydrochloric acid according to GOST 3118 density of 1.19 g/cm — (50±1) cm;

nitric acid according to GOST 4461 density of 1.35 g/cm — (5,0±0,1) cm;

water according to GOST 6709 — (50±1) cm.

Etching all of the above steels and alloys is carried out by an electrochemical method at a temperature of 40 °C — 50 °C and a current density (0,5−0,6)·10A/min the solution:

phosphoric acid according to GOST 6552 density 1.68 g/cm — (34±1) cm;

nitric acid according to GOST 4461 density of 1.35 g/cm — (11±1) cm;

water according to GOST 6709 — (955±3) cm.

The samples are etched until complete removal of scale. After etching the samples are thoroughly washed with water. The samples after etching should not be rastravleniya grain boundaries and/or pitting.

Allowed to carry out chemical etching in other solutions and with other modes, ensuring full scale removal.

The differences in the test results, the etching is carried out only in solutions listed above.

The surface roughness of samples before testing should be not more than 0.8 µm according to GOST 2789. To a specified surface roughness is adjusted, controlled bending of the samples tested according to the methods of AMU, AMWF, WU, and the whole surface of the samples, the test method do. The required surface roughness is achieved by polishing or grinding, while the overheating of the surface is not allowed.

Before testing, the samples mark shock mark or electrocorundum (for brittle materials) on one or both ends of the samples at a distance of 5−10 mm from the end and degreased with organic solvents: acetone, ethanol, etc.

4 the Test specimens in sulfuric acid solution and copper sulphate in the presence of metallic copper. Method of AMU

4.1 the essence of the method

Samples of the steel is kept in a boiling aqueous solution of copper sulphate and sulphuric acid in the presence of metallic copper (chips).

The method used to control the steel:

— ferritic class stamps 08KH17T, 15KH25T, 01−015Х18Т-VI, 01Х18М2Т-VI, 01Х25ТБЮ-VI;

— austenitic-ferritic class stamps 08KH22N6T, 08KH21N6M2T, 08KH18G8N2T, 02Х24Н6М2;

— austenitic grades 09KH16N15M3B, 03KH16N15M3B, 10X17H13M2T, 10H17N13M3T, 08KH17N13M2T, 08KH17N15M3T, 12H18N9, 12KH18N9T, 04KH18N10, 08H18N10, 08CR18NI10TI, 12CR18NI10TI 12H18N10E, 06KH18N11, 03Х18Н11, 03Х18Н12, 08KH18N12T, 12Х18Н12Т, 08KH18N12B, 03KH17N14M3.

Note — Steel austenitic-martensitic class stamps 20KH13N4G9, 09H15N8YU, 07KH16N6, 09KH17N7JU, 09KH17N7JU1, 08KH17N5M3 and austenitic steel grades 10Х14Г14Н3, 10KH14G14N4T, 10KH14AG15, 07KH21G7AN5, 12H17G9AN4 should be tested by method A (Annex E), the test duration is 15 h.

4.2 Reagents and solutions

4.2.1 For testing used the following reagents:

copper sulfate (CuSO·5HO), GOST 4165, h. h. or h. d. a., or copper sulphate according to GOST 19347, H. h;

sulfuric acid according to GOST 4204 density of 1.83 g/cm, h. d. a. or H. h;

distilled water according to GOST 6709;

copper in the form of chips according to GOST 859;

hydrochloric acid according to GOST 3118 density of 1.19 g/cm, h. d. a. or H. h;

nitric acid according to GOST 4461 density of 1.40 g/cm, h. d. a. or H. h

4.2.2 Solution for the test

K (1000±3) cmof water was added copper sulfate (50±0,1) g, in small portions sulfuric acid (250±3) cmand before loading samples into the flask with the solution was added copper shavings in a quantity to provide all-round contact with the samples and the lack of contact between samples.

4.3 testing

4.3.1 Tests carried out in a glass flask with reflux condenser.

You may load samples of the same steel grade in several rows provided that the rows of the samples that have to be copper shavings, will not come into contact with each other.

Download samples of different steels in the same flask is not allowed.

Then the flask filled with solution to test about 4−8 cm1 cmthe surface of the sample, wherein the level of the solution should be 1.0−1.5 cm above the sample surface or layer of the chip.

The reaction vessel with solution and the samples for testing heat and boil continuously without heating the refrigerator.

4.3.2 Duration of exposure in a boiling solution (8,00±0,25) h.

4.3.3 in case of involuntary interruption in the test, assuming no evaporation of the solution, samples can remain in solution up to 48 hours.

The test duration is defined as the total number of hours boiling.

4.3.4 After soaking in the solution the samples were washed with water and dried. When the deposition on the samples of the copper layer, with permanent running water, it is removed by washing the samples in 20% -30% strength solution of nitric acid at a temperature of 20 °C — 25 °C.

4.3.5 you can reuse the solution for testing under condition of preservation of its color, with the exception of tests conducted in differences.

4.3.6 Copper shavings are used repeatedly. In the case of the darkening of the chips during storage it has been washed to lighten 20% -30% nitric acid solution and then with water.

4.4 Detection of ICC

4.4.1 At the end of the test to detect ICC samples bend to an angle of 90°±5° according to GOST 14019.

The radius of curvature of the mandrel is selected depending on specimen thickness, grade of steel and type of steel, which is made from samples (table 3).


Table 3

In millimeters

If you don’t know the surface of the sheet from which the cut sample is working in the current equipment as well as for the detection of MKK caused by the presence of the carbonized layer on the surface of the sample, inspect both surfaces, curving the specimen Z-shaped. In case of impossibility of the Z-shaped bending of the sample hold dual bend number of samples: one half-bend on one of the surfaces, the second — on another.

The differences in the assessment of the presence of cracks on curved samples, i.e. in the case when one of the parallel samples is cracked, and the other is not or when one researcher sees the crack and the other does not, should conduct a metallographic examination of two samples tested. Upon detection of ICC in only one of the samples tested the test should be repeated on a double number of samples.

4.4.2 Specificity of ICC detection in samples

Samples from pipes:

— samples of seamless pipes in the presence of the control requirements of both surfaces of the sample curve Z-shape;

— the outer surface of the pipes, is cut of seamless tubes with outer diameter not more than 10 mm, control curve, and the inner surface — metallographic method or by removing part of the wall of the pipe (in accordance with table 1) and bending the remaining part of the nozzle;

rings and pipes, made of seamless pipes according to GOST 9940 and GOST 9941диаметром more than 8 mm, controlled by the flattening of the convergence of compressible planes to distances in mm, calculated by the formula

, (1)

where  — outside diameter of pipe, mm;

 — wall thickness of pipe, mm.

When flattening samples of an austenitic-ferritic or ferritic steels distance , mm, is determined by the formula

. (2)

The internal surface of rings and tubes is controlled by metallographic methods.

Allowed for austenitic steels, the control of the inner surface of rings carry flare to a diameter determined by the formula

, (3)

where the inside diameter of rings, mm.

Welded samples after the tests in the solution curve:

— type 1 (table 1): two samples — on the weld, two samples — the heat affected zone under the control of a welded joint as a whole.

Sample of two is on the weld during testing of weld metal, two samples — the heat affected zone under the control of the base metal steel or alloy;

— type 2 (table 1): two samples perpendicular to the weld seam under the control of the weld metal, heat affected zone and the welded joint as a whole; in the case of the need to control both sides of the samples bent Z-shaped.

In the case when it is difficult to identify the weld metal on welded samples, they should etch at room temperature for 1−3 min. a Solution for the identification of welds: (20±1) cmwater dissolve the copper sulphate (4±0,1) g, and add hydrochloric acid density of 1.19 g/cm, a volume of (20±1) cm.

The bending is carried out so that the weld is facing to the working environment, was on the outside of the sample. If the unknown side-seam facing to the working environment, on the outside of the sample should be a seam exposed to the maximum number of heatings.

Samples in the form of rings and tubes with longitudinal or circumferential seam taper in accordance with 4.4.2. Flattening is carried out in accordance with GOST 6996, ring seal should be placed on the axis of compressive load, and longitudinal — Diametric plane, perpendicular to the action of compressive loads.

4.5 Evaluation of test results the ICC

4.5.1 determination of the presence of the ICC with the bending of the sample

Inspection of curved samples is carried out with the help of a magnifying glass by increasing 7−12.

Absence of cracks on specimens bent after test, with the exception of the longitudinal cracks and cracks directly on the edges indicates the resistance of steel or alloy to the ICC.

Cracks on specimens bent after test, and no cracks on curved the same way the control samples indicates the propensity of the steel to the ICC.

If bending control samples are broken or they find a crack, or impossible bending of the sample due to its size (3.4), should be carried out metallographic investigations of samples after the test.

4.5.2 Metallographic method for the determination of the ICC

To identify ICC by metallographic methods of nesehnuti portion of the sample tested, cut the cone so that the plane of the cut was perpendicular to the sample surface. When cutting out the thin section of the welded sample, the cutting line should be held perpendicular to the weld seam and the cutting plane must include the weld metal, heat affected zone and base metal.

Recommended length of the cone for controlled surface needs to be at least 15−20 mm.

The cutting plane should be the plane of the thin section.

A method of manufacturing a cone to ensure that no dam edges and burrs.

The presence and depth of ICC mounted on stained sections at magnification of at least 200.

The etching is performed only to identify the weak grain boundaries.

Reagents and etching of thin sections to identify the ICC is given in Appendix G.

Thin section scan from the controlled surface of the sample.

Determine the maximum depth of fracture identified in six fields of view. In these fields of view must be included sites with the greatest depth of ICC.

A symptom of resistance to the ICC at the metallographic control consider the destruction of the grain boundaries to a maximum depth of 30 µm, in the samples of steel of a thickness of less than 1.5 mm to a depth of not more than 10 µm, unless otherwise indicated in the normative documents for steel and products from it.

5 the Test specimens in sulfuric acid solution and copper sulphate in the presence of metallic copper and of sodium fluoride or potassium fluoride. Method AMWF

5.1 the essence of the method

The steel specimens kept at a temperature of 20 °C and 30 °C in an aqueous solution of copper sulphate, sulphuric acid, fluoride of sodium or potassium in the presence of metallic copper. The method used for the control of steel grades for 4.1, except for the steel grades specified in the note 4.1.

The method is rapid compared with the method of the AMU.

In case of disagreement in the evaluation of metal quality tests carried out by AMA.

5.2 Reagents and solutions

5.2.1 For testing reagents used in 4.2.1 with the additions:

sodium fluoride according to GOST 4463, h. d. a. or H. h;

potassium fluoride according to GOST 20848, h. d. a. or H. h

5.2.2 Solution to test: (1000±3) cmwater dissolve (50±0,1) g of copper sulphate, (128,0±0,1) g of sodium fluoride, and then in small portions (to prevent heating of the solution) is added to (250±1) cmof sulfuric acid. Pets instead of sodium fluoride add (177,0±0,1) g of potassium fluoride.

Preparation and storage of the solution should be in a plastic container.

5.3 testing and evaluation of results

5.3.1 All preparatory work and testing carried out in the fume cupboard in a plastic container.

At the bottom of the reaction vessel is poured a layer of copper shavings to the surface where you load samples, fill the container with solution for testing in the amount of 8 cmby 1 cmsample surface 1.0−1.5 cm above the sample surface or layer of copper shavings and then close it with a lid.

5.3.2 duration of the test for steels without molybdenum (2,0±0,1) C containing molybdenum — (3,0±0,1) h.

5.3.3 you can reuse the solution and metallic copper at 4.3.5, 4.3.6.

5.3.4 Detection of the ICC and evaluation of results of tests carried out in accordance with 4.4 and 4.5.

Inspection of curved samples may be performed with a magnifying glass when you increase from 16 to 20.

6 the Test specimens in sulfuric acid solution in the presence of ferric sulfate. Method WU

6.1 the essence of the method

Samples of steel or alloy is kept in a boiling aqueous solution of ferric sulfate and sulfuric acid.

The method used to control the steel grade 03KH21N21M4GB and have iron-Nickel alloys grades: 06HN28MDT, 03KHN28MDT and ХН30МДБ.

6.2 Reagents and solutions

Sulfuric acid according to GOST 4204 density of 1.83 g/cm, h. d. a. or H. h

Iron (III) sulfate [Fe(SO)·9HO] GOST 9485, h. d. a. or H. h

Distilled water according to GOST 6709.

Sulfuric acid with a density of 1.83 g/cm, a solution of mass fraction (50,0±0,2)%, a density of 1,395 g/cm.

6.3 testing and evaluation of results

6.3.1 Testing is performed in a glass flask, equipped with reflux condenser.

At the bottom of the reaction vessel placed beads, glass tube or a porcelain boat, which is placed on top of the samples.

In a porcelain mortar grind iron sulfate to a powder at the rate of 40 g per 1000 cmof sulfuric acid solution with a density of 1,395 g/cm. The resulting powder was poured into the flask with sample and pour it with cold sulfuric acid solution.

The number of solution — at least 8 cmby 1 cmsample surface. The solution level should be 1.0−1.5 cm above the sample surface.

Joint download of the flask samples of steels and alloys of different brands is not allowed.

6.3.2 the Duration of exposure to boiling the solution should be (48,0±0,25) h.

6.3.3 Boiling is carried out continuously without heating the refrigerator.

When the forced break in the test samples can remain in solution not more than 8 h. the test Duration count as total hours at the boil.

6.3.4 Detection of the ICC and evaluation of results of tests carried out in accordance with 4.4. and 4.5.

7 Testing of samples in 65% nitric acid. Method do

7.1 the essence of the method

Samples incubated in a boiling aqueous solution of 65% nitric acid.

The method used to control the steel grades: 02Х18Н11, 03Х18Н11, 03Х18Н12, 03KH17N14M3, 03Х24Н6АМ3, 02Х25Н22АМ2.

7.2 Reagents and solutions

Nitric acid, OS.CH., 11125 according to GOST mass fraction (65,0±0,2)%, a density of 1,391 g/cm.

Distilled water according to GOST 6709.

7.3 testing

7.3.1 Prior to the test specimens and measure their length, width (or diameter) and a thickness of not less than 3 places, the measurement error should not exceed 0.1 mm.

The samples were then degreased with organic solvent, washed with water, dried and weighed on an analytical balance, the error of mass measurement should not exceed 0.1 mg.

The tests are carried out in a glass flask with reflux condenser.

At the bottom of the flask put glass beads, tube or porcelain boat which is placed the sample.

In one flask test the samples of the same steel grade, melt and heat treatment.

Samples poured nitric acid solution with a volume of 10 cmby 1 cmsample surface and 1.0−1.5 cm above the sample surface.

The differences in the assessment of the resistance to the ICC test again in the nitric acid solution volume of not less than 20 cm1 cmthe surface of the sample and 1.0−1.5 cm above the sample surface.

The test is carried out at a weak uniform boiling is not allowed the evaporation of the solution and separation of nitrogen oxides brown color that is determined using indicator paper placed at the outlet in the upper part of the back of the fridge. In the case of evaporation of the solution should be added 65% nitric acid to the original level.

7.3.2 the test Duration of 240 h, five cycles (of 48.00±0,25) h each with a change of solution after each cycle.

Permitted by agreement with the consumer for steel grades 02Х18Н11, 03Х18Н11 and 03Х18Н12 after the third cycle, a further test is not conducted if the corrosion rate in the second and third cycles does not exceed 0.30 mm/year.

7.3.3 After each test cycle (48 h) samples recovered from the flasks, washed with water, dried, and weighed to determine the corrosion rate in each of the cycles.

7.3.4 in case of involuntary interruption of the boiling, the samples recovered from the flasks, washed and dried. The solution is used to continue the cycle.

7.4 Evaluation of results of tests on the ICC

7.4.1 To assess the ICC determine the rate of corrosion , g/m·h , mm/year, according to the following formulas

; (4)

, (5)

where is the mass loss of the sample during the cycle, g;

 — the surface of the test specimen, cm;

 — test duration, h;

 — test steel density, g/cm.

7.4.2 Samples is considered not satisfactory if the corrosion rate of steels, welded joints, weld metal or weld metal after the second or subsequent cycles greater than 0.5 mm/year and 0.3 mm/year for steel grade 02Х25Н22АМ2, and also if the corrosion rate of welded joint is not more than 0.5 mm/year, but the heat-affected zone or heat affected zone or the weld metal was subjected to high travelmasti compared to the base metal; sample inspection should be carried out with increase of no less than 7 times.

7.4.3 In cases of doubt, when assessing the quality of a welded joint carrying out metallographic analysis.

Samples are considered not satisfactory if the average depth of rastravleniya the HAZ or heat affected zone, or weld metal by at least 30 µm more than the base metal.

8 test report

The test report should indicate:

— grade of steel, the steel material of the sample, the number of melt;

— marking of the sample;

— type of sample (base metal, welded sample, the weld metal, the weld metal);

— heat treatment regime;

test method;

the result of the test;

samples resistant or prone to the ICC at the test one of the methods: AMU, AMWF, WU, or by the method described in Annex E;

— the corrosion rate by the method of DU in each of the cycles and the evaluation of the resistance to the ICC.

Annex a (recommended). The test specimens in sulfuric acid solution and zinc powder. Method In

APPENDIX A
(recommended)

A. 1 the essence of the method

Samples incubated in a boiling aqueous solution of copper sulphate and sulphuric acid with addition of zinc powder.

The method is applied to control of alloy 06HN28MDT, and is less reliable than the method of WU.

A. 2 Reagents and solutions

Copper sulfate (CuSO·5HO), GOST 4165, h. d. a. or hç, or copper sulphate according to GOST 19347, H. h

Sulfuric acid according to GOST 4204 density of 1.83 g/cm, h. d. a. or H. h

Distilled water according to GOST 6709.

The zinc powder according to GOST 12601, class A.

Solution to test: (1000±3) cmwater dissolve (110,0±0,2) g of copper sulphate, then in small portions was added (55,0±0.3) cmof sulfuric acid.

A. 3 testing and evaluation of results

A. 3.1 the Tests are carried out in a glass flask with reflux condenser.

At the bottom of the flask placed beads, glass tube or a porcelain boat, which is placed on top of the samples. Then the flask filled with solution to test the amount of not less than 8 cmby 1 cmsample surface and 1.0−1.5 cm above the surface of the samples and add (5,0±0,1) g of zinc powder at every (1000±3) cmvolume of solution. When violent reaction of hydrogen runs out, the reaction vessel connected to a refrigerator.

A. 3.2 Duration of exposure in the solution (144.0 dt±0,25) h. the Solution was heated continuously to prevent heating of the refrigerator. If forced break, the samples can remain in solution up to 48 h.

The test duration is defined as the total number of hours boiling.

A. 3.3 Treatment of samples after testing is carried out in 4.3.4 of this standard.

A. 3.4 Detection of intergranular corrosion is carried out according to 4.4 and 4.5 of this standard.

APPENDIX B (recommended). Anodic etching of specimens in inhibited sulfuric acid. Method B

APPENDIX B
(recommended)

B. 1 the essence of the method

Steel subjected to anodic etching in an aqueous solution of inhibited sulphuric acid.

The method used to control products and parts fabricated by welding, hot stamping and bending of steel grades 12H18N9, 12KH18N9T, 04KH18N10, 08X18H10, 12X18H10T, 08KH18N10T, 03Х18Н11, 06KH18N11, 08KH18N12T, 12Х18Н12Т and two-layer steels of these grades for a preliminary evaluation of resistance of steel products of the ICC, subject to the control methods of AMU and AMUF.

The weld metal is not controlled by this method.

B. 2 Equipment

The scheme of installation for inspection of metal by method B is shown in figure B. 1.

Figure B. 1 — diagram of an apparatus for inspection of metal by method B

1 — lead container-cathode; 2 — rubber cuff; 3 — sample; 4 — a constant current source; 5 — ammeter with a scale division of not more than 0.1 A; 6 — rheostat or a resistance; 7 — the switch or the key

Figure B. 1 — diagram of an apparatus for inspection of metal by method B

B. 3 Reagents and solutions

Sulfuric acid according to GOST 4204 density of 1.83 g/cm, a solution with a mass fraction (60,0±0,2)%.

Methenamine (CH)Naccording to GOST 1381 or other inhibitor for sulfuric acid solution with a mass fraction of (0,50±0,05)%.

Distilled water according to GOST 6709.

The solution is to test contains (20±1) cmof a solution of hexamine and (1000±3) cmof sulfuric acid solution.

B. 4 testing and evaluation of results

B. 4.1 the Surface areas to be controlled, polished to a roughness of µm. After grinding tests degreased with organic solvents.

B. 4.2 the Test is carried out by anodic etching of the controlled areas of the workpiece surface, which are included in a circuit of constant current at a current density of (0,65±0,01)·10A/m. The cathode is a lead vessel (figure B. 1) which is fixed on the controlled surface of the test article or material with rubber cuffs. In a vessel pour from 3 to 5 cmof the solution.

Allowed to produce vessels of another metal, corrosion-resistant solution for testing (B. 3).

Test temperature is (20±10) °C. In case of impossibility of application of the design vessel, is shown in figure B. 2, is allowed to change its structure in relation to controlled goods.

Figure B. 2 — Recommended vessels for testing

and is the vessel for testing of horizontal surfaces; b — vessel for testing vertical surfaces; 1 — rubber cuff

Figure B. 2 — Recommended vessels for testing

B. 4.3 When testing weldments in control of the heat affected zone around the weld. In this case the anode spot is applied so that the edge of the spot seized not more than 1 mm width of weld metal.

In areas subject to control, the strengthening of the seam is removed.

The test is performed on both sides of the seam in a checkerboard pattern. When the weld length up to 2 m heat-affected zone is controlled not less than four points.

B. 4.4 Products having cross and T-shaped joints, feel for the heat affected zone in all cross seams (figure B. 3).

Figure B. 3 — Test products, with cross and T-shaped seams in the heat affected zone in all cross seams

1 — weld; 2 — places of anodic etching

Figure B. 3

B. 4.5 Duration of test after switching on the current is (5,0±0,20) min. At high travelmasti experience and repeat the test duration may be reduced to 1−2 min.

When the test is complete the current is turned off, the vessel and the control surface is washed with water, wiped with filter paper and wipe with ethanol.

B. 5 Evaluation of results

The resistance of steel to ICC estimate during the inspection of the anode spot on the surface of the sample or the product if you increase 20.

The absence of grid indicates the resistance of the metal to the ICC.

In the presence of the grid (figure B. 4) or rastravleniya precipitated secondary phases (figure B. 5) requires testing of samples by AMU or AMWF, since in the conditions of etching (positive potential) may rastravleniya precipitated carbides.

Figure B. 4 — Test samples by AMU or AMUF in the presence of a mesh

Figure B. 4

Figure B. 5 — Test samples by AMU or AMUF when rastravleniya precipitated secondary phases

Figure B. 5

Note — figures B. 4 and B. 5 samples of this if you increase 50.

ANNEX b (recommended). The dimensions of the samples

THE APP
(recommended)

Table B. 1

ANNEX G (recommended). Reagents and etching of thin sections to detect intergranular corrosion

APPENDIX D
(recommended)

Table G. 1

APPENDIX e (mandatory). Determination of resistance to intergranular corrosion of stainless steels. Part 1. Austenitic and ferritic-austenitic (two-phase) stainless steel.

APPENDIX E
(required)

Determination of resistance to intergranular corrosion of stainless steels. Part 1. Austenitic and ferritic-austenitic (two-phase) stainless steel. Corrosion tests in nitric acid by determining the mass loss (testing for Hugh) (ISO 3651−1:1998)

D. 1 Scope

The method used for the determination of the resistance to intergranular corrosion (ICC) by testing the nitric acid by measuring the mass loss of rolled, forgings, tubing and casting, austenitic and ferritic-austenitic (two-phase) steels intended for use in strongly oxidizing media (e.g. nitric acid). Testing by the method of Hugh should not be used for steels, molybdenum-containing if steel is not intended for use as a material for handling nitric acid.

The test results of the ICC according to the method of Hugh are indicative only for the determination of the resistance of steel to ICC in these environments and cannot be used to determine the resistance of steel to other types of corrosion damage (General corrosion, pitting, corrosion cracking, etc.).

D. 2 Purpose of tests

2.1 on the ICC Test carried out to detect the corrosive effects of the environment on the grain boundaries due to one or several reasons:

— precipitation at the grain boundaries of chromium carbides;

— the precipitation of intermetallic compounds such as a -phase in the steels containing molybdenum;

— segregation at the grain boundaries of polluting elements.

These processes can occur when exposed to austenitic and ferritic-austenitic stainless steels at temperatures of 500 °C — 1000 °C, by which steel may be subjected to during hot working (forging, rolling) and during welding due to technological disruptions.

Evaluation of test results (e.g., maximum allowable corrosion rate) is carried out by agreement between the consumer and the manufacturer.

D. 3 application of the method

3.1 by Hugh in control of austenitic steel with increased corrosion resistance to the ICC is designed to strongly oxidizing environments. Control samples of steel is carried out after precipitating heat treatment.

The specimens of thin sheets are not subjected to provoking heat, because in the process of equipment manufacturing thin sheets are rapidly cooled.

D. 4 Provoking heat

D. 4.1 Provoking heated before the test, the ICC subjected to stable and low carbon (C=0,03%) steel. To this end, the sample is kept for 30 minutes at a temperature of (70±10) °C with subsequent rapid cooling in water.

D. 4.2 Duration of temperature increase should not exceed 10 min.

Provoking other modes of heating are possible only by agreement with the customer.

Welded samples subjected to provoking heat.

D. 5 Corrosion tests

5.1 the essence of the method

The sample, prepared under D. 4 and D. 5.2, weighed, then immersed in boiling nitric acid solution for 5 cycles of 48 h each. The criterion for evaluation of test results is the loss of mass determined by weighing after each test cycle.

5.2 Samples for testing

5.2.1 the Sample for the study taken from the processed pressure metal should be larger in the direction of rolling. From the processed pressure rolling and casting cut sample should be as close as possible to the surface of rolled products. The size of the sample is determined depending on the weighing device and the amount of solution used.

Sample length should be no less than two times greater than its width, and the total area of the surface of the sample perpendicular to the rolling direction or grain of the sample should be less than 15% of the total surface area of the sample. In the comparative tests, the ratio of the total area of the sample surface to the total area of the surface parts of the sample should be constant.

5.2.2 Processing

Depending on the purpose of the test (D. 3) the samples subjected or not subjected to heat provoking, must meet the requirements of D. 5.2.2.1 and 5.2.2.2.

5.2.2.1 machining

Samples for testing should be machined over the entire surface by cleaning the surface of the N 120 abrasive paper or cloth, not containing iron.

5.2.2.2 Chemical treatment

The scale is removed without preliminary machining and immersing the samples for 1 h in a solution of 50 volumes of hydrochloric acid (=1,19 g/cm), 5 volumes of nitric acid (=1,40 g/cm) and 50 volumes of water at a temperature of 50 °C — 60 °C or in a solution of 50 volumes of hydrochloric acid and 50 volumes of water at ambient temperature.

This treatment you need to be sure that it does not cause the ICC.

5.2.2.3 Degreasing

Prior to immersion in corrosion solution, the samples shall be cleaned with solvent containing no chlorine ions.

D. 6 Equipment

6.1 Erlenmeyer Flask with a capacity of 1 DM, close or submersible penlight fridge or fridge chetyrehochkovym with cone, the use of which should be verified by means of an indicator that couples acid out of the apparatus during the test (figure D. 1).

Figure D. 1 — Apertura for testing

1 — glass tube-refrigerator; 2 — device for preventing the delay of the condensate; 3 — the Erlenmeyer flask

Figure D. 1

Note — it Should be noted that the corrosion rate obtained using the ball of the refrigerator slightly higher than when using the refrigerator, pencil, due to the large loss of steam.

6.2 specimen Holders are typically made of glass.

When testing multiple samples in the same flask, the specimen holder must ensure the requirement of D. 8.

6.3, the Heating device must provide a continuous boiling of the solution.

D. 7 the Solution for testing

Solution for testing needs to be (65±0,2)%(by weight) aqueous solution of nitric acid (=1,40 g/cm).

It should be used with the h product. d. a., containing total solids of 0.05 g/1000 g, and each of the possible additives in the following amount:

lead (Pb)0.005 g/1000 g;

iron (Fe)0,014 g/1000 g;

manganese (Mn) (negative reaction);

arsenic (As)0.001 g/1000 g;

chlorine ion (Cl)0.003 g/1000 g;

the sulfate ion (SO)0.05 g/1000 g;

phosphate ion (PO)0.01 g/1000 g;

of the fluoride ion (F)0.05 g/1000 g

D. 8 performance test

The volume used acid for corrosion testing (D. 7) shall be not less than 20 cm/cm.

Usually only one sample is placed in a flask.

However, it is allowed to load multiple samples in one flask under the condition that all samples of the same grade of steel and are insulated from each other by not less than 0.5 cm Increased corrosion of one of the specimens can increase the corrosion rate of the other samples tested along with it.

D. 9 processing of the results

The effect of nitric acid is determined by measuring the weight loss of each sample after each cycle and for all cycles of testing.

The corrosion rate , g/m·h or mm/year, determined by the formula:

; (D. 1)

(Doctor 2)

where  — the average mass loss after each cycle or all cycles of testing, g;

 — the original surface of the test specimen, cm;

 — the density of the test sample (8 g/cmfor hromonikelemolibdenovyh steels and 7.9 g/cm — for stainless steel), g/cm;

 — the actual boiling time.

D. 10 test report

The test report shall contain:

room;

— steel grades;

— mode of heat treatment;

— used types of refrigerators;

— the average corrosion rate;

— situations that could influence the results.

Usually leads average test results.

The results of the tests, depending on the requirements of the customer, represent either the average corrosion rate or corrosion rate in each of the cycles.

ANNEX E (mandatory). Determination of resistance to intergranular corrosion of stainless steels. Part 2. Ferritic, austenitic and ferritic-austenitic (two-phase) stainless steel.

ANNEX E
(required)

Determination of resistance to intergranular corrosion of stainless steels. Part 2. Ferritic, austenitic and ferritic-austenitic (two-phase) stainless steel. Corrosion test in media containing sulfuric acid (ISO 3651−2:1998)

E. 1 Scope

This standard specifies methods for the determination of resistance to intergranular corrosion (ICC) ferritic, austenitic and ferritic-austenitic (two-phase) stainless steel, manufactured in the form of a casting, rolled products, forgings and pipes for a weak oxidizing environments (such as sulfuric and phosphoric acids).

Resistance to the ICC checking either low carbon steel with a carbon content of not more than 0.03%, or stable steel. Metal control after provocative heating or after welding. A thin sheet of negligible thickness at a sufficiently fast cooling rate control in the delivery state, without provoking pre-heated.

E. 2 Purpose of tests

Tests for intergranular corrosion is carried out in order to detect the predominant influence of environment on grain boundaries due to the Union of grain boundaries in chromium as a result of loss of one or more chromium-rich phases, chromium carbides, phase or other intermetallic phases.

These processes can occur when exposed to a ferritic, austenitic and ferritic-austenitic (two-phase) steels at temperatures of 500 °C — 1000 °C, by which steel may be exposed during hot working (forging, rolling, etc.), and also when welding.

Depending on the chemical composition controlled metal (addition to Appendix E) apply one of the methods of control of the ICC with the use of solutions of sulfuric acid:

method A — 16% sulfuric acid and copper sulfate (method Monypenny-Strauss);

In a method of 35% sulfuric acid and copper sulfate;

method — 49% sulfuric acid and ferrous sulfate (IV).

E. 3 Provoking heat

E. 3.1 To check the resistance to the ICC is necessary to conduct provoking heat stabilized steels and steels with low carbon content. To do this, samples intended for testing, incubated for 30 min at the heating temperature (700±10) °C with subsequent cooling in water (mode ) or for 10 min at a temperature of (650±10) °C with subsequent cooling in water (mode ).

The above triggers the heating operation is applied to two-phase austenitic and ferritic-austenitic steels.

Duration of temperature rise to the set value should not exceed 10 min.

By agreement with the customer other conditions provoking heat.

Type provoking heating point in the normative documents for the products. If you do not specify the mode of precipitating the heating use the mode .

E. 3.2 Welding of samples for testing can be used as an alternative to provoking heated (by agreement between the interested parties).

In this case, a sample after welding is not subjected to provoking heat. Welding as an alternative of provoking to heating are applicable to all steels listed in the Appendix to Annex E.

E. 4 Corrosion tests

E. 4.1 the essence of the method

Samples for testing are prepared according to E. 4.2 and E. 4.2.2, is immersed in one of the solutions of sulphuric acid methods, (E. 2) as specified in E. 6.1.2. The samples were then subjected to bending. After bending, the convex surface of the sample are examined to detect cracks. Cracks attests to the ICC.

Pipe with a diameter of 6.0 cm (diameter of the pipes should be smaller than the hole of the vessel with the solution for test) instead of test curve flatten.

E. 4.2 Sample for testing

E. 4.2.1 the test Specimen should have a surface area of from 15 to 35 cm. For a sheet thickness of more than 0.6 cm treated with one of the rolling surfaces sostragivajut up to a maximum thickness no more than 0.6 cm, the second treated surface should be preserved. Part of samples for testing should be retained as a control and subjected to test in the event of a dispute. Samples shall have the following dimensions, cm:

— thickness — 0,2−0,6;

width of not less than 1.0;

— length — not less than 5.0.

Samples of specified dimensions is subjected to bending.

E. 4.2.2 Welded samples are made as follows: a flat plate manufactured two samples with a length of 10.0 cm, a width of 5.0 cm and weld them together. Of the plates cut out samples, as shown in figure E. 1. For pipes with circular cross-seam samples are cut in accordance with figure E. 2. When four samples are welded between the cross-seam, the first seam is placed in the longitudinal direction to the sample, as shown in figure E. 3. When the material thickness is more than 0.6 cm test specimen sostragivajut to 0.6 cm on one side. Nestroganye the sample surface must be on the convex side when bending. For welded pipes with outer diameter more than 6.0 cm test samples made length of 5.0 cm and a width of 2.2 cm, as shown in figure E. 4.

Figure E. 1 — Specimen, butt-welded

Figure E. 1 — Specimen, butt-welded

Figure E. 2 — test Specimen from the pipe, butt welded

Figure E. 2 — test Specimen from the pipe, butt welded

Figure E. 3 — test Specimen from plate or strip with cross stitch

Figure E. 3 — test Specimen from plate or strip with cross stitch

Figure E. 4 — Specimen with longitudinal weld of welded pipe

Figure E. 4 — Specimen with longitudinal weld of welded pipe

E. 4.3 Preparation of samples for testing

The samples, subjected to provoking heat, and without it, prepare in accordance with E. 4.3.1 and E. 4.3.2. Method of surface preparation should be specified in the test Protocol.

E. 4.3.1 Mechanical preparation

The specimen should to descale machined in the longitudinal direction on all sides, the edge region is treated with abrasive N 120. During machining to avoid overheating of samples.

E. 4.3.2 Chemical preparation

The sample whose surface is free from oxides and has not previously undergone treatment for descaling or scale completely immersed for no more than 1 h in a solution of 50 volumes of hydrochloric acid (=1,19 g/cm), 5 volumes of nitric acid (=1,40 g/cm), 50 volumes of water at a solution temperature of from 50 °C to 60 °C or in a solution of 50 volumes of hydrochloric acid and 50 volumes of water at ambient temperature.

In the case of chemical surface preparation of the sample to be confident that the ICC will not appear during the processing of the sample. This process is carried out after microablation for each grade of steel.

E. 4.3.3 Degreasing

Samples must be degreased and any suitable chlorine-free solvent cleaned and dried before immersion in a corrosive environment.

E. 5 Instrument

E. 5.1 Erlenmeyer Flask with a capacity of 1000 cmor another similar flask with a refrigerator, having at least four ball.

E. 5.2 the sample Holder is usually made of glass (for a method).

E. 5.3 the Heating device, providing boiling of the solution.

E. 6 test Methods

E. 6.1 Method a: test at 16% sulfuric acid with copper sulfate (method of Monypenny-Strauss)

E. 6.1.1 Solution for corrosion tests

To prepare the solution, use the reagents h.d. a.

Dissolve 100 g of pathiraja copper sulfate (II) (CuSO·5HO) in 700 cmof distilled water. Then 184 g (100 cm) sulfuric acid (=1.84 g/cm) is added to distilled water to a total volume equal to 1000 cm.

E. 6.1.2 In each bulb can be tested more than one sample, while ensuring the volume of solution not less than 8 cm/cmon the entire surface of the sample. The test sample should be completely surrounded by the conductive pieces of copper located on the bottom of the flask. The amount of copper should be not less than 50 g in 1 DMsolution. The samples must be in contact with the copper, but not with each other. The test specimen is first immersed in a cold solution for testing, then the solution is heated and the beginning of the boiling point of the solution is considered the beginning of the test. The solution should boil for (20±5) h. In case of dispute, the test time should be 20 h. the Pieces of copper, after the test is washed with hot water, can be used for the following tests. The corrosion solution can be used only once.

E. 6. Method 2: testing in 35% sulfuric acid with copper sulfate

E. 6.2.1 the Solution for tests prepared from reagents of CH. d. a.: 250 cmof sulphuric acid (=1.84 g/cm) was carefully added to 750 cmof distilled water. Dissolve 110 g patentnogo copper sulfate (II) in a warm solution.

E. 6.2.2 In one flask it is possible to test more than one sample, provided that the number of solution not less than 10 cm/cmfor a total surface of test specimens. The specimen should be surrounded on all sides by copper sawdust or shavings. The quantity of copper filings should not be less than 50 g/1000 cmof solution. The samples should be in contact with copper filings, but should not touch each other. The samples are first placed in a cold solution for testing, then the solution is heated and the beginning of the boiling point of the solution is considered the beginning of the test. The solution should boil for (20±5) h. In case of dispute, the test time should be 20 hours

E. 6.3 Method: the test of 49% sulfuric acid with iron sulfate (III)

E. 6.3.1 Solution for corrosion tests

The solution for tests prepared from reagents of CH. d. a.: 280 cmof sulphuric acid (=1.84 g/cm) was carefully added to 720 cmof distilled water. Dissolve 25 g of ferric sulfate (III) [Fe(SO)·9HO], containing approximately 75% iron sulfate in a warm solution.

Note — the corrosion Rate is increased if full use of the sulphate of iron.

E. 6.3.2 tests

In one flask, you can test more than one sample, provided that the number of solution falling on the entire surface of the test specimen — not less than 10 cm/cm. Samples placed in a cold solution, then the solution was heated to boiling and the beginning of the boil is considered the beginning of the test. The solution should be boiled (20±5) h. In case of dispute, the test duration should be 20 h. the Solution can be used once.

E. 6.3.3 bend Test

Cylindrical and flat samples after corrosion tests are subjected to the bending test (bending angle 90°) on the mandrel, the radius of which is equal to the thickness of the sample. Samples of castings is tested on a mandrel, whose radius is twice the thickness of the test specimen.

Pipe external diameter up to 60 mm are investigating after flattening. The distance between the plates , mm, after the load is calculated by the formula

, (E. 1)

where  — outside diameter of pipe, mm;

 — plate thickness, mm.

Welded pipes with a longitudinal seam having a maximum bending stress across the joint (figure E. 2).

E. 7 Assessment

The convex surface of a curved sample, the last test, inspect with the naked eye or with a small increase (less than 10).

In the case of inconclusive test results on bending (bending angle 90°) is subjected bending the second sample prepared by the above method, but not subjected to corrosion test.

Comparative analysis of the two samples allows to determine whether the cracks are a result of the ICC.

Note — When there is doubt in the evaluation of the test results of the samples after testing should be subjected to metallographic investigation, it is necessary to cut the transverse length of the sample piece and examine it on presence of cracks and their depth.

E. 8 test report

The test report shall contain:

— method used with reference to this standard;

— steel grades;

— the method of sample preparation (mechanical or chemical);

— assortment of samples for testing;

— apply a heat treatment;

— test results;

accidents, which may affect the test results.

SUPPLEMENT TO ANNEX E. List of steels that are subject to control by these methods

SUPPLEMENT TO ANNEX E

Application of the method depends on the properties and aggressiveness of the environment. The following examples are given for information. Only one method can be used for each grade of steel.

Method A:

— austenitic steel containing 16% Cr and 3% Mo;

— ferritic steel containing 16%-20% Cr and 0% -1% Mo;

— dual-phase steel containing 16% Cr and 3% Mo.

Method:

— austenitic steel containing more than 20% Cr and 2% -4% of Mo;

— dual-phase steel containing more than 20% Cr and 2% Mo.

Method:

— austenitic steel containing more than 17% Cr and more than 3% Mo;

— austenitic steel containing more than 25% Cr and 2% Mo;

— ferritic steels containing more than 25% Cr and 2% Mo;

— dual-phase steel containing more than 20% Cr and 3% Mo and more.