GOST 6032-2003 (ISO 3651-1:1998

ISO 3651-2:1998)

MULTI-STANDARD

Steel and Alloys

CORROSION-RESISTANT

Test method for resistance

To intergranular corrosion

INTERSTATE COUNCIL

On Standardization, Metrology and Certification

MINSK

Foreword

1 Developed by the Russian Federation, the Inter-State Committee for Standardization Technical MTC 145 "Methods of control of steel", "Scientific Research and Design Institute of Chemical Engineering (JSC" NIICHIMMASH ")

INTRODUCED by the Russian State Standard

2 Adopted by the Interstate Council for Standardization, Metrology and Certification (Minutes № 24 dated December 5, 2003)

Voted for the adoption of:

Name The name of the state of the national standards body

Azerbaijan Azstandart

Armenia Armstandart

Belarus State Standard of the Republic of Belarus

State Standard of the Republic of Kazakhstan Kazakhstan

Kyrgyzstan Kyrgyzstandard

Moldova Moldovastandart

The Russian Federation Russian State Standard

Tajikistan Tajikstandart

Turkmenistan MDCSU "Turkmenstandartlary"

Uzbekistan Agency "Uzstandard"

Ukraine Ukraine Derzhspozhivstandard

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 test in nitric acid by determining the weight loss (on Hugh test) "- in fact part of the method and the sample preparation; ISO 3651-2:1998" Determination of the resistance to intergranular corrosion of stainless steels. Part 2. Ferritic, austenitic and ferritic-austenitic (two-phase) stainless steel. Corrosion tests in media containing sulfuric acid "- a component of the test solutions, sample preparation and evaluation of resistance to intergranular corrosion

4 Resolution of the State Committee of the Russian Federation for Standardization and Metrology of March 9, 2004 № 149-item interstate standard GOST 6032-2003 (ISO 3651-1:1998, ISO 3651-2:1998) was put into effect immediately as the national standard of the Russian Federation from January 1, 2005

5 Instead of GOST 6032-89

GOST 6032-2003 (ISO 3651-1:1998

ISO 3651-2:1998)

MULTI-STANDARD

Steels and alloys corrosion-resistant

Test method for resistance to intergranular corrosion

Corrosion-resistant steels and alloys.

Test methods of intercrystalline corrosion resistance

Introduction date 2005-01-01

1 Scope

This standard specifies test methods for resistance to intergranular corrosion (hereinafter - ICC) of metal from corrosion-resistant steels and alloys, including double-layer, austenitic, ferritic, austenitic-ferritic, austenitic-martensitic grades according to GOST 5632, and their welded joints and weld metal.

IWC is caused by combining the grain boundaries in chromium loss due to chromium-rich grain boundary phases: carbides of chromium, σ-phase intermetallic inclusions in steels or alloys aging at 500 ° C - 1000 ° C.

Depending on the chemical composition of the steel and alloy and their destination choose one of the following methods of test for resistance to intergranular corrosion of metal: AMU, AMUF, VC, RC, B, B.

Selection of the test method is determined by the chemical composition of the metal and the instructions in the relevant standard produced equipment.

Methods of test for resistance to intergranular corrosion B and C as defined in Annexes A and B are recommended.

Application of the methods provided in the annexes D and E, is allowed in addition to the basic test methods for resistance to intergranular corrosion of this standard.

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

The legend of methods of AMU, AMUF, VU, control, B, C letters refer to:

A, B, C, D - letter name of methods;

M - in the presence of test solution of the metal copper;

F - in the presence of test solution of fluoride ion;

U - accelerated testing.

2 References

This standard references to the following standards:

GOST 859-2001 Copper. Stamps

GOST 1381-73 Urotropin technical. Specifications

GOST 2789-73 roughness of the surface. 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 3776-73 Chromium (VI) oxide (chromic anhydride). 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 and alloys corrosion-resistant, heat-resistant and heat-resistant. Stamps

GOST 6552-80 Phosphoric Acid. Specifications

GOST 6709-72 distilled water. Specifications

GOST 6996-66. Welds. Methods for determining the mechanical properties

GOST 9485-74 Iron (III) sulphate, 9 water. Specifications

GOST 9940-81 Seamless hot corrosion-resistant steel. Specifications

GOST 9941-81 Seamless cold and deformed corrosion-resistant steel. Specifications

GOST 11125-84 Nitric acid purity. Specifications

GOST 12601-76 Zinc powder. Specifications

GOST 14019-2003 (ISO 7438:1985) Metallic materials. Test method for flexural

GOST 19347-99 Copper sulfate. Specifications

GOST 20848-75 Potassium fluoride 2-water. Specifications

GOST 22180-76 Oxalic Acid. Specifications

3 Sample Preparation

3.1 Cutting blanks for samples

Blanks for samples cut out:

- Sheet thickness of not more than 10 mm, and a wire belt - from any positions in the longitudinal direction;

- Sheet thickness of over 10 mm - from the surface layers in the longitudinal direction. Allowed to test methods of AMU, AMUF, VU and cut to the workpiece on the cross section of the metal;

- Of the varietal: round, square, hexagonal, flat, structural shapes - from the axial zone in the longitudinal direction, from other types of flats - from any location;

- From a tube blank - of axial zones in the longitudinal or transverse direction;

- A pipe - from any location;

- From forgings - the body of an overlap or forgings;

- From castings - casting of the body, of the tides or separately cast samples;

- Of weld metal - from the surface layers;

- Of weld metal - axial zone of the longitudinal or transverse direction.

Allowed the selection of blanks for the conduct of the intermediate samples of pig blanks provided subsequent austenitization and provoking heating or austenitizing without provoking heating manufactured from her samples.

Dimensions of blanks for the samples must be sufficient to make the required number of samples.

3.2 Specimen Preparation of blanks

The samples were prepared following species:

- Of sheet, strip, rods and structural shapes, billets, forgings, castings, weld metal, weld metal - flat (Table 1).

Allowed to produce cylindrical samples of wire diameter cylindrical workpieces up to 10 mm, and the test method control - of all kinds of metal products;

- A pipe - the segments of the ring (D ≥ h), tubes (D <h) (Table 1).

Table 1 - Test Samples

View a sample non-welded sample weld sample

Type 1 Type 2

Flat

Connection

Ring

Segment

Cylinder

Legend: Ø D - diameter of the sample; b - width of the sample, c - the thickness of the sample; h - length of the tubular sample, sample height or pipe, and - the length of the sample.

Note - the weld metal and the weld samples manufactured similar to flat non-welded pattern.

Family manufacturing flat samples of thick-walled pipes of large diameter and a pipe wall thickness of 1.5 mm by a collapsing ring or nozzle with subsequent cutting of the parties or by scanning ring or nozzle with subsequent straightening. In nozzles nominal outer diameter of 5 mm is allowed to remove 1/2 of the circumference wall of the pipe at one of its ends or in the middle of 1/2 the length of pipe (Table 1) for all test methods, other than control;

- From double rolled and bimetallic tubes - such as from sheet metal and pipes respectively.

Samples made of the cladding layer after removing machining main and transition layers, and control method for testing and further cladding layer is removed to a depth of at least 0.5 mm from the side adjacent to the core layer. Completeness of disposal of metal base layer is determined soaking the sample (3 - 5 min) at room temperature in solution 4.2.2.

The desired thickness of the samples is achieved by machining workpieces:

- Sheet of - one of the surfaces in the presence of a surface-treated metal is removed from the surface;

- Of shapes, sections, forgings, castings, billets - any of the surfaces;

- Of heat and cold pipes - the outer surface;

- From hot-deformed pipes - one or both surfaces;

- Of weld metal - from the side, the back surface of the upper rollers;

- Of weld metal - the root of the weld.

If data are available regarding the conditions of the product metal removal is carried out from the side, not in contact with the medium.

3.3 Specimen Preparation of welded joints

Of welded joints are made samples of the following species (Table 1):

- Of welds sheet, rods and structural shapes, castings and forgings - flat samples of type 1 or 2;

- Of welded tubes - segments (type 2) with a seam in the middle, tubes, rings;

- Of the annular welded joints - pipes, rings, segments of type 1;

- Welds of steels after removal bilayer core and transition metal layers - such as the sheet of the welded joints or pipes.

MCA methods, AMUF, VU, welded to the test samples of types 1 and 2, the method of control - samples of type 2.

In the welded specimens of type 1 and 2 increased weld removed mechanically, with the allowed processing of all sample surfaces to a depth of not more than 1 mm, and for thin specimens - to a depth of not more than 0.1 mm.

Adjust welded butt joint or welded sample to a desired thickness by mechanical removal of the metal surface which is not in contact with a corrosive environment, in the absence of data - with the side surface on which the weld metal and the weld metal is subjected to the least heat welding.

Bringing up a desired thickness of the welded samples pipe - to 3.2.

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

The weld metal test on flat specimens (Table 1) cut out of the upper layers of the multilayer deposition or weld metal made to GOST 6996 controlled welding consumables (unused lower cladding layers allowed to perform other welding consumables similar chemical composition).

3.4 Dimensions of test specimens

Sample sizes for testing methods of AMU, AMUF, VU, B must provide the ability to:

- Bending angle of 90 ° ± 5 ° flat sample segment cylinder or tube diameter of 10 mm, a wire;

- Squeeze the ring;

- Inspection of surface curvature on the site, the width of which reveals intergranular cracks considering the possible impact of edges.

Samples for testing control method must meet the following requirements:

- The maximum size of the sample must be in the direction of rolling;

- The length of a flat sample, a segment (a) or the length of the cylinder and nozzle height (h) should be not less than double the width or diameter;

- The area of the smaller side for the flat surfaces of the sample and the ends of the segment or area for the ring, pipe, cylinder must not exceed 15% of the total surface of the sample.

Recommended sizes of all these types of test specimens are given in Annex B.

3.5 Number of samples

To test the methods of AMU, AMUF, VU, manufactured in four samples: non-welded, weld metal and weld metal, two of which are control. For the sheet and tube austenitic steels - two samples (control samples are not required).

Welded samples manufactured in 8 pieces., 4 of which are control.

Control samples not subjected to boiling in solutions used in the above methods. They are designed to determine the reaction of the metal for bending without affecting the environment.

To test controller manufactured by at least two samples for all grades of steels of these types of metal, as well as welds weld metal and the weld metal.

3.6 provokes the heat

Stabilized steel alloys (containing titanium and / or niobium) and unstabilized steel and alloys with carbon content not exceeding 0.030% tested for specimens made from preforms subjected to additional heating for provoking modes given in Table 2.

Table 2

Mark steel or alloy heating mode * Wednesday cooling

Temperature, ° C Duration of exposure, min

08H17T, 15H25T, 01-015H18T-VI, 01H18M2T-VI, 01H25TBYU-VI in 1100 ± 20, 30 ± 5 Water

08H22N6T, 08H21N6M2T, 08H18G8N2T 550 ± 10 60 ± 5 Air

03HN28MDT, HN30MDB, 03H21N21M4GB 700 ± 10 60 ± 5 Air

06HN28MDT 700 ± 10 20 ± 5 Air

All remaining unstabilized and stabilized carbon steel with not more than 0.030% ** 650 ± 10 60 ± 5 Air

* Previously degreased preform is charged into a furnace heated to a temperature provoking heating.

Steel grades ** 03H17N14M3, 03H24N6AM3, 02H25N22AM2 have control method on samples without provoking heating in the absence of other requirements of the consumer.

Be subjected provoking heated samples.

When a disagreement between the consumer and the manufacturer is subjected to heat-provoking piece.

Allowed by agreement between the manufacturer and provocative conduct heat in other modes.

Unstabilized steel (containing no titanium or niobium) with a carbon content over 0.030% tested on samples without provoking heating, unless otherwise specified in the regulations for steel products.

In the case of steel after heat treatment, in the condition of delivery test carried out on samples produced from preforms subjected to the same heat treatment and additional heat provoking.

Steels and alloys subjected to repeated heat treatment other than provoking heating is considered as a new batch of metal.

Welded joints, weld metal and weld metal is not subjected to heat-provoking.

Steel used in the cold-worked or polunagartovannom able to experience on the samples without provoking heating.

Permitted in lieu of testing samples with heating provoking experience of steel and alloys welded samples.

When testing welds equipment which in the manufacturing process is subjected to heat treatment tests are performed on weld samples subjected to the same heat treatment.

3.7 Preparation of samples for testing

When testing methods AMU, AMUF, slaves in scale formed on the surface of samples after provoking heating, grinding or polishing to be removed by chemical or electrochemical etching or machining (gouging) to a depth not exceeding 1.0 mm, and for thin-walled parts - to a depth of 0.1 mm.

When tested by the controller to scale grinding removed only by chemical etching or by mechanical means.

Chemical etching samples of austenitic steels, austenitic-ferritic and austenitic-martensitic grades, and iron-nickel-based alloys is performed at a temperature of (20 ± 5) ° C in a solution:

nitric acid according to GOST 4461 density of 1.35 g/cm3 - (620 ± 3) cm3;

ammonium fluoride in accordance with GOST 4518 - (76 ± 0,1) g;

water in accordance with GOST 6709 - (300 ± 3) cm3.

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

hydrochloric acid according to GOST 3118 density 1.19 g/cm3 - (50 ± 1) cm3;

nitric acid according to GOST 4461 density of 1.35 g/cm3 - (5,0 ± 0,1) cm3;

water in accordance with GOST 6709 - (50 ± 1) cm3.

Etching all the above steels and alloys is carried out by an electrochemical method at 40 ° C - 50 ° C and current density (0.5 - 0.6) · 104 mA/cm2 in the solution:

phosphoric acid according to GOST 6552 density 1.68 g/cm3 - (34 ± 1) cm3;

nitric acid according to GOST 4461 density of 1.35 g/cm3 - (11 ± 1) cm3;

water in accordance with GOST 6709 - (955 ± 3) cm3.

The samples were etched until the descaling. After pickling, the samples are thoroughly washed with water. The samples after etching should be observed rastravlivaniya grain boundaries and / or pitting.

Allowed to carry out chemical etching in other solutions in other modes, providing full scale removal.

When differences in the results of tests carried out only in the etching solutions mentioned above.

The surface roughness Ra of samples prior to testing should be no more than 0.8 mm in accordance with GOST 2789. Is brought up to the specified surface roughness controlled by bending the samples tested by the methods of the AMU, AMUF, VU, V, and the entire surface of the samples tested by the method of control. The required surface roughness is achieved by polishing or grinding, wherein the surface is not allowed to overheat.

Before testing, the samples marked impact mark or elektrokarandashom (in brittle materials) on one or both ends of the sample at a distance of 5 - 10 mm from the end and degreased with organic solvents: acetone, ethanol, etc.

4 test samples in a solution of sulfuric acid and copper sulphate in the presence of metallic copper. The method of AMU

4.1 Principle

Sample steels kept boiling aqueous solution of copper sulfate and sulfuric acid in the presence of copper metal (chips).

The method is used for the control of steel:

- Ferritic class brands 08H17T, 15H25T, 01-015H18T-VI, 01H18M2T-VI, 01H25TBYU-VI;

- Austenitic-class brands fsrritnogo 08H22N6T, 08H21N6M2T, 08H18G8N2T, 02H24N6M2;

- Austenitic grades 09H16N15M3B; 03H16N15M3B, 10H17N13M2T, 10X17N13M3T, 08H17N13M2T, 08H17N15M3T, 12H18N9, 12X18H9T, 04H18N10, 08H18N10, 08H18N10T, 12Cr18Ni10Ti 12H18N10E, 06H18N11, 03H18N11, 03H18N12, 08H18N12T, 12H18N12T, 08H18N12B, 03H17N14M3.

Note - Steel austenitic-martensitic class brands 20H13N4G9, 09H15N8YU, 07H16N6, 09H17N7YU, 09H17N7YU1, 08H17N5M3 and austenitic steel grades 10H14G14N3, 10H14G14N4T, 10H14AG15, 07H21G7AN5, 12H17G9AN4 be tested by A (Appendix E), the duration of the test - 15 hours

4.2 Reagents and solutions

4.2.1 For the tests used the following reagents:

copper sulphate (CuSO4 · 5H2O) in accordance with GOST 4165, reagent grade or analytical grade, or bluestone, GOST 19347, reagent grade;

sulfuric acid in accordance with GOST 4204 density 1.83 g/cm3, analytical grade or reagent grade;

distilled water as per GOST 6709;

copper in the form of chips according to GOST 859;

hydrochloric acid according to GOST 3118 density 1.19 g/cm3, analytical grade or reagent grade;

nitric acid according to GOST 4461 density 1.40 g/cm3, analytical grade or reagent grade

4.2.2 Test Solution

K (1000 ± 3) cm3 of water were added copper sulfate (50 ± 0,1) g sulfuric acid in small portions (250 ± 3) cm3 sample loading and to the flask was added a solution of copper chips in an amount providing a comprehensive contact with samples and lack of contact between the samples.

4.3 Testing

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

Be loaded samples of the same grade of steel in several rows on the condition that the series of samples, among which must be copper shavings, do not touch each other.

Loading samples of various grades in the same flask was not allowed.

The flask was filled with the test solution for about 4 - 8 cm3 per 1 cm2 of the surface of the sample when the level of solution should be 1.0 - 1.5 cm above the sample surface or layer chip.

The reaction vessel with the solution and the test sample is heated and boiled continuously, without allowing the heating appliance.

4.3.2 The soak in boiling solution - (8,00 ± 0,25) h

4.3.3 In forced a break in the trial, in the absence of evaporation of the solution, the samples can remain in solution up to 48 hours

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

4.3.4 After soaking the sample solution was washed with water and dried. When deposited on samples of copper, indelible water jet, it is removed by rinsing the samples in the 20% - 30% nitric acid solution at a temperature of 20 ° C - 25 ° C.

4.3.5 reusable test solution while maintaining its color, except for testing at odds.

4.3.6 The copper shavings used repeatedly. If browning during storage chip is washed to lighten 20% - 30% nitric acid solution and then with water.

4.4 Detection of the ICC

4.4.1 Upon completion of the tests for the detection of the ICC samples bent at an angle of 90 ° ± 5 ° in accordance with GOST 14019.

Radius of the mandrel is selected depending on sample thickness, steel grade and type of metal from which the samples were prepared (Table 3).

Table 3

In millimeters

Type of metal and woodwork austenitic steels and alloys austenitic-ferritic-martensitic and austenitic ferritic steels

The thickness of the sample radius mandrel thickness of the sample thickness of the sample radius mandrel radius mandrel

Sheet, rolled, billet, forgings, tubes 1.0 and less than 1.0 and less than 1.0 and less than 3.0 1.0 3.0

More than 1.0 is not more than 1.0 of thickness of the sample is not more than three sample thicknesses 1.0 Not more than three thicknesses of the sample

Castings, welded joints, the weld metal, weld metal and less than 2.0 1.0 or less 1.0 or less 3.0 1.0 3.0 not more than

More than 1.0 is not more than two thicknesses of 1.0 to 3.0 incl. No more than three sample thicknesses from 1.0 to 5.0 incl. No more than three sample thicknesses

More than 3.0 10

If you do not know what the surface of the sheet from which the sample is cut, is working in the operating equipment, as well as for the detection of ICC caused by the presence of carbonized layer on the surface of a sample, check both surfaces, bending Z-shaped pattern. If unable Z-shaped bend bending sample is carried out double the number of samples, one half is bent by one of the surfaces, the second - on the other.

When differences in the assessment of cracks on curved samples, ie when one of the parallel samples were found cracks and the other - there is one, or when the researcher crack spots, while the other - there should hold metallographic study of two samples tested. Upon detection of the ICC only one of the samples tested, the test should be repeated to double the number of samples.

4.4.2 The specificity of detection in samples of MCC

Samples of the tubes:

- In samples of seamless pipes in the presence of control requirements of both surfaces of the sample Z-shaped bend;

- An outer surface of the pipes cut from seamless pipe outer diameter of 10 mm, controlled bending, and the inner surface - the metallographic method or the removal of the nozzle wall (in accordance with Table 1) and bending the remaining part of the pipe;

- Rings and tubes made of seamless pipes as per GOST 9940 and GOST 9941, with a diameter of 8 mm, control flattening through the convergence of compressible plane to a distance H, mm, calculated by the formula

 Mm (1)

where D - outer diameter of the pipe, mm;

S - pipe wall thickness, mm.

When flattening samples austenitic-ferritic or ferritic steels distance H, mm, is given by:

H = 0,5 D + 2S. (2)

The inner surface of the rings and nozzles control the metallographic method. Allowed for austenitic steels control the inner surface of the rings carry flanged to the diameter determined by the formula

Dotb ≥ 1,56 S + d, (3)

where d - diameter of the inner ring, mm.

Welded samples after the test solution is bent:

- Type 1 (Table 1): two samples - to weld two sample - at HAZ during weld control as a whole.

Two samples - at the weld at the control of the weld metal, the two samples - at the heat affected zone under the control of the base metal or alloy steel;

- Type 2 (Table 1): two samples - perpendicular to the weld seam under the control of the weld metal and HAZ of the welded joint as a whole and, if necessary on both sides of control samples of Z-shaped bend.

In the case where detection is difficult to weld metal welded samples should be etched at room temperature for 1 - 3 min. Solution for detecting welds: In (20 ± 1) cm3 of water were dissolved copper sulphate (4 ± 0,1) g was added hydrochloric acid and 1.19 g/cm3 density, volume (20 ± 1) cm3.

Bending is carried out so that a weld facing the working medium located on the outer side of the sample. If unknown seam side facing the working environment, on the outside of the sample must be seam, exposed to the maximum number of heating.

Samples in the form of rings and pipes with longitudinal or circumferential seam is flattened in accordance with 4.4.2. Flattening is performed in accordance with GOST 6996, an annular seal to be placed axially compressive load application, a longitudinal - in a diametrical plane perpendicular to the action of a compressive load.

4.5 Evaluation of test results on the ICC

4.5.1 Determining whether the ICC by bending the sample

Inspection of curved samples is carried out using the magnifying glass with an increase in 7 - 12x.

No cracks on samples bent after the test except longitudinal cracks and cracks on the edges directly indicates resistance of the steel or alloy to intergranular corrosion.

Cracks on the samples after the test bent, and there are no cracks on curved in the same way the control samples indicates the tendency of steel to intergranular corrosion.

If the flexural test pieces are broken or show cracks or bending is not possible due to its sample size (3.4) to be metallographic study of the samples after the test.

4.5.2 Metallographic method for determining the ICC

To identify the MCC metallographic method unbent portion of the sample passed the test, grinding cut so that the cutting plane is perpendicular to the test surface of the sample. When cutting a thin section of the sample weld cutting line should be at right angles to the plane of the weld and cut to include the weld metal, heat-affected zone and the base metal.

The recommended length of the section on the test surface must be at least 15 - 20 mm.

The plane of the cut should be a plane of the section.

A method for manufacturing thin section needed to ensure that the dam edges and burrs.

The presence and depth of the IWC set on the etched thin sections with an increase of at least 200x.

Etching is carried out only to identify the weak grain boundaries.

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

Cone viewed from the surface to the sample.

Determine the maximum depth of destruction identified in the six fields of view. In view of these fields must be included areas with the greatest depth of the IWC.

A sign of resistance to intergranular corrosion in a metallographic control believe the destruction of the grain boundaries to a maximum depth of 30 m, in samples of metal thickness less than 1.5 mm - to a depth of no more than 10 microns, unless otherwise specified in the regulations for steel and products thereof.

5 test specimens in a sulfuric acid and copper sulphate in the presence of metallic copper and sodium fluoride or potassium fluoride. Method AMUF

5.1 Principle

Samples were maintained at 20 ° C - 30 ° C in an aqueous solution of copper sulfate, sulfuric acid, sodium or potassium fluoride in the presence of metallic copper. The method is used for the control of steel grades by 4.1, except for the steel grades specified in the note to 4.1.

The method is rapid compared to the method of AMU.

In case of disagreement in the assessment of the quality of the metal tests are carried out by the MCA.

5.2 Reagents and solutions

5.2.1 For the test reagents are used on 4.2.1 with the additions:

sodium fluoride to GOST 4463 ch.da or reagent grade;

potassium fluoride, GOST 20848, analar. or reagent grade

5.2.2 Test solution B (1000 ± 3) cm3 of water were dissolved (50 ± 0,1) g of copper sulphate, (128,0 ± 0,1) g of sodium fluoride, and then in small portions (in order to prevent heating of the solution) was added (250 ± 1) cm3 of sulfuric acid. Instead allowed to add sodium fluoride (177,0 ± 0,1) g of potassium fluoride.

Preparation and storage of the solution should be carried out in a polyethylene container.

5.3 Testing and Evaluation

5.3.1 All the preparatory work and the tests are carried out in a fume hood in a plastic container.

At the bottom of the reaction vessel is poured layer of copper shavings, which are charged to the surface samples and the vessel is filled with the test solution in an amount of 8 cm3 per 1 cm2 of the surface of the sample at 1.0 - 1.5 cm above the sample surface or a layer of copper shavings and then close it cap.

5.3.2 The test period for steels without molybdenum - (2,0 ± 0,1) h containing molybdenum - (3,0 ± 0,1) h

5.3.3 reusable solution and copper metal on 4.3.5, 4.3.6.

5.3.4 Detection of the IWC and the evaluation of the results of tests carried out in accordance with 4.4 and 4.5. Inspection of curved samples is allowed to conduct with a magnifying glass with increasing 16 - 20x.

6 The test samples in a solution of sulfuric acid in the presence of ferric sulphate. Method VU

6.1 Principle

Samples of steel or alloy is maintained in boiling aqueous solution of ferric sulphate and sulfuric acid.

The method is used to control 03H21N21M4GB steel and iron-nickel alloys on the basis of marks: 06HN28MDT, 03HN28MDT and HN30MDB.

6.2 Reagents and solutions

Sulfuric acid in accordance with GOST 4204 density 1.83 g/cm3, analytical grade or reagent grade

Iron (III) sulphate [Fe2 (SO4) 3 · 9N2O] according to GOST 9485, ch.da or reagent grade

Distilled water in accordance with GOST 6709.

Of sulfuric acid density of 1.83 g/cm3, a solution of the mass fraction (50,0 ± 0,2)%, a density of 1.395 g/cm3.

6.3 Testing and Evaluation

6.3.1 Tests carried out in a glass flask equipped with a reflux condenser.

At the bottom of the reaction vessel placed beads, glass tube or porcelain boat, which was placed over the samples.

In a porcelain mortar and triturated to ferrous iron powder 40 g per 1,000 cm3 of sulfuric acid with density 1,395 g/cm3. The resulting powder was poured into the flask and the sample is poured with cold sulfuric acid solution.

The amount of solution - not less than 8 cm3 per 1 cm2 of the surface of the sample. The level of the solution should be 1.0 - 1.5 cm above the sample surface.

Joint loading the flask samples of steels and alloys of different brands are not allowed.

6.3.2 The soak in boiling solution should be (48,0 ± 0,25) h

6.3.3 Boiling is carried out continuously, preventing the heating appliance.

In forced a break in testing samples can remain in solution is not more than 8 hours test duration is counted as the total number of hours at the boil.

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

7 The test samples in 65% nitric acid. Method of control

7.1 Principle

Samples were kept in a boiling aqueous solution of 65% nitric acid. The method is used for the control of steel grades: 02H18N11, 03H18N11, 03H18N12, 03H17N14M3, 03H24N6AM3, 02H25N22AM2.

7.2 Reagents and solutions

Nitric acid, a. hours, in accordance with GOST 11125 mass fraction (65,0 ± 0,2)%, a density of 1.391 g/cm3. Distilled water in accordance with GOST 6709.

7.3 Testing

7.3.1 Prior to testing of the samples was measured length, width (or diameter) and a thickness not less than three places, the measurement error does not exceed 0.1 mm.

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

Tests carried out in a glass flask with reflux condenser.

At the bottom of the flask put glass beads, tubes or porcelain boats, which are placed on the samples.

In one flask test samples of the same grade of steel melting and heat treatment. Samples poured nitric acid of 10 cm3 per 1 cm2 surface of the sample and 1.0 - 1.5 cm above the sample surface.

When differences in evaluating resistance to intergranular corrosion test was repeated in a solution of nitric acid, of not less than 20 cm3 per 1 cm2 of the surface of the sample and 1.0 - 1.5 cm above the sample surface.

The test is carried out at a uniform low boiling evaporation solution is not allowed and NOx emissions brown, as determined by pH paper is placed on the top outlet of the reflux condenser. In the case of evaporation of the solution to be added 65% nitric acid to the initial level.

7.3.2 The test duration is 240 hours, five cycles (48,00 ± 0,25) every hour with the change of the solution after each cycle.

Permitted by agreement with the customer for steel grades 02X18N11, 03H18N11 03H18N12 and after the third cycle, further testing is not performed if the corrosion rate in the second and third cycles is less than 0.30 mm / year.

7.3.3 Each test cycle (48 hours) the samples are removed from the flask, washed with water, dried, weighed and the corrosion rate determined in each of the cycles.

7.3.4 In forced break boiling the samples are removed from the flask, washed and dried. The solution is used to continue the cycle.

7.4 Evaluation of test results on the ICC

7.4.1 To assess the ICC determine the corrosion rate of vK, g/m2 · h, and v'K, mm / year by the following formulas

                                                              (4)

                                                              (5)

where Δm - loss of mass of the sample in a given cycle, g;

S - surface of the test specimen in cm2;

t - test duration, h;

ρ - density of the tested steel g/cm2.

7.4.2 Samples are considered not to pass the test if the rate of corrosion of steel, weld, weld metal and weld metal after the second or subsequent cycles - more than 0.5 mm / yr and 0.3 mm / year for the steel 02H25N22AM2 as well, if corrosion rate weld - not more than 0.5 mm / year, but the weld zone or thermal effect zone, or the weld metal subjected to elevated etched compared with the parent metal, the sample inspection should be carried out by increasing by at least 7 times.

7.4.3 In cases of doubt, when assessing the quality of the welded joint can be held metallographic analysis.

Samples are considered not to pass the test if the average depth rastravlivaniya heat-affected zone or HAZ or weld metal not less than 30 microns over base metal.

8 Test

The test report should indicate:

- The steel grade, type of metal from which the sample is made, heat number;

- Marking of the sample;

- Type of sample (base metal, welded sample weld metal, weld metal);

- The mode of heat treatment;

- Test method;

- The result of the test;

- Samples of resistant or susceptible to intergranular corrosion when tested by one of the methods: AMU, AMUF, V, VE or by the method described in Annex E;

- The rate of corrosion control method in each of the cycles and assessment of resistance to intergranular corrosion.

APPENDIX A

(Recommended)

The test sample in a solution of sulfuric acid and zinc powder. Method B

A.1 Principle

Samples were kept in a boiling aqueous solution of copper sulfate and sulfuric acid with the addition of zinc powder.

The method is used to control the alloy 06HN28MDT and is less reliable than the method of slaves.

A.2 Reagents and solutions

Copper sulfate (CuSO4 · 5H2O) in accordance with GOST 4165, ch.da or chemically pure, or copper sulfate according to GOST 19347, reagent grade

Sulfuric acid in accordance with GOST 4204 density 1.83 g/cm3, analytical grade or reagent grade

Distilled water in accordance with GOST 6709.

Zinc powder to GOST 12601, Class A.

A solution for the test: (1000 ± 3) cm3 of water were dissolved (110,0 ± 0,2) g of copper sulphate, and then added in small portions (55,0 ± 0,3) cm3 of sulfuric acid.

A3 testing and evaluation of results

A.3.1 The test is carried out in a glass flask with a reflux condenser.

At the bottom of the flask placed beads, glass tube or porcelain boats, over which the samples are placed. The flask was filled with the test solution, of not less than 8 cm3 per 1 cm2 of the surface of the samples and 1.0 - 1.5 cm above the sample surface, and added (5,0 ± 0,1) g of zinc powder for every (1000 ± 3) cm3 of solution. When a violent reaction of hydrogen evolution is over, the reaction vessel is connected to the refrigerator.

A.3.2 The soak in the solution - (144,0 ± 0,25) h The solution is heated continuously, avoiding heating appliance. When stimulated suspension samples may remain in solution over 48 hours

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

A.3.3 The processing of the samples after the test is carried out by 4.3.4 of this standard.

A.3.4 Identification of intergranular corrosion is carried out on 4.4 and 4.5 of this standard.

APPENDIX B

(Recommended)

Anodic etching is inhibited samples in sulfuric acid. Method B

B.1 Principle

Steels subjected to anodic etching in an aqueous sulfuric acid solution inhibited.

The method is used for the control of products and parts made by welding, hot stamping and folding of steel grades: 12H18N9, 12X18H9T, 04H18N10, 08H18N10, 12Cr18Ni10Ti 08H18N10T, 03H18N11, 06H18N11, 08H18N12T, 12H18N12T and double-layer steel of these brands, a preliminary assessment of resistance to intergranular corrosion metal products, subject to the control methods of AMU and AMUF.

The weld metal is not controlled by this method.

B.2 Hardware

The experimental setup for metal control method B is shown in Figure B.1.

 

1 - lead vessel - cathode, 2 - rubber sleeve, 3 - sample 4 - constant current source, 5 - ammeter with a scale up to 0.1 A, 6 - or rheostat resistance store, 7 - or a key switch

Figure B.1 - Sema installation for metal control method B

B.3 Reagents and solutions

Sulfuric acid in accordance with GOST 4204 density 1.83 g/cm3, a solution with a mass fraction (60,0 ± 0,2)%.

Methenamine (CH2) 6N4, GOST 1381 or another inhibitor for sulfuric acid solution with a mass fraction (0,50 ± 0,05)%.

Distilled water in accordance with GOST 6709.

A test solution (20 ± 1) and hexamine solution cm3 (1000 ± 3) cm3 of sulfuric acid.

B.4 testing and evaluation of results

B.4.1 The surface areas to be monitored, polished to a roughness Ra ≤ 0,8 m. After sanding the control sites degreased with organic solvents.

B.4.2 Testing carried controlled anodic etching of surface areas, which include a DC circuit with a current density (0,65 ± 0,01) · 104 mA/cm2. The cathode is the lead vessel (Figure B.1), which reinforce the on the surface to test the product or material with a rubber sleeve. Poured into the vessel 3 to 5 cm3 of the solution.

Is supposed to produce vessels of another metal, corrosion-resistant in the test solution (B.3).

Test temperature - (20 ± 10) ° C If you can not use the vessel design, shown in Figure B.2 is allowed to change its structure in relation to controlled products.

 

and - a vessel for testing horizontal surfaces b - test vessel vertical surfaces, 1 - rubber cuff

Figure B.2 - Recommended test vessel

B.4.3 In testing weldments control HAZ near the weld. In this case, the anode spot is applied in such a way that the edge spots captured less than 1 mm, the width of the weld metal.

In areas subject to control, strengthening the joint are removed.

The test is performed on both sides of the seam in a checkerboard pattern. When weld length 2 m HAZ control at least four points.

B.4.4 Products with the intersecting and T-joints tested in the heat-affected zone in all the intersections sutures (Figure B.3).

B.4.5 The test after the current - (5,0 ± 0,20) min. With increased experience etched and repeat the test period may be reduced to 1 - 2 minutes.

When the test current is turned off, and the vessel reference surface was washed with water, wiped with filter paper and wiped with ethanol.

B.5 Evaluation

Resistance of the steel to intergranular corrosion is evaluated by examination of the anode spot on the sample surface or article with an increase 20x.

The absence of the grid indicates resistance to intergranular corrosion of the metal.

In the presence of the grid (Figure B.4) or rastravlivaniya precipitated secondary phase (Figure B.5) requires testing of samples by MCA or AMUF as in etching (positive) may rastravlenie dropped carbides.

 

1 - weld, 2 - on the anodic etching

Figure B.3

 

Figure B.4

 

Figure B.5

Note - Figures B4 and B5 samples are given with increasing 50s.

APPENDIX

(Recommended)

Sample sizes

Table B.1

Kind of flat steel thickness or diameter of cylindrical samples for methods

AMU, AMUF, VU, B1) RU2)

Rolled sheet with thickness up to 10 mm thickness equal to the thickness of metal. Allowed to bring the thickness of 3 - 5 mm 3)

Rolled sheet thickness St.. 0.1 mm thickness - less than 10 mm. Allowed - 3 - 5 mm 3) Thickness - 3 - 5 mm

The two-layer sheet metal thickness equal to the thickness of the corrosion layer

Long products and wire diameter or thickness of 10 mm diameter or thickness equal to the diameter or thickness of the metal. Allowed bringing the thickness or diameter of up to 3 - 5 mm 3)

Pipes, electric thickness equal to the thickness of metal

Circumferential welds pipe thickness of 5 mm, and St.. 5 mm thickness equal to the thickness of metal. Allowed to bring the thickness of 3 mm

Welds sheet, rolled and cast thickness - 3 - 5 mm 3) Thickness - 3 - 5 mm

Long products and pipe billet diameter over. 10 mm is allowed to bring the diameter of 5 - 10 mm3), and the thicknesses of up to 3 - 5 mm thickness - 3 - 5 mm.

Diameter - 5 - 10 mm

Forgings Thickness - 3 - 5 mm 3) Thickness - 3 - 5 mm

Casting Thickness - 3 - 5 mm 2) Thickness - 3 - 5 mm

Seamless pipes with diameter up to 5 mm thickness equal to the thickness of metal

Seamless pipes with diameter up to 10 mm thickness equal to the thickness metalloproduktsii3) thickness equal to the thickness of metal

Seamless pipes with a diameter of 10 mm. Sample - The wall thickness of segment segment - less than 3 - 5 mm

Welds two-layer sheet metal thickness equal to the thickness of the cladding (corrosion resistant) layer. Allowed to bring the thickness of 3 - 5 mm 3) Thickness - 3 - 5 mm

1) The length of the transverse weld seam samples and samples of the base metal - 50 mm, width - 20 mm. Length welded longitudinal seam samples - not less than 80 mm, width - 30 mm.

2) The sample length - not less than 50 mm, - 20 - 30 mm.

3) Family bringing the thickness or diameter of the sample for ferritic, austenitic-martensitic, austenitic-ferritic steels up to 3 mm.

APPENDIX D

(Recommended)

Reagents and modes of etching thin sections to identify the intergranular corrosion

Table D.1

Grades reagent regime and etching

12H18N9, 12X18H9T, 04H18N10, 08H18N10, 08H18N10T, 12Cr18Ni10Ti 12H18N10E, 03H18N11, 06H18N11, 03H18N12, 08H18N12T, 12H18N12T, 08H18N12B, 02H18N11 Chemical etching in a mixture of:

(92 ± 3) cm3 of hydrochloric acid density of 1.18 g/cm3 according to GOST 3118,

(5,0 ± 0,1) cm3 sulfuric acid density of 1.83 g/cm3 according to GOST 4204

(3,0 ± 0,1) cm3 nitric acid density of 1.4 g/cm3 according to GOST 11125. Temperature 20 ° C - 30 ° C. The reagents are applied to the surface of the section with a cotton swab.

Electrolytic etching in a solution of oxalic acid with a mass fraction (10,0 ± 0,2)% according to GOST 22180. Temperature 20 ° C - 30 ° C. The current density (1,0 ± 0,2) · 104 mA/cm2

03H16N15M3, 08H16N15M3B, 09H16N15M3B, 03H17N14M3, 08H17N13M2T, 08H17N15M3B, 10H17N13M2T, 10X17N13M3T, 08H17N15M3T, 02H25N22AM2 Chemical etching in the solution:

(50 ± 0,1) cm3 of hydrochloric acid density of 1.18 g/cm3 according to GOST 3118,

(5,0 ± 0,1) cm3 nitric acid density of 1.41 g/cm3, GOST 11125,

(50 ± 0,1) cm3 of water. Boiling Point.

Electrolytic pickling in solution:

(8,50 ± 0,05) g/dm3 citric acid in accordance with GOST 3652, (8,50 ± 0,05) g/dm3 ammonium sulfate according to GOST 3769. Boiling Point. The current density (1.0 ± 0.2) × 104 A/m2

20H13N4G9, 08H18G8N2T, 10H14G14T, 12H17G9AN4, 07H21G7AN5, 03H21N21M4GB, 06HN28MDT, 03HN28MDT, HN30MDB, 10H14G14N3, 10H14G14N4T, 10H14AG15 Chemical etching in the solution:

(50,0 ± 0,1) cm3 of hydrochloric acid density of 1.18 g/cm3 according to GOST 3118,

(5,0 ± 0,1) cm3 nitric acid density of 1.41 g/cm3, GOST 11125,

(50 ± 1) cm3 of water. Boiling Point.

Electrolytic pickling in solution:

(10,0 ± 0,2)% oxalic acid in accordance with GOST 22180. Temperature 20 ° C - 30 ° C. The current density (1,0 ± 0,2) · 104 mA/cm2

09H15N80, 07H16N6, 09H17N7YU, 09H17N7YU1, 08H17N5M3 electrolytic etching in the solution:

(8,50 ± 0,05) g/dm3 citric acid in accordance with GOST 3652,

(8,50 ± 0,05) g/dm3 ammonium sulfate according to GOST 3769. Temperature 20 ° C - 30 ° C. The current density (1,0 ± 0,2) · 104 mA/cm2.

Electrolytic pickling in solution:

(10,0 ± 0,2)% of chromic anhydride in accordance with GOST 3776. Temperature 20 ° C - 30 ° C. The current density (1,0 ± 0,2) · 104 mA/cm2

08H22N6T, 08H21N6M2T, 03H24N6AM3 Chemical etching in the solution:

(50 ± 0,1) cm3 of hydrochloric acid density of 1.18 g/cm3 according to GOST 3118,

(5,0 ± 0,1) cm3 nitric acid density of 1.41 g/cm3, GOST 11125,

(50,0 ± 0,1) cm3 of water. Boiling Point.

Electrolytic pickling in solution:

(8,50 ± 0,05) g/dm3 citric acid in accordance with GOST 3652,

(8,50 ± 0,05) g/dm3 ammonium sulfate according to GOST 3769. Temperature 20 ° C - 30 ° C. The current density (1,0 ± 0,2) · 104 mA/cm2

08H17T, 15H25T, 01-015H18T-VI, 01H18M2T-VI, 01H25TBYU-VI Chemical etching in the solution:

(50 ± 0,1) cm3 of hydrochloric acid density of 1.18 g/cm3 according to GOST 3118,

(5,0 ± 0,1) cm3 nitric acid density of 1.41 g/cm3, GOST 11125,

(50 ± 1) cm3 of water. Boiling point

APPENDIX D

(Required)

Determination of resistance to intergranular corrosion of stainless steels.

Part 1. Austenitic and ferritic-austenitic (two-phase) stainless steel. Corrosion test in nitric acid by determining the mass loss (testing by Hugh) (ISO 3651-1:1998)

E.1 Scope

The method is used for determination of the resistance to intergranular corrosion (ICC) by the test in nitric acid with the measurement of the weight loss rolled forgings, tubing and casting austenitic and ferritic-austenitic (two-phase) steels intended for use in highly oxidizing environments (for example, in concentrated nitric acid). Tests by the method of Hough not be applied to steels containing molybdenum steel if not intended for use as a material for equipment operating with nitric acid.

Test Results ICC method Hugh indicative for determining resistance of the steel to intergranular corrosion in these environments and can be used to determine the resistance of steel to corrosion damage to other species (general corrosion, pitting, stress corrosion cracking, etc.).

E.2 Purpose Test

A.2.1 tests carried ICC to detect corrosion protection on the grain boundaries due to one or several causes:

- The grain boundary precipitation of chromium carbides;

- Precipitation of intermetallic compounds such as σ-phase in steels containing molybdenum;

- Segregation at grain boundaries pollutants.

These processes can take place under the action of austenitic and ferritic-austenitic stainless steel temperatures of 500 ° C - 1000 ° C, which may be steel during hot processing (forging, rolling), and also due to technological welding process violations.

The evaluation of the test results (eg, the maximum allowable rate of corrosion) is carried out by agreement between the purchaser and the manufacturer.

D.3 Application of the method

D.3.1 control method Hugh austenitic steel with increased corrosion resistance to intergranular corrosion, designed for highly oxidizing environments. Control samples of steel heat treatment is carried out after provoking.

Samples not subjected to thin sheets provoking heat as in the manufacturing process equipment rapidly cooled thin sheets.

D.4 provokes the heat

E.4.1 provoking heating prior to the test at the ICC subjected to stable and low-carbon (C = 0.03%) steel. To this end, the sample was kept for 30 minutes at a temperature of (70 ± 10) ° C followed by rapid cooling in water.

E.4.2 Length increasing temperature shall not exceed 10 minutes.

Other modes of provoking heating is possible only by agreement with the customer.

Welded samples were not subjected to heat-provoking.

D.5 Corrosion tests

E.5.1 Principle

The sample prepared by E.4 and D.5.2 were weighed, then immersed in a boiling nitric acid solution for 5 cycles of 48 hours each. The criterion for evaluation of the test is the weight loss determined by weighing after each test cycle.

D.5.2 The test samples

D.5.2.1 sample for investigation, taken from the treated metal pressure should be larger in the rolling direction. Of pressure-treated steel casting and cutting of the model should be as close as possible to the surface of the steel. Sample size is determined depending on the weighing device and the volume of solution used.

Sample length should be no less than twice its width, and the total surface area sides of the sample perpendicular to the rolling direction or the fibers of the sample, should be less than 15% of the total surface area of the sample. In comparative tests the ratio of total surface area of the sample to the total surface area of the sample pieces to be constant.

D.5.2.2 Processing

Depending on the purpose of the test (D.3) samples, uncooked or provoking heating shall conform to the requirements of D.5.2.2.1 and D.5.2.2.2.

D.5.2.2.1 Machining

Test samples to be processed on the entire surface mechanically by abrasive cleaning surface 120 number on paper or cloth containing no iron.

D.5.2.2.2 Chemical Treatment

Scale was removed without any preliminary mechanical treatment by immersing the samples for 1 h in a solution: 50 volumes of hydrochloric acid (ρ20 = 1,19 g/cm3) 5 volumes of nitric acid (ρ20 = 1,40 g/cm3), and 50 volumes of water at a temperature of 50 ° C - 60 ° C or dissolved in 50 volumes of hydrochloric acid and 50 volumes of water at ambient temperature.

In this treatment, you must be sure in advance that it does not cause the IWC.

D.5.2.2.3 degreasing

Prior to immersion in the corrosive solution samples to be cleaned with a solvent containing no chlorine ions.

E.6 Equipment

D.6.1 Erlenmeyer flask with a capacity of 1 dm3, lockable or submersible fingertip fridge or fridge Four ground joint, the use of which should be checked by means of an indicator that the acid vapors do not come out of the machine during the test (Figure E.1).

 

1 - glass stopper - a refrigerator, 2 - a device to prevent the delay of condensate, 3 - Erlenmeyer flask

Figure E.1

Note - It is worth noting that the corrosion rate obtained by using ball refrigerator somewhat higher than when using a pencil-type refrigerator, due to a large loss of steam.

D.6.2 sample holders are usually made of glass.

When testing several samples in the same flask sample holders should ensure demand D.8.

D.6.3 The heating device shall provide continuous boiling of the solution.

D.7 solution for testing

The test solution to be (65 ± 0,2)%-tion (by weight) aqueous solution of nitric acid (ρ20 = 1,40 g/cm3).

Apply to be analytically pure product containing a total solid residue ≤ 0,05 g/1000 g, and each of the possible additives in the amount of:

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;

chloride ion (Cl-1) ≤ 0,003 g/1000 g;

sulfate ion (SO4) -2 ≤ 0,05 g/1000 g;

phosphate ion (PO4) -3 ≤ 0,01 g/1000 g;

fluoride ion (F-1) ≤ 0,05 g/1000 g

D.8 Procedure

The volume of acid used for the corrosion tests (D.7) must be at least 20 sm3/sm2.

Normally, only one sample was placed in a flask.

However, several samples be loaded into one flask, provided that all samples have the same brand and insulated from each other by at least 0.5 cm Increased corrosion of one of the samples may increase the corrosion rate of the other samples tested therewith.

D.9 of results

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

The corrosion rate of K1, g/m2 · h, or K2, mm / year is determined by the formulas:

                                                         (A.1)

                                                            (A.2)

where m - the average weight loss after each cycle or for all test cycles, g;

S - the original surface of the test specimen in cm2;

ρ - density of the sample (8 g/cm3 - hromonikelmolibdenovyh for steel and 7.9 g/cm3 - for chromium-nickel steel), g/cm3;

t - the actual time of the boil.

D.10 Test

The test report shall contain the following:

- Number;

- Steels;

- Thermal treatment;

- Used types of refrigerators;

- The average rate of corrosion;

- Situations that may affect the results.

Lead usually average test results.

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

APPENDIX 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 International Standard specifies methods for the determination of resistance to intergranular corrosion (ICC), ferritic, austenitic and ferritic-austenitic (two-phase) stainless steels, produced in the form of castings, steel, forgings and pipes for slabookislitelnyh environments (such as sulfuric acid and phosphoric acid).

For resistance to intergranular corrosion check or low-carbon steel with a carbon content not exceeding 0.03%, or a stabilized steel. Metal monitored after provoking heating or after welding. A thin sheet of negligible thickness at a sufficiently rapid cooling rate control as supplied without exposing prior provoking heated.

E.2 Purpose Test

Intergranular corrosion tests carried out in order to detect the priority of exposure at the grain boundaries due to the union of grain boundary Cr resulting loss of one or more chromium-rich phases: carbides of chromium, σ-phase or other intermetallic phases.

These processes can take place under the action of ferritic, austenitic and ferritic-austenitic (biphasic) temperatures were 500 ° C - 1000 ° C, which can become hot when subjected to the processing (forging, rolling, etc.), as well as welding.

Depending on the chemical composition controlled metal (supplement to Annex E) use one of the methods of control of the IWC, using solutions of sulfuric acid:

Method A - 16% sulfuric acid and copper sulphate (method Monipeni-Strauss);

Method B - 35% sulfuric acid and copper sulfate;

Method C - 49% sulfuric acid and ferrous sulfate (IV).

E.3 provokes the heat

E.3.1 To test the resistance to intergranular corrosion is necessary to carry out provocative heat stabilized steels and steels with low carbon content. For the samples to be tested, maintained for 30 minutes at a heating temperature T1 (700 ± 10) ° C, followed by cooling in water mode (T1) or within 10 minutes at a temperature T2 (650 ± 10) ° C, followed by cooling in water mode (T2).

The above provoking heating modes are applied to the two-phase austenitic and ferritic-austenitic steels.

Length increase in temperature to a predetermined value must not exceed 10 min.

By agreement with the customer, other terms of provoking heating.

Type provoking heating point in the regulations for steel products. If not specified provoking heating mode, use the mode T1.

E.3.2 Welding of test pieces can be used as an alternative provoking heating (by agreement between the parties).

In this case the sample is not subjected to post-weld heat provoking. Welding as an alternative provoking heating is applicable to all steels listed in the Appendix to Annex E.

F.4 Corrosion tests

E.4.1 Principle

Test pieces prepared by E.4.2 E.4.2.2 and was immersed in a solution of sulfuric acid methods A, B, C (F.2) on specified time in E.6.1.2. The samples were then subjected to bending. After the convex bending surface of the sample examined to identify cracks. Cracks evidence of the IWC.

Pipes with a diameter up to 6.0 cm (diameter must be less than the vessel opening with the test solution), instead of bending test flattened.

E.4.2 The test sample

E.4.2.1 test specimen must have a total surface area of 15 to 35 cm2. For sheets thicker than 0.6 cm from one treated sostragivayut rolling surfaces to a maximum thickness of not more than 0.6 cm, the second treated surface must be maintained. Part of the test specimens should be retained as a control, and were tested in the case of disagreement. The samples should have the following dimensions, cm

- Thickness - 0.2 - 0.6;

- Width - at least 1.0;

- Length - not less than 5.0.

The samples were subjected to bending the specified dimensions.

E.4.2.2 Welded samples manufactured as follows: a flat plate manufactured two samples of length 10,0 cm, width of 5.0 cm and welded among themselves. Samples cut from the plate, as shown in Figure E.1. For tubes with circular cross-stitch patterns are cut according to the pattern E.2. When four specimens of a cross weld seam between the first joint placed in the longitudinal direction of the sample, as indicated in Figure E.3. For material thicknesses greater than 0.6 cm test sample sostragivayut to 0.6 cm on one side. Non-planed surface of the sample should be on the convex side during its bending. For the welded pipe over the outer diameter of 6.0 cm test pieces are made of 5.0 cm long and 2.2 cm wide, as shown in Figure E.4.

 

Figure E.1 - Test piece welded butt

 

Figure E.2 - Test piece of butt-welded pipe

 

Figure E.3 - test sample from a plate or strip with a cross-seam

 

Figure E.4 - Test piece with a longitudinal weld of welded pipe

E.4.3 Preparation of test samples

The samples subjected to a heat-provoking, and without it, prepared according to E.4.3.1 and E.4.3.2. The method of surface preparation must be indicated in the test report.

E.4.3.1 Mechanical preparation

The sample should be descaling process mechanically in a longitudinal direction on all sides, sharp edges treated with grit number 120. During machining to avoid overheating the sample.

E.4.3.2 Chemical preparation

The sample surface is free from oxides and not previously been treated for removal of scale or scale, is submerged by no more than 1 hour to a solution of 50 volumes of hydrochloric acid (ρ20 = 1,19 g/cm3) 5 volumes of nitric acid ( ρ20 = 1,40 g/cm3), 50 volumes of water at a solution temperature of from 50 ° C to 60 ° C or in solution: 50 volumes of hydrochloric acid and 50 volumes of water at ambient temperature.

In the case of chemical preparation of the sample surface to be sure that the ICC will not appear in the processing of the sample. To do this, after the treatment is carried out mikroobsledovanie for each grade of steel.

E.4.3.3 degreasing

Samples should be degreased and any suitable solvent containing no chlorine, cleaned and dried prior to immersion in a corrosive environment.

E.5 Equipment

E.5.1 Erlenmeyer flask with a capacity of 1000 cm3 or other similar flask with a condenser having at least four balls.

E.5.2 sample holder is typically made of glass (for method C).

E.5.3 heating device, ensuring the boiling solution.

E.6 Test Methods

E.6.1 Method A: a test in 16% sulfuric acid copper sulphate (method Monipeni-Strauss)

E.6.1.1 solution for corrosion testing

To prepare the solution should be used analytical grade reagents

Pyatigidrata Dissolve 100 g of copper sulfate (II) (CuSO4 · 5N2O) in 700 cm3 of distilled water. Then 184 g (100 cm3) of sulfuric acid (ρ20 = 1,84 g/cm3) was added to distilled water to a total volume of 1000 cm3.

E.6.1.2 Each flask can experience more than one sample, while ensuring the volume of the solution at least 8 sm3/sm2 the entire surface of the sample. The test specimen must be completely surrounded by conductive copper pieces, located at the bottom of the flask. The amount of copper should be less than 50 g per 1 dm3 of solution. Test samples should be in contact with copper, but not with each other. The test sample is first immersed in a cold solution of the test, the solution is heated and said initial boiling point of the solution to testing. The solution should boil for (20 ± 5) In case of disagreement hours test time should be 20 hours Pieces of copper, after testing washed with hot water can be used for the following tests. The corrosive solution used only once.

E.6.2 Method B: Test of 35% sulfuric acid, copper sulfate

E.6.2.1 The solution prepared for tests of analytical grade reagents: 250 cm3 of sulfuric acid (ρ20 = 1,84 g/cm3) was carefully added to 750 cm3 of distilled water. Dissolve 110 g of copper sulfate pentahydrate (II) in a warm solution.

E.6.2.2 In one flask can experience more than one sample with the proviso that the amount of the solution - not less than 10 sm3/sm2 the total surface of the test samples. The test specimen shall be completely surrounded by copper dust or shavings. The number of copper filings must be at least 50 g/1000 cm3 solution. Test samples should be in contact with copper filings but should not touch each other. Test samples were first placed in a cold solution of the test, the solution is heated and said initial boiling point of the solution to testing. The solution should simmer for (20 ± 5) hours in the case of disagreement, the test shall be 20 hours

E.6.3 Method C: a test in 49% sulfuric acid with iron sulfate (III)

E.6.3.1 solution for corrosion testing

Test solution prepared from analytical grade reagents: 280 cm3 of sulfuric acid (ρ20 = 1,84 g/cm3) was carefully added to 720 cm3 of distilled water. Dissolve 25 g of iron sulfate (III) [Fe2 (SO4) 3 · 9N2O] containing about 75% iron sulfate in the warm solution.

Note - The corrosion rate increases if the full use of ferrous sulfate.

E.6.3.2 Testing

In one flask can experience more than one sample with the proviso that the amount of solution falling on the entire surface of the test sample, - at least 10 sm3/sm2. Samples were placed in a cold solution and then the solution was heated to boiling and evaporating said start test begins. The solution should boil (20 ± 5) hours in the case of disagreement, the test period should be 20 hours, the solution can be used once.

E.6.3.3 The bend tests

Cylindrical and planar samples after corrosion test was subjected to the bending test (bending angle 90 °) on the mandrel with a radius equal to the thickness of the sample. Samples castings were tested for the mandrel with a radius twice the thickness of the test specimen.

Pipe outside diameter up to 60 mm inspected after flattening. The distance H between the plates, mm after the load is calculated by the formula

                                                                                (E.1)

where D - outer diameter of the pipe, mm;

t - plate thickness, mm.

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

E.7 Assessment

The convex curved surface of the sample, after the tests, examine the naked eye or with a slight increase (up to 10x).

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

A comparative analysis of the two samples to determine whether the result of a crack IWC.

Note - If in doubt in the evaluation of the test results after the test samples should be subjected to metallographic examination, it is necessary to cut the length of the sample cross-piece and examine it for the presence of cracks and their depth.

E.8 Test

The test report shall contain the following:

- The method used, with reference to this International Standard;

- Steels;

- The method of sample preparation (mechanical or chemical);

- Assortment of samples for testing;

- Applied heat treatment;

- The results of the test;

- Accidents that can affect the test results.

SUPPLEMENT TO ANNEX E

List of steel to be controlled by these methods

Application of the method depends on the nature and aggressiveness of the environment. The following examples are provided for information. Only one method may be used for each grade of steel.

Method A:

- Austenitic steels containing more than 16% Cr and up to 3% Mo;

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

- Two-phase steel, containing more than 16% Cr and up to 3% Mo.

Method B:

- Austenitic steels containing more than 20% Cr and 2% - 4% Mo;

- Two-phase steel, containing more than 20% Cr and more than 2% Mo.

Method C:

- Austenitic steels containing more than 17% Cr and more than 3% Mo;

- Austenitic steels containing more than 25% Cr and more than 2% Mo;

- Ferritic steel containing more than 25% Cr and more than 2% Mo;

- Two-phase steel, containing more than 20% Cr and 3% or more Mo.