GB/T 38269-2019Corrosion of metals and alloys - Accelerated cyclic corrosion tests with exposure to synthetic ocean water salt-deposition process - Dry and wet conditions at constant absolute humidity (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard uses the translation method equivalent to ISO 16539..2013, "Corrosion of metals and alloys, the cycle of salt deposition in artificial seawater

Accelerated corrosion test Dry/wet at constant absolute humidity.

For documents in China that have a consistent correspondence with the international documents referenced normatively in this standard, see Appendix NA.

The following editorial changes have been made to this standard.

--- Added informative appendix NA.

This standard is proposed by China Iron and Steel Industry Association.

This standard is under the jurisdiction of the National Steel Standardization Technical Committee (SAC/TC183).

This standard was drafted. Institute of Metal Research, Chinese Academy of Sciences, Institute of Information Standards of Metallurgical Industry.

Introduction

With or without a protective metal material, it will be affected by many environmental factors, and its importance depends on the type of metal material and the environmental

Different types. Therefore, it is impossible to consider all environmental factors affecting corrosion resistance when designing an accelerated corrosion test in a laboratory. So, real

Accelerated laboratory tests are often used to simulate the most important factors that can accelerate the corrosion of metallic materials.

The accelerated corrosion test described in this standard is intended to simulate and enhance the environmental impact of metal materials when exposed outdoors.

Corrosion is accelerated in salt environments.

The two test methods in this standard are faster than traditional accelerated tests [such as the neutral salt spray test (NSS) and

The accelerated test of cyclic exposure to salt spray, dry and humid conditions as specified in ISO 14993 has unique advantages, and its advantages are reflected in two

All of them can better reproduce the corrosion behavior of metallic materials in the atmospheric environment containing a large amount of sea salt particles.

The accelerated corrosion tests that simulate atmospheric corrosion in these environments are expected to include the following.

a) Constant Absolute Humidity. In an outdoor environment, the temperature and relative humidity change under the condition that the constant absolute humidity is maintained. Suction of deposited salts

Water is an important factor affecting atmospheric corrosion behavior. Similarly, in the dry/wet cycle, the constant absolute humidity is also the temperature and relative

The purpose/expected presence of humidity in an actual environment.

b) Control of salt deposition. Determine the amount of salt deposited on the surface of the sample according to the corrosive properties of the metal materials used in the atmosphere. by

Dilute the concentration of the salt solution or adjust the spraying time to provide the same annual average salt deposition as the actual environment.

Therefore, the test methods described in this standard include salt deposition and drying/wetting cycles under constant absolute humidity.

The obtained results should not provide more in-depth conclusions on the corrosion resistance of the tested metal materials in various atmospheric environmental conditions. But for research

Investigating the performance of materials exposed to salty media similar to the test environment provides useful information.

Corrosion of metals and alloys containing artificial seawater deposits

Cyclic accelerated corrosion test of process

Dry/wet under humidity

1 Scope

This standard specifies two accelerated corrosion test methods, Method A and Method B, for the evaluation of metals and alloys with or without a coating on the surface.

Corrosive behavior in the atmospheric environment and specifies the equipment selected. Both tests include salt deposition and drying at constant absolute humidity

Dry/wet circulation environment.

Method A applies to. metals and their alloys (including corrosion-resistant alloys).

Method B works for.

--- Metals and their alloys;

--- Covered metal and its alloy [including metal cover (cathode or anode), organic coating and conversion film].

2 Normative references

The following documents are essential for the application of this document. For dated references, only the dated version applies to this article

Pieces. For undated references, the latest version (including all amendments) applies to this document.

ISO 4628-1 Evaluation of paint and varnish coatings for ageing. Identification of the number and size of defects and the degree of uniform change in appearance.

Part 1. General identification system (Paintsandvarnishes-Evaluationofdegradationofcoatings-Designation

ofquantityandsizeofdefects, andofintensityofuniformchangesinappearance-Part 1. Generalin-

troductionanddesignationsystem)

ISO 4628-2 Evaluation of aging of paint and varnish coatings. Identification of the number and size of defects and the degree of uniform change in appearance.

Part 2. Determination of foaming levels (Paintsandvarnishes-Evaluationofdegradationofcoatings-Designation

ofquantityandsizeofdefects, andofintensityofuniformchangesinappearance-Part 2. Assessment

ofdegreeofblistering)

ISO 4628-3 Evaluation of paint and varnish coatings for ageing. Identification of the number and size of defects and the degree of uniform change in appearance.

Part 3. Evaluation of rust grades (Paintsandvarnishes-Evaluationofdegradationofcoatings-Designation

ofquantityandsizeofdefects, andofintensityofuniformchangesinappearance-Part 3. Assessment

ofdegreeofrusting)

ISO 4628-4 Evaluation of ageing of paints and varnish coatings Identification of the number and size of defects and the degree of uniform change in appearance

Part 4. Evaluation of cracking grades (Paintsandvarnishes-Evaluationofdegradationofcoatings-Designation

ofquantityandsizeofdefects, andofintensityofuniformchangesinappearance-Part 4. Assessment

ofdegreeofcracking)

ISO 4628-5 Evaluation of paint and varnish coatings for ageing. Identification of the number and size of defects and the degree of uniform change in appearance.

Part 5. Evaluation of peeling grades (Paintsandvarnishes-Evaluationofdegradationofcoatings-Designation

ofquantityandsizeofdefects, andofintensityofuniformchangesinappearance-Part 5. Assessment

ofdegreeofflaking)

ISO 8407 Corrosion of metals and alloys-Corrosion of metalsandaloys-Re-

movalofcorrosionproductsfromcorrosiontestspecimens)

ISO 8993 Anodized Aluminum and Aluminum Alloys Evaluation Method for Evaluation of Pitting Corrosion (Anodizingofaluminiumand

itsaloys-Ratingsystemfortheevaluationofpittingcorrosion-Chartmethod)

ISO 9227 Artificial Corrosion Test Salt Spray Test (Corrosiontestsinartificialatmospheres-Saltspraytests)

ISO 10289 Ratings of specimens and test pieces after corrosion testing of metals and other inorganic coatings on metal substrates (Methodsfor

corrosiontestingofmetalicandotherinorganiccoatingsonmetalicsubstrates-Ratingoftestspeci-

mensandmanufacturedarticlessubjectedtocorrosiontests)

ISO 11130..2010 Corrosion of metalsandaloys-

Alternateimmersiontestinsaltsolution)

ISO 14993 Accelerated tests on corrosion cycles of metals and alloys exposed to salt spray, "dry" and "wet" conditions (Corrosionof

metalsandaloys-Acceleratedtestinginvolvingcyclicexposuretosaltmist, "dry" and "wet" conditions)

ISO 17872 Guidelines for Scratch Marking of Sheet Metal Coatings for Corrosion Testing of Paints and Varnishes (Paintsandvarnishes-Guidelinesfor

theintroductionofscribemarksthroughcoatingsonmetalicpanelsforcorrosiontesting)

3 Test solution

4 Equipment

5 Sample requirements

5.1 The number and type of test specimens shall be selected according to the specifications of the test materials or products. If not specified, it shall be decided through consultation between the supplier and the supplier.

5.2 Samples should be carefully cleaned before the test to remove dirt, oil stains or other impurities, so as not to affect the test results. The cleaning method used should be taken

Depending on the nature of the materials and contaminants, abrasives or solvents that should corrode the surface of the specimen should not be selected.

5.3 For metals or alloys without any organic or inorganic coating, a suitable organic solvent should be selected.

The sonic cleaning device thoroughly cleans the sample. The cleaning process should be performed in a container filled with solvent. After cleaning, rinse again with clean solvent

Blow dry after.

5.4 Unless otherwise specified, samples with protective organic coatings need not be cleaned before testing. If cleaning is necessary, apply alcohol

Wipe the sample with gauze to avoid damaging the sample surface. Please note that the samples should not be contaminated after cleaning.

5.5 If the sample is cut from a covered sample, the damaged area of the cover should be avoided. Unless otherwise specified, the edges of

A covering that is stable during the test is protected. Such as paint, wax or tape.

6 Measurement method of salt deposition

The test solution is deposited on the surface of the sample. The average value of salt deposition should be determined by measuring the change in sample mass before and after salt deposition.

To 1mg. To prevent the sample from drying, the measurement process should be completed as soon as possible.

7 Sample preparation

After the salt on the surface of the sample is deposited, it is placed in the cabinet. Avoid contact between the sample and the cabinet when placing. The specimen should be placed horizontally. As long as the droplets do n't

The sample is dropped on the surface of the sample or the sample is not placed directly under other samples. The sample in the box can be placed on a different plane.

8 Operating conditions and procedures

The operating conditions are shown in Table 2 (Method A) and Table 3 (Method B). The operation process is shown in Figure 1 (Method A) and Figure 2 (Method B). Test sink

The salt solution should not be reused. During the test, the pressure in the box should be maintained at atmospheric pressure.

Table 2 Test conditions for method A

Process conditions

a) Salt deposition

1) Temperature

2) Test solution

3) frequency

4) Salt deposition

1) Room temperature

2) See Chapter 3

3) After each cycle

4) The deposition amount of salt solution on the test surface should be 250g/m2 +/- 50g/m2. Solution concentration is not lower than human

1/1000 of seawater concentration

b) "Dry" ambient temperature and relative humidity

1) A (49 +/- 1) degrees C (32 +/- 5)%

2) B (54 +/- 1) degrees C (25 +/- 5)%

3) C (55 +/- 1) degrees C (24 +/- 5)%

4) D (54 +/- 1) degrees C (25 +/- 5)%

5) E (49 +/- 1) degrees C (32 +/- 5)%

c) "Wet" environment (30 +/- 1) degrees C (90 +/- 5)%

d) Washing with clean distilled water (not exceeding 40 ° C)

Table 2 (continued)

Process conditions

e) the length and composition of an exposure cycle (a

(The exposure period is 24h)

"Wet" 6h36min

"Dry" 10h48min

"Wet" 6h36min

f) those that meet the specified conditions during an exposure cycle

time

"Wet" to "Dry (A)" 2h22min

"Dry (A)" to "Dry (B)" 1h40min

"Dry (B)" to "Dry (C)" 1h22min

"Dry (C)" to "Dry (D)" 1h22min

"Dry (D)" to "Dry (E)" 1h40min

"Dry (E)" to "Wet" 2h22min

Note 1. The temperature and humidity should change linearly within the specified time interval [see f) in this table. Continuous drying processes A to E give the same absolute humidity,

Dew point temperature of 30 ° C.

Note 2. Under equilibrium conditions, the tolerances on the given parameter values --- temperature and relative humidity are allowed to fluctuate. This does not mean that the value can be given at random

Changes in the total value of the set value.

Explanation.

T --- temperature, degrees C; s --- salt deposition;

R --- relative humidity,% RH; r --- cleaning treatment.

t --- time, h;

Figure 1 Test process for method A

Table 3 Test conditions for method B

Process conditions

a) Salt deposition

1) Temperature

2) Test solution

3) frequency

4) Salt deposition

1) Room temperature

2) See Chapter 3

3) After 8 cycles and 11 cycles

4) The deposition amount of salt solution on the test surface shall be 28.0g/m2 +/- 2.8g/m2. Solution concentration is not lower than

1/1000 of artificial seawater concentration

b) "dry" environment

Temperature and relative humidity

(60 +/- 1) degrees C (35 +/- 5)%

c) "Wet" environment (40 +/- 1) degrees C (95 +/- 5)%

d) Washing with clean distilled water (not exceeding 40 ° C)

e) the length and composition of an exposure cycle (a

(The exposure period is 24h)

"Dry" 3h

"Wet" 3h

Until the specified conditions are met

"Dry" to "Wet" for 1h

"Wet" to "Dry" for 1h

f) Test process

1) Salt deposition

2) Dry/wet cycle. 8 cycles

After the end of the cycle, when the temperature reaches 60 ° C, the sample should be quickly removed from the box.

3) Cleaning treatment

4) Salt deposition

The cleaning process and salt deposition process should be completed under dry conditions.

5) Dry/wet cycle. 11 cycles

After the end of the cycle, when the temperature reaches 60 ° C, the sample should be quickly removed from the box.

6) Cleaning treatment

Note 1. Dew point temperature is 39 degrees C, temperature and humidity should be changed under the same absolute humidity.

Note 2. Under equilibrium conditions, the tolerances on the given parameter values --- temperature and relative humidity are allowed to fluctuate. This does not mean that the value can be given at random

Changes in the total value of the set value.

Explanation.

T --- temperature, degrees C; s --- salt deposition;

R --- relative humidity,% RH; r --- cleaning treatment.

C --- cycle;

Figure 2 Test process for method B

9 Sample treatment after test

After the test, remove the sample from the box and dry it for 0.5h ~ 1h before rinsing to prevent the corrosion products from falling off. Before the sample is tested,

The sample was gently rinsed in clean tap water at a temperature not exceeding 40 ° C to remove the salt solution remaining on the surface of the sample, and then immediately used not more than

Dry with.200kPa compressed air.

10 Test continuity

It is best to maintain continuity throughout the test. If you need to interrupt the operation, try to minimize the interruption time. When it is necessary to interrupt the test, the sample should be made

Handle as follows. The sample should be removed from the test box and processed in accordance with the method in Chapter 9, and then stored in a desiccator until the test is resumed.

11 Duration of test

The test time shall be determined according to the specifications of the test materials or products. If not specified, it should be decided through consultation between the supply and demand sides.

Recommended test time.

a) Method A. 3 cycles (72h), 7 cycles (168h), 21 cycles (504h), 42 cycles (1008h);

b) Method B. 7d, 14d, 21d, 28d, 42d, 56d, 70d.

Note. Appendix D gives the recommended test cycle.

12 Results Evaluation

The evaluation of test results meets special needs by different criteria, such as.

a) the time immediately before signs of corrosion appear;

b) morphology after the test;

c) the number and distribution of corrosion defects (e.g., pits, cracks, rust or creep in paint stains; their evaluation methods are described in ISO 8993

(Or ISO 10289, see parts of ISO 4628 and ISO 17872 for colored paint);

d) surface morphology after removal of corrosion products (see ISO 8407);

e) quality change;

f) changes in microscopic analysis;

g) changes in mechanical or electrical properties.

Note. Appendix E gives the recommended evaluation methods.

13 Test report

The test report includes the following information.

a) the number of this standard;

b) test equipment description;

c) description of test materials;

d) the size and shape of the specimen, the surface properties and area of the specimen;

e) details of sample preparation, including cleaning treatment and edge protection of the sample before the test;

f) test solution concentration, salt deposition amount and salt deposition process;

g) the temperature and relative humidity of each salt deposition and "dry" and "wet" environment during the test;

h) the frequency and duration of the interruptions;

i) test duration;

j) The method of cleaning the sample after the test, if appropriate, indicate the quality loss caused by cleaning and correct the quality loss.

method;

k) test results, such as the loss of mass and thickness of the cover sample, the blister width and peel width of the cover sample;

l) If necessary, a picture record and/or a description of the appearance of the specimen.

Appendix A

(Informative appendix)

Salt deposition cycle tester (two box type)

A two-box salt deposition cycle tester is shown in Figure A.1.

Explanation.

1 --- Atomizer;

2 --- drying box;

3--sample room;

4--sample tray;

5 --- sample;

6 --- Sample roller/Sample drive;

7 --- filter;

8 --- nozzle transmission;

9 --- host door;

10 --- exposure box;

11 --- blast motor;

12 --- air heater;

13 --- cooling device;

14 --- freezer;

15 --- flush nozzle;

16 --- blower (remove water droplets);

17 --- exhaust gas treatment device;

18 --- Exhaust.

Figure A.1 Salt deposition cycle tester (two-box type)

Appendix B

(Informative appendix)

Salt deposition cycle tester (single box type)

The single-box salt deposition cycle tester is shown in Figure B.1.

Explanation.

1 --- blower (remove water droplets);

2--Atomizer;

3--sample;

4--solution tank;

5 --- solution pump;

6 --- blast motor;

7 --- flush nozzle;

8 --- control panel;

9 --- freezer;

10 --- air heater;

11 --- cooling device.

Figure B.1 Salt deposition cycle tester (single box type)

Appendix C

(Informative appendix)

Manual spraying salt deposition method

C.1 Equipment

The device for spraying the test solution shall include a clean air supply device, a pressure control device and a solution storage device.

The atomizing pressure should be controlled between 0.12MPa ~ 0.3MPa, and it is best to continuously control it at 0.15MPa.

C.2 Salt deposition method

The dried sample should be placed vertically in front of the sprayer.

The sample is 300 mm from the spray nozzle.

The test solution shall be sprayed within the expected time to allow salt to be deposited on the sample surface. An example of the relationship between salt deposition and spray time is

Figure C.1.

The average amount of salt deposition was calculated from the change in sample mass before and after salt spraying, and was accurate to 1 mg. Measurements should be made as soon as possible to prevent samples

The surface is dry.

Explanation.

A --- salt deposition (unit. grams, g);

S --- spraying time (unit. seconds, s).

Note. The sample is a zinc-plated steel sheet treated with a chromium passivation agent, with a size of 70mm x 70mm x 0.8mm. The mass concentration of the salt solution is 3.60g/L +/-

0.36g/L. The atomizing pressure is 0.15 MPa. The sample is 300 mm from the spray nozzle.

Figure C.1 Relationship between salt deposition and spraying time

Appendix D

(Informative appendix)

Recommended test period

Correlation between the corrosion of samples exposed to the marine environment (Okinawa, Japan), classified as C4 according to the corrosion level in ISO 9223,

Develop accelerated corrosion tests.

Representative data are as follows.

Table D.1 shows the correlation between exposure of stainless steel rusted areas to the marine environment (Okinawa, Japan) and exposure to the method A environment.

For stainless steel grade evaluation, the 13 cycles in Method A are generally recommended.

Table D.2 shows the exposure of the cold-rolled carbon steel sheet and the covered steel sheet to the marine environment (Okinawa, Japan)

Method B. Mass loss in two environm...