GB/T 15260-2016Corrosion of metals and alloys - Test methods for intergranular corrosion of nickel alloys (English PDF)

3.1 Sampling and preparation

3.1.1

For the recommended sample of Method A, C and D, the total area is 500 mm2

~ 2000 mm2, the ratio of the area of the sample to the area of the two faces shall not be more than 20 %. The welding samples shall include welds, heat affected zones and base metals, both of which are not more than 13 mm.

3.1.2

The dimension of the recommended bending sample of Method B. the length is

80 mm ~ 100 mm, the width is 20 mm, the thickness is 3 mm ~ 4 mm (samples with a width or a thickness less than the recommended dimension shall be taken according to the actual dimension). Pipes with an outside diameter of not more than 40 mm shall be taken at 25 mm in length. In Method B, it shall take the original surface as the outer surface of bending.

3.1.3

The sample shall be taken in the direction of the forging, and the surface shall be as close as possible to the surface of the material in use. If necessary, the surface of the sample is allowed to be machined, and the surface roughness is generally Ra <=

0.80 µm.

3.1.4

When cutting the sample, it shall remove the deformed metal by grinding or machining before the test. The sample shall be prevented from overheating during machining.

3.1.5

The sample shall be degreased by non-chlorinated solvents, rinsed and dried before the test.

3.2 Sensitization treatment of samples

3.2.1

For samples require sensitization treatment before the test, the surface needs to be cleaned before the sensitization treatment, to remove carbon-containing lubricants, grease, etc. To obtain a clean surface, mild surface grinding or pickling shall be carried out, followed by washing with non-chlorinated solvents, rinsing and drying.

3.2.2

The sensitization system shall be negotiated by both supply and demand parties.

3.2.3

The sensitization treatment shall be carried out before the sample is finished.

3.2.4

For samples that do not require sensitization treatment, the test shall be carried out in a state where the final conditions of use are simulated. For alloy materials that need to be welded or heat-treated, they shall be treated as much as possible with the same treatment as the material being manufactured or used.

3.2.5

Before the test, remove the scale of the sensitized sample by grinding.

3.3 Test equipment

3.3.1 Test devices

Figure 1 and Figure 2 are two recommended test devices. Figure 1 is a ground flask with a capacity of 1 L and Soxhlet or Aster's condenser with at least four condensed

The precision of the analysis balance shall not be less than 0.001 g.

4.1 Scope of application

This method is suitable for the determination of the susceptibility of nickel alloys to intergranular corrosion in ferric sulfate (III) - sulfuric acid test solution.

4.2 Test solution

4.2.1 Preparation of 600 mL of test solution

POUR 400 mL of distilled or deionized water INTO the flask; ADD slowly 236 mL of sulfuric acid (excellent grade) as specified in GB/T 625 TO the flask (to prevent bruising).

4.2.2

WEIGH 25 g of ferric sulfate (excellent grade) and add to the sulfuric acid solution.

4.2.3

To prevent bruising, it is recommended to use debris of pure aluminum oxide to be added to the test solution.

4.2.4

INSTALL the condenser on the flask and pass through the cooling water; HEAT the solution to boil until all the sulfuric acid is dissolved.

4.2.5

It shall protect the eyes and wear rubber gloves in the operation. PLACE the test flask in a fume hood.

4.3 Test procedures

4.3.1

MEASURE the sample dimension (including the internal dimensions of all holes), accurate to 0.1 mm; CALCULATE the total exposed area.

4.3.2

WEIGH the sample, accurate to 0.001 g.

4.3.3

PLACE the sample on the glass bracket in the test solution. It is recommended that one sample be placed in a flask. Samples of the same grade can also be tested in the same flask, but the amount of test solution shall be ensured to be greater than

20 mL/cm2, but the samples shall not be in contact with each other.

4.3.4

The test shall be carried out continuously. See Table 1 for the recommended test duration and density constant of part of alloy materials.

Table 1 Recommended test duration and density constant of part of alloy materials

Alloy Test duration/h Density/(g/cm3) Grade Unified digital number

NS1101 H08800 120 8.03 e) test duration;

f) mass of the sample before and after the test;

g) corrosion rate and corrosion rate ratio of the sample.

5.1 Scope of application

5.1.1

This method is suitable for the determination of intergranular corrosion susceptibility of nickel alloys in copper - copper sulfate -16 % sulfuric acid test solution.

Determination of intergranular corrosion susceptibility associated with chromium carbide or chromium nitride precipitation.

5.1.2

This method may be used to evaluate the heat treatment system of the material delivery state and the effect of adding stabilizing elements (Nb, Ti, etc.), as well as to reduce the content of inter... […]