GOST 28057-89
GOST 28057−89 (ISO 6509−81) Alloys copper-zinc. Method of determining resistance to bestintown
GOST 28057−89
(ISO 6509−81)
Group B59
STATE STANDARD OF THE USSR
ALLOYS COPPER-ZINC
Method of determining resistance to bestintown
Copper and zinc alloys. Method of determining resistance to dezincification
AXTU 1709
Date of introduction 1990−07−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
3. INTRODUCED FOR THE FIRST TIME
4. The period of examination 1995
The frequency of inspection 5 years
5. The standard fully conforms to the international standard ISO 6509−81
6. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Item number |
| GOST 9.302−88 |
6.2 |
| GOST 4167−74 |
3.5 |
| GOST 6709−72 |
3.6 |
| GOST 18300−87 |
3.7 |
| GOST 25336−82 |
3.3, 3.4 |
7. REISSUE
This standard specifies the research method of determining the resistance of the copper-zinc alloys (brass) bestintown in fresh or salt waters.
This method may be used as a control.
1. THE ESSENCE OF THE METHOD
The method consists in maintaining the samples in a solution of dichloride of copper with subsequent investigation of the microstructure.
2. SAMPLES FOR TESTING
2.1. Sampling of copper-zinc alloys (hereinafter referred to as alloys) is carried out in a way that eliminates the change in material properties.
2.2. From each batch presented for testing is taken at least three test specimens.
2.2.1. In the manufacture of samples of cast or wrought alloys of at least one test specimen taken from the area with the smallest cross-section and at least one from the area of greatest cross section.
2.2.2. In the case of tests of alloys with a specific fibre direction, depending on the production method and the drawing or rolling in rod or sheet, test specimens with fibers in both directions — parallel and perpendicular to the direction of deformation.
2.3. The surface area of the sample should be about 100 cm. In the case that the size of the part or the cross-sectional area of the tested prefabricated alloy small to provide the required for the testing of surface area, it is the largest possible area.
3. EQUIPMENT, REAGENTS, SOLUTIONS
3.1. The test installation with a thermostatic regulated water or oil bath ensures that the temperature (75±5) °C (Fig.1).
1 — heating device; 2 — oil or water bath; 3 — polymer film are secured using elastic cord; 4 — beaker containing a solution of copper dichloride; 5 — sample for testing
Damn.1
3.2. Microscope metallographic aggregate, for example the brand of METAM-P1 for the study of the microstructure of test specimens.
3.3. A glass chemical glass with GOST 25336 covered in plastic film (e.g. polyethylene), reinforced elastic cord, or other insulating non-metallic material.
3.4. Desiccator, according to GOST 25336.
3.5. Copper dichloride according to GOST 4167, 1% solution, freshly prepared: 12.7 g of copper dichloride is dissolved in water and the volume was adjusted to 1000 cm.
3.6. Distilled water according to GOST 6709, or water of equivalent purity.
3.7. Rectified ethyl alcohol according to GOST 18300.
3.8. Phenolic resin or other non-material with similar properties to the fill samples.
4. PREPARATION FOR TESTING
4.1. The samples should be soaked in phenolic resin, and subjects the surface polished by using wet sanding paper with grain size 500 and above (DWG.2).
1 — phenolic resin or equivalent material; 2 — polished test surface; 3 — sample
Damn.2
4.2. Test surface of the samples directly before the test, purified ethyl alcohol.
4.3. The samples are placed in a beaker containing a solution of dichloride of copper, so that test surface were in a vertical position at a distance of not less than 15 mm from the bottom of the glass. Then on top of the glass place the plastic sheeting and fix it.
Required for testing the volume of the solution taken from the calculation (250) cm
100 mm
test sample surface.
5. TESTING
5.1. Beaker with the samples was placed in a temperature-controlled bath. During the test, the glass must be maintained at a temperature (75±5) °C.
Different brands of alloys should not be tested simultaneously in the same beaker.
5.2. Samples experiencing continuously for 24 h. after this period the samples are removed from the beaker, washed in water, rubbed with alcohol and dried in air.
6. PROCESSING OF TEST RESULTS
6.1. The study of the microstructure of samples should be conducted as soon as possible after the test. Before the study of the microstructure of the samples should be in the desiccator.
6.2. Each test sample should be cut at a right angle to the test surface. From the obtained samples produce sections according to GOST 9.302 for metallographic studies.
The total length of the cone should be at least 5 mm.
If the dimensions of the test sample make this impossible, the incision should be made so that to provide the maximum possible common length.
6.3. Cone made from each test sample, examined in the metallographic microscope. Thus it is necessary to determine the maximum depth value Obeschanie.
6.4. If metallographic study observed edge effect, i.e. the greatest depth of obeschanija located along the line of boundary between the material to fill the specimen and the brass, the maximum depth of obeschanija should be determined at a sufficient distance from the interface.
6.5. The allowable depth of obeschanija establish standards and specifications for material.
7. PRESENTATION OF RESULTS
A report on the results of the tests must contain:
the name of the product;
grade;
the number of samples tested and the total surface area;
the length of the studied section;
increase, used for metallographic study;
the maximum depth of Obeschanie (if necessary, average depth of obeschanija and the nature of its distribution).
