GOST 21549-76

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  ГОСТ 21549-76

GOST 21549−76 Pike. A method of determining the erosion of the brazed material (with Amendments No. 1, 2)

GOST 21549−76*

Group B09

STATE STANDARD OF THE USSR

SOLDERING

A method of determining the erosion of the brazed material

Brazing and soldering.
Method for determination of erosion of parent material

Date of introduction 1977−01−01

The decision of the State Committee of standards of Ministerial Council of the USSR of February 5, 1976 N 347 the introduction installed from 01.01.77

Proven in 1986 by Decree of the state standard from 07.04.86 907 N validity extended till 01.01.92**
________________
** Expiration removed by the resolution of Gosstandart of the USSR from 15.08.91 N 1358 (IUS N 11, 1991). — Note the manufacturer’s database.

* REISSUE (April 1982) with Amendments No. 1, 2, approved in August 1981, April 1986 (IUS 10−81, 7−86).


This standard specifies the metallographic method for the determination of erosion when soldering and tinning, its depth.

The depth of erosion produced when selecting solder and material goods, development of technological process of soldering and tinning and change its parameters.

The standard does not apply to products made of thin film materials.

(Changed edition, Rev. N 2).

1. SAMPLING

1.1. Sections to determine erosion during soldering and tinning are made of solder or tin plated lap joint samples.

1.2. The number of test samples shall not be less than five for each mode and combination of materials and solder.

1.3. For products manufactured by any method of soldering, set the sample lap, the shape and size of which should match those in hell.1.

1 — base plate; 2 — upper plate; 3 — strip

Damn.1

The thickness of the lower and upper plates of the sample — (1,0…2,0) * 0.1 mm.

When the thickness of the brazed material greater than 2 mm allowed machining of the side plates, not subjected to solder to the desired thickness.

Note. In the case of determining the magnitude of erosion in the solder seam connecting the sintered hard alloy metal, plate thickness hard alloy 2 — (1,0…6,0)±0.1 mm.


(Changed edition, Rev. N 1).

1.4. For products manufactured by dip soldering and tinning, use of samples, the form and dimensions of which should correspond to those on features.2.

For precious and rare metals allowed the use of smaller sample thickness while maintaining uniformity of the gap during soldering.

1.5. Samples should be cut from the brazed material in any way, not causing changes in their structure.

(0,5…2,0)±0.1 mm; (0,5…2,0)±0.1 mm;

(0,5…2,0)±0.1 mm; (2,0 10,0.)±0.1 mm.

Damn.2

1.6. The samples marked by the batch number or the conditional index on a non-working part to the sample of wire attached tag for marking.

2. PREPARING FOR THE TEST

2.1. Preparing for the test specimen lap joint.

2.1.1. The thickness of each plate should be measured with a micrometer according to GOST 6507−78 not less than three places, with error no more than 0,01 mm.
________________
* On the territory of the Russian Federation GOST 6507−90. Here and hereinafter. — Note the manufacturer’s database.

The thickness of the plate should take the arithmetic mean of three measurements.

2.1.2. The method of preparing the sample surface, the shape and placement of solder and the size of the gap is adjusted in accordance with technological process of manufacture of a brazed product.

In the absence of regulated surface preparation the choice of preparation method and surface roughness — the results of tests 20485−75 GOST, GOST 23904−79 and of this standard.

Note. When laying the solder gap should be placed at a lower side of the upper plate.

2.1.3. The gap () between the plates should be set gaskets 3 — wire or strips.

Allowed to produce the gap by making a groove on one of the plates, as indicated in claim 1.5.

The shape and size of groove shall be as specified in the hell.3.

2.1.4. Plate is fixed in a predetermined position with the clamp or in any other way.

Limit deviation of the size …of±0.01 mm.

Damn.3

2.1.5. The gasket material and the retaining device when soldering should not melt independently or in contact with the sample material or solder.

2.1.6. The volume of solder for the soldering of the sample overlap should be 150% of the volume of the gap.

2.1.7. Ration samples that are installed in a horizontal position, should be carried out in a gas atmosphere, vacuum or flux modes used in the respective processes.

2.1.8. For temperature measurement should be applied thermocouples according to GOST 6616−74 and devices according to GOST 7164−78.

2.1.9. The working end of the thermocouple should be fastened in the center of the outer surface of one of the plates (see the devil.1) zachekanka, by spot welding or other method which provides reliable thermal contact with the sample.

The direct impact of the heat source for a thermocouple is not allowed.

2.2. Preparing to test samples from strip, tubing and wire.

2.2.1. The thickness of the strip or tube wall, the diameter of the wire before tinning should be measured with a micrometer according to GOST 6507−78 or with a microscope with an accuracy of at least 0,01 mm.

2.2.2. Surface preparation of the strip, pipe and wire according to claim 2.1.2.

2.2.3. The prepared strip, tube or wire must be immersed into the crucible with molten solder to a depth of not less than 20 mm. Lower end of the sample should not touch the bottom of the crucible.

The volume of the solder must be not less than 6 cm.

Notes:

1. Is not allowed the interaction of the crucible material with solder.

2. Each sample shall be immersed in a new batch of solder.

3. Strip, pipe and wire when tinning suspension technological hole or loop.

2.2.4. The process of tinning the sample should be carried out in a gas atmosphere, vacuum or submerged in the modes to be applied in the relevant technological processes.

2.2.5. Temperature measurement — in accordance with paragraph 2.1.8.

3. TESTING

3.1. For the manufacture of thin sections samples should be cut with a method specified in claim 1.5. The cutting plane is indicated on the devil.1 and 2.

3.2. A method of manufacturing thin sections not regulated.

3.3. The plane of the cone must be perpendicular to the solder or tin-plated surfaces of the sample. A blockage of edges is not allowed.

3.4. Identification of the structure of the solder connections on the socket should be chemical, electrochemical, or other methods depending on the chemical composition of soldered material and solder, providing the detection of the border of the solder joint.

The most common reagents for chemical etching of metallographic sections in the reference Appendix 1.

3.5. In the manufacture of thin sections and identification of their structure must not be damaged solder joints — spalling, burn-out, etching its components or a change in its structure.

3.6. Sections should be studied under a metallographic microscope.

3.7. On the solder lap joint samples should be measured a minimum thickness of each plate from the capillary area of the solder joint with a total chemical erosion with increasing 50−120and the maximum depth of the local chemical erosion of the throat and the capillary area of the solder joint with increasing 200−500. Measurement error the total chemical erosion — not more than 0.02 mm, the local chemical erosion is not more than 0.01 mm. the Diagram of the measurement given on features.4.

Damn.4

(Changed edition, Rev. N 1).

3.8. On tin-plated samples have to be measured for minimum thickness of the strip or tube wall, or the minimum diameter of the wire when you increase the 50−120and the maximum depth of the local chemical erosion with increasing 200−500. Measurement error the total chemical erosion — not more than 0.02 mm, the local chemical erosion not more than 0.01 mm.

4. PROCESSING OF THE RESULTS

4.1. The depth of chemical erosion should be determined in millimeters.

4.2 For each brazed sample overlap should determine the total chemical erosion and local chemical erosion of the plates in the fillet and in the capillary area of the solder joint.

4.3. The total chemical erosion of a brazed joint overlap equal to the difference in thickness of each plate before and after soldering () and ()

4.4. Local chemical erosion in the throat and in the capillary area brazed seam lap-joints of equal measured under the microscope the depth of local chemical erosion of the sample in these areas.

(Changed edition, Rev. N 1).

4.5. The total chemical erosion tinned strip, tubing and wire equal to half the difference of the strip thickness, the tube wall, the diameter of the wire before and after tinning.

4.6. Local chemical erosion strip, tubing and wire equal measured under the microscope the depth of local chemical erosion of the sample.

4.7. The amount of each type of erosion brazed material should be defined as the arithmetic average of the erosion of the established number of samples.

4.8. If the degree of dispersion of the test results of more than 20%, the failure of the thermocouple or detection Naropa more than 5% of the area of overlap tests must be repeated, the number of samples must match the number of invalid test results.

4.9. The test results of each sample should be recorded, the form of which is given in the mandatory Annex 2 to GOST 21548−76.

ANNEX 1 (reference). THE MOST COMMON REAGENTS FOR CHEMICAL ETCHING OF METALLOGRAPHIC SECTIONS OF BRAZED JOINTS

ANNEX 1
Reference

Notes:

1. The etching of the solder joint, you should first identify the structure of the solder joint.

2. Modes of etching are selected experimentally.


ANNEX 2 (Deleted, Rev. N 1).