GOST R 50708-94
GOST R 50708−94 (ISO 9649−90) Wire. Test method for alternating torsion
GOST R 50708−94
(ISO 9649−90)
Group В79
STATE STANDARD OF THE RUSSIAN FEDERATION
WIRE
Test method for alternating torsion
Wire. Reverse torsion test
ISS 77.040.10
77.140.65
OKP 12 0100
Date of introduction 1996−01−01
Preface
1 DEVELOPED AND SUBMITTED by the Technical Committee TC 146 «Hardware"
2 ADOPTED AND put INTO EFFECT by the Resolution of Gosstandart of Russia from November 8, 1994 N 266
3 this standard contains the full authentic text of international standard ISO 9649−90 «metal Materials. Wire. Test alternating the twist» with additional requirements that reflect the needs of the national economy
4 INTRODUCED FOR THE FIRST TIME
5 REISSUE
1 Scope
This standard specifies a method for determining the ability of metallic wire of diameter from 0.3 to 10 mm subjected to plastic deformation under alternating torsion. This test is conducted to detect surface and internal defects in the wire.
Additional requirements that reflect the needs of the economy, in italics.
2 Normative references
GOST 1545−80 Wire. Test method for torsion
3 Symbols and definitions
Wire designations are shown in figure 1 and in table 1.
Figure 1
Table 1
| Marking |
Definition | Unit |
| The diameter of the round wire |
mm | |
| Length of tested part of the specimen (distance between clamps) |
mm | |
| The number of twists in one direction |
- |
4 the essence of the method
A sample of wire is twisted a specific number of times 360° around its axis in one direction and the same number of times 360° in the opposite direction.
5 testing Equipment
5.1 the Grips should be solid to ensure the rigidity and resistance to abrasive wear and must be installed on the machine so that during the test they were on one axis and subjected to sample the effects of a bending force.
5.2 the Machine shall be so designed as not to prevent change of the distance between the grips during the test.
5.3 One of the grippers of the machine should rotate around the axis, the other must not have angular deviations, with the exception of cases when such deviation is necessary to measure torque.
5.4 the distance between the hooks should be adjusted depending on the length of the specimen.
5.5 Testing machine should be so designed as to subject the sample it was possible to make the necessary tensile stress in accordance with 7.2.
5.6 Machine must provide the ability to change the direction of torsion.
6 the Procedure for preparation of samples for testing
6.1 cut the wire that is used as a sample, should be straight.
6.2 If necessary, edit the sample manually, or, if possible, with a hammer of wood, plastic or copper on the flat surface of the same material.
6.3 When editing the surface of the wire must not be damaged and the test sample shall be subjected to torsion.
6.4 Wire with sharp local curvature should not be used as a test sample.
6.5 If in the relevant standard there is no special clause, the distance between the grips (nominal) shall be those specified in table 2.
Table 2
In millimeters
Nominal diameter of wire |
The distance between the grips (nominal) |
0,3 |
200 |
1 |
100 |
5 |
50 |
* 50 | |
1
57 test Procedure
7.1 Tests shall be carried out at a ambient temperature from 10 to 35 °C.
Arbitration trials conducted at a temperature of (25±5) °C.
7.2 the Sample in the grips so that its longitudinal axis coincides with the axis of the grips and to remain straight throughout the test. If there is a special dogovorennosty in the relevant standard, this may be achieved by application to the sample of wire constant tensile stresses sufficient for straightening of the sample, the value of which shall not exceed 2% of the nominal value of the temporary resistance.
7.3 After securing the test sample in the car one of the grips should rotate at a speed not exceeding one revolution per second for wire diameter less than 5 mm and 0.5 revolution per second for diameter of wire 5 mm or more. The number of revolutions in one and opposite directions must be established in the relevant standard on the wire.
One twist of the take a turn of 360°.
After the test, the surface of the sample between the grips and check visually if there is a special clause in the relevant standard.
7.4 the Absence of visible defects is reasonable to assume that the sample passed the test.
7.5 If the failure of the specimen occurred in the seizure of the car or near the grips (at least 2) and the sample did not maintain the required number of twists, the result of this test is not considered. The test should be repeated on another sample selected from the same coil (coil), a sample of which collapsed.
8 test report
8.1 the test report shall contain:
a) the number of this standard;
b) characteristics of the test sample;
in) diameter sample;
g) the method changes the sample;
d) test conditions (for example, the length of tested part of the specimen, tensile stress);
e) test results.
