This test method is applicable to the determination of tensile properties of various metal conductors (including rods) and bare wires of wires and cables. This test method is to subject a certain length of test piece to increasing tensile stress, usually until the sample breaks, and determine its breaking force and elongation after breaking. GB 4909.3-1985 Bare wire test method Tensile test GB4909.3-1985 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for bare wires
Tensile test
UDC621.815.14
620112
GB 4909.3--B5
The provisions of this standard are consistent with the provisions of international standards IEC 207, 208, 209 (1966), and refer to international standards ISO R956 (1969) and relevant BS standards.
1 Scope of application
1.1 This test method is applicable to the determination of the tensile properties of various thick conductors (including rods) and bare wires of wires and cables. 1.2 This test method is to subject a certain length of test piece to increasing tensile stress, usually until the sample breaks, and determine its breaking force and elongation at breaking.
2 Definitions and symbols
2.1 Gage length The specified length of elongation of the specimen measured at any instant during the test. In particular, the following definitions should be distinguished: bzxz.net
2.1.1 Original gauge length (L) The gauge length before the specimen is deformed. 2.1.2 Final gauge length (L,) The gauge length after the specimen has broken and the broken parts have been carefully aligned.
2.2 Maximum load (F) The maximum load to which the specimen is subjected during the test. 2.3 Tensile strength (α,) The maximum load divided by the original cross-sectional area of ​​the specimen, that is, the stress equivalent to the maximum load will be the permanent elongation LL of the gauge length after fracture. Expressed as a percentage of the original gauge length L. 2.4 Elongation at break (8)
3 Testing equipment
Tensile testing machine, the indication error is not greater than ± 1%. 4. Preparation of test specimens
4. 1 Solid conductor
4.1.1 Sampling Take three test specimens from one end of the sample on the appearance inspection grid. The length of the test specimen is the original gauge length plus twice the length of the jaw 1 change.
When sampling, the test specimen should be protected from tension, torsion, bending or other mechanical damage as much as possible. 4.1.2 Straightening The test specimen should be carefully straightened by hand. If necessary, the test specimen can be placed on a wooden pad and gently tapped with a wooden pad. When only tensile strength is measured, the test specimen does not need to be straightened.
4.1.3 Marking the gauge length Mark the original gauge length of 200mm in the middle of the straight test specimen. The marking method should not cause premature fracture of the test specimen. The marking line should be thin and clear. Gauge length error: +0.2mm for hard wire test specimens and ±0.5mm for soft wire test specimens. Non-circular cross-section conductors with larger widths can also be machined into test specimens with smaller widths. The size of the test piece can be found in GB228-76 "Metal Tensile Test Method".
Shou.2 Stranded conductor
National Bureau of Standards 1985-01-31 Issued
1985-12-01 Implementation
GB 4909.3-85
4.2.1 Sampling Three test pieces are cut from the samples that have passed the appearance inspection. The length should ensure that the effective length of the test piece between the two jaws meets the following requirements:
For nominal cross-sections of 50mm2 and below, it is not less than 0.5m; for nominal cross-sections of 50mm2 and above, it is not less than 5m. 4.2.2 Processing of test pieces Untie the strands at both ends of the test piece, separate and bend them into round hooks, clean them, and pass the cone end with low-melting alloy or resin porcelain. It can also be made by crimping or clamping. 5 Test steps
5.1 Hold the specimen in the jaws of the testing machine, and the marking line should be exposed at the jaws. After clamping, the position of the specimen should ensure that the longitudinal axis of the specimen coincides with the center line of the stretch. 5.2 Select the stretching speed
Soft copper specimens: not more than 300mm/min
Aluminum, aluminum alloy and hard copper specimens: not more than 100mm/min. 5.3 Start the testing machine, the loading must be smooth, the speed is uniform, and there is no impact. 5.4 When the specimen is stretched and broken, read and record the maximum load, taking three significant figures. Remove the test piece and carefully align the fracture, squeeze it, measure and record the final gauge length Lu°
6 Test results and calculations
6.1 The tensile strength is calculated according to the following formula, accurate to 1N/mmFe (N/mm2)
Where: Fm
Maximum load, N
Measured cross-sectional area of ​​the test piece, mm. Measure according to the provisions of GB4909.2--85 "Bare Wire Test Method Dimension Measurement". 6.2 The elongation at break is calculated according to the following formula,
When calculating, if the elongation is less than 5%, it is accurate to 0.1%, and if it is greater than or equal to 5%, it is accurate to 1%. 6.3 The test result is the arithmetic mean of the calculated data of 3 test pieces. 7 Precautions
7.1 During the elongation test, the fracture of the specimen should occur within the gauge length and be greater than 20mm from the marking line. If the distance between the fracture and the marking line is less than 20mm, and the elongation does not meet the requirements, another specimen shall be taken for retesting. Regardless of the fracture position, if the elongation reaches the specified value, the measurement is considered valid. 7.2 The elongation of specimens with a nominal diameter of 0.30mm or less can be taken as the difference between the distances between the two jaws before and after stretching. The jaw distance before stretching is the original gauge length.
Additional Notes:
This standard was proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Cable Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Shanghai Cable Research Institute of the Ministry of Machinery Industry and others. The drafters of this standard are Jianhua Mi and Musheng Wu.
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