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By certification 
The character for tungsten wire:
The resistivity of tungsten wire is 5.3*10^-8. Tungsten has a high melting point, high resistivity, good strength and low vapor pressure. It is the best material for making incandescent filaments among all pure metals. But tungsten is hard and brittle and it is difficult to process. When the current passes through the tungsten wire and is heated to a certain temperature, the resistance value of the tungsten wire also increases to a certain value (generally, the resistance value of the metal wire increases with temperature). The resistance of this object should be 1370℃-2000℃ at normal temperature, but the resistance value will change when the length of the cross-sectional area of the tungsten wire changes.
The different chemical composition for tungsten wire:
Grade |
W1 |
W2 |
W content min,% |
≥99.95 |
≥99.92 |
Total impurity elements max,% |
≤0.05 |
≤0.08 |
Each element max,% |
≤0.01 |
≤0.01 |
The sag performance of φ0.4mm tungsten wire should meet the requirements of the following table:
Description |
WAL1 |
WAL2 |
Sagging value △h/mm |
≤4.0 |
≤8.0 |
Residual creep elongation /mm |
≤2 |
≤4.0 |
Tungsten wire tensile strength standard:
d μm |
Lower limit of ultimate tensile strength of 200mm wire segment |
|
N/mg |
N/mm2 |
|
5≤d≤12 |
0.9316 |
3578 |
12≤d≤26 |
0.8826 |
3389 |
26≤d≤36 |
0.8532 |
3276 |
36≤d≤40 |
0.7943 |
3050 |
40≤d≤45 |
0.7649 |
2937 |
45≤d≤55 |
0.7061 |
2711 |
55≤d≤112 |
0.6669 |
2561 |
112≤d≤140 |
0.6472 |
2485 |
140≤d≤200 |
0.5884 |
2260 |
Tungsten wire tensile test method
d μm |
≤30 |
＞30~100 |
＞100~200 |
Test speed mm/min |
50~70 |
80~100 |
130~150 |
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