The Brazing Programs of Tungsten Carbide and Steel
The brazing technique right or not for tungsten carbide tools plays very important role ti influence brazing quality .The heating speed takes apparently influence on the brazing quality .Too quick heating process would lead to crack or temperature-ununiform of the cemented carbide ,however ,if overheating also results of surface oxidization and make the toughness low .Parts of cemented carbide brazing allowable heating speed as following .
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Length of Tungsten Carbide Parts
(mm)
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YG8
|
YT5
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YT15
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YT30
|
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Allowable Heating Speed in Brazing/℃·s-1
|
|
Below 20
20～40
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80～100
20～30
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60～80
15～20
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50～60
12～15
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30～40
10～12
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When braze cemented carbide tool, it is the basic condition that uniformly heat the shaft and tungsten carbide cutting inserts. If the heating temperature on cemented carbide inserts is higher than the shaft ,the melted brazing alloy will wet cemented carbide inserts but not on shaft ,the joint toughness will be impaired, meanwhile ,when cut the tungsten carbide along with the welding layer ,the brazing alloy would be destroyed ,but departed with the cemented carbide ,in addition the milling marks would be found on the welding layer. On the contrary, if heating temperature is too quick and the shaft temperature is higher than cemented carbide, the opposite phenomenon emerged.
The place order and mutual position of brazing flux ,brazing alloy and tungsten carbide play direct influence on the welding quality .The correct place methods is :to put the brazing alloy on the cutter groove, sprinkled with brazing flux and then place tungsten carbide ,meanwhile to sprinkle a layer of brazing flux along the side welding seam of tungsten carbide top. By this way ,it is much easy to control the brazing temperature and reduce extra brazing alloy adhered on the welding seam.
