The main factors of tungsten carbide knives is tungsten carbide blade welding method and process parameters when tungsten carbide blade brazing and welding body hardened. Tungsten carbide blade at high frequency brazing prone weld cracks, thus affecting the quality and life of tungsten carbide knives.
1. The heating rate
High frequency welding heating rate of welding quality, especially for generating blade weld cracks, has a very significant impact. If heated too fast, can not make carbide blade and the blade is fully preheated and quick access to the high temperature phase, the thermal conductivity of Invar alloy to be much larger than the heat transfer rate is much slower than steel, carbide while the blade and blade expansion at different speeds, coupled with the blade surface and the interior of the temperature too much, resulting in excessive stress leaving tungsten carbide knives weld cracking.
2. The cooling rate
Cooling rate after welding has a very significant impact on the weld cracking. After welding, the cooling process, due to the large difference in thermal expansion coefficient alloy steel cutter body and cemented carbide inserts and thermal conductivity, the blade itself there is a great residual stress and thermal stress of welding, if the cooling speed, forcing the blade sharp plastic deformation will cause the blade to crack.
In order to reduce post-weld cooling rate, temperature insulation measures may be appropriate. After the welding tool, the insulation material is placed slowly cooled in a certain temperature, or the use of temperature programmed furnace was slowly cooled better, thereby eliminating residual stresses that may arise in the blade cooling process, to avoid cracks. To improve the performance of tungsten carbide knives.
3. Other parameters of the problem
High-frequency welding method parameters typically include weld gap brazing, induction loop shape and size, solder, solder flux and other factors added. In addition to the heating rate and the cooling rate of the two main factors are still some gaps including brazing weld, shape and size of the induction coil, solder, a brazing flux is added and other factors, these factors affect the weld quality is also a minor factors, these factors must have an appropriate group with range, avoid adverse fluctuations would tungsten carbide knives quality factors.