What are the reasons for the desoldering of tungsten steel strips?

       ① The brazing surface of tungsten steel has not been sanded or polished before welding. The oxide layer on the brazing surface reduces the wetting effect of the brazing filler metal and weakens the bonding strength of the weld.

② Desoldering can also occur due to improper selection and use of the flux. For example, when borax is used as the flux, the raw borax cannot effectively deoxidize due to its high water content. As a result, the solder cannot well wet the surface to be brazed. , and desoldering occurs.

③ The correct brazing temperature should be 30-50℃ above the melting point of the brazing filler metal. Desoldering will occur if the temperature is too high or too low. Excessive heating will cause oxidation in the weld. The use of zinc-containing solder will make the weld blue or white. When the brazing temperature is too low, a relatively thick weld will be formed, and the inside of the weld is full of pores and slag inclusions. The above two conditions will reduce the strength of the weld, and desoldering is easy to occur when sharpening or using.



④ During the brazing process, the slag discharge is not timely or insufficient, so that a large amount of flux slag remains in the weld, which reduces the strength of the weld and causes desoldering.