The vacuum brazing process

The vacuum brazing process

Brazing temperature is the most main technical parameters of vacuum brazing, conclude that the vacuum brazing temperature is the important basis of the selected the melting point of solder and heat treatment of the brazing standards. Vacuum brazing temperature should be higher than the melting temperature of solder, appropriate to reduce the surface tension of the liquid solder, improved wet and caulking, and make the solder and parent metal energetic effect each other, the strength of the joint progress. At the same time, appropriate temperature is higher than the melting temperature of solder and set aside to meet space, also can prevent due to inaccurate temperature control device, workpiece temperature uneven may cause solder melting bad faults. But brazing temperature can be harmful, it may cause solder high vapor pressure elements evaporation, parent metal grain grew up or burnt, and far effect and cause of solder and dissolution, brittle compound layer and intergranular into such questions, make joint function decline, and may be serious weaken the function of the parent metal.
Generally speaking, the vacuum brazing temperature should be higher than the liquidus temperature of the solder 20 ~ 60 ℃, but on different solder, need solder itself above the liquidus temperature scale is different, sometimes even need to drill under the below the liquidus temperature of the solder
Welding. Solder on strong and parent metal effect each other, because of its branch in the process of caulking attacks constitute a very big change and new alloy, concluded that the brazing temperature should be made up of brazing seam in new alloy on the basis of the melting point. Solder on melting temperature scale wide, because above the solidus temperature for liquid phase, and must have liquidity, so the brazing temperature can also be selected below the liquidus temperature of the solder. About eutectic reaction brazing and soldering temperature only in eutectic reaction temperature slightly.
Thinking to the functions of the parent metal for vacuum brazing welding thermal cycle, the influence of brazing temperature pick it necessary to think about the impact on the function of parent metal, brazing shall be in the parent metal attack intense temperature below that at which grain growth or burnt. Drafting of brazing temperature still need harmony with standards of heat treatment after brazing. Brazing temperature can be selected and material, for example, the temperature of the solid solution treatment temperature, and can choose integration of brazing, heat treatment technology, soldering heat preservation after the completion of direct cooling by heat treatment requirements, within a heat cycle end brazing and heat treatment technology at the same time. During the heat treatment after brazing, selection of heat treatment temperature remelting is best not to make solder attack.