On 2018-08-08 14:48:54
Influence of brazing gap on brazing quality
The size of brazing gap has a great influence on the capillary caulking of solder, the density of solder joint, and even the strength of solder joint. When other process conditions are determined, the joint with the maximum strength can be obtained by selecting the minimum feasible gap. At this time, the capillary effect is significant, and the liquid metal is easy to fill the whole street gap so as to obtain the joint with less void defects. The shear resistance of the joint is the best.
Brazing relies on capillary force to make filler metal fill the gap. The size of the gap greatly affects the density of brazing and joint strength.
If the gap is too small, due to the uneven contact surface, it is difficult for the solder to flow in, slag inclusion and incomplete penetration are formed in the solder joint, resulting in the decrease of joint strength; if the brazing gap is too large, the capillary effect of the gap will be weakened, the solder can not fill the gap, and the density of the joint will be damaged, and the strength of the weld will be reduced. Only by ensuring a reasonable street space, can the capillary function be carried out smoothly, so as to obtain the best effect.
In the actual production, most of the welding is between different materials. In the design, in addition to the factors such as whether to use flux, the degree of interaction between base metal and solder, the fluidity of solder and the position of the street, the influence of expansion coefficient on the street gap under the brazing temperature must also be considered.