Brazing joints generally use the form of sheet overlap and sleeve embedding. In this way, the joint surface between weldments can be increased to make up for the insufficient strength of the solder and ensure the bearing capacity of the joint. This type of joint is also convenient for controlling the gap of the joint. The proper gap can make the solder evenly distributed in the joint and achieve a good brazing effect. The gap of the brazed joint is generally 0.05 to 0.2 mm. The bearing capacity of the brazed joint is related to the size of the joint interface.Therefore, lap joints and kits are generally used for brazing to make up for the lack of brazing strength.Classification brazing is to use a metal with a lower melting point than the base metal as the brazing material. After heating, the brazing material melts, and the weldment does not melt. The liquid brazing material wets the base material, fills the joint gap and diffuses with the base material, and welds the weldment Connected firmly.According to the difference of the melting point of the solder, soldering is divided into soldering and brazing.
Soft soldering: The solder has a melting point of less than 450 ° C and a lower joint strength (less than 70 MPa). Soft soldering is mostly used for welding conductive, gas-tight and water-tight devices in the electronics and food industries. Soldering with tin-lead alloy as the solder is commonly used.Brazing: The melting point of brazing filler metal is higher than 450 ° C, and the joint strength is higher (greater than 200 MPa). Brazed joints have high strength, and some can work at high temperatures. There are many types of brazing filler metals. The filler materials based on aluminum, silver, copper, manganese and nickel are widely used. Aluminum-based solders are often used for brazing aluminum products. Silver-based and copper-based solders are often used for brazing of copper and iron parts. Manganese-based and nickel-based solders are mostly used for welding stainless steel, heat-resistant steel and high-temperature alloy parts that work at high temperatures.