Flux-cored silver solder with toughening alloy

Abstract

The invention discloses flux-cored silver brazing filler metal with toughening alloy. The flux-cored silver brazing filler metal comprises a silver base brazing filler metal skin and core powder, the silver base brazing filler metal skin is filled with the core powder, and the core powder is formed by mixing brazing flux, silver alloy and copper alloy. Sn, Ni, Si and other elements are added into the brazing flux in the form of intermediate alloy, when the concentration of the alloying elements of the brazing filler metal skin is low, it can still be guaranteed that the brazing filler metal skin has excellent processing performance, the brazing filler metal has good wettability and fluidity, meanwhile, weld strength, the low-temperature impact toughness and the anti-cracking ability are improved, and ductile-brittle transition temperature is lowered. On the premise of not changing the components of the skin, weld joints with different components can be obtained by flexibly adjusting the proportion of metal in the core powder. When a large-gap assembly is brazed, it can be ensured that the brazing filler metal has enough filler content. The brazing flux can be pre-added conveniently and efficiently, the advantages of being convenient to assemble in the brazing process, achieving automatic production easily, being low in cost and the like are achieved, and an automatic brazing process can be applied and popularized conveniently.

Description

technical field [0001] The invention relates to welding materials, in particular to a flux-cored silver brazing filler metal with a self-toughening alloy. Background technique [0002] Silver solder has a moderate melting point, good welding processability, and good strength, toughness, electrical conductivity, thermal conductivity and corrosion resistance. It is the most widely used type of brazing material. In recent years, my country's air-conditioning and refrigeration industries have rebounded from the bottom after experiencing the trough of the economic crisis in 2008. Especially in 2013, with the support of national urbanization construction, home appliances to the countryside, and subsidies for energy saving and benefiting the people, they quickly stabilized and rebounded. applications provide room for sustainable growth. [0003] The traditional brazing process is to use wire or strip brass brazing flux, or use gas flux or pre-coat the flux on the workpiece before h...

AI Technical Summary

Problems solved by technology

[0006] At present, the proportion of flux-cored solder in automatic welding is increasing, but when the content of tin, nickel, manganese and other elements in the existing flux-cored silver solder is high, there are processing difficulties. The powder flux covered with a predetermined proportion is easy to break during rolling and processing, and it is difficult to process it into a flux core solder

The melting temperature of silver-copper-tin solder with higher tin content can be reduced very low, but it is brittle. Experiments have proved that silver-copper solder has good ductility when the tin content is less than 12.5%, and the tin content is greater than 12.5%. %, the plasticity of the alloy decreases significantly, and hot embrittlement occurs at around 480°C. For example, the melting temperature of BAg45Cu35Sn20 solder is 550-600°C, and it can only be processed at 450-520°C. It cannot overcome its brittleness, so the tin content in silver-tin solder is generally not higher than 10%

In addition, due to the need to ensure that the solder has a certain filling amount when brazing components with large gaps, and when preparing the solder skin of the flux-cored solder, if the solder skin is too thick, it will increase the processing difficulty and also affect the strength of the flux-cored solder. Application of materials in large gap brazing