Brazing flux used for melt-brazing of aluminum alloy/stainless steel

Abstract

The invention relates to brazing fluxes used for welding, in particular to a brazing flux used for melt-brazing of aluminum alloy / stainless steel. The brazing flux is characterized in that the brazing flux is prepared by mixing and grinding powder of potassium tetrafluoroaluminate+potassium hexafluoroaluminate (KAlF4+K3AlF6) eutectic, potassium fluorosilicate, potassium fluoroborate, aluminum, zinc, tin and copper; the brazing flux comprises, by weight, 40%-60% of potassium tetrafluoroaluminate+potassium hexafluoroaluminate (KAlF4+K3AlF6) eutectic, 0-10% of potassium fluorosilicate (K2SiF6), 0-10% of potassium fluoroborate (KBF4), 10%-30% of aluminum (Al), 0-10% of zinc (Zn), 0-10% of tin (Sn), and 0-10% of copper (Cu); the sum of the weight percents of all the raw materials is 100%. According to the brazing flux, the good wetting spreading property of an existing brazing flux is maintained, and meanwhile, the texture of a connector is improved, and forming of brittle intermetallic compounds is reduced, so that the mechanical property of the connector of melt-brazing is improved, and finally dissimilar metal of the aluminum alloy and the stainless steel is connected reliably with high quality. The brazing flux further has the advantages that the melt-brazing process is relatively simple; the energy consumption and the cost of the raw materials are low; the residual quantity of the brazing flux is small after welding; and residues are easy to clean up.

Description

technical field [0001] The invention relates to a flux for welding, in particular to a flux for melting and brazing of aluminum alloy and stainless steel. Background technique [0002] Aluminum alloy / stainless steel composite structure has comprehensive characteristics such as light weight, high strength and corrosion resistance, so it is widely used in aerospace, automobile, shipbuilding and other fields. However, aluminum alloy and stainless steel have extremely low solid solubility and large differences in thermophysical properties, and brittle intermetallic compounds are easily formed during the welding process, which causes great difficulties in the connection of the two. [0003] In recent years, fusion brazing has become a popular research direction for the connection of aluminum alloy / stainless steel dissimilar materials. The essence of aluminum alloy / stainless steel fusion brazing is that molten aluminum and welding wire are combined with solid steel through interf...

AI Technical Summary

Problems solved by technology

These added components have auxiliary effects on removing the oxide film on the metal surface, improving the spreading and wetting of the solder, and increasing the interfacial activity. However, there are also problems in the aluminum / stainless steel fusion brazing process, the increase in the cost of component raw materials, and the increase in energy consumption. , especially it is difficult to significantly improve the structure and performance of brittle intermetallic compounds in the process of melting and brazing

In addition, the method of plating Cu, Ag, and Ni layers on the surface of stainless steel can better improve the state and distribution of brittle intermetallic compounds in the joint, but its overall cost is high and the process is complicated, so it is difficult to promote in actual industrial applications

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