Silver free copper-base brazing filler metal used for braze welding of stainless iron/copper/stainless steel

Abstract

The invention relates to silver free copper-base brazing filler metal used for the braze welding of stainless iron / copper / stainless steel. The brazing filler metal comprises the following element components in percentage by weight: 5.0-7.0 P, 1.0-10 Sn, 0.1-2.0 Si, 0.1-1.0 Zr, 0.05-0.5 La and the balance of Cu. The silver free copper-base brazing filler metal is applied to the high frequency induction pressure braze welding for accomplishing the large area composite braze welding of dissimilar metal, such as stainless iron / copper / stainless steel, by one time, the welding seam shearing strength taub is higher than or equal to 100 MPa, the cost of the brazing filler metal is only one fifth to one fourth of Ag Cu Zn Sn or Ag Cu Zn Sn Cd, and the silver free copper-base brazing filler metal is applicable to the large-scale production of ferromagnetic double-bottom pans.

Description

technical field [0001] The invention relates to a silver-free copper-based solder for brazing, in particular to a silver-free copper-based solder for stainless iron / copper / stainless steel brazing. Background technique [0002] In recent years, the application of dissimilar metal brazing has become more and more extensive. For example, a stainless steel pot with a ferromagnetic double bottom used in an induction cooker is combined with a layer of copper plate for uniform heat and a layer of ferromagnetic iron on the bottom of the pot by brazing. The production process of the 430 stainless steel plate involves large-area composite brazing of 430 stainless steel (commonly known as stainless steel) / copper / 304 stainless steel. When brazing, high-frequency pressure brazing technology is used to complete the stainless steel / copper / stainless steel three times at one time. Large-area composite brazing of two heterogeneous materials, the brazing temperature is 750-800 °C. Due to the ...

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Problems solved by technology

[0003] The P and Sn in the silver-free CuPSn series solder can greatly reduce its melting temperature, and can make this series of solder have excellent fluidity and wettability. The brazing temperature is 750-800 ° C. The brazing temperature is similar, but because this series of solder contains P, Sn and other elements, it will form brittle intermetallic compounds with Cu and Fe. When brazing stainless iron / copper / stainless steel composite brazing, although copper and stainless steel Between weld shear strength τ b ≥100MPa, but the shear strength of the weld between stainless iron and copper is too low (τ b ≤50MPa)