Method for brazing steel pipe and copper pipe

Abstract

The invention provides a method for brazing a steel pipe and a copper pipe. The method comprises the following steps of: a, applying a layer of paste QJ102 brazing powder to the brazing point on the surface of a steel pipe, wherein the surface of the steel pipe is galvanized; and b, heating the brazing point of the steel pipe and a copper pipe according to common brazing requirements, adding copper-phosphorus brazing filler metal onto the brazing point, and naturally cooling, wherein the copper-phosphorus brazing filler metal is a copper-phosphorus brazing filler metal in the National Standards of Peoples Republic of China-copper base brazing filler metals, the method breaks the rules to braze the steel pipe and the copper pipe by adopting the copper-phosphorus brazing filler metal (BCu93P-A, BCu93P-B, BCu91PAg and BCu88PAg), and each index of the brazed product can achieve the result of brazing by adopting a silver brazing filler metal after detection and is in accordance with national standard. According to the method, the brazing cost is greatly reduced.

Description

Technical field: [0001] The invention relates to the technical field of brazing, in particular to a brazing method for steel pipes and copper pipes used in air-conditioning heat exchangers. Background technique: [0002] At present, in the brazing industry, the brazing of steel pipes and copper pipes generally adopts the silver copper zinc, silver copper zinc tin or silver copper zinc cadmium in the publication number GB / T10046-2008, "National Standard of the People's Republic of China - Silver Brazing Materials" Brazing filler metals, while silver brazing filler metals have high silver content and are expensive at present; especially silver-copper-zinc-cadmium filler metals have been banned by the air-conditioning industry because they contain cadmium as a pollutant. [0003] Although the cost of brass solder is low, the brazing temperature is high, the operation is difficult, it is easy to melt the thin-walled copper tube, and the welding leakage rate is large. Phosphorus...

AI Technical Summary

Problems solved by technology

[0002] At present, in the brazing industry, the brazing of steel pipes and copper pipes generally adopts the silver copper zinc, silver copper zinc tin or silver copper zinc cadmium in the publication number GB / T10046-2008, "National Standard of the People's Republic of China - Silver Brazing Materials" Brazing filler metals, but currently silver brazing filler metals have high silver content and are expensive; especially silver-copper-zinc-cadmium filler metals have been banned by the air-conditioning industry because they contain cadmium pollutants

[0003] Although the cost of brass solder is low, the brazing temperature is high, the operation is difficult, it is easy to melt the thin-walled copper tube, and the welding leakage rate is large

Phosphorus-containing copper-based filler metals are recognized as being unable to braze steel and copper, because the welding is brittle, easy to leak, and difficult to weld

Images