Pretreatment method for hard solder on partial surface of magnesite product

Abstract

The invention relates to a preprocessing method for brazing on the partial surface of magnesium material, wherein, the preprocessing method includes two novel technologies including the magnesium alloy surface upgrading and processing technology without electronickelling and the technology for manufacturing special soldering flux to coordinate with a plurality of leadless tin alloy solders; the welding method adopts the process flow that the medium phosphorus (the content of phosphorus is 3-7 percent ) without electronickelling process is performed on the surface of the magnesium-alloy work piece at first, then the high phosphorus (the content of phosphorus is 7-12 percent) without electronickelling process is performed, and the tin welding process is performed finally.

Description

【Technical field】 [0001] The invention belongs to the technical field of magnesium alloy welding, and in particular relates to a pretreatment method for local surface brazing of magnesium materials. 【Background technique】 [0002] The properties of magnesium alloy workpieces are extremely sensitive to heat treatment. The reason is that the thermal expansion coefficient of magnesium alloys is 2 to 3 times higher than that of ordinary metals. If the heating is uneven, problems of deformation and internal stress will be left inside the magnesium alloy; It will also leave the problem of segregation and denaturation. Therefore, the traditional heat welding (welding temperature exceeds the melting point of the material) method is not suitable for magnesium alloy workpieces, and it is especially difficult to weld thin plates. In terms of thin plates, the best way is to consider cold welding (welding temperature is lower than the melting point of the material) to avoid the aforemen...

AI Technical Summary

Problems solved by technology

[0002] The properties of magnesium alloy workpieces are extremely sensitive to heat treatment. The reason is that the thermal expansion coefficient of magnesium alloys is 2 to 3 times higher than that of ordinary metals. If the heating is uneven, problems of deformation and internal stress will be left inside the magnesium alloy; It will also leave the problem of segregation and denaturation

Therefore, the traditional heat welding (welding temperature exceeds the melting point of the material) method is not suitable for magnesium alloy workpieces, and it is particularly difficult to weld thin plates.

In terms of thin plates, the best way is to consider cold welding (welding temperature is lower than the melting point of the material) to avoid the aforementioned shortcomings. There are not many previous efforts: Falke, et al. in US Patent 4,613,069, etc., use copper nickel The alloy is electroplated on the surface of the magnesium alloy, and then the magnesium alloy is cold-welded with a tin-lead alloy. This process does not take into account the corrosion of the flux to the magnesium alloy; in US Patent 4,925,084, Persson uses a local explosion method to weld the aluminum-magnesium alloy, and the aluminum alloy that can be used Magnesium alloys are limited to alloys with superplasticity, and are also limited by the shape and cost of the workpiece; Kujas uses stearic acid, palmitic acid, and oleic acid in US Patent 4,739,920 as The main component of flux, this process does not take into account the corrosion of flux to magnesium alloys

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