A welding method for friction stir welding of dissimilar materials

Abstract

The invention relates to a stirring head for friction stir welding of a special material and a welding method. The stirring head comprises a shaft shoulder and a stirring needle which is arranged in the center of the bottom of the shaft shoulder and protrudes downward, wherein the shaft shoulder is made from mold steel; the stirring needle is made from a high strength alloy; during welding, an upper metal and a lower metal are stacked according to the technical demand; then, the stirring head is pressed down at a high speed; and when the stirring needle is about to penetrate through the uppermetal, the pressing speed is reduced and the stirring needle presses down at a low speed till welding is finished. Compared with the prior art, according to the compound stirring head provided by theinvention, the stirring needle and the shaft shoulder are matched, the shaft shoulder can be made from the steel which is relatively low in cost and relatively soft in texture, and only the stirring needle is made from the ultrahigh strength alloy which is relatively high in cost, so that the integral cost is lowered greatly, and the welding quality is not decreased; and in addition, in the firstwelding stage, a relatively high pressing speed is adopted for pressing, so that the time efficiency of integral welding is improved greatly.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a stirring head for friction stir welding of dissimilar materials and a welding method. Background technique [0002] Friction stir welding is a solid-phase welding technology invented in the UK in 1991, which is widely used in the connection of light metals such as aluminum and magnesium. It has many advantages that traditional welding methods cannot match, such as good material compatibility, good mechanical properties of joints, few defects, no need for shielding gas and solder, energy saving and environmental protection, etc. [0003] Use friction stir spot welding to connect two materials with large differences in properties, especially when one of the materials has a higher hardness, the stirring needle part of the stirring head is easy to wear out in long-term use. The current mainstream method is to use ultra-high Materials with high hardness, such as tungsten-rhenium a...

AI Technical Summary

Problems solved by technology

[0003] Use friction stir spot welding to connect two materials with large differences in properties, especially when one of the materials has a higher hardness, the stirring needle part of the stirring head is easy to wear out in long-term use. The current mainstream method is to use ultra-high Materials with high hardness, such as tungsten-rhenium alloy, tungsten-rhenium alloy, tungsten carbide-cobalt alloy, but the cost of making stirring head with these materials is very high. The mixing head will also be more worn, so the overall replacement cost is very high

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