Friction stir welding method based on surface nanocrystallization treatment

Abstract

The invention provides a friction stir welding method based on surface nanocrystallization treatment. The friction stir welding method comprises the steps that firstly, the surface of a base material to be welded is ground and polished; supersonic particle bombardment surface nanocrystallization treatment is conducted, a nanometer layer with the thickness not lower than 50 micrometers is formed on the surface of the base material to be welded, and the average size of surface nanometer crystals is not greater than 50 nm; oil stains, generated after surface nanocrystallization, on the surface of the base material to be welded are removed with acetone, and then friction stir welding is conducted; trimmings on the upper surface of a joint are shoveled after welding is completed, and a transition zone is polished smoothly; and finally surface mechanical rolling is conducted on the surface of the friction stir welding joint. According to the friction stir welding method, the nanometer layer can be formed in the friction stir welding joint, the performance of weak links such as a thermo-mechanically affected zone in the welding joint is improved, the surface roughness of the welding joint is lowered greatly, the purpose of improving the comprehensive performance of the welding joint is achieved, and industrial application of the surface nanocrystallizaiton technology in the friction stir welding field is further expanded.

Description

technical field [0001] The invention relates to a friction stir welding method for high-quality welding of metal materials. Background technique [0002] Friction stir welding is a new solid-phase joining technology invented by the British Welding Institute. It can effectively avoid various defects such as pores and cracks caused by traditional fusion welding. It has energy saving and environmental protection, low joining temperature, small residual stress after welding and joint A series of advantages such as high performance can realize high-quality welding of high-strength aluminum alloys (such as 2××× series and 7××× series aluminum alloys) that are traditionally considered unweldable. The schematic diagram of the device is as follows figure 1 . Since its invention, it has received extensive attention. It is the connection technology with the shortest time span from invention to industrial application in the history of the world's welding technology development. It is k...

AI Technical Summary

Problems solved by technology

[0003] After friction stir welding of metal materials, the weld seam will be coarsened or remelted under the action of high temperature thermal cycle generated by friction stir, which will cause the thermal mechanically affected zone of the weld seam to become the weak link of the welded joint. , tensile strength, corrosion under stress and other aspects need to be improved urgently. At the same time, the surface roughness of the friction stir welded joint is very large, which further affects the comprehensive performance of the welded joint.

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