Research Progress of Submerged Friction Stir Processing for Magnesium Alloy

As a new severe plastic deformation processing technology, friction stir processing (FSP) has a very broad application prospect in microstructure modification of materials, preparation of fine - grained superplastic materials and improvement of comprehensive properties of materials. Compared with the specimens processed by normal friction stir processing (NFSPed), the grain sizes of the specimens treated by submerged fiction stir processing (SFSPed) were smaller, the microstructure was compact and uniform, and the microhardness, tensile rate and wear resistance were all greatly improved. Moreover, the specimens treated with double - pass submerged friction stir processing had smaller grain sizes, more compact and uniform microstructures and higher tensile rates than that treated with single - pass submerged friction stir processing. In this paper, the technical characteristics of submerged fiction stir processing were reviewed and the evolution of microstructure and mechanical properties of magnesium based alloys after FSP under different processing conditions were compared. At the same time, the research progress and deformation mechanism of superplasticity of magnesium alloys processed by submerged fiction stir processing were introduced, and furthermore, its industrial application was prospected.