Localized microstructure enhancement via Friction Stir Processing for die cast components

摘要

Friction stir processing (FSP) is an outgrowth of Friction stir welding (FSW) that locally manipulates the microstructure by imparting a high level of energy in the solid state resulting in improved mechanical properties. This study has shown that FSP can be implemented as a post-casting method to locally eliminate casting defects, such as porosity, which is generated by gas evolution during casting. Coarse second phases are broken into fine nearly equiaxed particles and uniformly distributed in the matrix. Moreover, grain refinement is obtained by dynamic recrystallization during FSP. This results in improved microhardness, tensile properties and fatigue properties of the cast FSP processed A206 alloy. In addition, FSP is a viable means to produce localized composite structures in cast Al components. Such improvements have important implications for manufactured components for a variety of automotive and other industrial applications. The convenience of FSP as a post-processing step that can easily be adapted during machining operation makes it very attractive to adopt. These results will be reviewed and discussed.