Chapter 5 - Characterization of FSP by electrical conductivity

This chapter presents a new technique for characterization of microstructures produced by solid state processing as Friction Stir (FS), Friction Stir Processing (FSP) or Friction Stir Welding (FSW), based on electrical conductivity measurements. This characterization technique has shown to be an expedite method to assess the microstructural variations along the different material processing zones. The electrical conductivity can be correlated with the hardness with a good spatial resolution, and the the two measuring techniques are complementary from the point of view of the phenomena and the area under analysis. In fact, electrical conductivity depends on the electron mobility, while hardness depends mostly on plastic deformation. On the other hand, hardness indentations can be of some micrometres, while the area under analysisis typically about 2 or 4 mm. The chapter also presents the fundamentals and the factors governing the electrical conductivity, the measuring approaches and some experimental results.