Microstructure and property of H62 brass joints obtained by friction stir welding

The 6mm thick H62 brass plate was welded by friction stir welding and the microstructures and mechanical properties of the joints were investigated. Meanwhile, the potentiodynamic polarization and electrical resistivity of the joints were compared to the base metal, respectively. The results show that the welds have finer crystal grains under the thermal and mechanical force. The average grain sizes of weld nugget zone, thermo-mechanically affected zone and heat affected zone were 3.8 μm, 22.2 μm and 30.6 μm, respectively. The maximum measure value of weld hardness is in the nugget zone and the fracture of specimens occurred at the advanced side because of lower hardness. Many dimples that had different size can be observed on the tensile fracture surface by SEM. The corrosion potential of the weld was more positive than the one of the base material, and the corrosion current density was less than the one of the parent material. In addition the electrical resistivity of weld exceeds the base material.