Friction Stir Welding of Dissimilar Materials: An Investigation of Microstructure and Nano-Indentation Study

摘要

Friction stir lap welding of aluminum and steel structures yields inhomogeneous microstructural changes, hooking defects and non-uniform layer of intermetallic compounds in the weld zones. These metallurgical changes and hooking defect affect the mechanical and metallurgical properties of the welds. In the present study, authors have quantified the mechanical properties of the weld regions, steel hook and inter-metallic which include hardness, elastic modulus, and stiffness by using lap shear tensile test and nano-indentation. Variations in the local mechanical properties at various locations of the welds have been investigated through a qualitative and quantitative study of microstructure size, the fraction of dynamic recrystallization and Inter-metallic compounds. Intermetallic compounds such as Fe2Al5, Fe4Al13, FeAl3Si2, and FeAl2Si have been found at the weld interface which has higher hardness (8.4-11.6 GPa) and elastic modulus (278-301 GPa) than the weld regions. Indentation depths on the IMC layers and the weld regions have also been studied to analyze the deformation behavior during indentation.