Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions
CLEMSON UNIV SC
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A critical assessment is carried out of the microstructural changes in respect of the associated reductions in material mechanical properties and of the attendant ballistic-impact failure mechanisms in prototypical friction stir welding FSW joints found in armor structures made of high-performance aluminum alloys including solution-strengthened and age-hardenable aluminum alloy grades. It is argued that due to the large width of FSW joints found in thick aluminum-armor weldments, the overall ballistic performance of the armor is controlled by the ballistic limits of its weld zones e.g., heat-affected zone, the thermomechanically affected zone, the nugget, etc.. Thus, in order to assess the overall ballistic survivability of an armor weldment, one must predictidentify welding-induced changes in the material microstructure and properties, and the operative failure mechanisms in different regions of the weld. Toward this end, a procedure is proposed in the present study which combines the results of the FSW process modeling, basic physical-metallurgy principles concerning microstructureproperty relations, and the fracture mechanics concepts related to the key blastballistic-impact failure modes. The utility of this procedure is demonstrated using the case of a solid-solution strengthened and cold-worked aluminum alloy armor FSW-weld test structure.
- Metallurgy and Metallography
- Fabrication Metallurgy