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RESEARCH PRODUCT

Towards ductilization of high strength 7XXX aluminium alloys via microstructural modifications obtained by friction stir processing and heat treatments

Lv ZhaoLv ZhaoFlorent HannardA. OrekhovA. OrekhovAude SimarHosni IdrissiHosni IdrissiMatthieu Baudouin LezaackJérôme AdrienArttu MiettinenArttu MiettinenArttu Miettinen

subject

Equiaxed crystalsFriction stir processingMaterials scienceAlloyIntermetallicchemistry.chemical_element02 engineering and technologyengineering.material030226 pharmacology & pharmacy[SPI.MAT]Engineering Sciences [physics]/Materials03 medical and health sciences0302 clinical medicineAluminiumFormabilityGeneral Materials ScienceComposite materialDuctilityMicrostructureCrack propagationPhysicsDuctilizationAluminium alloysFriction stir processing (FSP)021001 nanoscience & nanotechnologyMicrostructurechemistryengineering0210 nano-technology

description

Abstract High strength 7XXX aluminium series reach exceptional strength, higher than all other industrial aluminium alloys. However, they suffer from a lack of ductility compared to softer series. This work presents a procedure to improve the ductility of 7475 Al alloy in high strength condition, reaching a true fracture strain of 70% at full 500 MPa T6 yield strength. Using friction stir processing (FSP) and post-FSP heat treatments, 100% of industrial rolled material T6 yield stress is maintained but a 180% increase in fracture strain is measured for the processed material. This ductility improvement is studied by in-situ synchrotron X-ray tomography and is explained by the reduction of intermetallic particles size and the homogenization of their spatial distribution. Furthermore, the microstructure after FSP shows equiaxed refined grains which favour crack deviation as opposed to large cracks parallel to the elongated coarse grains in rolled plate. These results are paving the way to better formability and crashworthiness of 7XXX alloys.

yearjournalcountryeditionlanguage
2021-12-01
10.1016/j.mtla.2021.101248https://hal.archives-ouvertes.fr/hal-03483518