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The aim of the present experimental study was to investigate improvement of the toughness and strength of grey cast iron by reinforcing with steel fibres. The carbon content of the steel fibres was chosen to be sufficiently low that graphite flakes behaving as cracks were removed by carbon diffusion from the cast iron to the steel fibres during the solidification and cooling stages. To produce a graphite free matrix, steel fibres with optimum carbon content were used and the reinforced composite structure was cast under controlled casting conditions and fibre orientation. Three point bend test specimens were manufactured from steel fibre reinforced and unreinforced flake graphite cast iron and then normalising heat treatments were applied to the specimens at temperatures of 800 and 850uC. The fracture toughness and strength properties of the steel fibre reinforced material were found to be much better than those of unreinforced cast iron. The microstructures of the composite at the fibre-matrix transition zone were examined.

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In this work the rolling process and properties of a 6.35-μm twin-roll casting AA8079 aluminum alloy foil was analyzed. First, the 8-mm-thick sheets were produced with a twin-roll casting technology. This product was annealed and cold rolled to a 6.35-μm foil with suitable processing conditions. The mechanical tests and microhardness measurement was applied to specimens derived from all the foil-rolling process stages. On the other hand, the specimens' surface roughness and the surface structure are visualized with an atomic force microscope and an SEM. The microstructural investigation is realized with an optical microscope and XRD. The von-Misses total effective strain was calculated by determining the incremental work for all of the cold-rolling cycle. The alloy showed very low ductility in the tensile tests because of the second-phase metastable intermetallic particles such as Al3Fe. The maximum elongation at the breaking value was measured for 256-μm-foil as 4.5 %. On the other hand, the alloy did not show any significant strain hardening after the cold rolling during the plastic-deformation stages. Keywords: aluminum foil, cold rolling, twin roll casting V delu je bil analiziran postopek valjanja in latnosti 6,35 folije iz AA8079 aluminijeve zlitine, ulite med dvema valjema. Najprej je bil izdelan 8 mm debel trak po postopku ulivanja med dvema valjema. Trak je bil primerno`arjen in hladno zvaljan v 6.35 μm folijo. Iz vseh stopenj procesa valjanja so bili vzeti vzorci na katerih so bile dolo~ene mehanske lastnosti in izmerjena mikro trdota. Poleg tega je bila hrapavost povr{ine in struktura povr{ine vizualizirana z mikroskopom na atomsko silo (AFM) in iz SEM. Preiskava mikrostrukture je bila izvr{ena s svetlobnim mikroskopom in z rentgensko difrakcijo (XRD). Za dolo~anje stopnjujo~ega dela, med celotnim ciklom hladnega valjanja, je bila izra~unana celotna von-Misses efektivna napetost. Zlitina je pokazala zelo nizko duktilnost pri nateznih preizkusih zaradi vsebnosti delcev sekundarne metastabilne intermetalne faze Al3Fe. Maksimalni raztezek pri poru{itvi je bil pri 256 μm debeli foliji 4.5 %. Po drugi plati pa zlitina ni kazala nobenega ob~utnega napetostnega utrjevanja med posameznimi fazami plasti~ne deformacije. Klju~ne besede: aluminijeva folija, hladno valjanje, ulivanje med dvema valjema