Mechanical properties of B206 aluminium alloys with additions of iron and silicon were studied to investigate the combined effect of these additions on tensile strengths and ductility. Properties are highly influenced by the iron to silicon ratio and the nominal concentration of the single elements. The best properties were obtained with both a ratio close to one and low concentrations of iron and silicon. Present experimental results show that it is possible to multiply by two or three the present limit of 0?1 wt-%Fe in these alloys at natural aging (T4) and still obtain the minimum of 7% elongation required by the automotive industry. At artificial aging (T7), it will be very difficult however to reach the 7% elongation with y0?2 wt-%Fe and 0?2 wt-%Si, while this seems impossible with y0?3 wt-%Fe and 0?3 wt-%Si. It was found that macrosegregation of Cu in the gage section of the ASTM B108 test bars is responsible for an enrichment of 0?8-0?9 wt-% of this element in the test zone. This has produced microstructures saturated in Cu with little Al 2 Cu phase remaining after the solution heat treatment. Owing to the low amount of this phase and the round shape of the particles, the remaining Al 2 Cu phase did not have a significant impact on the ductility. One benefit of working with a Cu saturated microstructure is that one can estimate the true temperature of the solution heat treatment by conducting a post-analysis of Cu content in the dendrites. This should be helpful to reduce the variability in properties and to improve the temperature distribution in heat treating furnaces.

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Solidification of B206 aluminum alloys with additions of iron and silicon was studied to investigate their combined effect on the formation and precipitation of intermetallics, particularly Fe-rich phases. Iron is precipitated mainly by either (CuFe) or (MnFe) phases, or both depending of the iron and silicon content, as well as the cooling rate. It was found that in alloys having up to 0.3wt% Fe, the precipitation of (CuFe) phase can be largely suppressed if the ratio Si/Fe is close to 1 and the cooling rate is moderately high. The low mobility of the large facets of the (CuFe) platelets is likely the cause limiting the amount of this phase, especially when the iron atoms have the possibility to be captured by another phase, in this case, the (MnFe) phase.

Hot tearing of B206 aluminum alloys with additions of iron and silicon was studied with constrained mould casting (CRC) to investigate the combined effect of these additions on hot tear resistance. Susceptibility to hot tearing was found to increase gradually with iron content when the conditions were favourable to the formation of the (FeCu) phase. Additions of silicon with a Fe/Si mass ratio ≤ 1 and rapid cooling rates, which together promote the (MnFe) phase at the expense of the (FeCu) phase, were found beneficial to the hot tearing resistance. Hot Tearing Sensitivity (HTS) of the alloys were evaluated with a new index defined to reflect the compliance of the cracked specimens. This index showed an excellent qualitative agreement with the Katgerman's hot tearing index (HCS), providing that one defines the temperature where inadequate feeding starts to be the temperature where 2% of the interdendritic volume is occupied by intermetallic phases. Examinations of the tear surfaces and crack profiles revealed that a premature crack opening created by insufficient healing correlates well the explanations based on the theoretical hot tearing index. The deleterious effect of iron on hot tearing was demonstrated on alloys having a coarse grain microstructure having Ti contents below or equal to 0.01wt%. Above this limit, fine grain microstructures were obtained and the influence of iron was not strong enough to have a significant impact on the castings produced.

a b s t r a c tTo obtain the T832 material behaviour, 6063-T4 tubes need to be cold drawn before artificial aging to enhance their mechanical properties. Since a high area reduction is required, multiple drawing passes are generally necessary to avoid fracture of tubes during the drawing process. These several steps need a time consuming process which could be reduced by optimization. The optimization of the tools geometry has been done through a finite element model with the objective of reducing the maximum stress level to draw tubes in one pass. Based on the optimum design, a new tool was built and acceptable accordance was observed between experiments and numerical results.Crown