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Abstract: In this paper, a dislocation-based model based on the rate-sensitive crystal plasticity is proposed for the prediction of forming limits diagrams (FLD) without assuming an initial geometry imperfection (the M–K approach). The misorientation of pairs of chosen crystal grains inside and outside the narrow band is assumed to be responsible for the initial formation of the band and its subsequent deterioration into localized necking. Analytical expressions for the calculation of forming limit strains are derived for several pairs of crystal grains with ideal orientations, such as Goss, Cube, Copper and Brass to evaluate the influence of microstructure on forming strain. The analysis demonstrates the feasibility of deriving and constructing the FLD of a polycrystalline sheet metal from a knowledge of the misorientation distribution of grain orientations. [Copyright &y& Elsevier]

Abstract: In this study, the right-hand portion of the forming limit diagram (FLD) of a strain rate-sensitive FCC metal sheet with different combinations of two texture components, (cube component) and (copper component) orientations and dislocation hardening effect at meso level, was predicted. Unlike the Marciniak–Kuczynski (M–K) model, no surface grooves in the sheet were assumed in the calculation. Because of the non-uniformity of microstructure in the thermal-mechanically processed sheet, narrow bands of grains with a similar orientation are assumed to exist instead. These bands behaved like a single crystal and deformed differently from their neighboring grains. The result from the simulation at the meso level was compared with two experimentally measured FLDs of a direct chill (O-temper) and continuous cast (H-temper) Al sheets. [Copyright &y& Elsevier]

Abstract: Hot band of an AA5182 Al alloy produced by a continuous cast (CC) method was heat treated at 400°C and two heating rates, 0.65°C/min for 3h in an air furnace and 833°C/min for 15min in salt bath annealing, respectively. It was found that rapid heating led to a much smaller, more equiaxed and uniform grain structure, and a stronger cube texture than slow heating. The cube texture in the CC hot band annealed at the rapid heating rate was equivalent to that found in the direct chill (DC) cast AA5182 Al alloy hot band. Tensile, earing cup and bending tests were conducted on the CC hot band before and after heat treatments and on the DC hot band for comparison. The mechanical isotropy of the CC hot band was significantly improved after both the heat treatments and that it was comparable to that of the equivalent DC hot band within the rolling plane. The microstructure and mechanical properties of the CC hot band after annealing were comparable to those of the DC hot band. [Copyright &y& Elsevier]