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Nickel Aluminum Bronze (NAB) alloys have been widely used in different kinds of machine parts where the superior resistance to corrosion and erosion in saltwater is needed. In this work, mechanical properties at high temperatures and microstructures of a NAB alloy were investigated. First, NAB specimens were prepared as an as-cast ingot and were subsequently heat-treated at 675°C for 6 hours in order to improve microstructure and mechanical properties. The mechanical properties at high temperatures in form of the plastic flow curves of the NAB alloy were characterized by a deformation dilatometer. The NAB samples were compressed at high temperature and rapidly cooled down to room temperature. The deformation temperatures of 825°C, 850°C and 900°C, a strain rate of 0.01 s-1, and a maximum compression strain of 0.4 were considered. The influences of the temperature on flow behavior of the NAB alloy were investigated. The plastic stress-strain curves at different temperatures were compared with regard to the rate of material strain hardening and softening. It was found that the compression stresses decreased with increasing temperatures. Additionally, the resulted hardness and microstructures of the alloy after forming at high temperatures were analyzed.

Advanced High Strength (AHS) steels have been increasingly applied in the automotive industries due to their distinguished mechanical properties. Microstructures of these steels play an important role and are designed by constituent phases with distinct characteristics. AHS steels exhibit sophisticated damage mechanisms that complicate the prediction of material formability. In this work, Ductile Crack Initiation Locus (DCIL) was developed for describing failure behavior of dual phase steel sheet. A hybrid experimental and numerical analysis was used to determine the DCIL. Tensile tests of various sample geometries were experimentally carried out and crack initiation occurred during forming was identified by the Direct Current Potential Drop (DCPD) method. Then, FE simulations of the corresponding tests were performed to evaluate local stress triaxialities and equivalent plastic strains of the critical area. The damage curves for both crack initiation and localized necking were obtained. Additionally, the von Mises, Hill48 and Yld2000-2d yield criterion were defined in the calculations in order to examine effect of yield model on the resulted curves. To verify applicability of the damage curves, Nakazima test of uniaxial sample was taken into account.

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