Enhanced Fluidity of ZL205A Alloy with the Combined Addition of Al–Ti–C and La

The effects of Al–Ti–C and La on the fluidity of a ZL205A alloy after separate and combined addition were studied by conducting a fluidity test. The fluidity of the ZL205A alloy first increased and then decreased with the increasing addition of Al–Ti–C and La; it peaked at 0.3% and 0.1% for Al–Ti–C and La, respectively. The combined addition of Al–Ti–C and La led to better fluidity, which increased by 74% compared with the base alloy. The affecting mechanism was clarified through microstructure characterization and a DSC test. The heterogeneous nucleation aided by Al–Ti–C and La, the number of particles in the melt, and the evolution of the solidification range all played a role. Based on the evolution of the fluidity and grain size, the optimal levels of Al–Ti–C and La leading to both high fluidity and small grain size were identified.

Hot Tearing Evaluation and Contraction Behaviors of Four AA7xxx Alloys

The hot tearing susceptibilities (HTS) of some AA7×××alloys, AA7050, AA7055, AA7085 and AA7022 were evaluated with constrained rod casting (CRC). Thermal contraction behaviors during solidification were measured as well in a T-shaped setup. The results showed that alloys with HTS from high to low were AA7055, AA7085, AA7050 and AA7022. Zn content in 7××× aluminum alloys seemed to play a major role with respect to the HTS index. Remarkable differences could be seen on thermal contraction behaviors within solidification range for each alloy. The rate and amount of thermal contraction for AA7055 was most prominent, followed by AA7085 and AA7050, while contraction curve of AA7022 was very flat together with least amount of thermal contraction. There was a well consistency between the amount of thermal contraction and HTS. Despite complex interactions of many variables in the formation of hot tear, thermal contraction behaviors within solidification range could give a quick evaluation of hot tearing susceptibility.

Thixo Lateral Forging of a Commercial Automotive Spindle from LTT45 Steel Grade

The present paper is focused on the thixo lateral forging of a nearly 3 Kg commercial automotive spindle. A thixoforming cell has been implemented in the forming lab consisting on an induction unit, six-axes industrial robot for the handling tasks and a servo-mechanical forming press. A special tool has also been designed in order to use all the press capacity during the forming stage. First trials have been made using LTT45 steel. The usual material for this spindle fabrication is a CrMo alloyed steel (W-Nr 1.7225) employed in automotive components with high requirements on toughness. The selected thixoforming steel has been modified to have a wider solidification range and lower solidus temperature.