The simulation for damage of metal powder compacts during forming
The main models of describe metal powder compacting are introduced in this paper. Based on a new model derived from Lee's metal powder compacting model and plastic theory for porous material, the scent of damage status of two-level flanged metal powder compacts during forming is simulated and the damage state and cracking process of compacts in different load process are followed up.
Stage 1 Compaction Behaviour of Tool Steel Powder Under Die Pressing
Abstract The stage 1 compaction behaviour of tool steel powder under die pressing was studied. The effects of friction between the powder and the die wall were also investigated under different die pressing modes. The e1astop1asticconstitutive equations based on the yield functions by Fleck et al. and by Shima and Oyane were implemented in a finite element programme to simulate die compaction processes. Finite element calculations were compared with experimental data for densification and density distributions of tool steel powder under single and double action die pressing. Finite element calculations using the yield function by Fleck et al. agreed better with experimental data than those by Shima and Oyane. PM/0775
Joint strength of aluminum ultrasonic soldered under liquidus temperature of Sn–Zn hypereutectic solder
Abstract In order to obtain high-strength aluminum joints, ultrasonic soldering of 1070 aluminum was conducted under liquidus temperature of Sn–Zn hypereutectic solder. A device for ultrasonic soldering was assembled, which propagated ultrasonic vibrations in a direction perpendicular to joining surfaces. This device joined 1070-Al using quasi-melting Sn–Zn hypereutectic solder without using any artificial spacers. The strength of the solder joints was evaluated by tensile tests. The optimum joining conditions were determined, and the effects of solder compositions and soldering temperature on the joint strength and the solder layer thickness were examined. In this ultrasonic soldering process, the highest tensile strength was obtained for the solder joints fabricated at 220 °C for the Sn–23Zn and Sn–40Zn solder compositions. The joint strength was equivalent to that of 1070-Al heat treated at 220 °C. The sound joints were obtained at 300 °C using Sn–82Zn solder, the liquid phase volume fraction of which was theoretically only 0.24. The present work also revealed that the thickness of retained solder layer in the joint after ultrasonic soldering could be estimated. Accordingly, ultrasonic soldering under the liquidus temperature of Sn–Zn hypereutectic solder could be a spacer-free soldering method to obtain high-strength aluminum joints.