Experimental Study On ZL101 For Reheating And Micro-forward-extrusion

As an advanced metal forming technology, micro-forming technology plays a very important role in micro-parts manufacturing. Obvious size-effects in material flow, yield stress, flowing stress differed from macro-forming technology will limit the micro-forming technology extensive using. Therefore, to research and develop micro-forming technology has profound theoretical meaning and wide applicable perspective.Based on the research and development of micro-forming in domestic and aboard, in this paper, the micro-formability of semisolid ZL101 alloy is studied by using experiments for reheating and micro-forward-extrusion.The micro-die for experimental study was designed and manufactured. The heating device and the temperature controlling system were redesigned. Taguchi experiment for reheating and micro-extrusion was done and the feasibility of micro-forming process was validated. Relationship between the forming temperature, extrusion diameter, ratio and the micro-formability of semisolid metal was studied with the results as below.1)The maximum extrusion pressure(σ_p) affected much by forming temperature is lower in semisolid forming than in hot forming process under the same extrusion ratio.2) Size-effect related to forming dimensions seems to exist in the reheating process. The part with extrusion ratio 400 was successfully formed through thixo-forming process. 3) The P_m /S₂ seems to be linear with extrusion ratio in semisolid forming while non-linear in hot forming and both of them increases with extrusion ratio. The ratio of the maximum extrusion pressure and the extrusion area ( P_m/S₂) increases with the decreasing of extrusion diameters.The microstructure evolvement based on semisolid ZL101 alloy during reheating process was discussed in this paper. Some rules were summarized based on the results. The temperature for extrusion is a key factor in affecting the microstructure since it can change the microstructure of the eutectic crystals; The grains become larger and the grain boundaries become more apparent under the extrusion diameter of 0.5㎜ compared with the other larger extrusion diameters.The results of this paper are of great importance in the process design, die design and application of new materials, which also verified the vested research findings.