Microstructure and Mechanical Properties of 7000 Series Al Alloy via Tiny-Molten-Pool Solidification Forming

Abstract:

As the grains of 7000 series Al alloy prepared by traditional casting method are usually quite coarse, and there exists serious segregation of composition and structure in the alloy, a new forming process for high-alloying alloy is in urgent need. Here we demonstrate a new method called tiny-molten-pool solidification forming to improve the above mentioned problems. In detail, the alloy powder was melt by the plasma and then deposits on the base plate. 7075 Al alloy bulk specimens with the size of about 200 mm × 8 mm × 4 mm were prepared and the effects of homogenizing treatment, cold rolling, T6 heat treatment for the alloy were studied. The results show that there were no oxide film inclusions in the single-pass multi-layers specimen prepared by AC tiny-molten-pool solidification forming, and the microstructure was homogeneous; The grains were homogeneous and mainly equiaxed grains with a uniform size of about 20 μm, which were much smaller than that of traditional casting 7075 Al alloy; After the homogenization treatment (470 °C × 48 h), most of the net-shape eutectic structure in the alloy is re-dissolved. After cold rolling with a total deformation of 60%, the alloy became compact as the stomata were compressed. The hardness of the alloy was HV183.51 after T6 heat treatment (480 °C × 2 h + 120 °C× 15 h). The micro-molten-pool solidification forming is feasible for the forming of bulk 7000 series Al alloy.

• Periodical: Materials Science Forum (Volume 850)
• Pages: 664-670
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.850.664
• Online since: March 2016
• Authors: Qi Zhao Shen, Jing Ye Jiao, Ai Chao Cheng, Ren Fei Guo, Tie Tao Zhou*
• Keywords: 7000 Series Al Alloy, Mechanical Properties, Micro-Molten-Pool Solidification Forming, Microstructure

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