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  • Essay / texture - 818

    Polycrystalline materials exhibit very high tensile elongations under certain circumstances, such as high temperatures, low stresses, etc. generally called superplastic materials. In industry, particularly in the aeronautics and automotive sectors, we are capable of producing complex shapes and curved parts using this technique. [1]The minimum microstructural and operational requirements for superplastic flow have been well established. The grain size should be less than 10 micrometers and the operating temperature should be greater than 0.5 Tm, where Tm is the melting temperature. Thus, during superplastic forming, grain growth must be restricted in order to improve the superplastic property. [2] Historically, the superplastic property observed even from ancient ages. Examples of this include the use of Damascus steels from 300 BC and the use of Wootz steels in ancient India. In 1912, Bengough achieved an elongation of 163% for brass and in 1928, Jenkins reported an elongation of 300% for Cd-Zn and Pb-Sn alloys. After this, in 1934, Pearson achieved a very high tensile elongation of 1950% for the Pb-Sn eutectic alloy [Langdon]. In 1945, the structural superplasticity of Zn, Al alloys was observed by Bochvar and Sviderskaya. After this work, a number of superplastic systems were discovered, such as aluminum, copper, aluminum-silicon, copper-magnesium, and tin-lead. Backofen, Turner and Avery did their research on superplasticity in near-eutectoid zinc-aluminum alloy and postulated a phenomenological relationship linking stress and strain rate [2,3,4]. Two types of superplasticity are : Structural superplasticityEnvironmental superplasticityConventional metal forming dies are very expensive due to its hardness to create the necessary plastic deformation. Cost savings can be achieved in the middle of the paper......eys, N Ridley, “In situ observations of microstructural evolution during deformation of Supral 100”, Materials Science Forum Vols. 447-448 (2004) Pp 381-386[78] MT Perez-Prado, TR Mcnelley, Scripta Materialia, Vol. 40, no. 12, p. 1401-1406, 1999[79] MT Perez-Prado, MC Cristina, OA Ruano, G Gonza Lez-Doncel, Materials Science and Engineering A244 (1998) 216-223[80] PL Blackwell, PS Bate, Metall. Trans. A 24 A (1993) 1085.[81] KA Padmanabhan, J Hirsch, K Lucke, J Mater. Sci. 26(1991) 5309.[82] Y Huang, J. Mater. Sci. Technol., 2012, 28(6), 531-536[83] Liu, DJ Chakrabarti, Acta Mater. 44 (1996) 4647.[84] TR Mcnelley, ME Mcmahon, “Evolution of microtexture and grain boundaries during microstructural refinement processes in SUPRAL 2004,” 28 (September 1997), 1879-1887.[85] F. Li, WT Roberts, PS Bates, Acta mater. Flight. 44, no. 1, p... 217-233, 1996