Beta-Forging of Titanium Ti6Al4V Alloy Powders: Phase Evolution Modeling and Strain-Rate Relation

Abstract:

Ti6Al4V is one of the best known and studied titanium alloy for the optimization of the thermo-mechanical treatments. The Ti-forgings represent a valid opportunity for the aircraft manufacturers and designers because of high tensile and fatigue properties. Nevertheless the total-cost reduction of the manufacturing-chain requires both: the ability to manufacture nearer-shaped components by mean of forging-process-modification and less final machining (material scraps). Even if Ti6Al4V is a well known alloy, any process parameters modification introduced still represents a challenge for the metallurgists and manufacturers.The idea, at the base of the present work, has been the feasibility study of forging experiments in the Beta-field using Hot Isostatic Pressed (HIP) powders billets. The preliminary compression tests has been carried out in laboratory and the results have been validated in a industrial Forging-Workshop. The deformation behavior of Ti6Al4V HIPped powders during high temperature deformation tests is reported. Laboratory compression and tensile tests have been coupled with relaxation tests in order to achieve robust data about strain rate sensitivity m-coefficient and activation energy Q.The obtained results have been fitted for the assessment of generalized exponential deformation law. The final result is a “Dorn model” that takes into account and compares all the results from the three different deformation tests: compression, tensile and relaxation. The deformation tests have been carried out at temperatures ranging from 1173 K up to 1373 K and strain rate from 0,01 s^-1 up to about 1 s^-1, trying to describe the high temperature complex shape forging operations.Finally the recorded deformation curves has been used for modeling by means of FEM DeformTM code the deformation process and microstructure evolution by means of an Avrami type law.

• Periodical: Key Engineering Materials (Volumes 622-623)
• Pages: 15-26
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.622-623.15
• Online since: September 2014
• Authors: Claudio Testani, Antonino Squillace, Antonello Astarita
• Keywords: Dorn-Law, Powder Forging, Ti6Al4V Beta Forging

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