FEM Study of Superplastic-Like Forming of Ti-6Al-4V Alloy

Abstract:

A superplastic-like forming (SPLF) process involving the use of hot drawing along with blow forming is studied here. The hot drawing stage helps in enhancing the formability and in fast forming the metal sheet into a hollow shape with desired amount of material draw-in. During the blow forming stage, gas pressure was applied onto the pre-formed part to complete the forming process at a targeted strain rate. Ti-6Al-4V sheets have been successfully formed by this process at 800 °C in 16 min. In this paper, finite element modeling (FEM) was used to demonstrate the effects of each stage (hot drawing and blow forming) during SPLF. A plasticity model based on tensile test data was adopted as a material model for simulation. The pressure cycle which was predicted from the simulation has been used in the process to maintain the sheet forming at an average strain rate (e.g. 10^-3, 5×10^-4 and 10^-4 s^-1. Experimental measurements, i.e. material draw-in and thickness distribution, were used to compare and validate the results from simulations. The validated simulations have shown the capability of the model to be used for the forming process. The influences of varying process parameters, such as drawing stroke, blank-holder force, friction coefficient and pressure cycle, were investigated by the simulations. It was found that the punch geometry and drawing stroke played significant roles on the thickness uniformity of the final part, from which an optimized hot-drawing system that could result in minimum thinning has been designed by FEM.

• Periodical: Materials Science Forum (Volumes 783-786)
• Pages: 607-612
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.783-786.607
• Online since: May 2014
• Authors: Jun Liu*, Mei Ling Guo, Ming Jen Tan, Beng Wah Chua
• Keywords: Finite Element Modeling (FEM), Sheet Forming, Superplastic Forming, Ti6Al4V

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