Metallurgical and mechanical modelling of Ti-6Al-4V for welding applications

Villa, Matteo (2016). Metallurgical and mechanical modelling of Ti-6Al-4V for welding applications. University of Birmingham. Ph.D.

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Abstract

Complex heat treatments and manufacturing processes such as welding involve a wide range of temperatures and temperature rates, affecting the microstructure of the material and its properties. In this work, a diffusion based approach to model growth and shrinkage of precipitates in the alpha + beta field of Ti-6Al-4V alloys is established. Experimental heat treatments were used to validate the numerical predictions of the model for lamellar shrinkage, whilst data from literature have been used to evaluate the numerical model for the growth of equiaxed microstructures. The agreement between measurements and numerical predictions was found to be very good. Experimentally-based approaches were used both to describe the growth of alpha lamellae and martensitic needles while cooling down from temperatures above the beta transus, and beta grain growth for temperatures remaining above the beta transus. Such models were coded in the commercial FE software Visual-Weld for the prediction of microstructure evolution during welding simulations. Experimental welding tests were carried out to validate the predictions. The metallurgical models developed were linked with a mechanical physically based model to predict the flow properties and the initial implementation of the coupled models in Visual-Weld is discussed.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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