UBC Theses and Dissertations

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UBC Theses and Dissertations

Quantification of the heat transfer during the plasma arc remelting of titanium alloys Ji, Shiwei


Plasma-arc cold hearth melting (PAM) is an important technology used in the melting process for titanium alloys. Compared to the more common, electron beam cold hearth re-melting process, PAM allows an inert gas environment which significantly reduces the evaporation rate of alloying elements. To develop a better understanding of the effects of the plasma torch in the PAM process, a numerical model is being developed. However, this model requires an accurate description of the torch heat flux distribution. This research presented in this thesis focused on developing and verifying an inverse heat transfer analysis methodology to characterize the heat flux distribution from a plasma torch. A test block trial was conducted with in an industrial scale plasma arc furnace to measure the temperature history in a test block during heating and cooling. Following the trial, the test block was sectioned to get the liquid pool profile. The distribution of heat flux calculated from the inverse analysis assumed a Gaussian-like distribution, decreasing radially from the centerline to the edge of the block. Predictions for temperature history and liquid pool profile are in good agreement with the measured results from the experiment. Sensitivity analysis was performed to find some key factors that influence the prediction.

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