UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

EDX investigation of evaporative losses during the EB melting of SS316 Ritchie, Mark Thomas

Abstract

Changes in chemical composition due to evaporative losses during the EB (electron beam) melting of SS316 have been studied via x-ray analysis. A technique based on EDX has been developed to acquire, process, and interpret x-ray spectra in the UBC EB melting furnace. The present work consists of a series of experiments which correlate evaporative losses, and liquid surface composition to x-ray spectra for a number of different processing conditions. The parameters studied were beam voltage, beam power, and beam focus for two different mould types each with different fluid flow characteristics. An empirical relationship between measured x-ray intensities and surface composition is presented for the four major alloying elements in SS316( Mo, Cr, Fe, and Ni) and is considered to be accurate within ±1.5 at.%. The liquid surface.composition was found to be equal to the bulk liquid composition at the centreline, and to be depleted in Cr toward the edges. This relationship, however, does not hold for highly focussed, high power beams in the ceramic mould. In addition to the experiments, a numerical model was developed to predict the heat transfer and fluid flow within the molten pool for the experimental conditions. It was found that variations in beam power, and surfactant levels can have a significant effect on the evaporation and mixing characteristics in the pool when the electron beam is highly focussed.

Item Media

Item Citations and Data

Rights

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.