An investigation into microstructure and microstructural control of additive layer manufactured Ti-6Al-4V by electron beam melting.

An additive layer manufacturing (ALM) technique, electron beam melting, has been used for the production of simple geometries, from pre-alloyed Ti-6Al-4V powder. Microstructure, texture and mechanical properties achieved under standard conditions have been investigated, alongside numerical modelling of the electron beam and attempts to modify solidification through the addition of boron. Experimentation reveals an asymmetric electron beam which can be manipulated to produce different material responses. The electron beam has been used in this work, at its least powerful, as a means of preheating powder particles and, at its most powerful; to produce what is effectively a macro-scale electron beam weld. Numerical modelling and extraction of solidification parameters reveal that solidification occurs in the columnar region - columnar grains are observed experimentally and are a feature of the process. I Observed microstructures indicate a complicated thermal history that is capable of producing diffusion-less and diffusional transformation products. Electron backscatter diffraction (EBSD) and prior ~ grain reconstruction reveal a strong texture perpendicular to the build axis. Mechanical properties, tested over a range of build temperatures, are sensitive to temperature over the tested range of 625 - 700 °e. Attempts to disrupt columnar solidification via the addition of boron to Ti-6Al-4V, before subsequent EBM processing, were unsuccessful. Solidification remained in the columnar regime with no refinement in grain morphology observed

A Comprehensive Case Study of Macrosegregation in a Steel Ingot

This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s11663-015-0386-yA case study is presented that examines the macrosegregation and grain structure present in a 12-tonne steel ingot, which was cast for experimental purposes. Details of the casting procedure were well documented and the resulting ingot was characterized using a number of techniques that measured chemical segregation, shrinkage, and porosity. The formation of the porosity and segregation patterns is discussed in reference to the particular grain structure observed in the ingot. It is hoped that this case study can be used as a tool for the validation of future macromodels.This work was undertaken as part of a Project sponsored by Rolls-Royce Power Nuclear plc in collaboration with Sheffield Forgemasters International

A Comprehensive Case Study of Macrosegregation in a Steel Ingot

This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s11663-015-0386-yA case study is presented that examines the macrosegregation and grain structure present in a 12-tonne steel ingot, which was cast for experimental purposes. Details of the casting procedure were well documented and the resulting ingot was characterized using a number of techniques that measured chemical segregation, shrinkage, and porosity. The formation of the porosity and segregation patterns is discussed in reference to the particular grain structure observed in the ingot. It is hoped that this case study can be used as a tool for the validation of future macromodels.This work was undertaken as part of a Project sponsored by Rolls-Royce Power Nuclear plc in collaboration with Sheffield Forgemasters International