Additive manufacturing titanium components with isotropic or graded properties by hybrid electron beam melting/hot isostatic pressing powder processing

摘要

A methodology has been demonstrated to consolidate Ti-6Al-4V powder without taking it to the liquid state by novel combination of the electron beam melting additive manufacture and hot isostatic pressing processes. This results in improved static mechanical properties (both strength and yield) in comparison to standard EBM processed material. In addition, the ability to generate microstructurally graded components has been demonstrated by generating a component with a significant change in both microstructure and mechanical properties. This is revealed by the use of electron backscattered diffraction and micro hardness testing to produce maps showing a clear distinction between materials consolidated in different ways. The variation in microstructure and mechanical properties is attributed to the different thermal history experienced by the material at different locations. In particular, it is found that the rapid cooling experienced during EBM leads to a typical fine α lath structure, whereas a more equiaxed α grains generated by diffusion is found in HIP consolidated powder.