Effect of powder properties and heat treatment on microstructure evolution of selective laser melted titanium alloy

Abstract:

The effects of physical properties of powders on the quality of selective laser melted(SLM) components, deposition state and microstructure after heat treatment were studied using different particle size distribution of titanium alloy powder obtained by powder screening and mixing. The results show that the increase in the proportion of fine powder, powder median size decreased, fluidity decreases and the bulk density did not change significantly; the density of parts manufactured by three kinds of powder particle size was more than 99%, the surface roughness increases with the increase of fine powder; quantity of fine powder in 23%, the minimum porosity formed after deposition; the microstructure of cross section of primary grain, internal acicular martensite, the longitudinal section of the visible columnar crystal; heat treatment results show that the decomposition of martensite at 600-800℃, and alpha + beta layer thicker at 800℃, heat treatment should be strictly controlled the annealing temperature and time to avoid layers coarse and impact performance.

Key words:powders properties ; selective laser melteing; microstructure; heat treatment