Process-property-geometry correlations for additively-manufactured Ti–6Al–4V sheets
Abstract
This study presents results and statistical analysis of more than 300 mechanical tensile testing and their associated microstructure, microhardness, porosity, and elemental analysis for additively-manufactured Ti–6Al–4V sheets. Square sheets of 84 mm with thicknesses ranging from 0.5 mm to 1.6 mm are fabricated using direct metal laser sintering (DMLS) and traditionally-manufactured sheets are used for the benchmark experiments. The effect of thickness, orientation, distance from free edges, and height and their correlation to material microstructure and thermal history as dictated by DMLS process parameters are investigated. First, a method is developed to differentiate the specimen geometry effect on mechanical properties from the effects of material/manufacturing process, allowing specimen geometry-independent study of the thickness effects on DMLS-manufactured sheets. The results show that the tensile strength linearly decreases by decreasing the thickness while there is no statistically significant variation in elongation at break. The tensile strength increases as the orientation angle of the specimens increases to 30°–45° followed by decreasing to the vertically-oriented specimens; the reverse of this behavior is observed for elongation at break. Furthermore, the tensile strength slightly decreases by increasing the height till ~40 mm followed by a more severe decrement at higher heights. Finally, no significant variation of tensile strength is observed by variation of the specimen distance from the free edges. Moreover, the microhardness variations with respect to thickness and height are studied. These observations are correlated to the porosity volume fraction variation and their elongation direction, prior β grain width variation, and their relationships to the thermal history of the sheets during the DMLS process, β nanoparticle volume fraction, martensitic α’ decomposition to α+β and α” orthorhombic structure, and Oxygen content variation.
Publication Title
Materials Science and Engineering A
Recommended Citation
Fotovvati, B., Etesami, S., & Asadi, E. (2019). Process-property-geometry correlations for additively-manufactured Ti–6Al–4V sheets. Materials Science and Engineering A, 760, 431-447. https://doi.org/10.1016/j.msea.2019.06.020
