Effect of recycling powder on the fatigue properties of AM Ti6Al4V

Additive manufacturing (AM) techniques offer significant advantages with respect to conventional manufacturing (CM) ones such as the realization of highly customized components both dealing with their geometry and their mechanical properties. An important advantage of AM is the significant reduction of wasted material with respect to CM. However, AM techniques, such as the powder bed fusion, involve during the production an amount of powder higher than that needed to realize the final component even if the excess of powder in not interested by the melting process and can be recovered and used again. However, it is obvious to expect that the new powder feedstock that include this reused powder has different morphology characteristics since it has been subjected to a thermal history in the building chamber. These changes in the material feedstock can results in a different morphology of defects and consequently in different fatigue properties even for AM components realized with the same design geometry and same process parameters. In the present study, the effect of the use of recycled powders on the fatigue properties of AM Ti6Al4V has been investigated by considering specimens realized from virgin powder and recycled powder. The specimens fracture surfaces are investigated to correlate the effect of the powder on fatigue properties with the effect on the defects' morphology.