The change rule of powder properties of SS316L stainless steel powder after recycling is studied

and the evolution mechanism of powder morphology and particle size distribution is clarified. The results show that as the number of powder cycles increases

the particle size distribution of the powder becomes narrow and coarser

the apparent density and tap density of the recycled powder are improved to a certain extent

and the flowability of the powder is also improved comparing with the original powder

but the change trend of Hausner’s ratio is opposite to that of Hall’s flow rate. The surface chemical components of recycled powder particles are oxidized severely

and the ellipsoidal oxidation spots and metal vapor condensate are found on the surface of powder particles. In this study

the irregular particles in the recycled powder are divided into two categories: the first is laser-induced molten pool spatter particles

the second is gas entrainment induced particles

and the formation mechanism of the two kinds of irregular particles is described respectively. The results of this study emphasize that in the recycling process of raw materials

the oxidation of powder and the generations of irregular particles are unavoidable.In the future

more consideration should be given to the effects of irregular particles

vapor condensates and oxide particles on the quality of the processed parts.