An investigation into the recycling of Ti-6Al-4V powder used within SLM to improve sustainability

This paper considers the steps to be taken in investigating the effects of recycling Ti-6Al-4V powders for Selective Laser Melting (SLM). A research methodology is presented that shall allow for investigation in to the change in powder characteristics through repeated use, and will provide the basis for eventual determination of any effect that these changes have on the chemical, mechanical and metallurgical properties of laser melted parts. An in depth understanding of the link between powder and part characteristics is essential for SLM, and measuring powder characteristics after building production parts may prove to be an important marker for part quality. Initial powder characterisation testing was conducted on powder that had been recycled up to five times. The results showed a trend towards increased Particle Size Diameter (PSD) through repeated recycling, with a reduction in the number of fine particles. Additionally, a roughening of the powder surface was observed, with a reduction in the sphericity of powder particles. Chemical composition tests on the powder to determine changes in interstitial oxygen and nitrogen showed negligible change through repeated recycling