A collaborative project researching alloy composition and grain microstructure has addressed a common problem often experienced when titanium is 3D-printed.
Current titanium alloys used in additive manufacturing often cool and bond together in column-shaped crystals during the 3D printing process, making them prone to cracking or distortion. Unlike other commonly-used metals, there is no commercial grain refiner for titanium in order for manufacturers to effectively refine the microstructure in order to avoid these issues.
RMIT University, CSIRO, the University of Queensland, and the Ohio State University, have discovered a new titanium-copper alloy, which printed with exceptional properties and without special process control or additional treatment.
Of particular note was its full equiaxed grain structure: this means the crystal grains had grown equally in all directions to form a strong bond, instead of in columns, which can lead to weak points liable to cracking, says Mark Easton, a Professor from RMIT Universitys School of Engineering. “Alloys with this microstructure can withstand much higher forces and will be much less likely to have defects, such as cracking or distortion, during manufacture,” Easton explains.
CSIRO Senior Principal Research Scientist, Dr. Mark Gibson, comments that their findings also suggest similar metal systems could be treated in the same way to improve properties. “Titanium-copper alloys are one option, particularly if the use of other additional alloying elements or heat treatments can be employed to improve the properties further. But there are also a number of other alloying elements that are likely to have similar effects. These could all have applications in the aerospace and biomedical industries.”
Gibson points out that the new breed of alloys could increase manufacturers’ production rates and allow for more complex parts to be manufactured.
“In general, it opens up the possibility of developing a new range of titanium-based alloys specifically developed for 3D printing with exceptional properties,” says Gibson.
Image courtesy of RMIT University