Most of us want our 3D printing to be perfect. But at Cornell University, they have been experimenting with deliberately introducing defects into printed titanium. Why? Because of the use of post press heat treatment and pressure treatment, they can convert these defects into assets, resulting in stronger and more ductile printed parts.
The most common way to print metal is to use melted powders, which can lead to tiny pores in the material, weakening the final product. Using Ti-6Al-4V, the researchers deliberately produced a poor quality print with more defects than usual. Then they apply extreme heat and pressure to the final workpiece. Pressure leads to pore closure, which changes the internal structure of the material and makes it more like a composite material.
It is reported that the performance of forged parts is better than that of forged parts. In addition, the printing process usually produces parts that are stronger in some directions than in others. Post treatment breaks the fact that directionality and finished parts have the same strength in all directions.
Hot isostatic pressing (hip) is not a new process – it is usually used for metal and ceramic processing – so this method doesn’t need anything more strange. It is true that even cheap printing presses from China start at about $7000 and then go up, but if you are 3D printing titanium, it may not be a big expense. The only drawback seems to be that if the process partially treats any defects, it may lead to fatigue failure in the future.
We would like to know whether this development will affect all recent automotive parts printed with titanium alloy. If you need to print something on titanium, consider your ribs.