3D-printing ranges from fragile resin pieces to metal durable enough to use as rocket nozzles. This article was about 3D printed titanium, so the resulting piece is likely stronger than bone but weaker than machined titanium would be.

It is most likely made of welded titanium particles as others point out.

Imagine a thin layer of titanium dust. Then shine a laser on the points where you want to weld. When done, add another layer over it and repeat.

Or imagine a nozzle which sprays titanium dust. Directly after the nozzle there is a focused laser point. When the dust goes through the laser it welds together. So when you do this close to a titanium surface you can add more titanium to it.

And there are other methods for 3D printing metal. But most of them are just advanced welding techniques.

3D printing metal is usually done by sintering a metal powder. The technology is good enough for turbine blades in aircraft engines.

Turbine blades in modern aircraft are gamma-TiAl, which is a single crystal. These are not 3d printed and the process for making them is similar but more advanced than making silicon wafers.

This is a decent documentary on Rolls Royce that discusses the single crystal blade. I think each one has 18 tons of centrifugal force, and uses a few micron layer of air to cool it, so running an engine too slow will melt them. Fascinating stuff.

https://youtu.be/1Ufd5nDeEK8

It's made of titanium (though almost certainly some alloy) so they probably used a DMLS (direct metal laser sintering), SLM (selective laser melting) or DMLM (direct metal laser melting) process. All will result in fairly strong material structure. Probably not as strong as tempering/quenching would make it though. Either way, this is not something you can do with a hobby 3D printer :-)

The article says it’s titanium

This is just “manufacturing” which has little resemblance to the consumer makerbot products

Hmm sure but it’s still 3D printing? It’s hard to imagine a conventional CNC machine doing this.

But then again I know nothing about CNC machines.

Some components with complex overhangs and voids can be impossible to mill with a CNC. A sintering 3D printer isn't constrained in that regard, and can make arbitrarily complex geometry without sacrificing precision.

Look up arcam.