Titanium Surface Nitriding

When nitriding titanium, nitrogen is introduced into the surface, creating a hard, wear-resistant titanium nitride layer. But that stuff is also quite brittle and sensitive to heat. If you want to weld such a part, you have to completely grind or mill off the hard layer in the weld area beforehand, otherwise the weld will crack for sure. The weld itself should be kept as cool as possible, so don't put too much heat in and control the cooling. After welding, you can re-nitride the area if needed, but that's a separate step.