Pulsed Plasma Nitriding

Plasma nitriding with pulsed discharge is a case-hardening process. The workpiece is connected as cathode in a nitrogen atmosphere under low pressure. The pulsed voltage ignites a glow discharge that cleans and heats the surface, so nitrogen diffuses into the case and forms hard nitrides. If you want to weld afterwards, you must grind or mill off the nitrided layer completely. The layer is extremely hard and brittle, and if you weld over it, you'll get cracks and porosity. The part must be bare at the weld spots, otherwise the weld won't hold.