WCT N-Cote is a salt bath heat treatment process that diffuses nitrogen into the surface of a metal at sub-critical temperatures at ferritic stage to create a case hardened surface. It is predominantly used on steel, but also can be used on titanium, aluminium and molybdenum. The processes are named after the medium used to donate.
N-Cote salt bath nitriding the nitrogen donating medium is a nitrogen-containing salt such as cyanide salt. The salts used also donate carbon to the workpiece surface making salt bath a nitrocarburizing process. The temperature used is typical of all nitrocarburizing processes: 550–570 °C. The advantages of salt nitriding is that it achieves higher diffusion in the same period time compared to any other method.
nitriding These processes are most commonly used on low-carbon, low-alloy steels, however they are also used on medium and high-carbon steels.

Examples of easily nitridable steels include the SAE 4100, 4300, 5100, 6100, 8600, 8700, 9300 and 9800 series, UK aircraft quality steel grades BS 4S 106, BS 3S 132, 905M39 (EN41B), stainless steels, some tool steels (H13 and P20 for example) and certain cast irons. Ideally, steels for nitriding should be in the hardened and tempered condition, requiring nitriding take place at a lower temperature than the last tempering temperature. A fine-turned or ground surface finish is best. Minimal amounts of material should be removed post nitriding to preserve the surface hardness.

Typical applications include gears, crankshafts, camshafts, cam followers, valve parts, extruder screws, die-casting tools, forging dies, extrusion dies, injectors and plastic-mold tools. The process is used to improve three main surface integrity aspects such as scuffing resistance, fatigue properties, corrosion resistance(when followed by WCT-OXY Cote.