Nitrocarburising.

What we do

Nitrocarburising

Nitrocarburising is a shallow case variation of the nitriding process. This process is done mainly to provide an anti-wear resistance on the surface layer and to improve fatigue resistance.

Nitrocarburising exists in two industrially recognised forms:

• Gas nitrocarburising (GNC) – the most widely used method, suited to medium–high volumes, general engineering and automotive components.

• Plasma (ion) nitrocarburising (PNC) – used for precision components requiring tight control of the compound layer, minimal distortion and cleaner surfaces.

Benefits of nitrocarburising

• Relative low cost;
• High resistance to wear;
• Excellent scuffing and seizure resistance;
• Fatigue properties improved by up to 120%;
• Considerably improved corrosion resistance;
• Good surface finish;
• Negligible shape distortion;
• Predictable growth characteristics; and
• Alloy substitution – plain carbon steels replacing low alloy steels.

Gas nitrocarburising (GNC)

Gas nitrocarburising uses gaseous atmospheres to diffuse nitrogen and carbon into the steel surface. It is ideal for:

• Medium to high-volume production

• Components with complex geometries or large batch sizes

• Applications requiring good wear and fatigue performance at competitive cost

Key characteristics of gas nitrocarburising:

• Produces a robust compound layer with good scuffing and seizure resistance

• Offers enhanced corrosion protection when followed by post-oxidation

• Provides excellent repeatability for approved specifications

• Well suited to automotive, agricultural, oil & gas and general engineering components

Plasma (ion) nitrocarburising (PNC)

Plasma nitrocarburising uses a glow-discharge environment to diffuse nitrogen and carbon in a highly controlled manner. It is selected when component precision or surface condition is critical.

Key characteristics of plasma nitrocarburising:

• Very precise control of compound layer growth

• Cleaner surface finish with minimal post-processing

• Excellent for distortion-sensitive components

• Allows nitrocarburising of complex alloys, including stainless steels in some cases

• Ideal for tooling, aerospace and high-precision mechanical components

Application & materials

Advantages of the process include the ability to harden materials which are not pre-hardened, the relatively low temperature of the process which minimises distortion, and relative low cost in comparison to carburising or other case hardening processes.

Typical industries:

Oil and gas, valve, pump, agriculture equipment, automotive, stamping, textile, extrusion and injection moulding, and firearms components.

Typical parts:

• Oil and gas – gears and pinion shafts
• Valve components – gates, seats, balls, stems, regulator valves
• Pump components – impellor housings, bodies, plungers, cylinders
• Agriculture equipment – harvesting combine cutters, separators, crop transfer, chopping components
• Automotive – diesel engine oil pumps, gears, crankshafts and camshafts
• Stamping – dies, tooling
• Textile – grooved drums
• Extrusion and injection mould – moulding augers, barrels, die components
• Firearms – slides on automatic firearms

Nitrocarburising can be applied to the same materials as in nitriding, as well as unalloyed materials, where good wear resistance and some improved fatigue resistance are needed at a low cost. It is widely used for stampings, as an alternative to hard plating.

Nitrocarburising process details

Nitrocarburising is carried out at sub-critical temperatures and involves the diffusion of nitrogen and carbon into the surface of carbon steel to give a somewhat harder case and soft core with a very thin compound layer on the surface.

The compound layer is wear and corrosion resistant and yet is not brittle, unlike its counterpart in the nitriding process. Since it provides an essential part of the properties required from the process it must not be removed by subsequent machining. Below the compound layer, the thin case significantly enhances the fatigue resistance of the component.