Carburizing & Nitriding

What’s Carburizing & Nitriding

Vacuum Carburizing with Acetylene (AvaC)

The AvaC vacuum carburizing process is a technology that uses acetylene to virtually eliminate the soot and tar formation problem known to occur from propane, while greatly increasing carburizing power even for blind or through holes.

One of the most important advantages of the AvaC process is high carbon availability, ensuring extremely homogenous carburizing even for complex geometries and very high load densities. The AvaC process involves alternate injection of acetylene (boost) and a neutral gas, such as nitrogen, for diffusion. During boost injection, acetylene will only dissociate in contact with all-metal surfaces allowing for uniform carburizing.

The most remarkable benefit to AvaC can be found when the different hydrocarbon gases for low-pressure carburizing are evaluated for their penetration power into small-diameter, long, blind holes. Vacuum carburizing with acetylene results in a complete carburizing effect along the whole length of the bore because acetylene has a totally different carburizing capability than that of propane or ethylene.

Benefits of the AvaC process:

Continuous high-throughput capability

Guaranteed process repeatability

Optimum acetylene gas deployment

Open, maintenance-friendly modular system

Increased carbon transfer

Reduced process time

Improved microstructure, increased stress resistance, and superior surface quality of parts

Economical extendibility for capacity increase

Various quenching capability with helium, nitrogen, mixed gases, or oil

Advantages over atmosphere furnaces:

Better work environment with cold-wall design, which provides lower shell temperature

No costly exhaust hoods or stacks required

Faster start-ups and shutdowns

No endothermic gas generators required

Gas quench furnaces require less floor space and no post-washing to remove quench oils

No pits or special foundation requirements needed

Carbonitriding

Carbonitriding is a case hardening process similar to carburizing, with the addition of nitrogen, used to increase wear resistance and surface hardness. Compared to carburizing, the diffusion of both carbon and nitrogen increases the hardenability of plain carbon and low alloy steels.

Typical applications include: gears and shafts pistons rollers and bearings levers in hydraulic, pneumatic and mechanical actuated systems.

Low pressure carbonitriding (AvaC-N) process uses acetylene and ammonia. Like carburizing, the resulting part has a hard, wear-resistant case. However, unlike AvaC carburizing, the resulting nitrogen and carbon case depth is between 0.003″ and 0.030″. Since nitrogen increases the hardenability of steel, this process produces parts with increased hardness within the indicated case depth. Since carbonitriding is performed at slightly lower temperatures than carburizing, it also reduces distortion from quenching.

Nitriding & Nitrocarburizing

Nitriding is a case hardening process that diffuses nitrogen into the surface of a metal, most commonly low-carbon, low-alloy steels. It is also used on medium and high-carbon steels, titanium, aluminum and molybdenum.

Nitrocarburizing is a shallow case variation of the nitriding process where both nitrogen and carbon diffuse into the surface of the part. Advantages of the process include the ability to harden materials at relatively low temperatures which minimizes distortion. It is also typically lower in cost compared to carburizing and other case hardening processes.

Benefits of Nitriding and Nitrocarburizing include improved strength and better wear and corrosion resistance

Nitriding and nitrocarburizing are used for gears, screws, springs, crankshafts and camshafts, among others.

Furnaces suggeted for carburizing and nitriding.