Low Pressure Carburising

Customers with case hardening requirements can confidently entrust their precision components to Bodycote Woodford. Low pressure carburising is an advanced technology that offers the design engineer an alternative to atmosphere carburising for improved case depth uniformity, dimensional control, part cleanliness, and process flexibility. Low pressure carburising is a method of pure carburisation combined with pure diffusion. The steel surface is vacuum conditioned eliminating surface oxide, trapped gases and foreign material that may deter carbon saturation of the austenite.

Cryogenic and Temper Treatment
To complement this low pressure carburising capability, Bodycote has installed additional cryogenic equipment capable of deep freezing to -196°C and tempering to 650°C within the same unit, therefore eliminating the risk of surface oxidation. The use of cryogenic treatment is recognised as a beneficial process, offering improved wear resistance and dimensional stability by achieving a refined grain structure, allowing components to function at optimum performance levels.

Features and benefits
• Enhanced mechanical properties
- Elimination of intergranular oxidation layer, improved fatigue properties
• Dimensional control
- Low distortion – predictable and repeatable
• Reduced total cost
- Shorter cycle times are possible, saving time and cost
- Environmentally friendly
- Reduced manufacturing steps such as post grinding, cleaning and inspection
• Enhanced cleanliness of products
• Precise control of case depth, microstructure and hardness
• Improved blind hole case penetration
• Better case depth uniformity for complex shapes
• Pay loads up to 600 kg gross

What are the applications?
Low pressure vacuum carburising has been successfully applied to a number of different components including gears, shafts, bearings, tool holders and fuel injection components to name a few. Industrial sectors such as automotive, aerospace, off-road, autosport, agricultural, power generation and tooling have already found particular benefits.
Process control
Case depth control is achieved with the use of computer programme and process simulators that take into consideration the surface area of the load, desired case depth, required surface carbon, case and core hardness and carbon profile, as a function of depth from the surface. Case depth uniformity can be maintained within ±0.002” in most
cases.

Control of carbide formation is achieved by the adjustment of the boost (carbon addition) and diffusion (carbon migration) steps of the process cycle so as to avoid carbide networking.
Material selection
A wide variety of materials can be vacuum carburised at Woodford.

BS 970 SAE Aircraft Steels
835M15 EN 39 / S 82
832M13 EN 36 / S 157
822M17 EN 355 / /
805M20 EN 362 8620, 8822 /
665M17 EN 34 4615, 4620 /

New materials are now being introduced that enhance vacuum carburising methods and promote the use of high pressure gas quenching as an alternative to oil. Complementing our facilities we also have a fully equipped metallographic laboratory on site.

Bodycote also has low pressure vacuum carburising at the following locations:

Kapfenberg (AUSTRIA) T +43 3862 33 7000 F +43 3862 33 7005
La Talaudière (FRANCE) T +33 4 77 47 69 20 F +33 4 77 47 69 29
Livonia (USA) T +1 734 427 68 14 F +1 734 266 94 27

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