Kolsterising® Fastener Enhancement

Kolsterising® (-KOL/-N-KOL)

Kolsterising® is an industry-proven, thermo-chemical, low-temperature, diffusion-based, surface hardening technology used to enhance certain grades of stainless steel, cobalt, and nickel-based alloys. Kolsterising® is not a coating but a low-temperature surface carbon diffusion treatment that enhances the hardness of the base material. The process adds large concentrations of carbon atoms that form high compressive stresses on the surface. These stresses and the filling of the interstitial sites by the carbon atoms not only significantly improves the hardness of the material, but also makes the surface resistant to corrosion, wear, and fatigue.

Kolsterising® is ideal for applications such as:

Medical devices that require biocompatible materials
Pharmaceuticals
Fasteners
Valve parts (balls, needles, seats, and housings)
Food and beverage filling/dispensing machine pistons and seals
Automotive components
Marine parts
Industrial fluid handling
And so many more

Kolsterising® eliminates:

Delamination
Galling in stainless steel alloys
Metal debris

Why chose Kolsterising®?

Complex shapes can be effectively hardened by this process
It offers consistent diffusion depth
Improved abrasive wear
Improved cavitation erosion resistance
Increased fatigue strength
Reduces galling
Exceptional scratch resistance
Does not affect the magnetic properties of the metal alloys
Good dimensional stability
The process does not change the part dimensions

kolsterised friction factor table — Figure 2: These plots compare the friction factors and measured loads using Hastelloy® C-276 fasteners in the untreated condition and those treated with Kolsterising®. It can be seen in the above charts that in the Kolsterised condition the friction factor remains constant and therefore the resulting load achieved is unaffected. Comparing this to the untreated fasteners, it can be seen that repeated loading causes the friction factor to increase and the resulting load to decrease indicating adhesive wear and galling of the thread has occurred.

Kolsterising® allows designers and engineers to use more common and inexpensive materials, while giving them the performance expensive alloys. The treatment can improve some austenitic and martensitic grades of metal, ferritic and duplex stainless steel, as well as certain cobalt-chromium and nickel-based alloys.

Kolsterising® FAQs

How does Kolsterising® change a fastener’s surface hardness?

Kolsterising® is a surface hardening process that combines increased durability while maintaining aesthetics. It is particularly beneficial for fasteners requiring reliability, longevity, high wear resistance, and dimensional stability in demanding environments.

Fasteners treated with the Kolsterising® process can achieve a surface hardness of up to 1,200 HV (Vickers Hardness). This significant increase in surface hardness is achieved without compromising the corrosion resistance of the underlying material. The exact hardness can vary depending on the specific material treated and the process parameters used. However, achieving around 1,000 to 1,200 HV is typical for austenitic stainless steels and similar alloys.

While the right coating or plating for your HV or UHV application is best defined by your process engineer, we are always here to assist you. UC Components, Inc. has been the world leader in high vacuum hardware since 1974.

UC Components, Inc.’s RediVac® fasteners, washers, nuts, and O-rings are designed for use in a wide range of high vacuum applications and other clean-critical environments. We offer a variety of specialized venting designs, numerous finishes, and complete Class 100/ISO Class 5 Cleanroom cleaning and packaging.