August 19, 2021 2 min read


What is the Rockwell Hardness scale and how does it work?

You’ve probably seen different knife makers describe their steel with something called Rockwell C Hardness. We do it too. But what is Rockwell hardness and how does it measure the quality of the steel? Let us explain!


The Rockwell C hardness scale

The Rockwell C hardness scale is a way of measuring how resistant and hard a metal is. To measure the hardness in each knife or axe, engineers use the Rockwell C testing process to calculate its strength. It is a measuring system that is industry standard. Knife makers all over the world use it to estimate the characteristics of their metal and steel.

 

The higher the number on the scale, the harder the metal and steel. But how does it work? The short explanation is that an indenter is pressed into the metal surface under a given load. Depending on the depth of the indentation a hardness number is calculated. It’s difficult to explain, but if you look at the illustration below it might be easier to understand how it works.

 

The Roselli Steel

Like said, most knives range between 45 HRC to 60 HRC. Our own UHC (Ultra High Carbon) steel measures about 66 HRC. Heimo Roselli’s years of refining forging techniques and studying metals led to a very particular smelting process and work formula — which to this day is a secret kept between Heimo and his men at the Roselli workshop in Harmoinen.

 

The Roselli steel has been independently tested many times, and is internationally recognised as the hardest steel in any modern knife — with the UHC (Ultra High Carbon) models measuring about 66 HRC. The hardest steel in the world has taken us decades to perfect.

 

 

Soft vs hard steel

There are both pros and cons to hard and soft steel, and different purposes for different kinds of steel. We made a guide to help you sort out what characteristics you’d want and need for your knife, depending on what you’re going to use it for. Read our blog post: What knife do I use for what purpose?

 

Our Carbon Steel Knives

Our standard carbon steel with 0,8% carbon is anything but standard. This steel measures 60 HRC and is our most trusted and used. Hard, durable and reliable - it is made to get the work done.

 

Our UHC (Ultra High Carbon) Steel Knives

Our own Ultra High Carbon (UHC) steel contains 1.8 - 2.0 % carbo. This Roselli steel measures 66 HRC. This level of strength makes an extreme sharpness possible, and an edge which will stay sharp for a very very long time.

 

 

If you’re curious about the differences between soft and hard steel you can read more about our UHC (Ultra High Carbon) steel and Carbon steel in the blog post: Chipping - soft vs hard steel

 

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