Understanding the difference between strength and toughness can help...
If you've ever compared and cross-shopped knives, you've likely noticed that there's a lot of terminology to understand. In the past, we've talked about blade grinds and profiles, knife steel types, and even the complete anatomy of a fixed-blade knife. There's still lots more that we haven't covered, however. Steel hardness is one such topic, and it's an extremely important concept to wrap your head around if you want to know more about knives.
In order to explain steel hardness correctly, we reached out to the team at KnifeArt.com. KnifeArt has nearly 20 years of experience as an online knife retailer, and offers blades ranging from affordable EDC workhorses to exotic custom designs. Site founder Larry Connelley wrote the following guide on steel hardness, and shared it with us:
“Knives are immensely versatile tools that with proper care and maintenance, can last an extremely long time. If you're in the market for a new, high-quality knife, you've probably come across mentions of the Rockwell Hardness scale and ratings. But what is this scale, and why is it important?
Generally, knives are described as having an HRC rating of X. “HR” stands for the Rockwell Scale of Hardness, and the “C” represents part C of the scale. The Rockwell Scale is used to determine the hardness of a material, and part C specifically refers to steel. The hardness of a steel is determined by the heat treatment of the blade.
In simple terms, the higher the number, the harder the steel. However, one steel is not better than another simply because it is harder. While a harder steel generally holds an edge longer than a softer steel, harder steel can be more brittle; some steel alloys can even shatter or crack because they are too hard!
Steel with a high number on the Rockwell scale will have higher edge retention but lower toughness. Likewise, steel with a lower Rockwell Hardness rating will not hold its edge for as long, but will be tougher. Axes and survival blades may tend to have low HRC ratings, making them tough enough to function well under frequent abuse and hard work. Folding knives tend to have higher ratings, because they are expected to hold sharp edges longer and are not typically used for heavy striking like an axe would.
When you're buying a new knife, take into account the primary purpose that knife will serve. If you want something that will retain its edge sharpness for a long time without a need for extreme toughness look for a knife with a higher Rockwell rating. If you need something that will be tough and survive hard jobs but may require more frequent sharpening, look for a knife with a lower Rockwell rating. Most often, knives are heat treated to a Rockwell hardness range that balances the needs of edge retention and toughness under a normal range of use for that individual knife.”
To learn more about the Rockwell hardness scale and other knife characteristics, check out KnifeArt's Knife Articles & Information section.