In its simplest form, steel is simply iron with carbon in it. The carbon hardens and strengthens the steel. High-carbon steel has more carbon (0.5% carbon or more) in it than other types of steel. Other metals are added to steel to enhance certain characteristics. Chromium is added for corrosion resistance, wear resistance, and to increase hardness. Steel with at least 13% chromium is termed “stainless.”
The type of steel and how it was treated will determine the strength, flexibility, and toughness of the blade. It also affects how well the blade takes and keeps an edge. Any quality knife, regardless of blade material, should be capable of most tasks thrown at it. Better steels will be stronger and hold an edge better but the difference isn’t usually very great. Honestly, unless you’re a “knife geek”, the difference between most types of steel is not worth worrying about. Besides, many of these steels are only available in expensive custom knives.
While the type of steel is important, how the steel was treated is at least as important. Heat-treating a blade involves heating up the blade then cooling it quickly. This makes the blade hard but brittle. The blade is then heated slowly to “temper” the hardness. If the blade is left too brittle it may break during use. If it is too soft it won’t hold an edge well. The best steel, if improperly heat-treated and tempered, could be worse than a properly prepared lesser quality steel.
· Holds an edge longer
· Slightly easier to sharpen
· Rusts quicker and more easily than stainless
· Requires more frequent maintenance
· Harder to store (like in a survival kit) because the possibility of rust
· Can be differentially tempered, with a hard edge and a flexible back.
· 5160 is a very popular, high-end steel. It has a good edge holding capability and is very tough. 5160 steel is often used in quality swords and knives and is put to hard use.
· L-6 is band saw steel. It is very tough and holds an edge well but easily rusts. This is a good steel to use if you’re making your own knives.
· The 10-series (1095, 1084, etc.) are common types of high-carbon steel. 1095 (0.95% carbon) is the most popular due to its ability to hold an edge and is considered the “standard” carbon steel. Unfortunately, it rusts easily. 1060 (0.65% carbon) and 1050 (0.50% carbon) are also popular and are used to make sword blades.
High-carbon is the steel of choice for someone who needs a really sharp edge (like woodcarvers). For these jobs, easier sharpening is more important than rust resistance. It is quicker and easier to bring back a razor edge on a high-carbon steel blade than a stainless steel blade.
· Resistant to rust – not rust proof. Remember, it’s stain “less”.
· More brittle than high-carbon steel.
· Requires less care and maintenance than high-carbon steel.
· Stainless steel is harder to sharpen with natural stones because the steel is harder. Stainless is usually only slightly more difficult with diamond, carbide, or ceramic sharpeners.
· Stainless will retain an edge longer because it is harder.
· Cannot be differentially tempered. The whole blade gets the same temper.
· Considered the best steel to use in wet environments, especially marine environments. This is because it’s more resistant to corrosion than high-carbon steel.
· 440 steels are used in better quality production knives. There are 3 grades that are used most often. 440A (0.75% carbon) is the most rust resistant, least hard, and least expensive type. Knives made of 440A steel are good enough for most jobs but are not considered “high-end”. 440B (0.9% carbon) is a mid-grade steel and very good at most jobs. 440C (1.2% carbon) is excellent high-end steel although less rust resistant than 440A. Quality 440C steel will outperform the best high-carbon steel. The bottom line is that quality high-carbon stainless steel is just as good as quality high-carbon steel.
· 420 steel (less than 0.5% carbon) is softer than 440 steel and doesn’t hold an edge well. It is very rust resistant though and used mainly for diving knives. Many cheaply constructed knives are made from 420 stainless steel.
Unfortunately, you’ll probably never know the exact type of steel your blade is made from unless you buy an expensive high-end or custom knife. And forget about learning how the blade was heat-treated. Most knife sellers only disclose whether the blade is stainless or high-carbon steel. The good news is that steel is steel. Even a cheap blade will do most jobs if maintained and used correctly.