High carbon stainless steel is a metal alloy containing relatively high amounts of carbon. The amount of carbon can be as much as 1.2% and as low as 0.2%. The reasons for this vary with the manufacturer and the type of blade they’re creating.
Stainless steel is an alloy that contains 10.5% or more of chromium (Cr) and iron (Fe) in excess of 50%. Chromium is the element that makes stainless steel so resistant to stains. In fact, stainless steel should be called stain resistant steel, as it can stain but is less likely to do so than pure steel. Stainless steel is also very easy to care for and doesn’t require regular maintenance to keep its beauty. Steel with a low carbon content is softer and doesn't hold a blade edge very well.
Carbon steel is has a good edge when sharpened properly and regularly, and it is a much harder material for using in knife construction. Carbon steel knives corrode more easily and need to be oiled on a regular basis. Follow manufacturer’s instructions for sharpening and seasoning to extend the life of a carbon steel knife.
When you combine carbon steel and stainless steel to get high carbon stainless steel you get the best of each alloy. This steel is resistant to rust or staining, it’s very hard, and holds an edge with minimal maintenance. It is generally thought of as a higher quality stainless steel alloy.
As in all things, there are higher quality and lesser quality products. Some of the issues that manufacturers face when making high carbon stainless steel are carbon content, tempering, and chromium content. Carbon content will harden the steel, so if too much is added, the alloy becomes brittle. If manufacturers use too little carbon, there’s not enough to harden the steel. The chromium content can have a huge impact on the end product as well. Chromium is attracted to carbon, which means that carbon can steal the chromium from the stainless steel. When this happens, the end product is less stain resistant than it should be. Tempering can also make for a very brittle blade. High carbon stainless steel generally has fairly low tolerance for heat, around 500°F (260°C), before it becomes too brittle for knife use.
When buying a knife, it’s best to follow the rule, “you get what you pay for.” Make sure that the blade extends all the way through the handle. You’ll want to see rivets holding the handle together. It should also feel good in your hand. A quality knife means you won’t be sawing through your food; instead you’ll be using less effort. A high quality high carbon stainless steel knife, or any high quality knife for that matter, is a safer product for your kitchen. The less effort you put into chopping your food, the less likely it is that your grip will slip and cause an accident.