Like a chef can fine tune a recipe by adding or removing ingredients we can fine tune steel alloys to ensure certain characteristics. To make a dish sweeter, you can add sugar. To make steel softer or harder you can add carbon. In its most basic form steel contains iron and carbon. The amount of carbon (C) ranges from 0.02% to about 1.70% for high carbon steels. This includes mild steels and exotic high carbon alloys. For knife steels the usable range is commonly in between 0.30 and 0.85%.
Other elements can be added for certain characteristics. Chromium (Cr) adds corrosion resistance. Vanadium (V) and Molybdenum (Mo) drive grain formation. This results, among other things, in a steel that can be better heat-treated. In a future blog post we will dive into more detail per ingredient and include some more exotic ingredients.
Process matters too: searing a steak changes its texture and flavour. Heating or cooling steel changes its characteristics. Just like multiple dishes can be made from the same set of ingredients, a steel can have greatly varying characteristics depending on the way it is processed.
For example: even high carbon steels can have a very low Rockwell-C Hardness rating if they are not quenched and tempered properly. The steel alloy only determines the upper and lower bounds for the characteristics of a knife. Just like a chef can go all sorts of ways with a set of ingredients and equipment, it is up to the knife maker to get the best results out of a certain steel alloy.
Every chef knows how to make basic recipes from basic ingredients. In the same way there are alloys and tempering procedures that every knife maker should know. This helps when you pick a knife. There are a dozen steel types you will commonly see. Their characteristics are well known, and how to process them is standardized.
Just like it is unwise to eat something without knowing the ingredients, don't buy a knife of which you don't know the steel alloy. We advise you to stick to the 'tried and tested' types of steel when starting out: you really cannot go wrong here. Once you know your style in cooking and have a solid grasp on the basics of knife skills and care you might want to branch out into more exotic steel types or boutique handcrafted knives. Or you might not! There is a lot to say for standardization when consistent quality is desirable.
As any chef will tell you cooking is a balancing act. Just as there is no dish that has the perfect flavour, there is no perfect knife steel. It is about personal preference. The ‘right’ steel type and treatment is very relative. For example: a harder steel will be more prone to rust and cracking. And a hard and rust-resistant steel will cost significantly more. A big part of the balancing act that is alloy composition comes down to cost. Just make sure you understand the trade-offs involved with your steel type of choice before buying a quality knife.
At BARE Cookware we choose to use X50CrMoV15 steel for our knives. This is a well-known knife steel with excellent corrosion resistance. Our steel alloy contains:
In our experience X50CrMoV15 strikes a perfect balance between price, rust-resistance, and hardness. Our knives bolster an impressive Rockwell-C hardness of 58. This hardness ensures our knives are razor sharp and stay that way but are still resistant to chipping or breaking. Can you get a harder steel? Sure, but you'll either compromise on rust-resistance, chip-resistance or pay dearly for it. In future posts we will elaborate on steel characteristics, alloy elements and composition, quenching and tempering methods, and the result of these factors in the final product.