High carbon steel knife
High carbon steel is often used for high-end kitchen knives because it is wear-resistant, meaning it stays sharper for longer.
Steel is found in everything from aerospace to kitchenware. Such diverse applications call for a versatile material – and steel fits the bill.
"Steel" actually describes an entire family of metal alloys, with hundreds of application-specific grades, but most people divide steel into two broad categories: carbon steel and stainless steel.
Carbon steel and stainless steel have the same basic composition of iron and carbon. The main difference between them is the alloy content - carbon steel has an alloy content of less than 10.5%, while stainless steel must contain 10.5% or more chromium. This essential difference is why carbon steel and stainless steel have unique physical properties.
steel composition
The basic elements of steel are iron and carbon. Generally speaking, steels with higher carbon content are hard and brittle, while steels with lower carbon content are ductile and ductile.
Of course, it's rarely that simple. Alloying elements such as chromium, molybdenum, nickel, manganese or silicon can be added to improve corrosion resistance or to achieve a better balance between strength and toughness.
Carbon steel
Carbon steel consists of iron and 0.12 - 2.00% carbon. A broader definition includes alloyed steels, which can also have an alloying content of up to 10.5%. Even within the carbon content range of less than two percent, there are huge differences in physical properties, especially hardness.
When people talk about carbon steel, they usually mean high carbon steel used in knives and tools. High carbon steels are very hard, which makes them resistant to wear and shape well. They can withstand a lot of force before deforming. Unfortunately, hard metals are also brittle: high carbon steels are more prone to cracking than bending when placed under extreme tensile stress.
Low carbon steels are more common than high carbon steels because (1) they are less expensive to produce, (2) they are more ductile, and (3) they are easier to manufacture. Mild steel tends to deform under stress rather than fracture, and this ductility makes mild steel easy to machine and weld. They are frequently used in automotive body panels, bolts, clamps, seamless tubes and steel sheets.

Stainless steel
Stainless steel stand mixer for kneading bread dough
Stainless steel is used in chemical plants and food plants because of its ability to function in wet environments without rusting.
Stainless steel contains iron, carbon and a chromium content of at least 10.5%. Chromium is the key - it reacts with oxygen to form a passivation layer that protects the steel from corrosion. This protection reduces the likelihood of stainless steel rusting - important for outdoor venue furniture such as bollards installed in wet environments. The higher the chromium content, the better the corrosion resistance.
When shopping for appliances and other bulky items, be sure to pay attention to stainless steel grades. Not all steel is the same. Stainless steel with a minimum chromium content of 10.5% is much cheaper and less durable than stainless steel with a chromium content of 16%, the difference will be reflected in maintenance costs and service life.
Carbon Steel vs. Stainless Steel Knives
Home cooks often choose stainless steel knives. Professionals often choose high carbon steel.
Why? Stainless steel knives are more common and easier to store. Martensitic stainless steels are often used for cutting edges. These stainless steels are harder than other grades. However, they're not as brittle as harder high-carbon steels: they can be thrown in the dishwasher or hit against marble.
For home cooks who don't do precision knife work, this is usually enough. In this case, rust prevention helps keep the blade sharp. Iron oxide on the cutting edge can dull the knife, like wear.
Professional chefs often (but not always!) prefer high carbon steel knives. These knives can be sharpened to very sharp edges and are generally more wear-resistant than stainless steel. High carbon grades maintain finer edges even with regular use. Very hard metals are also brittle: when the impact force is too high, the metal doesn't bend, it breaks. This means that the high carbon blade is less likely to deform on impact, leaving the blade lost through a series of warping. Instead, they'll keep a nice, clean line, and when they break, they'll crumble.
Hard steel like this needs more care. Oil before storage to prevent rust, rinse after use in very salty or acidic conditions, and re-edge on stone (not steel). These maintenance steps make high carbon steel more of a treat for high-end or professional chefs who cut paper slices than for the average home cook where precision is less important than ease of maintenance.

Carbon steel vs stainless steel?
Carbon steel and stainless steel are different, but not necessarily superior to the other. It's all about context. Each material has advantages and disadvantages - the key is matching the steel to the job requirements.

High-carbon steel
easy to rust
crisp
Wear-resistant

Stainless steel
Rust resistant
not so crisp
poor wear resistance