Stainless or corrosion-resistant: What does that mean for knife steel?

"Stainless" is a common term for knives, often referred to as the counterpart to carbon steels. However, "corrosion-resistant" or "rust-retardant" more accurately describes the properties of many knife steels. Even a corrosion-resistant steel can corrode under certain conditions. The chemical composition, microstructure, and heat treatment are crucial factors, among others.

What makes a steel corrosion-resistant?

Chromium plays a central role in corrosion resistance. It can form a passive chromium oxide layer on the surface, which protects the steel from further corrosion. However, there is no universal chromium content above which a steel is considered stainless under all conditions.

The reason: Not all the chromium contained in the steel is available for passivation. Some of it can be bound in chromium carbides, for example. Therefore, a high overall chromium content does not automatically mean correspondingly high corrosion resistance.

Why does carbon play a role?

Carbon can form chromium carbides together with chromium. This means that part of the chromium is no longer available for the passive layer. The heat treatment, in turn, influences how much of these carbides are dissolved and how much chromium remains available in the microstructure.

Therefore, the corrosion resistance of a knife cannot be reliably assessed solely on the basis of "X % chromium" or "stainless steel" information.

Corrosion-resistant does not mean insensitive

Even corrosion-resistant knife steels should be cleaned and dried after contact with water or aggressive substances. Especially saltwater and other corrosive environments place high demands on corrosion resistance.

Some steels are specifically designed for very high corrosion resistance. LC200N, for example, is one of the particularly corrosion-resistant knife steels. Other corrosion-resistant steels focus more on a combination of corrosion resistance, wear resistance, and other properties.

What is better: corrosion-resistant or non-corrosion-resistant steel?

That depends on the application. For kitchen, EDC, hunting, or fishing knives, high corrosion resistance can reduce maintenance. For outdoor and bushcraft knives, however, other properties such as toughness may play a greater role.

Corrosion resistance is therefore not a quality level, but a property of a steel, which is more or less important depending on the application.

Overview of more knife steels and their properties.