This post is all about stainless blade steels and high-carbon blade steels and what you can expect from them in terms of appearance, performance and maintenance when you buy a knife made from either of these steels.
High-Carbon Steel
All steel contains iron and carbon as well as other alloying elements to improve its function in particular areas. When the amount of carbon in a steel is around 0.6% or above it is able to become very hard by heat treating the steel in a certain way. Blade steels are among these high-carbon steels, sometimes referred to as tool steels.
I use high-carbon steels with between 0.8% and 1.2% carbon content.
High-carbon steel can be affected by the compounds that it comes into contact with. Water contact for a prolonged period of time will cause iron oxide, or rust, to form on the surface which also causes a pitting of the surface. So high-carbon steel knives especially should be dried after use and kept in a dry environment.
Acid and alkali substances that come into contact with a high-carbon steel will also have an effect on the metal’s surface. Although not destructive like rust, they do cause a discolouration.
Over time a high-carbon steel knife will attain a ‘patina’ of random patterns that are patchy grey. It does nothing to the functionality of the knife and won’t leave the edge blunt.
Patina on a Santoku
The acids and alkalis present in the foods we eat will stain the knife and over time it will achieve a rich patina.
Many appreciate the beauty of a richly patinated knife blade, me amongst them, while for others it makes the knife seem less beautiful than when it was new; all very subjective.
Stainless Steel
Stainless steel was invented just over 100 years ago. It was discovered that by adding at least 10.5% chromium to the steel alloy it would start to become resistant to rusting and oxidation from contact with water, acids and alkalis. Be aware, however, that it is stainless and not stain free. Resistance to rusting and staining does increase with more chromium being added to the mixture but it can have other adverse effects if too much is added at the expense of other alloying elements.
Stainless steel knife blades still have to have a high amount of carbon in the alloy so they can be hardened to give a good cutting edge.
One effect of adding chromium to the steel alloy is to make the finished steel harder. At first you may consider the harder the better for a knife blade but it can also mean more brittle and quite a bit more difficult to sharpen. Stainless blade steel is also comparatively expensive compared with non-stainless knife steels.
Maintainence
From a day-to-day point of view there is little to choose between the two steels when considering maintenance; both should be cleaned and dried soon after use. However high-carbon steel will need to be sharpened a little more frequently, but is easier to do than stainless steel
In Conclusion
A high-carbon blade will rust more readily and will stain to give a patina.
It is easier to sharpen.
It is less expensive than stainless steel.
Stainless steel blades are more resistant to rust and staining.
They are harder to sharpen and more brittle than non-stainless blades.
So there you are. When faced with that choice when ordering a knife from me you can make a well informed decision.
Bye for now
Tim
Further Reading
For a very in depth study of carbon steels and stainless steels head over to the excellent Knife Steel Nerds