A question that I tend to get from clients is whether carbon or stainless steel should be used for the blade. I would choose a Stainless Steel for most applications. However, there are some applications where I would definitely advocate a Carbon steel blade.
For a working knife, whether it be for hunting, camping, cooking or just cutting biltong, whose primary purpose is to cut, then stainless steel wins every time. Even the simplest plain carbon/chrome stainless steels will hold a sharp edge longer than carbon steels and some stainless steels can also be polished to a mirror finish. And the more highly alloyed stainless steels really do perform at a higher level. It’s called “edge holding” and this ability is the reason why one can no longer buy carbon steel razor blades!
Where greater toughness is required, for example when chopping, then carbon steels show the advantage of better toughness and greater versatility in heat treatment options
Plain carbon steels are simply alloys of iron and carbon with only small amounts of other alloying elements such as silicon and manganese necessary to make a good steel. These alloys require water or oil quenching to harden them fully and if left to cool in air they do not harden but form a much tougher and springy structure. “Differential hardening” is made good use of in bush craft knives and in Japanese style knives where a heat treatment pattern or ‘Hamon’ can be created. Differential hardening is virtually impossible to create with stainless steel as they are air hardening ie – they will harden almost fully if cooled in air during the hardening process.
Alloy carbon steels, eg – AISI 5160 which also contains chromium or En45, a carbon-silicon spring steel are much better knife steels than a plain carbon steel and can still be differentially hardened. Carbon steels are also very much easier to forge weld, the process used to make Damascus steel, which is why stainless Damascus is less common and much more expensive.
That’s my take on the perennial carbon/stainless steel question. Stainless for the best working knife and carbon steel for those special applications.
~ Graham Clarke