Article 2 - Carbon Steel

**Samurai Stu** · 29-10-2010, 15:19

In a modern world of stainless steel custom knives, much of the heritage of knifemaking has been lost. Only as recent as 70 years ago was stainless steel used for knives and other tools. Before that the norm was forged carbon steel blades. Some of these examples can be seen in museums still in pristine condition with little to no rust. This proves that when cared for a Carbon steel blade will last a long time.

Now today, the art of forged knives is being revived. With the refinement of modern carbon steels some of the toughest and sharpest knives are being made today. One of the key diferences between stainless and carbon steels (apart from the obvious) is the fact that carbon steels can be selectively hardened and tempered. A process that can be clearly seen in these blades.

As with a above knife there are techniques that bladesmiths can use to manipulated the pattern achieved from the quenching process.

Selective hardening offers the opportunity for the Smith to give the steel varying hardnesses. The edge quench makes the edge as hard as it can be. Too hard. It then needs to be tempered to reduce stress and increase toughness. Now the blade has a hard edge and a softer back. However we don't want the tip to be as hard as the edge. So the tip is over tempered to make it softer than the edge but still harder than the back. This is to avoid chipping should the blade fall tip down into something hard. Then the tang has to be a spring temper softer that the rest. So we now have a blade with four different hardnesses. The feat cannot be achieved with stainless steels due to their high alloy (mainly chrome) content.

The blade should then be tough enough to perform several cutting tasks and test without blunting or deforming from stress. Her I can be seen cutting a 2x4 with a knife I made. I performed this task twice and the blade was still razor sharp.

Now the knife should be able to perform a bend test. The blade is inserted into a vice and the maker has to bend the blade at 90deg without it snapping (as seen below)

These are qualities that all forged blades have no matter the size. A select few make forged knives in SA though we are trying to spread the word. Please visit the SABA (Southern African Bladesmiths Association) website www.sabladesmith.co.za for details on bladesmithing and meetings being held.

**Wanderin' Zero** · 29-10-2010, 17:23

I had absolutely *no* idea. Fascinating!

**FrankH** · 29-10-2010, 17:30

Thanks Stu

**marthinus** · 01-11-2010, 12:20

Great post Stu!

Some people forget the qualities of a good old carbon blade since the word 'stainless' came to the market. I just wish it would read 'stain less then carbon' as it can still rust (except H-1 and from Spyderco and 13cro.....from Victorinox but it has its trade offs like less edge retention).

**Mad Irish** · 03-11-2010, 09:14

Nice article

**Buffalo Hump** · 04-11-2010, 12:51

Stu as the owner of one of your blades I can attest to its toughness. I have used it hard and it just begs for more. I love differrentially treated carbon steel blades, they freaking rock! One swipe on the ol' crock stick after hard use and edge comes right back, and they can take some serious abuse. As much as I dig high end stainless steels in a folder I know that when it comes to a hard use (ie, fixed) blade, there aint nothng better than carbon steel!