Explain Damascus to me

First, do not use any abrasives, whether pad or compound, to clean the knife. Your pattern will be damaged. The pattern itself will be fine but the etch that brought that pattern to light will be damaged. The etch does provide some protection from corrosion. When cutting tomatoes or other acidic things, rinse the blade and dry it, just as you would with a carbon steel blade.

Because of the different steels along the cutting edge, they abrade away at a different rate. That results in a "micro saw tooth" effect that makes it cut differently than a homogenous steel blade. That's about the most simple explanation. Both 52100 and 15N20 have more carbon than 5160. Properly heat treated, they should out cut 5160. As the 5160 is being abraded by use, it exposes more of the 52100 and 15N20. The 52100 is the highest carbon content in the blade, notwithstanding carbon migration. Other elements, like nickel, chrome and manganese, also have something to do with how the blade cuts and wears.

That's a really basic over view. There are much longer treatises that explain it.

Gene

 

Note: I'm not perfect and have been known to make mistakes in the past so don't take this as verbatim--It's just how I understand it.

There are two kinds of steel that can be referred to as "damascus"--pattern welded and wootz. Pattern welded is the most common and dates as far as the Viking age and earlier. There are two practical reasons why this used to be done (and still is in some parts of the world.)

The first of those was that before "modern" (read: medieval) mining practices had been developed, iron was available only in relatively small quantities, and if making an object larger than the ingot you had, you had to forge weld it with others to give you a single homogenous piece of iron to work with. Given the abundance of steel scrap even in undeveloped countries makes this reason obsolete today.

The other reason for forge welding is when smelted steel is not fully homogenized in the bloom. This is common in many Asian or South Pacific traditional smelting methods. Carbon content varies throughout the ingot after smelting, and it must be broken apart and different pieces selected so that, when combined, carbon content is within the desired range. These pieces are then forge folded repeatedly to create a more homogenous product. Think of it like stirring your cookie dough so not all of the chocolate chips end up in one cookie.

Today, pattern welding is done purely for cosmetic effect. Edge retention etc. will be affected by the steels chosen for pattern welding. The steels should have similar heat treatment qualities for best results.

Wootz, "bulat" or "watered steel" does not have layers forming the pattern. Rather, it is the result of carbide banding within the steel. This is caused by using steel with trace amounts of carbide-forming elements like vanadium, and then working the steel using a particular low-temperature process after crucible smelting. It's thought this was originally discovered using iron mined in southern India which naturally contained these trace elements. When the mines dried up, so did wootz production, hence the reason why the knowledge of making it was lost until about a decade ago with the use of modern scientific equipment to analyze antique blades. The carbides in wootz give it much higher edge retention than anything else that was available back during its heigh-day which is why it was so sought after. Modern steels blow it out of the water, though.

 

You are in luck! An episode of Modern Marvles titled Built by Hand is on tonight on H2 (history channel 2) It shows how a knife maker in Washington State makes Damacas Steel. If you don't have H2 is available on DVD.

 

What variety? Pattern welded or wootz?

For reference, the Wikipedia article on wootz is actually pretty well done.

 

all i can say is it's not likely to have been invented in damascus, syria. more likely persia or india from where wootz was invented. other weapons centers (milan, toledo, solingen, sheffield, etc.) knew how to weld iron and steel together to make a patterned blade steel.

 

Exactly. Pattern welded steel is known all over the world. And true wootz steel was developed in India, then exported to the major trade centers of Damascus.