Pattern welded steel and its properties
Making Damascus knives is a very old art form that has more than one origin and can be traced back to nearly the age of steel itself. The India made blades, first seen in Damascus Syria, gave us the name. But it was the many layered Japanese swords and of course those Viking daggers with the composite blades with the chevron twists etc that gave us the method most used today to make Damascus knives.
The art very nearly became lost to obscurity, but due to the recent interest in knife making these past short 30 years, it has come a very long way since those early days. It’s been a real modern day renaissance if you will.
Making the Damascus bar stock and in turn making Damascus knives is one of those chores that keeps me inspired. Not only can you get caught up in the different designs possible, the thought of making Damascus blades that truly stands out in appearance and performs as well as any other blade or better is an ever on going quest. It’s more than just making a great art knife, it’s taking knife making to an art form.
First off, the components in the Damascus blades need to be compatible with each other or in other words all heat treat and forge the same. Second, the components need to be quality steel that will attain a good working hardness and be resilient. Third, the components should etch with good contrast if you expect Damascus knives to look like a Damascus knife.
The components, 1084 and 15N20 are almost standard with most smiths these days with good reason. On their own, each steel would make a good choice for blades and the contrast between the two is excellent.
The 1084, although a simple steel, has just the right amount of carbon to make a superior blade and the addition of manganese serves to help the hardening process along. It also serves to make it etch quite dark with ferric chloride.
The 15N20 has nearly as much carbon and has about 2,5% nickel content added to make the steel very tough. The second benefit of nickel is that it withstands the etch very well for a good contrast with its darker counterpart.
Another benefit of these steels is that they can be differentially hardened for a tough blade, such as a Damascus Bowie, sword or Damascus fighter, that can meet battle conditions and still retain a good edge.
One more very good point about these two steels is that the carbon is at the eutectoid point and that gives you plenty of carbon to make a fine blade but not enough to contribute to problems that can be encountered with higher carbon steels such as grain boundary embrittlement.
These steels also lend themselves very well to natural bluing and look very nice as bolsters on Damascus folders or other art knives.
I occasionally use other steels for making Damascus blades such as cable but 1084 and 15N20 are proven winners. Until I find a better pair of steels they will have a place in my shop.
Making Damascus knives is very addictive and therefore I found myself making it quite often when the Sunday bunch was still here. It was a lot like a mini hammer in every weekend. The upside of this is I have more Damascus in my pile than I can use and when I can find the time to open up some of these bars, I will be offering it for sale on the Shopping Cart.
Special sized patterns need to be considered when you want to use the steel for pocket knives
To make a Damascus or pattern welded billet you simply stack alternating layers of your chosen steels several inches high. These bars or strips of steel are cut to same length and cleaned of rust and scale before stacking, although some forgo the cleaning and let the flux do the job.
These pieces are tacked together with stick or wire feed welder and a handle of re-bar or square bar welded securely on.
The stack is placed in a carbon rich, oxygen free, forge capable of obtaining about 2300 to 2400 degrees Fahrenheit and heated to just a red color before anhydrous borax is added to the stack. The flux will not stick to cold metal but will stick to red metal and will melt into a liquid super solvent and cleaner at welding temperatures.
The flux does two very important functions; first it cleans up any dirt or rust on the metal and second it will protect the metal from the oxygen in the atmosphere when drawn out of the forge long enough press or hammer the strips of steel into a welded billet.
Care should be taken to not leave any pits or depressions in the steel parts prior to welding as the flux will be trapped and create a nasty inclusion in the finished billet of Damascus.
Any oxygen that contacts the steel will create oxide scale and oxygen will also attack the flux as well. So any oxygen that creeps into the gorge will eventually ruin the flux coating and it will need to be rushed of and replaced with fresh flux to keep the stack oxygen free.
At welding heat, a bright orange or yellow, the flux will run like water and will dance or bubble on the hot steel. When you think that the whole stack is hot all of the way through and the flux is still dancing or running, quickly draw the stack out of the forge and press or hammer it together to weld it up solid before the stack loses it welding heat.
If the stack loses its heat or the ends splay open, stop immediately and re-flux the stack and bring back to welding heat before further pressing or hammering.
Once welded, keep drawing the billet down until it is a flat bar about 3/8 or 1/2 inch thick and keep it squared up at all time while forging. The bar should be about 1.5 inch wide and several feel long. This will give you a laminar bar and no pattern that you could press grooves into and grind flat for a ladder pattern.
If you are going to build a w or zig zag pattern then stop when the billet is about 1.5 inches square and then rotate the billet 90 degrees and flatten into the 1/2 inch bar before cutting it into equal long pieces and stacking it for another weld.
Re-stacking and welding will give you a crazy zig zag pattern that you can use as is or use to create yet more intricate patterns.
Once you have create a pattern that you like, you will now need to open it up as the pattern only exist in the cross section of the billet and would result in no pattern at all if you forged it into a knife blade.
One way to reveal the pattern from a billet is to cut staggered and alternating even cuts across the billet from both sides about 2/3 of the way through and then heat the billet to welding heat and pry the cuts apart before ironing it out into a bar of Damascus.
The following Damascus knife was open using the method of cutting alternate cuts and prying billet open. This method puts a tremendous strain on the welds however and great care needs to be taken to prevent the bar from tearing apart at the welds.
A safer way to open the same billet is to cut out triangular shapes half way across the bar staggered down the bar and also alternating sides and simply heat to welding and iron it out between flat dies before drawing the bar down to desired thickness.
As you might have guessed by now, making Damascus knives can be a lot of work but can be both rewarding in more than one sense of the word and fun.
Historical Background of Damascus steel by Dr. John Verhoven