By Graham Fredeen
Here is the first part of a pattern welding tutorial I have had in the works. It covers (or eventually will) the complete process of making a pattern welded blade, from forging the billet, to patterning, to forging the blade, grinding, heat treatment, finishing and polish, handle assembly, and sheath making.
Pattern welding is the process of forge welding different grades and alloys of steel together in alternating layers, developing layer count, and manipulating the layers through actions like twisting, cutting, drilling, and variations in forging to create a pattern in the final layer structure of a blade or object. Pattern welded steel is widely referred to as “damascus steel.” This terminology is actually misused, or rather is a misconception for what the steel is. True damascus steel is actually what is known as wootz, which was made in southern India as early as 300 B.C. by heating iron ore, carbon, and other alloying elements in a crucible and casting the steel. Wootz contains bands of micro carbides within a tempered martensite/pearlite structure. These bands create a visible pattern within the blade. Europeans first encountered this steel in the city of Damascus and it became known as damascus steel. Over many, many years, due to some similarity in appearance, pattern welded steel has become known as damascus steel. In the modern world of bladesmithing, both terms are interchangeable, with damascus being the more popular of the two, but for the sake of correctness I choose to use the term pattern welded steel.
Forming the Billet
A pattern welded blade begins life as a stack of different steel grades, known as a billet. It is from this billet that the multiple layers and patterns of a pattern welded blade originate.
The first step in creating a billet and pattern welded blade is to select the types of steel which will be used for the blade. Steel used in pattern welded billets are selected largely for their contrasting appearances when the blade is done. It is the difference in carbon content, and presence of alloying elements in the varying layers which create visible distinction between the layers when a pattern is made. However, aside from the appearance of the steels there are other special considerations which must be taken into consideration as well. Firstly, whether any of the steels used contain alloying elements (like nickel) which prevent/slow carbon migration. If there is no barrier to stop carbon from moving around, over the course of a few welding heats, carbon will migrate from the higher carbon steel layers into the lower carbon layers until a roughly uniform carbon content is attained throughout the billet. In this case, the selected steels must contain enough carbon between the two to make a usable blade. For example, if a steel like 1050 (.5% carbon) is mixed with a mild steel like 1018 (.18% carbon), the resulting carbon content of the billet will lie somewhere between the two, say in the .35% range. This is not enough carbon to make a usable blade, so higher carbon steels should be used instead. If any of the selected steels have alloying elements that block carbon migration, it is important to select steels which have similar hardening techniques and similar performance characteristics. If the steels have different hardening and performance characteristics it is possible that delamination can occur during heat treatment as some layers may expand more than others. Additionally, soft and hard layers can exist, creating problems along the edge, etc. More than two steels may be selected, and can be stacked in many different ways depending on the desired pattern.
For this billet I have selected 1095 and 15N20. 1095 is a plain carbon steel and will etch black in the final blade. 15N20 contains nickel which will resist etching and appear silver. This creates a billet with strong contrast. Additionally the steels both harden similarly and have similar performance characteristics which make them a good choice.
This billet started 19 layers of the alternating 1095 and 15N20. First the stock was cut to length, and then all of the mating surfaces were ground clean to remove any mill scale, dirt, or rust which could contaminate the welds. When grinding the stock, it is advisable to not grind down the length of the billet, but rather perpendicular to it. The grooves and scratches act as channels for the flux, longer grooves create more chances for flux to become trapped in the weld, keeping the grooves heading toward the sides of the billet provides a quicker exit path for the flux.
After the stock has been cleaned, it is stacked into the billet with the alternating layers, clamped tightly in the vise and the ends of the billet are welded to keep the billet together. Billets can also be held together with wire.
To make handling and working with the billet easier, a handle is also welded on, so tongs are not necessary.
Now it is time to begin actually heating the billet. The billet is placed in the forge, which runs a reducing atmosphere to help prevent oxidization.
Once the billet is heated to a red to orange heat, it is removed from the fire and fluxed. Borax is used for the flux. The flux serves a few purposes, it firstly coats the billet and prevents oxidization from occurring which would contaminate the welds, secondly it also dissolves and carries away impurities which would also contaminate and create incomplete welds.
After fluxing, the billet is tapped lightly with the hammer to close any gaps and the billet is placed back into the forge and heated to welding temperature.
Note the appearance of the steel as it approaches welding temperature (2200 F +). As the steel gets close to welding temperature it takes on a bright yellow color and the molten borax begins to dance and bubble around on the surface. A good way to think of this is the steel begins to look like melted butter. (Note that the colors in the pictures differ slightly from what they actually look like due to IR washout and the auto light adjustment settings on the camera).
After the billet reaches welding temperature, let it soak for a few minutes to ensure that the entire billet is heated evenly and that the center is also brought up to temp.
Next the billet is quickly removed from the forge, taken to the anvil and hammered lightly to forge weld all of the individual layers together. Only firm, but light hammer strokes are necessary to weld the billet, too heavy a stroke can force out the flux too quickly and result in delamination. All of the work must be completed at or above welding temperature until the billet is completely welded. Working below welding temperature can result in delamination and weld failure.
After the initial weld is made, the billet is cleaned off with a wire brush, refluxed and placed back into the forge for another welding heat.
Here is a video which shows the first weld being made on the billet.
After the initial weld, the billet is brought back up to welding heat and this time it is hammered harder to help solidify the welds and ensure that the billet has become one solid piece of steel. The first few heats of the drawing out process are all worked at welding temperature with little work done below.
The billet is then turned 90 degrees and the edge of the billet is hammered. This will quickly show any bad welds which will result in delamination. If no delamination occurs, the welds are most likely solid. Should one of the welds fail, the billet can be refluxed, brought back to welding heat and re welded to fix the bad weld/s.
Now that the billet has been successfully welded and is one solid piece it is time to begin drawing the billet out. Usually, higher layer counts are desired in a billet to create the patterning. It is impractical to try and make a billet with 300 individual layers by stacking together 300 pieces of steel. As a result, layers are formed by drawing the billet out to roughly twice its length and half its thickness, and partially cutting through the billet and folding the billet over on top of itself.
Drawing out the billet is a long and drawn out process, excuse the pun, especially if the billet is being worked by hand.
Here is a short video and series of pictures of some of the drawing out process following the first welding.
To draw out the billet, the billet is worked on the thickest side to reduce its thickness. As the thickness is decreased, its length and width increase. The billet is then turned 90 degrees and worked on edge to reduce the width of the billet, which in turn increases the length and thickness of the billet. This process of decreasing the thickness and width of the billet while increasing the length is the process known as drawing out the billet.
After the billet is drawn out to the desired length and thickness it is trued up, to create even thickness and width, straightened, and then placed in the forge to anneal (softening process where the steel is heated above critical temperature and allowed to cool very slowly allowing carbon to diffuse out of solution and pearlite to form).
The billet after being drawn out for the first time.
Note that instead of allowing the billet to cool, and then cutting and restacking, the billet can be hot cut 90% of the way through, cleaned well with a wire brush, fluxed, and folded over on top of itself. In order to save on the number of times I have to draw out the billet, rather than just folding it over, I will clean the billet, cut it into 4 pieces and restack it.
The billet is then ground completely clean and all of the scale and oxidization from the forging process is removed. I will then divide the billet into 4 even sections (discarding the ends), cut the billet using the angle grinder, restack the billet, and tack weld it to hold it together for the next forge welding.
Here is a video showing the entire second welding process. After the second weld, the billet now has 76 layers (4 multiplied by the original 19).
Again, following the second welding, the billet is heated multiple times, and drawn out by decreasing its thickness and width to increase its length. The majority of this work is done around welding temperature as this is where it is easiest to move the steel, once the steel cools too much it becomes very difficult to move under the hammer, so the billet is straightened up for the next heat, excess scale is brushed off, and the billet is heated again.
To aid in the speed of the drawing out process it is often advantageous to have a striker (if you don’t have a power hammer or hydraulic press). This video shows the billet being worked with a 10 lb two handed hammer to make the drawing out process go faster. It is still a lot of work, but much faster and better than doing it with one arm and a 4 lb hammer. My shop helper for the day was still fairly new to the forging process and hadn’t developed the skill or technique to be a striker so I ended up doing the striking while he held the billet on the anvil and flipped it when necessary.
After drawing the billet out for the second time, it is again cleaned, cut into 4 pieces, restacked, and forge welded for a final time. This final weld will yield 304 layers (4 multiplied by 76).
As you have seen from the previous pictures and videos, drawing out a billet by hand takes a lot of time and effort. Additionally I work by myself the vast majority of the time, so it is rare to have a striker available to make the process go faster. As a result I took the time to build a small 20 ton air over hydraulic press to make the process more efficient. The final weld and drawing out was completed using the press.
Here is a video of the press in action, welding and drawing out the billet for the final time.
Now that the billet is welded and drawn out to the final desired layer count, it is time to begin the patterning process.
NEW INSTALMENT STARTS HERE
Patterning the Billet
The next process actually gives the pattern welded steel its pattern. Patterning is the manipulation of the layers of steel within the billet in order to achieve a specific appearance. The layers within the billet can be manipulated through any of the following techniques (or a combination thereof): cutting/grinding grooves, drilling shallow holes, twisting, forging techniques (such as heavy, un-uniform peining or fullering), cutting the billet apart and restacking and re-welding (usually done as part of the folding process). The position, depth, orientation, and size of the grooves/depressions/twists/etc will all greatly affect the pattern. Grinding/cutting/drilling grooves or depressions expose interior layers to the surface. When these grooves are forged out, the interior layers are brought to the surface where they become visible and can contribute to the pattern. Twisting manipulates all of the layers in the billet, and when forged and ground can develop patterns that resemble stars. There is an almost infinite number of different patterns that can be achieved, far too many to discuss individually in detail. If you have further questions about a specific pattern you come across, I will be more than happy to discuss it separately.
For this blade, I have chosen to go with what is known as a Dog Star pattern. The pattern consists of an arc of “rays” that originate from a single point of origin (usually on the spine of the blade, with the grooves moving radially outward).
I first grind off the scale and pitting and even up the billet. Then I lay out my grind pattern on the billet.
I will first trim off the end of the billet where you see the vertical line. The ends of billets are prone to having cold shuts and incomplete welds and additionally they are contaminated from the welds made to hold them together. Then I will use an angle grinder with a dressed grinding wheel (rounded over) to grind in the grooves.
When grinding the grooves, I will make the depth much deeper near the cutting edge of the billet, and shallower as they move towards the spine. Additionally, it is important to angle/round over all of the sharp edges after you grind the grooves. Sharp edges like to fold over and can form cold shuts within your final blade.
Both sides will be ground the same, and again, the edges of the grooves must be rounded over.
Now it is time to place the billet in the forge and start forging in the pattern. As mentioned above, when you cut grooves into the billet, they expose interior layers within the billet. By forging down the high spots on the billet, the lower, interior layers are brought to the surface and will form the pattern.
When forging in the pattern it is very important to only forge the high spots down, and not together. If you are not careful, you can fold the grooves together, forming cold shuts which will ruin your blade. Thus, during this process it is very important to work slowly and take the time necessary to ensure that cold shuts don’t happen.
Here is a video which illustrates the complete patterning process. It will probably be necessary to open the video in a larger youtube window.
Forging the Blade
Now that the pattern has been forged into the billet, it is time to finally turn the billet into a blade. You could take the billet, square it up and do a stock removal blade directly from the stock; however I prefer to forge my blades. The process of forging a blade goes for any steel you are using, not just pattern welded steel, so for those who are not at the skill level to try pattern welding yet, this portion of the tutorial and each portion thereafter will apply to any blade. This forging technique is firstly my own personal technique that I have developed over the years (I’m also completely self taught). There is definitely more than one way to go about this (some forge the tang first, some forge the tip first, some pre-curve before forging the bevels, some correct bends after or during the process of forging the bevels etc). This will give you some good ideas about how to go about things, and to see how the steel responds to the hammer. There are many subtle techniques that are hard to see, and frankly hard to explain and understand, unless you have done it yourself. Everyone will develop their own personal techniques and methods, what is important is to find out what works best for you and stick with it.
The process of forging a blade involves a few sub processes: pointing, drawing out the blade, forging the bevels, forging the tang. Each of these processes have certain techniques to keep in mind. And do not forget the ancient bladesmith’s proverb “If a blade is what you wish to win, forge it thick, and grind it thin.” Not sure where that actually originated from, but its great advise, especially for beginners. Always leave the blade oversized by a good amount. Grinding is a lot trickier than forging, and if you forge the blade too small or thin, you will end up grinding it into nothing, fast. You also have to remember that as you forge, due to oxidization, you are constantly loosing mass, so you’ll need extra. You will also need extra steel since after forging you’ll have to grind off all the scale that formed during forging and depending on how clean you were in your hammer technique, there can be some deep pitting and hammered in scale to grind out.
Since, when I forge a blade, I work from the tip to the tang, I begin the forging process by pointing the stock. Pointing is, as you might guess, tapering and beveling the front corners and edge of the stock into a point. This begins to form the tip of the blade. To start the pointing process, the stock is held on edge, on the face of the anvil, and is held at an angle (with the front of the stock on the face and the rear up off the face). The face of the hammer is also angled in a similar orientation. The top corner of the stock is struck at an angle, causing it to deform outward and downward, forming a chamfer. When ever you strike hot steel, the steel will always displace in every direction. If you hammer downwards on an edge, the steel will decrease in width, but the displaced steel will add to the length and thickness of the stock in that area. Thus as you work and start forming a blade, you must work the blade from all sides to keep things moving in the direction you intend (or that’s the idea anyway). When starting to form the point, I like to place the tip of the stock on a corner on the anvil. This gives plenty of clearance for the hammer. I usually stand behind the stock, with it in line with me. When I strike the stock, rather than hammer downwards and forward (which will cause the top corner to fold over and form a small cold shut at the point you are trying to form), I hammer in towards myself, which compresses the corner in towards the center of the stock. As the tip mushrooms out a bit from the hammering, I flip the stock onto its face and return it to its proper thickness, flipping and working both faces evenly as I do this. One way of thinking about it is as you work, you want to work the blade in a complete “circle” a.k.a. 360 deg. So if you start on an edge, you’ll want to flip the blade 90 degrees and work the face, then once you’ve worked that face you flip 180 degrees and work the other face, then 90 and the other edge or back to the original, etc. Granted this is not always the order to work things, it all depends on how the steel needs to be moved. Just remember you need to work the steel evenly.
After the point has been formed, it is time to start drawing out the blade. Drawing something out means you are taking stock larger in width (and maybe thickness) and forging it to make it longer, and thinner. During the drawing out process, the whole profile of the blade is established. This includes the profile taper, curvature, distal taper (blades whose thickness decreases from the guard to the tip). To draw the blade out, it is hammered on its edge to reduce its width, while the length and thickness increase. It is then flipped and hammered on its face to decrease the thickness, which cases the width and length to increase. Then the width is then decreased again, etc, etc which constantly causes the blade to increase in length. The angle and the amount of work done on a certain portion of the blade all affect the blades profile. It is difficult to explain, but when you see it done, or (especially if you) try it yourself, you will quickly learn how steel moves under the hammer.
Once the profile of the blade is established it is time to forge in the bevels. Some choose not to forge in the bevels, but I do because it saves on grinding, and there’s less steel wasted. If you are going to forge in the bevels, it is important to remember to forge the blade profile a bit smaller than the desired final size, as when you form the beveling the profile will expand, and it is not all that easy to try and down size the profile back to where it should be. To forge the beveling, I first forge in what is known as a micro bevel. This is a small, steep bevel that starts to thin the edge. This micro bevel is important because it helps to keep the edge directly in the center of the blade where it belongs, and not offset to one side or the other. To form the micro bevel, I align the edge of the blade with an edge of the anvil, this is to give the hammer clearance, otherwise you’ll hit the anvil face with the edge of your hammer. Much like the tapering process done when pointing the stock, the edge is angled on the face of the anvil, and the hammer is also angled in an equal (but opposite) manner. Work the edge to start to form the micro bevel. Then flip the blade over and work the other side. It is important to work both sides evenly, otherwise the edge will be offset to one side, and the angles on the bevels will differ from one side to the other.
Once the micro bevels have been established, use the same exact technique, but decrease the angle of your hammer and the angle you hold the blade at with respect to the face of the anvil and slowly bring the bevels up towards the spine.
Here is a video which illustrates the entire process of forging the blade.
Forging the Tang
After the blade has been forged to shape (for the most part, there will still be some adjustment at the end to deal with), it is time to draw out the tang. Drawing out the tang uses the same skill set as drawing out the blade. In the video I used my hydraulic press to draw out the tang to make things go a bit faster. It can definitely be done by hand. Something that makes this easier is to use a fullering tool (like a spring fuller), both to set the shoulders of the blade, and to make moving the steel easier. If you don’t have a fullering tool, you can use the edge of the anvil to form and square the shoulders of the blade. To see an older tutorial I did on forging a blade where I used this technique, please visit my website, and look under the tutorial section.
After the tang is drawn out and its adjusted, I usually knock off any of the tough scale that might have formed on the blade while I was working the tang. To do this I wet forge. Wet forging is placing some water on the face of your anvil, and then placing the steel on the anvil, dipping your hammer head in water and then striking the steel. Since the steel is very hot the water that is trapped between the anvil face and steel, and steel and hammer face, instantly vaporizes, causing a small explosion, so to speak. This rapid vaporization will knock off scale on the blade. Additionally, the steam generated from the vaporizing water helps to prevent oxygen from coming in contact with the hot blade and forming more scale. After I de-scale the blade, I adjust and straighten it in the black heat. It is very important during the forging process to never work the steel much below critical temp (or about a cherry red). While firstly you won’t move a whole lot of mass, more importantly you will create stress fractures, and if working with a high carbon steel, it will have some air hardening meaning things will crack all the sooner. The only thing you can do in the black heat is lightly hammer to straighten the blade. Before each heat, I always straighten and adjust the blade, this helps to keep things under control and progressing the way I want.
After the blade is finished being forged, it is placed back into the forge for a final heat, bringing it back up to critical temperature and then the blade is either placed in an insulating medium, or left in the forge after you shut it off to cool very slowly and anneal.
Here is the video which shows the forging of the tang and final adjustments on the blade.
The next step in the process is the rough grinding process, or for those without grinders, the filing and sanding to shape process.
I’ve already got the blade rough ground and it is currently ready for heat treatment. Just have a lot of video to edit and explanations to write up and then the grinding portion will be posted.
Much more to follow…