The famous Damascus steel. What qualities did these amazing blades have? What is the secret of ancient technology? Damascus for its time was a revolutionary breakthrough in the creation of high-strength metal and new technology. The legendary swords that cut through the silk scarf had an extraordinary sharpness. Isn't this a myth? The forge of the twenty-first century is the realm of traditional technology. The principle of creation has not changed for centuries. The main elements of this production: open fire, hammer, anvil, blacksmith's skill. A sign of the new time in the profession of a blacksmith is the raw materials. In the old days, artisans themselves mined ore, then processed it into metal. Modern blacksmiths, as a rule, operate with steel with alloying additives. These impurities give the metal individual characteristics.
Superiority damascus steel over all other alloys - a common myth. Scholars believe that this is a figment of the imagination of the writers of the early nineteenth century. In the historical novels of the time, the blades of Damascus had miraculous properties. They cut through like butter. Historians and metallurgists refute these legends. To resist modern steels, ancient Damascus could hardly have been able to. However, it was somewhat simpler chemical composition and the steels that were used in it were not so interesting. The "Damascus" that today's craftsmen create is, as a rule, the use of already initially high-strength steels with good characteristics.
Nevertheless, the "Damascus" of its time was really distinguished by its high strength and flexibility. This combination made Damascus steel an excellent weapon. The secret is in a special alloy.
In its purest form, iron, very soft metal, and does not fit . Therefore, a person uses alloys - compounds of iron with other chemical elements. An indispensable component of these compounds is carbon. It gives the alloy hardness. For example, in usually a nail, carbon is hundredths of a percent (0.06-0.16%) of the total metal. And in a railway rail from 0.5 to 0.7%. Iron alloys containing less than 2.14% carbon are called steel. After a special heat treatment, it acquires another important quality- elasticity.
The main secret of the Damascus production technology is a multi-layer blank, which consists of alloys with different carbon contents. Damascus steel is one of the first composite materials in history. "Damascus" is a welding technology when there is a diffusion convergence of layers of two, three or more steels by pressure. The main part of the package, which consists of steels rich in carbon, gives special hardness to "Damascus". The source of elasticity of the future product is alloying additives and iron. So, the alternation of layers of metal with a very high and very low carbon content, gave the new material: hardness, elasticity and toughness (impact resistance).
Traces of this cocktail can be seen with the naked eye. The characteristic pattern on the Damascus blade is the optical effect of the uneven distribution of carbon. "Damascus" has its own unique "face", its pattern, its beauty in iron. Homogeneous material is even in color, not so interesting. It is usually painted, or to create some kind of image.
The high qualities of a particular Damascus steel blade are laid down on initial stage. There is no perfect recipe for creating a "package". The selection of raw materials, their proportions, the principle of combining, in ancient times, any of the elements of this process, was the secret of the master, the foundation of the superiority of his weapons.
Made of Damascus steel - the pride of any hunter. Thanks to manufacturing technology, such a tool cuts the hardest natural materials and fabrics. He keeps a sharp edge well. However, the product of these masters is rarely used for its intended purpose. The main function of their steel works is decorative.
Buying a knife made of high-quality steel, of course, is not a problem. If there is not enough assortment of ordinary or branded blades, you can find a specialist working on an individual order.
However, you can go the other way - make a knife yourself. The first time to forge the perfect blade, most likely, will not work, but who knows ...
BUT homemade knife from wire rope is a worthwhile undertaking, the result can be a quality blade with a visible pattern on the blade formed by mixing layers of metal during the forging process.
Material selection
In our time, only true connoisseurs of this craft are engaged in the manufacture of blades. However, even a novice blacksmith and anyone can try to forge a homemade knife.
The easiest way to do this is from a piece of thick reinforcement, an old file, or a piece of an automobile spring. It will be a little more difficult to forge a drill or a bearing cage. You can get an interesting result from a triggered chain from a chainsaw or a car engine.
Another material that, after forging, can become a quality blade is cable. Its veins are made of carbon steel, capable of holding a good point after hardening. If you manage to keep the braided pattern after forging, you can get a very original blade, vaguely reminiscent of wild Damascus steel.
What you need to know to figure out how to make a rope knife? Two important nuances: the first is whether the properties of the high-carbon material will be preserved during processing; the second is whether a visible pattern will appear on the blade, gracefully turning into a sharpened point.
Damascus steel
Previously, sharp, plastic and reliable blades with a patterned pattern on the blade were called damask blades (according to one version - from the Fulad province in Persia, where they were made). Such characteristics and visible effect were achieved by various methods.
Steel could be smelted in a crucible by metallurgical casting, experimenting with the composition of the material. Another option is to “weld” steel strips of different hardness in a forge and then forge the resulting workpiece. Blades forged by blacksmiths using a special technique began to be called Damascus.
They differ precisely in the method of manufacture and technology, and not in the characteristics and degree of expression of the pattern. Having unforged a knife from a cable, you can try to create a blade with your own hands, vaguely resembling such material. And although the drawing on the blade is not an end in itself, it is still distinctive feature damascus steel.
Blacksmith tools and materials
To forge a knife from a cable with your own hands, you need to master the craft of a blacksmith at least at a minimum level. To do this, you need a pair of hammers: one is massive (up to 2 kg), the other is lighter (up to 0.5 kg) for fine work, tongs, an anvil and a home-made furnace (forge) with forced air supply.
You can not do without a grinder, electric welding in the manufacturing process. You will need a vice and charcoal from rocks that give great heat can serve as fuel for the crucible, because the workpiece will have to be heated to temperatures above 1200 ° C.
For better "welding" you can use borax as a flux. It removes scale and prevents carbon from burning out of the material. It is also necessary to prepare the oil for hardening, to ensure safety.
The ability to use someone's blacksmith shop or forge enterprise with a mechanical hammer will greatly facilitate the task.
Preparatory operations
To make a knife from a cable, you first need to make a sketch or sketch of it on paper. Then you have to find the right material. We need to check it and at least remotely determine the composition of carbon in it.
It depends on this whether the future blade will take hardening, whether it will hold the edge and whether it will be possible to carry out blacksmith “welding”. The test is carried out for sparks. A moderately dense orange sheaf of them will mean that welding is possible, carbon in the steel contains about 1%, which is enough for hardening.
Next, you need to cut a piece of cable of the required length. At this stage, they are determined with the method of manufacturing the handle. It can be from a single piece of cable without forging. The knife will look original, but have a decent weight.
Another option is to weld a reinforcement bar to a piece of cable by electric welding. It is convenient to hold on to such a handle, heating the workpiece in the crucible and processing it with hammers. Then you can make a type-setting handle on it or, having riveted it, install decorative overlays.
Before starting work, the cable is pulled together with steel wire clamps in several places. This is done so that the thin wires do not unwind during the heating process.
A workpiece is placed in a kindled crucible and allowed to warm up to 800 ° C. At this stage, the strands of the cable are released (annealing), the material becomes pliable. Additionally, oil and dirt burn out.
After cooling, the workpiece is clamped in a vise and one of the ends of the cable is scalded by electric welding. With an adjustable wrench, it “twirls” along the weaving to maximum density. The other edge is scalded with simultaneous fastening of a piece of reinforcement for ease of use.
Wire clamps are removed, the workpiece is heated to 1200 ° C, sprinkled abundantly with borax. This is necessary for a better penetration. After reheating, forge "welding" is performed. With a heavy hammer, the cable is forged along the plane, periodically sprinkled with borax.
The workpiece is constantly heated. The more often this is done, the more intensively the forging takes place, the better the material “welds”. After rough processing, they proceed to forging the blade, the future cutting edge, and the shank. At this stage, a smaller mass hammer is used more, giving the workpiece a shape resembling a sketch of the future blade.
The complexities of technology
It is necessary to constantly monitor the temperature of the workpiece, not allowing it to cool. Working with a heavy hammer, especially without proper practice and experience, can easily damage the curls of the cable in places where a distinct weave pattern should remain. Unwanted hits with an edge or a corner of a sledgehammer on a heated workpiece leave deep dents that are not always possible to grind off.
During operation, the process of burning out carbon from the metal is inevitable. There are craftsmen who forge a knife from a cable on dense wood laid on the plane of the anvil. When in contact with a heated metal, it smolders, the oxygen of the air at the point of contact is burned, which reduces the degree of carbon burnout from the material. In addition, by forging a cable on a tree, you ensure that the workpiece cools down more slowly, you can do more work in one cycle.
Special approach
Forging a knife from a cable is possible using another technology. There are craftsmen who pack an annealed and compacted cable blank of the required length into a piece of stainless steel pipe before forging “welding”. Its diameter is selected in such a way that the cable enters it very tightly, with some effort.
Both ends of such a case are welded by electric welding, fusing the ends of the cable with the pipe. The workpiece is heated to a temperature of 1200-1300 ° C and in this form is forged. The alloyed stainless steel of the pipe with the cable is not welded, but serves only as a protective cover against uneven forging. In addition, the hot cable does not come into contact with atmospheric oxygen and the carbon in it burns out minimally during forging.
If you use a hydraulic press, then you can significantly facilitate the forging "welding". After heating to 1300 °C, the case with the cable inside is placed under load and left to cool. If you use matrices, then you can immediately form thickenings under the neck for the transition from the blade to the handle and the butt of the shank. During the next heating by forging through the case, the shape of the blade is finalized.
After cooling, the pipe is cut off on the emery from the end, where the point will be. The case is carefully opened with a chisel. Further processing of the workpiece occurs on the emery wheel. Pre-cut off excess sections, make blade descents without final sharpening.
heat treatment
The hardening of the blade is just as important as the choice of steel. According to the technology, a cable knife after forging has tension, it must be removed. To do this, the workpiece is heated to 800 ° C and allowed to cool.
Hardening is carried out when the blade is heated up to 1200 °C. It is lowered with the tip down into the heated oil and held motionless. The blade must then be released. It is cleaned of carbon deposits, heated to 200 ° C and again lowered into oil.
Some craftsmen harden knives through oil (dipped for two seconds) and then placed in salted water.
Pickling and finishing work
After heat treatment, the cable knife is polished, and the blade blade and shank for attaching the handle are finalized. To develop the pattern, the workpiece is dipped into a solution (5%) and left for etching. The processing time depends on the desired effect and can be up to one hour.
If before that a stencil is glued onto the blade, on which the manufacturer's logo (initials or any pattern) is cut out, as a result it will be printed on steel and will testify to the authorship of the blade. After that, fine grinding with fine-grained sandpaper and polishing of the blade is performed.
Before this operation or after, the selected type of handle is mounted. These can be overlays made of precious wood with an interesting texture, typesetting washers of various materials in any sequence, or, for example, a piece of deer antler.
It may not be possible to make such an original and masterfully made knife from a cable (photo above) the first time, but if there is a desire to master the craft of making blades, one should strive for such a result.
Do-it-yourself Damascus steel knife. Do-it-yourself Damascus steel blade. Making Damascus steel at home. Making a knife from Damascus steel. Now we will talk about creating with your own hands a small, forged, and not carved, knife with the help of a homemade forge, anvil, hammer and determination. I do not pretend to be a professional, and this, of course, is not the only way to get welded Damascus, this is a story about how I managed to make it.
Step 1: Materials and Tools
- steel plates of two or more grades (preferably high carbon content) that will contrast with each other, I took high carbon 1095 steel and 15n20 steel, with a small nickel content, which will add brightness and contrast after etching
- flux (borax, which can be purchased at a hardware store)
- a piece of reinforcement, a long bar (will be welded to the workpiece as a handle)
- wood of your choice for the knife handle
- epoxy resin (hardening in 5 minutes is the most)
- brass rivets
- composition for wood processing of the handle, I used linseed oil
- oil for hardening metal (vegetable)
- ferric chloride
- an anvil (preferably a real steel anvil, although in the absence of one, some other solid objects will do: a piece of rail, a sledgehammer, a large metal blank, an old mooring bollard, or just a large strong, hard and even surface. Remember how it all started with stone strikes on a large stone)
- hammer (I used 1.3kg weight, with a transverse striker)
- ticks
- welding (optional, but desirable for welding the plates together and welding the handle, if you do not have welding, you can wrap the plates tightly with wire)
- forge forge (capable of heating the workpiece to the temperatures required for forging, which is very important for high-quality fusion of plates with each other, more on this later)
- belt sander or file with a mountain of patience
- oven or other method of hardening
- drill or drilling machine
- vice (a very useful thing)
Steel plates are cut to the desired size, mine, for example, is 7.6x1.2cm; at the same time, the larger the workpiece, the more difficult it is to form it with a hammer. Before welding them into a stack, the plates are cleaned from all sides of rust and scale. Next, the plates are stacked in a pile, alternating steel grades, so my workpiece consisted of 7 plates, three of which are 15n20, and four - 1095.
Aligned with respect to each other, the plates are seized by welding (do not pay much attention to my seam), and then a handle is welded to the stack to make it easier to operate with the workpiece during forging. There is nothing wrong, especially after the stack of plates has been welded, to use only tongs. I forged mine anyway.
Step 3: First stack forging
A little about my forge: it was made with my own hands from an empty (I bought a new one on purpose) gas cylinder, lined inside with a 5 cm layer of kaolin wool and refractory cement. It is heated with a Ron-Reil type burner, about which there are many good articles. The forge itself is not particularly large and heats up to the desired temperature without any problems.
So, the workpiece from the plates is heated to a cherry-red color, the heat for this is not very strong. The heated homemade workpiece is sprinkled with borax, which immediately begins to melt and must be allowed to seep between the plates. This will remove scale and prevent oxidation by preventing oxygen from contacting the metal. This action will ensure the purity of the workpiece metal.
Then the workpiece is heated again in the hearth and the procedure is repeated a couple more times, not forgetting to clean the scale if necessary. And after that, the workpiece is heated to the forging temperature, how much I can’t say for sure, but I think it’s somewhere in the region of 1260-1315 degrees Celsius. At this temperature, the workpiece will have a very bright yellow-orange color, about the same as moderate daylight.
In order not to waste time, make sure that the anvil and hammer are at hand and there is enough free working space.
Then the workpiece is quickly placed on the anvil and with light, soft blows, evenly over the entire area, the plates begin to be forged together. Next, the workpiece is again placed in the hearth and heated to forging temperature, and then forged with medium-strength blows.
And after that, the workpiece is pulled out so that it can be bent.
Step 4: Folding the workpiece
It's time to increase the number of layers in the workpiece. To do this, the workpiece is forged to a length twice the original, but it is important to stretch it evenly, and not just stretch it. In the middle of the stretched workpiece on undercut, with a chisel or other in a suitable way a transverse recess is made 3/4 or 4/5 in thickness, along which the workpiece is then folded in half at the edge of the anvil, turned over and forged along the entire length, while making sure that the halves have not moved relative to each other along the side edges.
Then the heating/forging process from the previous step is repeated: flux, heating, cooling, heating, forging, horn. The procedure for increasing the number of layers is repeated until the desired number of these layers, so I folded it 4 times and got 112 layers. (If you want more layers, please, the pattern will then be smaller. The formula for calculating the layers is: the initial number * 2 to the power of the number of folds, that is, 7 * 2^4 = 112).
Next, the homemade blank, heated to the forging temperature, is placed in the groove of the anvil, twisted well, and then it is again given a rectangular shape. But before twisting, the billet is punched at the corners so that its shape becomes more rounded, because when twisting and back forging into a rectangular billet, inclusions and impurities from the resulting folds can form if the billet temperature is less than forging.
After that, the workpiece is again forged (I repeated it several times), and cooled, and to make sure that the forging was uniform, I cleaned one of the ends of the workpiece. During the forging itself, especially at the first stage, it is important to keep the temperature of the workpiece high and be careful, otherwise you can tear off the layers from each other (in other words, this is called delamination, which is not good at all).
Step 5: Model and Rough Profile Formation
Now you need to imagine the profile of the future knife and roughly forge it from the workpiece. The more accurately you can forge the profile and bevel, the less hassle with grinding (on a machine or file). There are many articles on this subject by more experienced blacksmiths, so I won't go into too much detail. The bottom line is that the workpiece behaves approximately like plasticine, when it is heated, it is necessary to punch it in the right direction.
Step 6: Sanding the Profile
Fine shaping of the profile is carried out with a grinder and a file. Stock up on tea, because most likely it will take a lot of time, unless of course you have a grinding machine.
Step 7: Sanding, sanding, sanding...and reflecting on the meaning of life
After the profile of the craft is formed, it still needs to be finalized with a file with a finer grain, I used the 400s. The edge of the blade is sharpened almost, but not completely, it is necessary to leave it slightly unsharpened so that the edge material does not deform during hardening. After that, holes for riveting are drilled in the knife handle and wooden dies are prepared for this handle.
Step 9: Exciting Moment
She will either "create" your blade or destroy it. It is important to concentrate and be careful, otherwise you can deform and destroy the blade. The method I used is not the most thorough tempering method, but it was the only one available to me with the tools I had, and the oil was the best I could get.
Before hardening, the blade must be normalized. This will relieve stresses built up during forging and twisting and reduce the chance of warping during quenching. This normalization is done by heating the blade above its critical temperature (when it is no longer magnetized, so it is useful to have a magnet handy) and cooling in air. The process is repeated three to five times, so I did it 5 times. In addition, this action will help you train to remove the blade from the forge, because no hitches are allowed during hardening. This action is shown in the photo with my dangling knife. And this part is also cool in that during cooling, oxidation occurs, which begins to reveal the pattern of steel.
Hardening: the blade is again heated above the critical temperature, and then quickly removed and placed, first of all with the point, in a warm vegetable oil(for steel grades like mine). To heat the oil itself, you can simply heat something metal and throw it into a container of oil, for example, I used a crutch for sleepers. Mix the oil, so you get a more even hardening. If your steel is high carbon then don't use water to harden it, it will only ruin the blade because the water cools too fast which is not suitable for high carbon steel.
The craft should now be treated like glass, because if the blade has been tempered correctly, it is so fragile that it can break if dropped.
After that, it's time for vacation.
Step 10: Metal tempering
Tempering is the process of hardening a blade to increase its life and strength. This is achieved by heating the blade at a certain controlled temperature. I spent the vacation of my craft in the oven for an hour at a temperature of 205 degrees Celsius. “Bake” until the display shows “ready”.
Step 11: Etching
I apologize in advance for the lack of photos of this and the next steps, but the process is quite simple. Ferric chloride is prepared according to the instructions attached to it, and then the blade is aged in it, as much as indicated in the same instructions. In my case, this is 3 parts water to 1 part ferric chloride, and aging for 3-5 minutes. The process is really exciting, and its result looks like a Batman knife.
Step 12: Handle and Sharpening
Again, there are many techniques and instructions on how to make a knife handle and sharpen it, so I'll skip the details. Let me just say that for my craft I chose cherry dies, which I glued to the knife handle with epoxy glue and secured with two brass rivets. Sanded it with 400 grit and coated it with linseed oil.
For sharpening, I do not use any special, labor-intensive method, but mostly use an ordinary grindstone.
Step 13: Time to give yourself a pat on the back, the knife is ready...
This is my finished knife, about 15cm long. People might think this is pretty funny, but I have no idea how this fancy pattern came about. Now we will talk about creating with your own hands a small, forged, and not carved, knife with the help of a homemade forge, anvil, hammer and determination. I do not pretend to be a professional, and this, of course, is not the only way getting welded Damascus, this is the story of how I managed to make it.
Damascus steel today is called welded Damascus, obtained from welded metal plates of various steels, subsequently forged and twisted. It's like sticking plasticine of different colors together and twisting it to make a wavy pattern. After forging, such a workpiece is subjected to etching, in which dissimilar metals of the workpiece are corroded unevenly, thereby forming a beautiful contrast. The original Damascus steel is obtained in a different, very specific way (although it looks similar to modern Damascus), and few people know how to create it, this fact has created Damascus's reputation as a metal supposedly endowed with magical powers. And the reason for this "power", similar to that of samurai swords, is a process that allows you to get a more uniform, and therefore with necessary qualities, steel, which cannot be achieved by other methods, and makes it possible to include low-quality and high / low carbon steel in the composition of the workpiece. Which gives a much better quality blade.
Hundreds of modern steels are suitable for compiling a package, I will name only a small number. According to the chemical composition, wx15, wx4, wx20sg, wx15sg, 65g, 50xfa, 60s2xfa, 70g, 70s2xa, 5xnm, 5xgm, 5x2mnf, 6xvg, 5xnv, 9xs, hvg, u8, u10, u12, u13a, etc. are suitable. According to the temperature of forging and hardening, wx15, y8 and 65g are ideal for each other. The temperature for their welding is about 1100 degrees, the forging temperature is 900-1000 degrees, the hardening temperature is 850 degrees. All these steels comply with the "three rules", and they are easy to find in everyday life.
Used in equal proportions, these steels produce Damascus steel with a carbon content of 0.8%. To make a package, we will forge these steels into plates of approximately 15 * 5 * 1 cm of the same size. We will add a 6-layer package from them: y8 - wx15 - 65g - y8 - wx15 - 65g So that the package does not fall apart in the corners, we will grab it with electric welding and weld a handle from a piece of reinforcement 50-60 cm long from the end. The package for welding is ready. Now let's put it in a heated forge and bring it to a temperature of 850-900 degrees, this is a red-orange color. We will pull out the package from the forge by the handle and put it on the edge so that all layers of steel stand vertically. Put a handful of borax on top of the bag. The borax should melt and flow through the bag. If the borax has not leaked, you need to add more. If the borax is not all melted, you need to hold the bag with borax in the furnace over coal until the borax melts. Then you need to rotate the package 90 degrees so that all layers of metal are horizontal with respect to the ground. In this state, the drill should boil between the layers of steel for several minutes. This is necessary in order for the drill to dissolve all the slag and scale on the metal, which is formed when the metal is heated in the furnace. Then we take out the package warmed up to orange, this is about 900-950 degrees Celsius. We put the package under the hammer and with light blows we forge from one edge to the other. With this action, we squeeze out the liquid borax with all the slags. It is not desirable to forge over the entire surface of the package, a borax may remain inside the package, which will later lead to "lack of fusion". After all the borax is squeezed out of the package, the package has not yet been welded. there is no air access to the metal to be welded.This whole process must be carried out very carefully and preferably in protective glasses.Hot borax splashes from the bag several meters in different directions and this is very traumatic.Place the bag in the furnace again and heat it up to a welding temperature of about 1100 degrees, white heat.The color of the package should resemble the color of a hot sun.While the package is heated to welding temperature, it must be constantly monitored and constantly turned in the furnace so as not to get burned.As soon as the metal lit up like a Bengal fire, this is a burnout.The readiness of the package to welding is visible when the package is evenly heated to white heat, there are no dark spots on it and from it just starting to sparkle. The package ready for welding is removed from the hearth and forged on a hammer along its entire length. In the future, you need to stretch the package into a strip by forging. The hood in the strip must be carried out at a heating temperature lower than the welding temperature of about 950-1000 degrees - yellow heat. By forging the package "on edge" at a temperature of 950-1000 degrees, you will immediately see if there is a lack of penetration, at the place of "lack of penetration" the layers will disperse. Lack of penetration is not so terrible, in the place where the layers have diverged, borax is poured again and the welding process is repeated. Terrible burnout. In the place of burnout, steel is no longer treated. After the package is pulled into a strip, it can be cut into a hot one or simply cut with a grinder, let's say, into three equal parts. These parts are again folded into a bag and the welding process is repeated. So from 6 layers you get a package of 18 layers, then from 54, etc. The pattern resulting from this forging process is called "wild Damascus pattern". To get a clear contrasting wild pattern, you need to type in a bag of about 300-500 layers. During the forging process, only about 2 kg will remain from our 3.5 kg bag finished product, the rest of the metal burned out during the forging process. To improve the quality of Damascus steel, the last extraction of the package into a strip must be carried out at a temperature of 850-900 degrees red-orange color of heat. This allows you to achieve a fine-grained steel structure. It is best to harden Damascus steel in used engine oil. After hardening, the pattern on the steel becomes even stronger. It is impossible to harden Damascus steel in water, it can simply break there. Japanese blacksmiths harden their swords in water, but they coat them with refractory clay before tempering. After quenching in oil, Damascus will have a hardness of approximately 60-64 Rockwell units. To relieve internal stresses in Damascus steel, it must be released. This is done by heating the steel twice to a temperature of 180-200 degrees for 1 hour. This process can be carried out even at home in the kitchen in the oven. The pattern on steel is revealed by etching it in a 5% solution nitric acid or in ferric chloride. Each master selects the concentration of ferric chloride for himself. You need to start learning how to make Damascus steel from the “wild Damascus”, and from there you can already move on to making more complex patterns. One more piece of advice for those who warm up the package in a coal furnace. It is desirable to use coke as a fuel, it slagging the grate less and gives more heat. And the package itself is desirable to warm up in the upper layers of coal or even on top of the coal. In these layers, the air, passing from the bottom to the top, practically remains without oxygen. All oxygen burns out passing through coal, and in the upper layers of coal it is highly enriched carbon dioxide. As a result, in the upper layers of coal, the metal almost does not oxidize and is partially carburized and reduced.
About the properties of the legendary weapons steels - Damascus, damask steel and Wutz - any civilized person knows at least by hearsay. They are evidence unique opportunities masters of the metallurgical profession.
What is the secret of these amazing alloys, who and when produced them and how did they process them? It seems that modern science found answers to these questions.
Continuation of the cycle of publications from the encyclopedia "Metallurgy and Time".
Previous articles in the series:
,
)
"Cast iron" and "hardening"
The structure of a metal with high-carbon interlayers can be obtained by using crushed iron as a flux in forge welding.
At the welding temperature, the carbon of the cast iron instantly combines with the scale, taking away oxygen from it. As a result, instead of scale, carbon dioxide and reduced iron are formed, which immediately carburizes from contact with the carbon of liquid iron. cast iron in this case serves as a more efficient source of carbon than charcoal, since at the welding temperature it melts and carbon is in it in a dissolved, more chemically active form. Spreading over the surface of the workpiece, liquid iron cleans it from scale, simultaneously losing its carbon and, as a result, hardening. During subsequent forging, part of the liquid iron is squeezed out, but thin layers of sufficiently viscous, carbon-depleted cast iron and high-carbon steel remain.
Further forging of the package is carried out at slightly lower temperatures so that the high-carbon layers do not melt, so some gunsmiths say that they do not weld the package, but “solder” it with cast iron. The carburization of a metal surface with molten iron is called "cast iron" or "hardening". The result is an alternation of layers of ductile iron, steel and extremely hard white cast iron, i.e. "Ultimate" version of Damascus steel. The classic Japanese way of making blades was precisely to use molybdenum-containing iron, steel (according to some reports, imported from China) and crushed iron.
Cast steel forging
The historical coexistence of two types of weapons steel - cast and welded - corresponded to two forging technologies. It is known that the wutz billet before forging had a small mass (no more than 1 kg).
The lightness of the initial workpiece allowed the craftsmen to carry out accelerated heating of the product and widely use the local heating of its parts for subsequent forging.
If you look closely at the state of the microfibers that emerge on the surface of the Wootz, you can see not only their “whirliness” as a result of the use of complex forging techniques, but also their fragmentation. This circumstance indicates the implementation at a certain stage of forging of a powerful "one-time" impact on the fibers, previously brought into conditions favorable for crushing. Apparently, it was this forging operation that decisively influenced the final quality of damask steel and the totality of its phenomenal properties.
At the same time, many experts note that the condition for the correct forging of damask steel is its “graduality”. The quality of the damask blade is the higher, the slower the forging is. Accurate forging at low temperatures, which requires numerous heatings, leads to an increase in the contrast of patterns. When heated, small carbides and sharp edges of large carbides dissolve, and upon subsequent cooling, carbon is again released on the surface of large particles in a high-carbon strong fiber. Therefore, the initially blurred pattern acquires sharpness and contrast.
Damascus forging
In heterogeneous Damascus, the type of macrostructure greatly affects the properties of the blade. AT different countries dozens, and possibly hundreds, of welding steel grades have been developed. Despite such an abundance, all these varieties can be ordered by dividing according to the principle of education into several groups: “wild”, “stamp” and “twisted (Turkish)”.
The "wild" pattern of Damascus is formed by random mixing of metal as a result of simple hand forging. The best craftsmen preferred to forge blades from “stamp” Damascus with a regular pattern. The "stamp" pattern was called in Germany according to the method of its formation by applying a special stamp - a stamp of a strictly ordered relief to the blade blank, as a result of which the layers were distorted in the specified order during forging. There are few types of patterns formed in this case: stepped, wavy, rhombic (mesh) and ringed. The stepped pattern is characterized by relatively narrow strands of lines across the blade.
Scheme of the manifestation of the pattern (a) and the main types of heels for the manufacture of stamp Damascus (b)
A common type of "stamp" pattern is rhombic, which has two varieties. One of them is obtained by notching the surface of the workpiece with a chisel crosswise, which is why the pattern looks like a mesh woven from threads, thrown over the blade from “wild” Damascus. Accordingly, the pattern is called "mesh". The second variety is the pattern, which in Germany is called "small roses". It looks like clear concentric rhombuses and is stuffed with a stamp having pyramidal protrusions. The ringed form of the "stamp" pattern is called the "peacock eye" in the United States, although it is more similar to the "peacock tail", since numerous concentric circles are arranged on the blade in a clear order.
"Turkish" or "pink" damascus
The “Turkish” Damascus pattern is considered especially beautiful. So in the XVII-XVIII centuries. it was named in Europe when they saw sabers brought from the East from local varieties of welding metal. Its other name is “pink” damascus, due to the similarity of the type of pattern with rose flowers.
A distinctive feature of the "Turkish" Damascus was that the blades were forged from pre-tightly twisted bars of inhomogeneous metal. At the same time, the patterns turned out to be extremely diverse and bizarre. Berualdo Bianchini, the author of the book “On Damascus Blades of the Turkish Type”, published in 1829, wrote: “... the mass used today to create Damascus blades is exactly the same as that used to make completely ordinary blades, i.e. . a uniform mixture of steel and iron in a ratio of two to one.
Stages of pattern development in twisted Turkish Damascus
The drawing of twice refined blanks into a strip and the subsequent forging of the blade between two dies occur in the same way as in the manufacture of a conventional blade. The only difference is that the Damascus stamp must be provided with various reliefs that are desirable to be transferred to the blade. In hammer forging, successive sheets of steel and iron in the blade are pressed into the recesses of the die, resulting in recesses or relief, which, when then cut, give the desired pattern.
Gun steel hardening
The modes of heat treatment of damask steel products have always attracted the close attention of researchers. It is this stage of the technology of its production that is surrounded by the largest number of legends and mysteries that have come down from the depths of centuries.
And in relatively recent times, for example, in the 19th century, many metallurgists attached great importance to the methods of hardening damask steel and even attributed them to the main secrets of making damask weapons.
No one could then explain why the metal becomes stronger and harder, but there were a great many recipes for hardening: almost every master had his own secret.
It is known that both spring water and mineral spring water were widely used as a quenching medium. The temperature of the water and the salts dissolved in it had a great influence on the rate of cooling of the products, so the place where the water was taken and its temperature during quenching were kept strictly secret. Due to the fact that blades made of steel with a high carbon content, after hardening in cold water, easily broke on impact, in Persia, edged weapons began to be hardened in wet canvas. A known method of hardening, in which before heat treatment the blade for thermal insulation was coated with a thick layer of special clay with various impurities. The composition was removed only from the blade to be hardened in water. The resulting "demarcation" line in each workshop was given a kind of original drawing, by which it was possible to distinguish the master who made cold weapons.
Piss of a redhead boy and buttocks of a young slave
Metallurgists searched and were able to find media in which steel cools faster than in water. Thus, urine and other salt solutions take heat from hot metal faster than the coldest water.
Noticing this feature, medieval metallurgists developed various hardening options and sometimes achieved considerable success. Here is how Theophilus describes the hardening of steel, which cuts “glass and soft stones”: “They take a three-year-old ram, tie it up and do not feed anything for three days. On the fourth day, he is fed only ferns. After two days of such feeding, the next night the ram is placed in a barrel with holes punched at the bottom. A vessel is placed under these holes, in which the urine of the ram is collected. The urine collected in this way for two or three nights in sufficient quantities was withdrawn, and the tool was tempered in the indicated urine of the ram. There are legends according to which damask blades were hardened in the milk of a mother feeding her son, in the urine of a red-haired boy, a three-year-old black goat, etc.
According to legend, in ancient Syria, the blade was heated to the color of dawn and 6 times thrust into the buttocks of a young slave. Known methods of such hardening have become cooling in the body of a pig, ram or calf. In Damascus, saber blades were heated to the color of the rising sun and tempered in the blood of a killed Nubian slave. And here is the recipe for hardening a dagger, discovered in one of the temples in Asia Minor and dating back to the 9th century: “Heat (the blade) until it glows like the sun rising in the desert, then cool it to the color of royal purple, plunging into the body of a muscular slave. The strength of a slave, turning into a dagger, gives the metal hardness.
Ancient blacksmiths also knew how to protect metal from oxidation during the heating period for hardening. The blacksmith took bull horns, burned them on fire, mixed salt into the resulting ashes and sprinkled the products with this mixture, which were then heated and quenched in water or lard.
The Mystery of Cast Steel
Paradoxically, a person has not yet been able to fully understand the essence of damask steel, the nature of its unique properties and the features of the technology for its production. And this is despite the fact that for a long time he used products made of damask steel, improved it, lost the secrets of manufacturing and rediscovered the secrets of damask steel, just as he did in the middle of the 19th century. Russian metallurgist P.P. Anosov.
It should be noted that P.P. Anosov, repeatedly noting in his works high quality of the damask steel he received, which is not inferior to the best Asian damask steel, he never said that he had revealed the secret of the Indian wutz; moreover, he abandoned the concept of “Damascus steel” that was established at that time and put forward a new one - “Russian damask steel”.
Many prominent European scientists sought to unravel the secret of cast weapons steel, including Michael Faraday, the son of a blacksmith. In 1819, he examined samples of cast steel and came to the conclusion that its exceptional properties are due to the presence of small amounts of silicon and aluminum. Although this conclusion turned out to be erroneous, Faraday's article inspired Jean Robert Bréant, assayer at the Paris Mint, to conduct a series of experiments in which he introduced various elements into steel. It was Breant who for the first time in 1821 suggested that the unusual strength, toughness and appearance cast gun steel must be due to the high carbon content. He found that its structure had light areas of carburized steel against a dark background, which he called simply steel.
The production of ancient weapons from damask steel, surrounded by a legendary halo of super-dignities and sacred secrets, as is already well known, was carried out from Indian wutz. It was delivered to the markets of Persia and Syria in the form of a "cake" of cast steel cut in half. The carbon content of the wutz was very high. So, chemical analysis Wutz, conducted by order of P.P. Anosov, showed a carbon content of 1.7-2.0 wt%. and more.
The Indian Wootz blank had a diameter of about 12.5 cm, a thickness of about 1 cm, and a weight of about 1 kg. In addition, wutz ingots had peculiar patterns that were different from those on finished blades. According to most experts, the best blades were forged in the 7th-12th centuries. The blade of the Indian blade, after sharpening, acquired an incredibly high cutting ability. A good blade easily cut a gauze handkerchief in the air, while even modern blades made of the best steel can cut only dense types of silk fabrics. True, even an ordinary steel blade can be hardened to the hardness of a wutz, but it will be fragile like glass and will shatter into pieces at the first blow.
Unfortunately, in ancient India, the secret of smelting and the technology of making blades were so carefully hidden that, in the end, they completely lost them. Already in the XII century. Taban, for example, could not be made either in India, or in Syria, or in Persia. At present, not a single master, not a single company in the world can reproduce the best grades of Indian steel, samples of which are still preserved in some museums in Europe. The loss of the secrets of the production of Indian wutz in the presence of a wide market for its blanks indicates a limited number of craftsmen who owned the technology for the production of wutz, as well as rather high productivity indicators for their time, yield and reproducibility of the technology for producing wutz. With this in mind, we can assume the following: the technology for the production of an ingot of Indian wutz was quite simple (as, probably, it should have been, otherwise it was worth it to hide it so carefully), and the shape in the form of a cake was in those distant times the only correct one for representing the finished semi-product .
In the Middle Ages, when determining the advantages of a particular blade, real craftsmen evaluated the size of the pattern (width of fibers) of damask steel, the nature of the relief, weave and number of fibers, the color of the etched background of the blade and its ebb, the height and duration of the sound of the blade when struck, elasticity and etc. It seems to be largely understandable that these quality control criteria had a deep meaning, providing information, in particular, on the cutting properties of the blade. The width of high-carbon fibers characterized not only the method used to produce damask steel, but also the cutting properties of the blade, its elasticity and ability to self-sharpen.
Obviously, after sharpening and polishing the blade made of damask steel, its cutting edge already had a jagged relief, due to the hardness and wear resistance of its components that changed along the edge. Considering that each high-carbon fiber of damask steel has a profile of a certain curvature when it reaches the cutting edge - a factor that significantly increases the cutting ability of the blade, then the ancient craftsmen were simply obliged to evaluate the orientation of the fibers relative to the cutting edge of the blade and its handle.
The first to strictly scientifically explain the nature of damask steel and connect it with the properties of this amazing steel was the outstanding Russian metallurgist Dmitry Konstantinovich Chernov. He believed that during hardening, steel decomposes into two different compounds of iron and carbon, which “play a very important role in assigning such steel to blades: when quenched, a harder substance is strongly hardened, and another substance remains weakly hardened, but since both substances in thin layers and fibers are closely intertwined with one another, then a material is obtained that has both high hardness and high viscosity. Thus, it turns out that damask steel is incomparably higher than the best grades of steel prepared in other ways.
Legendary Composite
So, bulat is a composite material. Note that the idea of creating such materials was borrowed by man from nature.
Many natural structures (tree trunks, bones and teeth of people and animals) have a characteristic fibrous structure. It consists of a relatively plastic matrix substance and a harder and more durable substance in the form of fibers. For example, wood is a composition consisting of bundles of high-strength cellulose fibers of a tubular structure, bound by a matrix of organic matter (lignin), which gives the wood transverse rigidity. The teeth of humans and animals consist of a hard and viscous surface layer (enamel) and a softer core (dentin). Both enamel and dentin contain needle-shaped inorganic microcrystals of hydroxyapatite, located in a soft organic matrix.
Now we can say with confidence that damask steel was discovered not by chance and much earlier than is commonly thought. Metallurgists of the Bronze Age could not but pay attention to the fir-tree structure of bronze ingots. Having received the first ingot of iron with the same fir-tree structure, the ancient masters probably began to forge it like bronze. Of course, he crumbled. However, this did not stop the ancient metallurgists, and after some time, having gained experience, they managed to find a solution.
The uniqueness of damask steel lies in the fact that it represents a fundamentally new class of composite materials. It cannot be attributed to any of the known and scientifically defined types of natural and artificial composites, among which it is currently customary to define fibrous, layered and dispersion-strengthened. Special properties damask steel are achieved as a result of joint thermomechanical processing of fibers and matrix and subsequent thermal hardening of the composite through the mutual action of its individual components and the processes occurring in them.
In conclusion, we note that when certain conditions patterned ingot can be obtained from a homogeneous melt. This is achieved by slow crystallization of a high-carbon alloy, in which large grains-crystals grow, the size of which can reach several millimeters. Along the boundaries of these dendritic crystals, carbides are separated, forming a cementite network. Forging such a coarse-grained metal at low temperatures makes it possible to crush a continuous cementite network into small particles and form a pattern visible to the eye. The patterned metal obtained in this way is currently called by researchers "dendritic" steel - according to the dendritic nature of the crystallization of the ingot, or "liquation" damask steel - according to the mechanism of pattern formation due to carbon segregation. Modern blacksmiths forge blades from "liquation" damask steel when heated to temperatures not exceeding 850 ° C. it required condition; otherwise, with a stronger heating, the carbide particles completely dissolve and the magical patterns disappear.