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Steve, are you accurately using the term "broke" to describe your method of exposing the inside of your sample? If you are actually "breaking" the material then I don't think you can accurately diagnose the exposed edge.

Suppose you wanted to examine the inside of a marshmellow. I don't think forcibly tearing the marshmellow apart would yield an accurate image of what the inside looks like when leaving the marshmellow factory.

Right, wrong, or am I missing the point?

Thanks for the appreciation guys,
Perhaps I should explain the purpose of my work with the microphotography. I am searching to find a combination of steels to use for making damascus gun barrels. I am hoping that these steels will also be capable of heat treating to make knife blades. I have chosen 1018 steel as the replacement metal for what I believe is wrought iron in old barrels. I have welded several billets of damascus, having the 1018 layered with a different high carbon steel in each billet. The billets were drawn out into 1/2 inch square rods. I am subjecting the rods to different heat treating processes, which are the same as I will be doing to the material if used for a barrel or knife blade. After each heat treating process, the rods are etched with ferric chloride to see the result. I will also be etching these samples with a couple of different acids, as well as testing how well they are capable of taking browning and bluing. I have a lot of tests yet to do.

To better understand the results from my testing of these materials, I am studying the chemical reaction of different acids and metal salts (like ferric chloride and copper sulfate) on steel. As etchant solutions and bluing/browning chemicals are all types of acids, or metal salts, I feel that it is important to understand how they work, in order to be able to get predictable results in finishing the damascus. Acids and metal salts effect steel in ion exchange reactions. Essentially, like hooking a microscopic battery to the steel. My testing suggests that the "connections" for these electrical exchanges, are the edges of the steel's grains. The size of the steel grain structure appears to affect the number of electrical connections available for the ion exchanges to occur. This can be seen in the image that I posted earlier of the damascus rod of 1084/1018 steels. The finer grained rod etched very uniformly, because of the many connection points. The rod with the larger spherodized grain structure etched very coarsely, because the contact points for the exchange of ions were farther apart.

As there was no specific heat treatment utilized to control the size of grain structure in old damascus gun barrels, this could well be the reason why barrel refinishers sometimes will find a damascus barrel that does not finish well. The acids used for coloring the barrel cannot effect a uniform bite on the steel, because the grain structure was not refined after forge welding.



I am fairly confident that the "steel" component of old damascus barrels was actually high carbon steel. At that period in time, they fully understood what high carbon steel was and were capable of producing it efficiently. I also base my analysis of the material on its reaction to etching with ferric chloride. It etches and colors very similar to the 1084 steel that I use for knife blades. The reaction of steels to etchant solutions, can tell a lot about the alloys in the steel and also help to display the grain structure.



Agreed. I am using analytical 1018 steel. So, I know there is only a trace amount of silica in it. The fact that the etched 1018 sample appeared to have a similar large grain structure as the metal in the old barrel was what caused me to test the 1018 by breaking it. Note that the 1018 sample had undergone the same spheroidizing heat treatment as my high carbon steel samples. I was surprised to see that etching the 1018, caused it to appear as if it had a large grain structure. Breaking the 1018 sample, indicates that it does not have a grain structure as large as suggested by the etching. The crystalline appearance of the etched 1018 was solely a function of the etchant's effects on the steel. Why; I do not yet know. Another reason to get a better understanding of how etchants effect steel.



I think most will be more familiar with the spelling as coke, rather than choke. Coke (fuel), a solid carbonaceous residue derived from destructive distillation of coal.
Pete, I think you may be confusing silica with sulfur. Silica is not a major issue in steel. The inclusion of silica in wrought iron actually makes it easier to forge weld, causing it to be somewhat self fluxing. Sulfur is very damaging to steel. Too, sulfur will inhibit forge welding. Blacksmiths who use coal forges always seek out low sulfur coal. High sulfur coal in the forge can prevent forge welding.

Do you know where Cockerill got the iron ore for their steel making? I found an old book on mining, that has the chemical analysis' for ore samples from mines around the world. If we have information on where Cockerill obtained ore, we may be able to find the analysis for it and learn more about the alloys in the steel produced.



I did actually break the samples. It is an accurate way of exposing the grain structure in hardened steel. I have examined hundreds of broken knife blades, to see if the material was properly heat treated to reduce the grain size after forging the blade to shape. It is not an easy method to employ with soft steel. Hardened steel will snap off cleanly, leaving a surface that is easy to analyze. Breaking soft steel can leave so much structural damage, that there is often only a small place on the sample surface to analyze. Takes some experience to know the difference between grain boundaries and structural damage.

Duh! My stupid typo.

Thanks,

Pete

Thanks for your time Steve. I hope follow up thoughts are okay, not questioning your research and experiences. I'd suspect if wrought iron were used as one of the components, that the overall carbon percentage would even out to at best to what might be considered medium. Also, I think etch appearance of modern steels might be affected by added manganese, that would be interesting to know what amount may be present in historic barrels.

I've also noticed that barrel bulges are a common type of historic and modern barrel failure. There are many historic accounts of bulge repairs by hammering down and refinishing bulges. Even today it's a viable repair possibility and tools for slowly raising dents are available. My take on the mechanism of plastic barrel failure and the possibility to cold form it back may(?) be more generally successful on low carbon steels.

Thanks again for all your time, and thoughtful explanation, Craig

Am I correct that damascus barrels were not heat treated? Would that make them "soft" by comparison/classification to a damascus knife?

I also wonder what house manufactured the barrel sample you have in your possession? Was it of high quality, or one of the "belgian clunkers" from a substandard manufacturing process? I thought I was understanding this process until you came along with the other micrographs. I am still trying to understand the similarities, thus my question and comparison to tearing a marshmellow. A crude comparison, but one I thought my mind would understand.

When you say soft metals are harder to break, is that the result of the grains essentially stretching? Ductility?

Pretty amazing how many people on this board know about iron and steel. Impressed with the knowledge.

Follow-ups are quite welcome! I fear that I have nearly hijacked this thread. My intentions with my first posts, were to point out that there are numerous ways that anomalies can be created in micrograph images and that at 20X magnification, it can be very difficult to make a determination of exactly what they are. Didn't mean to get too far into my work. I guess as long as it pertains to analyzing old damascus barrels, it's still good.



CORRECT! Carbon migration is scientifically proven. Once the forge welds are solidly completed, the carbon seeks to find a balance between the laminated layers. I have some documentation that suggests the rate at which carbon will migrate between the materials. It is a time and temperature related chemical reaction. The higher the temperature, the faster the carbon migration. However the caveat to this, is the alloying content of the steels. Certain alloys will, and can be added to the steel for the purpose of controlling the carbon's molecular bond within the iron matrix. Obviously, this will affect the rate of carbon migration.

I believe that the overall carbon content of old damascus barrels will fall in the .35 to .40 carbon range. This is below the carbon content that would heat treat well for things like knife blades, but is just enough to affect the steel's grain structure.

Jumping forward to Jawjadawg's question about damascus barrels being heat treated; I do not believe that there was anything comparable to a hardening quench and tempering process done to them. However, I have read in several writings of the cold hammering of barrel tubes after welding. Greener states that this hammering �greatly increases the density of the metal� and was done to the best barrels. The tubes were not actually �cold�, but in blacksmith terms, at a heat that was too cold to effectively move the steel under the hammer. This would be from around 1400 degrees F, down to a temperature of about 900 to 1,000 degrees F. So they were aware that the process created barrels that had a better finished appearance. It appeared to them that the steel was more dense, but actually, it was simply of a smaller grain structure. The hammering that was done to the tube was unnecessary. It was the repeated heating and cooling of the tube that affected the grain structure.

This heating and cooling of the steel is called thermal cycling, or normalizing. We knifemakers do this to all of our forged knife blades; or, it should be done. The heating to low red heat and cooling in room air to a black heat is repeated three or more times. I am convinced that this is exactly what the barrel smiths were doing during the cold hammering of their barrel tubes.

Normalizing will not soften steel to the dead soft condition of being fully annealed. But fully annealed steel will not etch well, because it causes lamellar banding of the pearlite grain structure.



I have heard from many damascus smiths, that manganese will cause steel to have a darker appearance with a ferric chloride etch. However, my recent testing has not proven that conclusively. It could be that the etch coloration is more closely related to the grain structure. We knifemakers know that hardened steel etches darker than soft steel. If we make knife fittings out of damascus, we have to run them through a complete heat treatment, just like a knife blade, to get them to etch well.

I am acquainted with about 100 of the finest damascus smiths in the world. We all know how to go through the steps that we have learned, to make our damascus come out looking nice. Yet, none of the smiths that I have talked to can explain the chemical process that makes this work. That is the reason for my testing. So far, I have only been compiling test results. I have not had time to analyze them fully. At this point, I have many more questions than answers.



The barrel tube that I have is of Belgian manufacture. It is of two iron Crolle pattern. This I find a bit unusual, because most of the Crolle pattern barrels that I have seen were made of three twisted rods. I expect that this tube was intended for a lower grade gun. However, I view the workmanship of welding it to be superb. I doubt that they intentionally made "clunker" barrels. Some may have been made with the intention of keeping labor costs down; like perhaps with the barrel that I have. I expect that barrels of complicated damascus patterns, like Bernard and chain, were more likely to be welded by experienced smiths, due to their skill of uniform manipulation of the material. Barrels were probably graded after finishing and etching to display the damascus pattern. Barrels with very uniform patterns would be saved for best guns, while less perfect patterns were sold for use on lower grade guns. I doubt that the steel and iron used for barrels, were different for best barrels and lower grade barrels. The steel and iron would not be the major cost factor in barrel making and it would not be cost effective to run different grades of material. Too, it would be best for the barrel welders to always work with materials that they are familiar with.



Yes, the ductility makes breaking soft materials very difficult. I broke the piece of 1018 three times before I felt that I had a surface that I could analyze. I wouldn't have tried it at all, except that I was trying to match how the barrel material was exposed.

Thank you again, for taking the time to answer. I was asking about the maker of the tube because of the widely held belief in the vintage gun community that significant variations in quality exist in the pattern welded gun market. The term JABC is used to identify guns which are not usually even considered for safe shooting by members of the vintage gun community. I think it is safe to say that tubes produced by Henri Pieper are considered near the top of the pile in terms of quality, and therefore, consider more likely to be SAFER for shooting today.

Why the difference in quality? I suspect that the main difference is the manufacturing process (duh!) and perhaps a difference in materials and "additives". Sort of like the difference between Coca-Cola and a generic cola, or McDonald's French Fries and the ones you might buy at the gas station deli stop. Pieper didn't tell the rest of the Belgiam gun making guild his trade secrets, but I've read that the top American gun makers all sourced their barrels from a select few providers, Pieper believed to be among them. Was that strictly a cost driven decision, or had Pieper and the other "quality" tube producers demonstrating superior quality (safety) to the marketplace?

I believe Drew's study has the potential to alleviate or perhaps begin to change the way the shooting community views pattern welded barrels, depending upon the depth of the research. It might also demonstrate that pattern welded barrels shouldn't be kept in use. Who knows? Either way, I do not think the outcome of Drew's testing and analysis will do anything to change the view of anyone regarding the safety of shooting those guns we refer to as "JABC". I believe that the experience of the shooting community has demonstrated that JABC barrels are far more likely to pose a safety issue. For that reason, I was interested in understanding a little more about the comparison of the two materials - Drew's and the one you imaged.

The visible separation of the materials within the metal was far more evident in your sample than in Drew's micrograph. The basic point of my question is pretty simple...WHY?

Do we have two apples cut open, or is one of them an orange with understandably different grain structure?

I've wondered if the mentioned cold hammering, in the context of a low carbon steel, was a form of work hardening. Or, the perception of increased density by smiths of the era.

Maybe(?), after the tensile tests a 'typical' damascus barrel sample could be sent off for spectrometer chemical analysis. Say three or four samples off the same barrels, just to get a feel for how different or similar readings would be off same barrel. I'd spring for it if Doc Drew wanted, and if his lab wouldn't do it, maybe even the local Fastenal might.

The experience of good smiths seeing a forming pattern even if it wasn't visible was my thought process about the barrel grinders. I was just suspecting that there were some barrel grinders that could size up a blank better than others, and had a better sense of where the pattern was before it was finished. I wonder if more time consuming patterns were walked over to grinders that had the knack, just to give things a better chance to come out as hoped.

Pieper supplied "Finest Damascus" for Remington Model 1894 EE Grade guns and also "Oxford 4 S.J." The barrel makers were so skilled that they could produce this



Ernest Heuse-Lemoine (1834-1926) from Nessonvaux was a major barrel maker in the Vesdre Valley maintaining agents in London, Birmingham, and New York. Every 3 years he would travel aboard and upon his return, would be met by a band in celebration because he always came back with more orders than his own firm could handle. He would then distribute some of the work to smaller barrel makers. Gaier states that Heuse-Lemoine supplied damascus barrels for at least 50 years to US makers, and that he invented the names of "Boston" and "Washington" damascus especially for the American market.

Leopold Bernard barrels were highly regarded, but about every Belgian maker also produced Bernard pattern barrels
https://docs.google.com/a/damascusknowle...iP3FP0fXb0/edit

It is very likely that the U.S. makers used the same sources for 'rough forged tubes'. More infro here
https://docs.google.com/a/damascusknowle...s66tEXntqw/edit

Bottom line: barrel quality is best judged based on the overall quality of the gun
https://docs.google.com/a/damascusknowle...8WMIMkdKr0/edit

I suspect the JABC Twist barrels will have a lower tensile strength, but we'll see

I realized that should have stated clearly in yesterday's post, that I do not know the maker of the old barrel in my possession. I purchased an unfinished tube section from Dyson. I believe it to be from the mid area of a barrel. It does not include the breach area, where it would have held a maker's mark.

My little brain can't keep up with all of the manufacturer's names and dates. That is the realm of many of you fine Gentlemen. My knowledge is primarily of the technical aspects of barrel making.



The barrel specimens are not so much apples and oranges, but the micrographs are. Adam and I were prepping our samples to view entirely different properties in the steel. Adam used a very mild, nitric acid etchant solution. His use of the etchant, was to clean the steel of surface oxidation and to lightly color the metal. His purpose for viewing the sample was to examine structural damage. I am using a much stronger ferric chloride etchant solution. I am doing a deep etch, to replicate the finishing process that I use on damascus. I want to see what these test steels will look like if I make items from them.

There are many acids and metal salts that can be used to etch steel. Each will cause a different type of decomposition of the steel, and/or chemical change to the steel's surface. Etchants are chosen to prep test samples, depending on what it is that you are trying to determine from the analysis. The nitric acid that Adam used and the ferric chloride that I used, cause entirely different reactions with the steel.

Another variation, is the surface preparation of our samples. Adam was viewing his sample for structural damage. I expect that he did no finishing of the material before etching, as he wished to view how the material was ripped apart. I am sanding my samples before etching, to create a flat surface. The manner and quality of surface preparation, is critical to the ability to view specific qualities and anomalies in the material. This is partly why I question Adam's analysis of the chemical make-up of his sample. How can he look at an irregular surface and know that he is viewing carbon nodules and not artifacts of structural damage? I'm sure that Adam has a much more trained eye than I. So, my questioning of his analysis is more about learning, than arguing.



Some amount of work hardening from cold hammering is almost certain. However, reheating the steel for another round of hammering would soften the steel again.

Grain structure in steel is visible to the naked eye. Heat a piece of high carbon steel very hot, quench it and break it. The grain structure will look very large and crystalline. Take the same piece of steel and heat it to a dull red and allow it to cool in air. Repeat the heating to dull red and cooling in air three times. Then, bring the steel to a proper austinizing heat for hardening and quench it. Break the piece and look at the grain structure. It will have a dull, flat gray appearance. It looks more dense. This thermal cycling of the steel is called, normalizing.

There is no way to know for certain why the barrel makers perceived that hammering on cold steel caused it to be more dense; but I have a theory. With everything that is forged, the last thing you do is straighten it. Straightening is done at a lower heat, so the hammer is not actually moving material at the point of impact, but affecting the bending of a larger section of the piece. I can imagine that after cold hammering to straighten a crooked barrel tube, they noticed that the steel looked more dense. The more crooked the tube and more cold hammering required to straighten it, the more dense the steel appeared. They thought that the cold hammering was compacting the steel, not realizing that the repeated heating and cooling cycles were refining the grain structure.

This same myth existed in the blade forging community until fairly recently. When I started making knives, the old makers told us all about "edge packing". We were taught that the last thing you did when forging a blade, was to cold hammer along the edge of the blade to pack the steels grains together. About 20 years ago, someone finally put their thinking caps on and considered the fact that steel is a solid and you can't compress solids. Normalizing the blade's steel is now taught as a critical aspect of making forged blades.



I'm sure that the more intricate patterned barrels were only entrusted to experienced grinders. But, you have to consider exactly what the grinder's job was. After forging, the barrel tubes were sent to the boring shop. After boring out to final dimensions, they went to the straightening shop, where they were actually bent to make the bore straight. After the bore was straight, they went to the grinders. The grinder's job, was to grind the outside of the tube concentric with the bore and to remove the material required to leave the barrels walls the correct thickness and taper. If he varied the amount of material ground from the tube to affect the damascus pattern, the wall thickness and taper would be changed. This would even cause the finished gun to balance differently. The grinders job was primarily to grind the barrel for strength and balance. I have no doubt that the art barrels, like the ones with words welded into the pattern, were pulled from the grinding wheel and lightly etched to reveal how the pattern was developing. I expect that concessions were made for the balance of the gun, to accommodate these works of art.

The task of placing the damascus pattern where it will be properly developed from grinding, was entirely that of the barrel welder. If you have watched the silent video that Pete sells, you have seen the barrel smith checking the outer dimension of the barrel tube with a gauge. The smith knows that with the thickness of material he is working with, by forging the outside to a specific diameter, there will be sufficient material to bore the tube, plus leave the correct amount of material on the outside of the tube to develop the damascus pattern during grinding.



I am curious what the testing will reveal, but I expect that there will be little difference in the strength of JABC barrels. These barrels still had to pass proof. It would not be cost effective to make barrels that risked not passing proof. Too, the barrel maker's reputation depended on not having barrels blow up in a gun owner's hands.

I still maintain that the barrels that you Gentlemen refer to as JABC, were barrels of simple damascus patterns that required lower labor costs to make, and/or had irregular damascus patterns. I will be fun to see!!