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