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.
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.
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.
